*Article* **Impact of Ginger Root Powder Dietary Supplement on Productive Performance, Egg Quality, Antioxidant Status and Blood Parameters in Laying Japanese Quails**

**Zabihollah Nemati 1,\* , Zahra Moradi <sup>1</sup> , Kazem Alirezalu <sup>2</sup> , Maghsoud Besharati <sup>1</sup> and António Raposo 3,\***


**Abstract:** Medicinal plants with antibacterial effects have been used by humans for centuries. In the recent decade, due to the development of antibiotic resistant strains, many studies have focused on the use of natural compounds as feed additives in livestock. Ginger, among all, have repetitively shown numerous biological activities, antibacterial, and antibiotic properties. This study was conducted to evaluate the effects of ginger root powder (GP) on the performance, egg quality, and blood parameters of Japanese quail. A total of 240 10-weeks old female quails were used in a completely randomized design with 4 treatments, 4 replicates, and 15 birds per replicate. Dietary treatment were basal diet (control) and basal diet containing 0.5, 1, and 1.5 g/kg of ginger root powder. Growth performance and exterior and interior quality of egg were measured biweekly over eight-week period. At the end of experiment blood parameters were evaluated. The results showed that diet supplementation with different levels of GP had no significant effect on egg production, egg mass weight, and egg weight (*p* > 0.05). However, feed intake and feed conversion ratio were significantly lower in the treatment group than the control in the whole period (*p* < 0.05). Egg Quality traits (shape index, albumen index, the percentage of albumen, yolk and shell, yolk pH, and shell thickness and strength) were not affected by the supplements in the whole trial period. Addition of GP significantly increased the albumen height, Haugh unit, and albumen pH in comparison with the control treatment (*p* < 0.05). GP reduced blood triglyceride level yet was ineffective on blood total antioxidant capacity and malondialdehyde. In conclusion, dietary supplementation with GP, could improve productive performance and the egg quality of Japanese quails. Nonetheless a comprehensive study needs to be performed in order to evaluate the impact of quail dietary ginger supplementation on productive performance and egg quality and their stability during storage time for commercial use.

**Keywords:** antioxidant; egg quality traits; ginger; immunity; Japanese quail performance

#### **1. Introduction**

Today, many phytochemical rich medicinal herbs are considered as potential alternatives to antibiotics and growth promoters due to the ban of antibiotics use in livestock in the European union [1]. Aromatic plants have been successfully used to improve antioxidant capacity in poultry industry [2,3]. Ginger *(zingiber officinale roscoe)* belongs to the Zingiberaceae family, including 47 genera and 1400 species [4]. Ginger is a native tropical plant in Southeast Asia and its commercial cultivation is not limited to Asia as is grown worldwide [4]. The global production of ginger was 3.3 million tons in 2016 [5]. The ginger can be consumed as fresh produce, dehydrated, and or processed product. Fresh rhizome is widely used as a spice and food condiment whether in the form of powder, extract,

**Citation:** Nemati, Z.; Moradi, Z.; Alirezalu, K.; Besharati, M.; Raposo, A. Impact of Ginger Root Powder Dietary Supplement on Productive Performance, Egg Quality, Antioxidant Status and Blood Parameters in Laying Japanese Quails. *Int. J. Environ. Res. Public Health* **2021**, *18*, 2995. https://doi.org/10.3390/ ijerph18062995

Academic Editors: María José Benito and Paul B. Tchounwou

Received: 9 January 2021 Accepted: 11 March 2021 Published: 15 March 2021

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**Copyright:** © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

supplement, and or medicine [6]. Not only that the ginger rhizome is nutrient rich (amino acids, fatty acids, vitamins, and minerals) but the produce also contains compounds such as gingerol, gingerdiol, gingerdione, and shagaol that are potent intestinal mucous membrane and digestion stimulators [7]. The gingerols and shagaols are responsible for the pungency of fresh ginger and dried ginger, respectively [8].Ginger containing different phenolic component and they exhibited many bioactivities such as antioxidant [9], anti-anxiety [10], anti- Nausea [11], anti-inflammation [12], glucose-lowering [13], and health benefiting effects by reducing free radicals damage and improving cardiovascular status [14,15]. Furthermore, ginger is used for its various medicinal properties and alleviation and treatment of different symptoms such as animal mycotoxicosis [16], vomiting, pain, indigestion, and upper respiratory tract infection [17].

Throughout the production of ginger drink, powder, flakes and or ginger extract, significant amount of process discards, and byproducts are produced every year that could potentially be used as inexpensive feed additive in animal industry [18,19]. In a recent study, ginger supplement in broiler chicken diets stimulated the immune and digestive systems of the birds considerably [20]. In another study, Yusuf et al. [21] showed that, ginger in combination with probiotic and organic acid (citric acid) in laying Japanese quail diets improved the laying performances, feed conversion ratio (FCR), egg quality, bone characteristics, and reproductive indexes. Accordingly, diet supplementation with ginger powder increased total superoxide dismutase and glutathione peroxidase (Gpx) activities while it reduced malondialdehyde (MDA) and cholesterol concentrations in serum of broiler chickens at 21 and 42 days of age [22]. Ginger has also been reported to increase gastrointestinal secretion, digestive enzymes, improve circulation and intestinal movements [23]. It has been reported that using 4 and 8 g/kg of ginger powder of diet reduced feed intake but improved weight gain compared with control group [24]. In a study, ginger powder at 0.05 g/kg of diet, increased the egg production, hatching, reproductive performance, and economic efficiency of Japanese quail [25]. Other studies have reported that the addition of ginger essential oils at 300 µL/kg of diet, increased egg shell weight and shell thickness in laying hens [26]. Supplementation of broiler chickens diet with ginger reduced MDA and cholesterol concentration in serum of chickens at 21 and 42 days of age [22]. The effects of ginger supplementation in diets of broiler chicks at 64 weeks of age at 0.2, 0.4, and 0.6% showed a significant improvement in the feed conversion ratio in the treatment group containing 0.4% ginger powder [25]. Ibtisham et al. [27] have shown improvement of the production rate and feed intake of ginger powder and Chinese herbal medicine fed laying hens. They also concluded that ginger powder could be a suitable alternative to the antibiotic in poultry feed. In another study, Habibi et al. [28] reported that ginger powder and essential oils may be a vital replacement for synthetic antioxidants in broiler diets. Additionally, these researchers stated that ginger powder might be better than extracted essential oil for improving antioxidant status in broiler. The effect of diet supplementation with extract from thyme and ginger on the egg quality of laying hen was investigated by Damaziak et al. [29], who demonstrated that hen diet supplementation was improved Haugh unit of albumen and yolk color of fresh and hard boiled eggs. Recent studies suggest that Haugh unit and yolk color are important in the commercial production of table eggs which affected by dietary composition (e.g., protein sources and pigments) [30]. Color is an important qualitative feature of food acceptability as it affects consumers' perceptions of quality and flavor helping those making decisions about the purchase. Most consumers find yolk color related to the age and health of the animal and the quality of egg and its derivatives. Generally, edible additives and feeding methods are the main factors in the egg yolk color. For instance, natural pigments of plants such as carotenoids play an important role in the development of egg yolk color [25]. However, to the best of our knowledge, information regarding the potential benefits of these feed additive in the Japanese quail's diet is limited, so the present study was conducted to evaluate the effects of using different levels of ginger powder on the productive performance, eggs quality, and blood parameters in laying Japanese quails.

#### **2. Materials and Methods**

Animal welfare statement: All the methods and protocols used in this study were approved by the Research Bioethics Committee of Tabriz University (RBCT) for Use of Laboratory Animals of University of Tabriz (Approved number: IR.TABRIZU.REC.1399.032).

#### *2.1. Experimental Birds and Management*

A total of 240 laying Japanese quails (10 weeks old), after a two-week adaptation period, were randomly divided into 4 experimental groups (4 replicates each, 15 birds per pen). Dietary groups included the basal diet (control) and the basal diet supplemented with 0.5, 1, and 1.5 g ginger root powder per kg of diet. The birds were kept in a multi-story wired cages in a well-ventilated room with the temperature of 23–29 ◦C and 16L:8D light regime during experiment. Each cage had 3600 cm<sup>2</sup> floor space with size 45 <sup>×</sup> 45 cm<sup>2</sup> and was equipped with two nipple drinker and one feeder. The basal diet was formulated to meet the National Research Council (NRC) recommendations [31] as showed in Table 1. Quails received water and feed ad libitum throughout the experimental period.


**Table 1.** Ingredient and composition of the basal diet.

<sup>1</sup> Supplied per kg of feed: vitamin B1, 2.16 mg; vitamin B2, 7.92 mg; pantothenic acid, 12 mg; nicotinic acid;36, vitamin B6, 3.6 mg; folic acid, 1.2 mg; biotin, 0.12 mg; vitamin K3, 2.4 mg; vitamin E, 21.6 IU; chloin chloride, 300; antioxidant, 120 mg; vitamin A, 10,800 IU; vitamin D3, 2400 IU and vitamin B12, 0.018 mg. <sup>2</sup> Supplied per kg feed: FeSO4, 0.15 g; MnSO4, 0.12 g; CuSO4, 0.03 g; I, 1.2 mg and Se, 0.24 mg.

#### *2.2. Preparation of Ginger Powder Samples*

Fresh ginger root was purchased from the local market and then cut into slices. Ginger slices were air-dried (sunshade for 1 day) at room temperature and further oven-dried (at 40 ◦C for 40 h) (Memmert UNB400). Dehydrated slices were then processed by grinder device (IKA, MF 10 basic) to fine powder, and subsequently stored in moisture-controlled ziplock bags at 4 ◦C. Ethanolic ginger extract was prepared by mixing 2 g of ginger powder in the 100 mL of absolute ethanol. The mixture was processed for 30 min at 85 ◦C. The prepared extract was filtered by Whatman No. 1 filter paper. Dry extract (5 g) was dissolved in 10 mL of methanol solvent and sonicated for 30 min at 15 ◦C. Constituents of the extract were quantified by HPLC (Smartline, Knauer, Germany) method [32]. The contents of bioactive components were determined in the extract and the concentration of 6-gingerol, 8-gingerol, 10-gingerol, and 6-shogaol was 6163.1, 802.8, 783.9, and 839.9 mg/kg ginger (on dry weight basis), respectively. Nutrient compositions and total phenolic content of ginger root powder were analyzed according to standard method, Association of Official Analytical Chemists (AOAC) [33] and Nemati et al. [34], respectively and the results are given in Table 2.


**Table 2.** Nutrient composition of ginger powder (% DM) used in the experiment.

#### *2.3. Measurement of Productive Performance and Egg Quality*

In this study, egg production was recorded daily; however, feed consumption and egg weight [25] were recorded weekly. Moreover, feed efficiency was calculated by dividing the total feed intake by total egg mass during each period. The feed conversion ratio (FCR) [35] was expressed as kilograms of feed consumed per kilogram of egg produced. Six eggs (per replicate) were randomly selected to determine the traits related to the characteristics of quail eggs at 0, 2, 4, 6, and 8 weeks. Egg length and width were measured with a 0.01 mm digital caliper (Mitutoyo). For Haugh unit measurements six eggs were weighed and then cracked separately. Albumen heights of three near yolk areas were measured with a 0.01 mm digital caliper. The Haugh unit [35] was calculated using egg weight and albumen height data of each 6 egg. Furthermore, the yolk height and width were measured by 0.01 mm digital caliper. For calculation of yolk to albumen ratio as well as yolk and albumen percentages, yolk and albumen were carefully separated from each other and subsequently weighed by 0.001 g digital scale (A&D N92) [36]. For color measurements using Roche color fan, eggs were individually broken onto a flat surface and then color was recorded [35]. Egg shell thickness was measured using a 0.01 mm micrometer at three different points. Average of three points was considered as final thickness of each eggshell. The eggshell percentages were calculated using washed and dried eggshell weights [35]. For pH analysis, yolk and albumen were completely mixed with a glass rod prior to measurement separately (pH meter; Hanna 211, Woonsocket, RI, USA) [34].

#### *2.4. Blood Biochemical Parameters Analysis*

At the end of the experiment, two birds from each replicate were randomly picked up for slaughter (6 birds per treatment). Blood samples were collected from the neck vein of the birds using sterilized needles and then centrifuged for 15 min at 3000 rpm to separate the serum. The collected serum was stored at −20 ◦C for the analysis of glucose (Catalog No: 117500), albumin (Catalog No: 5017) and total protein (Catalog No: 128500), cholesterol (Catalog No: 110500), and triglycerides (Catalog No: 132500). Blood biochemical parameters were measured by a spectrophotometric analysis, using commercially available kits (Pars Azmun Diagnostic, Tehran, Iran).

#### *2.5. Antioxidant Status*

Ferric reducing antioxidant power assay was used to assess the total antioxidant capacity (TAC) of blood samples [37]. TAC was quantified by the reaction of phenanthroline and Fe2+ using a spectrophotometer at 520 nm. TAC is defined as the amount of antioxidants required to increase the absorbance by 0.01, in 1 mL of blood sample at 37 ◦C. Concentration of MDA in the serum, as an index of lipid peroxidation and oxidative stress, was determined using the thiobarbituric acid reactive substances (TBARS) method [37]. The principle is that TBARS reacts with MDA to form a stable pink color that could be measured spectrophotometrically at 532 nm. The values of MDA were expressed as (nmol/mL).

#### *2.6. Statistical Analysis*

Data of production performance and egg quality were subjected to one-way analysis of variance (ANOVA) using MIXED procedure (Repeated Measurement), SAS (version 9) as a completely randomized design [38]. Tukey multiple comparison test was used to compare the averages at a 5% confidence level. The Shapiro–Wilk and Levene tests were used for model assumptions of homogeneity of variance and normality, respectively. The percentage data including egg mass, egg production rate, yolk index, egg yolk, eggshell and albumen relative weight, and egg shape were transformed by arcsine of the square root before analysis to achieve homogeneity of variance. No statistical difference was observed between the two sets of data thus results of statistical analysis on the original data are presented in this article.

The statistical design model is as follows:

$$\mathbf{Y}\_{\rm ijkm} = \mu + \mathbf{T}\_{\rm i} + \mathbf{W}\_{\rm j} + \mathbf{T} \mathbf{W}\_{\rm ij} + \mathcal{Q} \mathbf{k}\_{\rm (ji)} + \mathbf{E}\_{\rm ijkm} \dots$$

In which Yijkm is observed parameters, µ is the mean of population, T<sup>i</sup> is the treatment effect, W<sup>j</sup> is the time effect, TWij is the treatment and time interactions, Øk(ji) is the random factor (bird), and Eijkm are residual effects.

Data of blood biochemical parameters and immune response were subjected to oneway ANOVA (general linear model (GLM) procedure), SAS following the statistical model. Comparison of means was performed using Duncan test at the confidence level of 5%. A level of *p* < 0.05 was used as the criterion for statistical significance.

$$\mathbf{Y}\_{\mathrm{ij}} = \boldsymbol{\mu} + \mathbf{T}\_{\mathrm{i}} + \mathbf{E}\_{\mathrm{ij}}.$$

In which Yijk is observed parameters (dependent variable), µ is the mean of population, Ti is the treatment effect and Eij are residual effects.

#### **3. Results**

#### *3.1. Productive Performance*

The effect of dietary supplementation with natural additives of ginger powder on the productive performance is presented in Table 3. The results showed that the experimental treatments had no significant effect on egg production rate among the treatments during the experimental period (*p* > 0.05). Egg mass and egg weight were not significantly affected by the level of ginger powder used (*p* > 0.05). As shown in Table 3, addition of different levels of ginger significantly reduced feed intake during the whole experimental period (*p* < 0.05) compared with the control treatment. Ginger powder had dose-dependent effect since highest concentration of 1.5 g/kg of diet was most the potent treatment. The effect of treatment and time interaction was insignificant on the feed intake, egg weight and egg mass (*p* > 0.05). Nonetheless, the treatment x time interaction was significant on the FCR (*p* < 0.05). According to our results, Table 3, GP supplemented diet reduced FCR compared with the control group during experiment period (*p* < 0.05). High levels of ginger powder at 1.5 g/kg level decreased FCR compared with other groups. The experimental treatments significantly reduced FCR during breeding weeks. Moreover, the effect of time on the FCR was also significant.


**Table 3.** Effects of ginger powder supplementation on productive performance in Japanese quails.

Different letters (a, b, c, d, e, f or <sup>g</sup> ) after the means within a column indicate significant differences among treatments (*p* < 0.05).

#### *3.2. Quality Traits of Eggs*

The effects of diet supplementation with different levels of ginger powder on qualitative traits of eggs are given in Table 4. The results showed that the effects of ginger powder on egg weight, shape index, albumen weight, shell weight, albumen, yolk and shell percentage, yolk pH, and shell thickness and strength were insignificant (*p* > 0.05). Ginger supplementation improved yolk index; however, it did not increase yolk weight compared with the control treatment (*p* > 0.05). Nonetheless, effect of time on yolk index was significant (*p* < 0.05). The highest yolk color was related to the highest level of ginger in the diet. The effect of treatment x time interaction, as shown in Table 5, were significant on yolk color, albumen height and albumen index during experimental period (*p* < 0.05). The albumen and yolk pH were significantly reduced by ginger powder experimental diet compared with the control treatment (*p* < 0.05). Ginger diet improved Haugh unit relative to control group (*p* < 0.05), but egg specific gravity (ESG) did not differ (Table 4).


**Table 4.** Effect of different level of ginger root powder on egg quality of Japanese quails.

Different letters (a, b or <sup>c</sup> ) after the means within a row indicate significant differences among treatments (*p* < 0.05).

**Table 5.** Effect of treatment and time Interaction on egg albumen and yolk traits in Japanese quails fed different level of ginger root powder.


Different letters (a, b, c, d, e, f or <sup>g</sup> ) after the means within a column indicate significant differences among treatments (*p* < 0.05).

#### *3.3. Blood Parameters and Egg Yolk Phenolic Compounds*

The effect of experimental diets on blood parameters of animals are presented in Table 6 and Figure 1. The results revealed that supplementation of ginger powder in the diet had significant effect on the level of triacylglycerol (*p* < 0.05). Nevertheless, serum albumin, cholesterol, glucose, MDA, and TAC were not affected by the diet (*p* > 0.05). Level of serum TAC only numerically elevated, while MDA level was reduced in birds fed medium level of ginger powder compared with the control group. The effect of experimental treatments on phenolic compounds of the yolk, as shown in Figure 1, was

significant (*p* < 0.05). Highest concentration of ginger powder (1.5 g/kg diet) was the most effective treatment in stimulating the production of phenolic. ment in stimulating the production of phenolic. **Table 6.** Biochemical parameters in blood serum of Japanese quail fed diets with ginger powder supplementation.

treatments on phenolic compounds of the yolk, as shown in Figure 1, was significant (*p* < 0.05). Highest concentration of ginger powder (1.5 g/kg diet) was the most effective treat-

The effect of experimental diets on blood parameters of animals are presented in Table 6 and Figure 1. The results revealed that supplementation of ginger powder in the diet had significant effect on the level of triacylglycerol (*p* < 0.05). Nevertheless, serum albumin, cholesterol, glucose, MDA, and TAC were not affected by the diet (*p* > 0.05). Level of serum TAC only numerically elevated, while MDA level was reduced in birds fed me-

**Table 6.** Biochemical parameters in blood serum of Japanese quail fed diets with ginger powder supplementation. **Treatments Protein Albumin Triacylglycerol Cholesterol Glucose** 

*Int. J. Environ. Res. Public Health* **2021**, *18*, x 8 of 13

*3.3. Blood Parameters and Egg Yolk Phenolic Compounds* 


Different letters (<sup>a</sup> or <sup>b</sup> ) after the means within a column indicate significant differences among treatments (*p* < 0.05).

**Figure 1.** Concentrations of malondialdehyde (MDA) (**a**) and total antioxidant capacity (TAC) (**b**) in Japanese quails fed different levels of GP. Values (means ± SEM) within the same week with uncommon letters are significantly (*p* < 0.05) different. **Figure 1.** Concentrations of malondialdehyde (MDA) (**a**) and total antioxidant capacity (TAC) (**b**) in Japanese quails fed different levels of GP. Values (means ± SEM) within the same week with uncommon letters are significantly (*p* < 0.05) different.

#### **4. Discussion**

**4. Discussion**  In general, inclusion of ginger powder in the diet of birds was effective on various productive parameters. In this experiment, production rate and egg mass were not influenced by the treatments, while feed intake and FCR decreased when birds received increasing levels of ginger powder. In agreement to our results, previous findings confirmed that dietary supplementation with ginger root improved FCR in broiler chickens [39] and decreased feed intake in guinea fowl [40]. Furthermore, ginger supplements had no adverse effect on the palatability of broiler feeds [39] and improved the digestibility of dry matter in guinea fowl [40]. Contrarily, Damaziak et al. [29] did not observe any positive effect of the ginger root on egg production rate in laying hens. However, findings of our study were not in agreement with the handful studies showing the insignificant effect of ginger powder [41] or ginger extract dietary supplementation [42] on the FCR. Akbarian et al. reported that using different levels of ginger (0.25, 0.5 and 0.75 g/100g of diet) in laying hens during 30 weeks had insignificant effect on FI and FCR [43]. The disparity of In general, inclusion of ginger powder in the diet of birds was effective on various productive parameters. In this experiment, production rate and egg mass were not influenced by the treatments, while feed intake and FCR decreased when birds received increasing levels of ginger powder. In agreement to our results, previous findings confirmed that dietary supplementation with ginger root improved FCR in broiler chickens [39] and decreased feed intake in guinea fowl [40]. Furthermore, ginger supplements had no adverse effect on the palatability of broiler feeds [39] and improved the digestibility of dry matter in guinea fowl [40]. Contrarily, Damaziak et al. [29] did not observe any positive effect of the ginger root on egg production rate in laying hens. However, findings of our study were not in agreement with the handful studies showing the insignificant effect of ginger powder [41] or ginger extract dietary supplementation [42] on the FCR. Akbarian et al. reported that using different levels of ginger (0.25, 0.5 and 0.75 g/100 g of diet) in laying hens during 30 weeks had insignificant effect on FI and FCR [43]. The disparity of this study with previous research results could be due to differences in ginger source, processing methods as well as poultry species [42,44]. Ginger contains many active compounds (e.g., brunel, camphon, limonene, humolin, gingerol, gingeron, gingerdiol, shogaols, some phenolic ketone derivatives, volatile oils, alkaloids, saponins, and flavonoids) [45] that could stimulate feed digestion and the digestive enzymes, thus increasing FI and FCR [38]. In the same way Platel and Srinivasan [46] stated that ginger enhanced the activity of pancreatic lipase, amylase, trypsin chymotrypsin, and bile acid secretion in albino rats. In fact, these enzymes, bile and biliary bile acids significantly affect the digestion and absorption of nutrients. In accord, Habibi et al. [28] indicated the stimulating effect of ginger root powder (7.5 g/kg of diet) on body weight and weight gain in broiler chicks at 22 days of the experiment. In another study, ginger powder increased production,

hatchability, reproductive performance, and economic efficiency at a level of 0.05 g/kg diet while increasing egg weight and feed intake in Japanese quail [25]. In present study, ginger powder supplemented diet had no effect on egg production, egg weight, and total egg mass among the treatments during the experiment period. Our findings were in line with the results of Wen at al. [42] and Herve et al. [47] reporting the insignificant effect of ginger supplemented diet in laying hen and quail. Moreover, Wen et al. concluded that egg weight was improved in ginger powder fed laying hen [47]. The results of studies on the effect of ginger at increasing levels of 0, 5, 10, 15, and 20 g/kg of diet on the performance of laying hens at the age of 27 weeks showed that all laying hens were in good health and no mortality was recorded in the whole period of the experiment. Average egg weight and laying rate were similar in treatments containing ginger powder. Egg mass was positively affected by the treatments compared with the control group, which can be related to the positive effect of ginger powder on laying rate as well as egg weight [48]. In contrast to the current quail study, egg production rate was increased in ginger extract/powder fed laying hen [48,49] alone or in combination with medicinal herbs [27]. This means that the beneficial effect of ginger on performance depends on the bird species, dosage of ginger, and its derivatives and interaction with other dietary components. However, information about mechanism of action of ginger intake are scarce [50].

In this study ginger powder was beneficial on the reducing the blood triacylglyceride levels yet its effects were not significant on serum cholesterol and glucose levels. Other serum parameters including albumin, and protein were not significantly affected by ginger powder (*p* > 0.05). Consistent with these results, studies have shown that diet supplementation with ginger extract at 0.4 and 0.6 mg/g of diet, significantly decreased glucose, triglyceride, and cholesterol levels [51]. Akhany et al. [52] concluded that ginger extract significantly reduced blood glucose levels and increased insulin levels. Some of the essential minerals (calcium, zinc, potassium, manganese, and chromium) are related to the mechanism of insulin release [53]. In another study, ginger at concentrations up to 2% of the diet reduced cholesterol, triglyceride, and glucose levels in comparison with the control group, while the serum protein was not affected by the experimental treatments [38]. Ginger has previously shown strong anti-lipidemic effect on serum cholesterol and triglyceride levels [54]; hence, its mode of action may be related to the inhibition of cholesterol synthesis (e.g., β-hydroxy-β-methylglutaryl coenzyme A (HMG—CoA) [51]. Correspondingly, ginger is a potent HMGR-inhibiting drug, known to cause liver-specific inhibition of cholesterol synthesis [55]. In addition, other reports showed that diabetic therapy with insulin helps in reducing the plasma triglycerides by affecting lipoprotein lipase levels [56]. Ginger has insulin-stimulating effect which could reduce plasma triglycerides [56]. Previous studies stated that phenols and flavonoids act as potent antioxidants [57]. Khalifa and Noseer [58] revealed that eggs produced by quail supplemented with combined ginger powder and probiotics had the lowest total cholesterol content in serum and yolk compared with the control, along with an increase in high-density lipoprotein (HDL) and decrease of low-density lipoprotein (LDL). Herve et al. [59] showed that total cholesterol and triglycerides, transaminases, and MDA decreased in quails supplemented with ginger essential oil at 50, 100, and 150 µL/kg body weight.

Haugh unit, albumen height, and yolk index are characterized as main reference associated with egg quality, which influenced by feed additive (e.g., green tea powder) [60]. In this study yolk index, albumen height, and Haugh unit of eggs were increased in diet supplemented with ginger powder. Several studies indicated that ginger supplementation in poultry diets significantly increased antioxidant enzymes as well as TAC and decreased MDA [22,28,43]. Improvement of egg yolk index and Haugh unit in the current study may be due to the effect of the phenolic compounds of ginger (gingerols and shagaol) which have antioxidant properties [61]. As discussed earlier, color of the yolk an acceptability and freshness feature of the egg, could be improved by natural products such as carotenoids. In this study, egg yolk color was positively affected by ginger powder consumption (1.5 mg/kg). However, others have reported the ineffectiveness of fermented

ginger powder (10 and 50 mg/kg of diet concentrations) [23] and ginger extract [42] on the yolk color and yolk and albumen percentage. The intensity of egg yolk color depends on the presence and utilization of pigments in the diet, because laying hens have no ability to produce pigments through their biochemical processes [62]. The darker yolk color of eggs from quails received ginger is probably due to the natural pigments found in ginger, including 6-dehydrogingerdione, which causes a deep yellow color [63]. No difference in other quality traits of quail eggs indicates that ginger does not affect the egg shell quality or egg composition (percentage of albumen, yolk, and shell). The results of present experiment consistent with the result of Wen et al. 2019 [42] showing that the use of ginger root as an additive in Japanese quail diet had significant effect on Haugh unit and albumen height yet being ineffective on shell thickness, shell strength, and egg composition percentage. We, in this study, observed concentration dependent potency of ginger powder on many important parameters of fresh egg quality (e.g., Haugh unit, yolk index, and yolk color) in laying quails; however, other variables associated with egg shelf life should be tested for a final statement.

#### **5. Conclusions**

The results of this study suggest that the inclusion of ginger root powder in Japanese quail diet can partially improve the productive performance, antioxidant status, and blood parameters. Moreover, ginger could improve yolk color and albumen quality expressed in Haugh units. The effects on the quail production performance seemed to be dose dependent and ginger at the highest tested level (1.5 g/kg of ginger powder) was most effective treatment. However, further studies are needed to conclude on the effect of ginger on quality of the poultry products as well as its mechanism of action.

**Author Contributions:** Conceptualization, Z.N.; methodology, Z.N., Z.M., and K.A.; software, Z.N. and Z.M.; validation Z.N. and Z.M.; formal analysis, Z.N. and K.A; investigation and resources, Z.M. and Z.N.; data curation, Z.N.; writing—original draft preparation, Z.M and Z.N; writing—review and editing, A.R. and M.B.; project administration, Z.N.; funding acquisition, Z.N. and A.R. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by The University of Tabriz (grant number: 11.934).

**Institutional Review Board Statement:** The study was conducted according to the guidelines of the National norms and standard for conducting medicinal research in Iran, and approved by the Research Bioethics Committee of Tabriz University (Approved number: IR.TABRIZU.REC.1399.032).

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Qualified researchers can obtain the data from the corresponding author. The data are not publicly available due to privacy concerns imposed by the RBCT ethical principles.

**Conflicts of Interest:** The authors declare no conflict of interest.

#### **References**


### *Article* **Halal Food Performance and Its Influence on Patron Retention Process at Tourism Destination**

**Heesup Han <sup>1</sup> , Linda Heejung Lho <sup>1</sup> , António Raposo 2,\* , Aleksandar Radic <sup>3</sup> and Abdul Hafaz Ngah <sup>4</sup>**


Kuala Nerus 21030, Terengganu, Malaysia; hafaz.ngah@umt.edu.my

**\*** Correspondence: antonio.raposo@ulusofona.pt

**Abstract:** Muslim tourism is one of the most rapidly developing sectors in the international tourism industry. Nevertheless, halal food performance and its relationship with international Muslim traveler decision-making and behaviors have not been sufficiently examined. The present research explored the influence of halal food performance, which encompasses availability, health/nutrition, accreditation, and cleanness/safety/hygiene factors, on the Muslim traveler retention process at a non-Islamic destination. A survey methodology with a quantitative data analytic approach was employed to achieve research goals. Our findings indicated that halal food performance increased destination trust and destination attachment, which in turn influenced Muslim traveler retention. Additionally, the efficacy of the higher-order framework of halal food performance was defined. Both destination trust and attachment mediated the effect of halal food performance on retention. A halal-friendly destination image included a moderating influence on the retention process. The effectiveness of the proposed theoretical framework for explicating Muslim traveler behaviors was uncovered. This research better introduces the importance of halal food performance and its attributes for the elicitation of Muslim traveler approach responses and behaviors at a non-Islamic destination to researchers and practitioners.

**Keywords:** halal food performance; availability; healthy/nutritional factor; accreditation; clean/safe/ hygiene factor; trust; attachment; halal-friendly image; retention; muslim travelers

#### **1. Introduction**

Muslim travelers are undoubtedly an emerging tourist group in the global tourism industry [1–5]. As the competition in the international tourism marketplace is intensifying, many destinations are eager to develop halal-friendly products and make a Muslim-friendly tourism environment to attract a greater number of Muslim visitors [1,4]. Developing new halal-friendly marketing and retention strategies is irrefutably important in expanding the business volume related to Muslim tourism at tourist destinations [1,5,6]. Halal food is frequently regarded as one of the most significant halal-friendly products at many places [7–10]. Increasing the halal food availability and improving its attribute quality is indisputably becoming essential to fulfill Muslim travelers' halal-friendly tourism needs and provide them with pleasant tourism experiences, especially in non-Islamic countries and tourism destinations [10,11].

Despite the rapid growth of Muslim tourism for the past few decades in the global tourism sector, the competitiveness with many non-Islamic destinations in the marketplace is still not strong enough [4,5,10]. According to [12], such weak competitiveness is mostly relevant to Muslim travelers' experiences with restaurants and foods that are not sufficiently

**Citation:** Han, H.; Lho, L.H.; Raposo, A.; Radic, A.; Ngah, A.H. Halal Food Performance and Its Influence on Patron Retention Process at Tourism Destination. *Int. J. Environ. Res. Public Health* **2021**, *18*, 3034. https://doi.org/ 10.3390/ijerph18063034

Academic Editors: Massimo Lucarini and Paul B. Tchounwou

Received: 4 January 2021 Accepted: 9 March 2021 Published: 16 March 2021

**Publisher's Note:** MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

**Copyright:** © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

halal-friendly. Nevertheless, the empirical endeavor investigating the possible influence of halal food performance on Muslim traveler post-purchase behavior at non-Islamic destinations has hardly been made. In addition, the existing studies indicated the criticality of trust and attachment in explicating the traveler retention process [13–16]. Scant research has unearthed the possible linkages between halal food performance and these essential concepts. Moreover, destination image is irrefutably a crucial variable, affecting the entire traveler post-purchase decision-making procedure [17–19]. A halal-friendly destination image is vital in Muslim traveler behaviors [20]. Yet, how a halal-friendly destination image determines the magnitude of the relation strength between halal food performance and its outcome constructs has hardly been examined. That is, the particular role of a halal-friendly destination image as a moderator in the Muslim visitor retention process has not been thoroughly explored.

Taking this into account, the current research was devised to build a theoretical framework that explicates Muslim traveler retention formation in a clear manner. Many previous studies focused on defining what halal food is and what halal tourism is. Thus, the current research tried to take a step further from the latent literature and develop both the theoretical and the practical contribution of halal food to halal tourism. In particular, we aimed (1) to assess the possible impact of halal food performance, which comprises availability, health/nutrition, accreditation, and cleanness/safety/hygiene factors as its constituents, on the Muslim visitor retention process at a non-Islamic destination; (2) to uncover the appropriateness of a higher-order structure of halal food performance and its competence; (3) to investigate the convoluted relations among halal food performance, destination trust, and destination attachment, and the possible influence on retention; (4) to assess the mediating role of destination trust and attachment; and (5) to unearth the moderating role of a halal-friendly destination image within the proposed conceptual framework. The remaining parts of this research are the literature review, methodology, data analysis and results, and discussion and implications. Investigating these five aims, this research will be able to not only build a theoretical framework of Muslim traveler retention but also discover practical contributions for ways to retain Muslim travelers.

#### **2. Literature Review**

#### *2.1. Halal Food and Its Performance*

Halal is an Arabic term indicating, "which is allowed by Islamic teaching" [9,11]. Halal dietary laws were developed within Asia for Islamic followers to practice a nutritious and healthy lifestyle [21]. The foods permitted under these halal dietary laws are called halal food [21]. Muslim travelers' demand for overseas traveling is rapidly increasing, and their primary distress is the accessibility and quality of halal food in an international destination [1,9,11]. Indeed, [22] recently reported that halal food consumption is a key aspect of Muslim tourism. Little availability (or unavailability) and low performance of halal food at a destination lowers the quality of Muslims' overall tourism experiences and generates their avoidance behaviors for that place [2,10]. Due to the recent growth of the Muslim tourism market [7,23], halal food is becoming a fundamental topic in the international tourism industry [8,11,20].

According to [24], the term "performance" indicates that individuals' evaluation of the excellence of a product and its attributes as compared to other products available in the marketplace offered by rival firms. Consistently, halal food performance in this research refers to travelers' appraisal of the excellence of halal food and its essential attributes as compared to the halal foods offered by competing destinations. Halal food performance is constructed as an amalgamation of multiple dimensions that explicate an intricate aspect of food and beverage consumption in a halal-friendly way [11,12]. Halal food availability factors, halal food health/nutrition factors, halal food accreditation factors (e.g., accreditation with a halal certificate, halal logos), and halal food cleanness/safety/hygiene factors are all crucial constituents of assessing halal food performance at international destinations [9,20,25]. Indeed, [12] and [11] asserted that availability, health/nutrition, accreditation, and cleanness/safety/hygiene are the main things for Muslims to consider related to halal food consumption when planning and practicing halal-friendly tourism activities at non-Islamic destinations.

Research on halal food and understanding its influence on Muslim traveler behaviors is still in its infancy in many non-Islamic destinations [1,6]. In these destinations, halal food and beverage are relatively a new type of tourism product [11,26]. Muslim travelers can be somewhat skeptical about whether the foods provided in non-Islamic destinations are pure halal [11]. Although the authenticity and decency of halal food in such destinations is not entirely certain [27], the quality performance of halal food often inspires Muslim travelers' high level of trust for the food and the places [1,12], elicits their affection and attachment to the places [8,20], and affects approach behaviors for the destinations [2,28]. Simply put, halal food and its performance are strongly relevant to responses and behaviors among overseas Muslim travelers [8,28].

#### *2.2. Destination Trust*

Because of the intangible form of hospitality and tourism products, trust and reliability of the products/services often become an important subject in the hospitality and tourism marketplace [14,15]. Many hospitality/tourism products entail a certain level of uncertainty/risk, particularly in the international tourism context [14,29,30]. While the definition of trust varies in the existing literature, one of the most broadly accepted definitions in tourism is that trust is the degree to which travelers rely on a product, place, brand, or exchanging partner [15]. Similarly, [31] conceptualized destination trust as the travelers' level of confidence and reliability toward a tourist destination and its performance. It is broadly known that trust is a critical influence factor on travelers' emotional attachment and approach behaviors [13,15,29,31]. Thus, destination trust will positively affect destination attachment.

For instance, in consumer behavior, [32] found that trust is an essential driver of repurchase intention. In addition, [15] uncovered that trust in a place helps visitors attach to the place and plays a vital role in building their positive intentions for the place in the international tourism context. In recent decades, the importance of trust has been especially emphasized in the Muslim tourism/consumer behavior sector [10,13,14]. Such trust is likely formed based on a Muslim-friendly tourism environment at the destination [10]. In the Muslim tourism context, trust also generates travelers' emotional responses and reactions that are favorable for tourism destinations [28,33]. In other words, destination trust will positively affect Muslim traveler retention.

#### *2.3. Destination Attachment*

A comprehension of attachment has a meaningful implication for understanding traveler behavior [16,34–36]. Due to its hefty contribution to a surge of positive decision/behavior of visitors, attachment to a destination/place has broadly been a crucial concept in hospitality and tourism [36]. Generating such attachment can be described as the process of building an emotional connection between an individual and a destination [16]. Coherently, destination attachment in the present research indicates Muslim travelers' emotional ties to a specific tourism destination. Attachment plays a crucial role when individuals choose tourism/leisure products [34,36,37]. Findings in the extant literature demonstrated that the high tourist attachment to a tourism product/service/destination affects his/her post-purchase decision formation, inducing positive behaviors for the product/service/destination [35,38].

In the hospitality context, [39] explored the influence of patrons' attachment/involvement. In [38], the findings revealed that the patrons' purchase decision formation for a hospitality product is significantly impacted by their level of product attachment. In the cruise tourism sector, [35] investigated the intricate process of passenger loyalty generation. Their empirical finding showed that passenger loyalty formation is significantly triggered by passenger attachment to the cruise line. In the festival tourism sector, [36] discovered that visitors' attachment to a festival destination is significantly associated with their loyalty for the place. More recently, [37] uncovered that travelers' level of attachment to the tourism product/place increases their approach behaviors, such as retention and word-of-mouth activities. Travelers' strong attachment to a destination boosts their willingness to revisit the place, whereas travelers' weak attachment increases their avoidance decisions [16,36]. Therefore, destination attachment will positively affect Muslim traveler retention.

#### *2.4. Halal-Friendly Destination Image*

Image has long been believed a crucial dimension when explaining patrons' decisionmaking procedures and attitudes of consumption [17,18,39,40]. Image refers to patrons' overall perception of a firm and its product(s) based on the relations held in their memory [41]. Kotler et al. [42] provided a more precise conceptualization of it where image is the overall set of consumers' perceptions, opinions, and beliefs about a firm and its product(s). Coherently, in this research, destination image indicates the summation of perceptions, opinions, and beliefs that Muslim travelers have about a place and its halal-friendly attributes. Individuals' impressions/thoughts/beliefs of a particular object are formed ultimately based on attained and processed information [43]. Baloglu, McCleary [44] and Lee et al. [45] thus indicated that building an image of a place/product in the consumer behavior context is a subjective and cognitive process of assessing such information about a place/product.

Image and its potential influence have been well documented in consumer behavior and tourism literature [19,39,45]. It is widely believed that increasing an image of a firm/place eventually results in increased repeat business and loyalty for the firm/place [40,44,46]. According to [47], one's image of a place significantly impacts the formation of his/her revisit intention in the hospitality sector. More recently, [19] uncovered that destination image among travelers' social network members has a considerable effect on their choice behaviors. It is likely that the entire customer retention process becomes strong when a customer image of a place/product is favorable, whereas said process becomes weak when he/she has an unfavorable image of the place/product [18,40,45]. Likewise, while a positive image of a place/product often reinforces the formation of patrons' post-purchase decisions, a negative image often weakens their decision formation [18,39,47]. It is also evident that travelers' image, which is positive for a particular destination/tourism product, considerably influences the process of generating their favorable behavioral intentions toward the destination/tourism product [45]. Consequently, it can be concluded that a halal-friendly destination image includes a significant effect on the relation between halal food performance and destination trust and the relation between halal food performance and destination attachment.

#### *2.5. Proposed Model and Hypothesis*

The proposed model shown in Figure 1 encompassed (a) halal food performance whose first-order factors are availability, health/nutrition, accreditation, and cleanness/safety/hygiene; (b) destination trust; (c) destination attachment; (d) halal-friendly destination image; and (e) Muslim traveler retention. The model contained a total of seven research hypotheses. Hypotheses 1–6 concern the causal relationships among research constructs. In addition, Hypotheses 7a–7b pertain to the moderating impact of a halal-friendly destination image.

**Figure 1.** The proposed conceptual framework. H1: Halal food performance includes a positive effect on destination trust. H2: Halal food performance includes a positive effect on destination attachment. H3: Halal food performance includes a positive effect on Muslim traveler retention. H4: Destination trust includes a positive effect on destination attachment. H5: Destination trust includes a positive effect on Muslim traveler retention. H6: Destination attachment includes a positive effect on Muslim traveler retention. H7a: Halal-friendly destination image includes a significant effect on the relation between halal food performance and destination trust. H7b: Halalfriendly destination image includes a significant effect on the relation between halal food performance and destination attachment. **Figure 1.** The proposed conceptual framework. H1: Halal food performance includes a positive effect on destination trust. H2: Halal food performance includes a positive effect on destination attachment. H3: Halal food performance includes a positive effect on Muslim traveler retention. H4: Destination trust includes a positive effect on destination attachment. H5: Destination trust includes a positive effect on Muslim traveler retention. H6: Destination attachment includes a positive effect on Muslim traveler retention. H7a: Halal-friendly destination image includes a significant effect on the relation between halal food performance and destination trust. H7b: Halal-friendly destination image includes a significant effect on the relation between halal food performance and destination attachment.

#### **3. Method 3. Method**

#### *Measures Measures*

The measurement items for the research factors used in this research were adopted from the existing studies [11,12,16,17,29,48,49] and adjusted to be appropriate to the current study context. All items were measured by a seven-point Likert scale. Additionally, multiple items were used to assess each construct. A total of six items were adopted to evaluate halal food performance. Specifically, two items for halal food availability (e.g., "Availability of halal food attracted me to visit tourist places"), two items for halal food health/nutrition (e.g., "Halal foods served in restaurants are healthy and nutritious"), two items for halal food accreditation (e.g., "Halal food providers in tourist sites are accredited with halal certification"), and two items for halal food cleanness/safety/hygiene (e.g., "Halal food and beverage offered in tourist sites/places were clean, safe, and hygienic") The measurement items for the research factors used in this research were adopted from the existing studies [11,12,16,17,29,48,49] and adjusted to be appropriate to the current study context. All items were measured by a seven-point Likert scale. Additionally, multiple items were used to assess each construct. A total of six items were adopted to evaluate halal food performance. Specifically, two items for halal food availability (e.g., "Availability of halal food attracted me to visit tourist places"), two items for halal food health/nutrition (e.g., "Halal foods served in restaurants are healthy and nutritious"), two items for halal food accreditation (e.g., "Halal food providers in tourist sites are accredited with halal certification"), and two items for halal food cleanness/safety/hygiene (e.g., "Halal food and beverage offered in tourist sites/places were clean, safe, and hygienic") were utilized.

were utilized. To measure destination trust, three items were used (e.g., "I have confidence in Korea as a halal-friendly destination"). Destination attachment was assessed with two items (e.g., "I feel emotionally attached to Korea as a tourist destination"). Additionally, we utilized three items to assess a halal-friendly destination image (e.g., "Overall, I have a good image of Korea as a Halal-friendly destination"). For assessing Muslim traveler retention, two items were utilized (e.g., "Korea as a Halal family-friendly place will be my first choice when it comes to choosing a destination"). The survey questionnaire comprising these measures was pre-tested with tourism researchers. A minor modification was adopted based on their feedback. The survey was then further modified by halal tourism To measure destination trust, three items were used (e.g., "I have confidence in Korea as a halal-friendly destination"). Destination attachment was assessed with two items (e.g., "I feel emotionally attached to Korea as a tourist destination"). Additionally, we utilized three items to assess a halal-friendly destination image (e.g., "Overall, I have a good image of Korea as a Halal-friendly destination"). For assessing Muslim traveler retention, two items were utilized (e.g., "Korea as a Halal family-friendly place will be my first choice when it comes to choosing a destination"). The survey questionnaire comprising these measures was pre-tested with tourism researchers. A minor modification was adopted based on their feedback. The survey was then further modified by halal tourism specialists' reviews. All measures used in this research are exhibited in Appendix A.

specialists' reviews. All measures used in this research are exhibited in Appendix A.

#### **4. Results**

#### *4.1. Data Collection and Sample Profiles*

A field survey was conducted. The survey was carried out in many tourist places of Korea, which include restaurants, hotels, shopping malls, cultural districts, and tourist sites. Many international travelers prefer these places. The surveyors contacted Muslim tourists and asked if they were willing to fill out the survey. All survey participation was voluntary. Detailed information about the survey and its objectives were explained to all participants. The participants were asked to read the mandatory survey instructions thoroughly and answer the questions. All responses were returned onsite. Throughout this process, the researchers attained a total of 326 usable responses, which were used to analyze the data. Of 326 participants, 54.3% were female tourists, whereas 45.7% were male tourists. The participants' age range was 20–69 years old. The average age was 29.17 years old. When visit frequency was questioned, roughly 65.6% showed that they had visited Korea only once. About 89.3% indicated that they had visited Korea three times or less. A majority of the respondents classified themselves as pleasure travelers (55.2%), then education travelers (36.2%), and lastly business travelers/others (8.6%). About 77.9% indicated that their annual income is less than USD 39,999 (77.9%), followed by between USD 40,000 and USD 99,999 (20.3%), and then USD 100,000 or higher (1.8%). The sample respondents were, in general, highly educated. About 55.2% indicated they are college graduates, then graduate degree holders (28.8%), and then high school graduates or less (16.0%). Asking the following question, "For you, how important are halal-friendly food products when choosing a destination," most survey participants reported that halal foods are important or very important when selecting a tourism destination (87.1%).

#### *4.2. Confirmatory Factor Analysis and Measurement Model Evaluation*

A confirmatory factor analysis was performed (shown in Table 1). The measurement model contained a satisfactory level of goodness-of-fit statistics (*χ <sup>2</sup>* = 318.108, df = 107, *p* < 0.001, *χ <sup>2</sup>*/df = 2.973, RMSEA = 0.078, CFI = 0.958, IFI = 0.958, TLI = 0.939). Each loading value was found significant at *p* < 0.01. A composite reliability test was conducted. All reliability values (halal food availability = 0.785, halal food health/nutrition = 0.903, halal food accreditation = 0.833, halal food cleanness/safety/hygiene = 0.737, destination trust = 0.945, destination attachment = 0.829, halal-friendly destination image = 0.949, and Muslim traveler retention = 0.732) were above the suggested threshold of 0.70 [50]. Therefore, the internal consistency of the construct measures was apparent. Additionally, the calculated average extracted values (halal food availability = 0.647, halal food health/nutrition = 0.824, halal food accreditation = 0.713, halal food cleanness/safety/hygiene = 0.584, destination trust = 0.852, destination attachment = 0.707, halal-friendly destination image = 0.861, and Muslim traveler retention = 0.579) were all higher than the recommended level of 0.50 [50]. Moreover, these values were higher than the correlations (squared) between factors (refer to Table 2). Hence, construct validity (convergent and discriminant) was evident in this research.



Note. HA: Halal food availability, HN: Halal food nutrition, HAC: Halal food accreditation, HC: Halal food cleanness, DT: Destination trust, DA: Destination attachment, HD: Halal friendly destination trust, MT: Muslim traveler retention.

**Table 2.** Measurement model and data quality assessment results (*n* = 326).


Note. Goodness-of-fit statistics: χ <sup>2</sup> = 318.108, *df* = 107, *p* < 0.001, χ <sup>2</sup>/*df* = 2.973, RMSEA = 0.078, CFI = 0.958, IFI = 0.958, TLI = 0.939. <sup>a</sup> Between-construct correlations are below the diagonal. <sup>b</sup> Between-construct correlations (squared) are within parentheses.

#### *4.3. Structural Model Analysis and Hypotheses Testing*

A structural equation modeling was performed. The proposed model was found to have an acceptable level of goodness-of-fit statistics (χ <sup>2</sup> = 283.934, df = 80, *p* < 0.001, χ <sup>2</sup>/df = 3.549, RMSEA = 0.089, CFI = 0.943, IFI = 0.944, TLI = 0.926). The details are exhibited in Table 3 and Figure 2. As exhibited in Figure 2, the higher-order model for halal food performance result indicated that the first-order dimensions (availability, health/nutrition, accreditation, and cleanness/safety/hygiene) and the higher-order latent construct are related in a significant manner (*p* < 0.01). Coefficient values (standardized) for such relationships were 0.918 (availability), 0.870 (health/nutrition), 0.938 (accreditation), and 0.964 (cleanness/safety/hygiene), correspondingly. The relations were all significant (*p* < 0.01). The first-order dimensions of availability (R<sup>2</sup> = 0.843), health/nutrition (R<sup>2</sup> = 0.758), accreditation (R<sup>2</sup> = 0.880), and cleanness/safety/hygiene (R<sup>2</sup> = 0.929) were sufficiently alleged to its global latent factor. The framework encompassing halal food performance dimensions as direct drivers of its outcome variables (the first-order formative research model) was run to compare it to the proposed higher-order model. However, the result indicated that most halal food performance factors within the first-order formative research model were not significantly associated with destination trust, destination attachment, and retention. Therefore, it was clear that the first-order variables related to one global factor of halal food performance.


**Table 3.** Structural equation modeling results and hypotheses testing (*n* = 326).

Note1. Goodness-of-fit statistics for the structural model (higher-order framework): χ <sup>2</sup> = 283.934, *df* = 80, *p* < 0.001, χ <sup>2</sup>/*df* = 3.549, RMSEA = 0.089, CFI = 0.943, IFI = 0.944, TLI = 0.926, \* *p* < 0.05, \*\* *p* < 0.01. *Int. J. Environ. Res. Public Health* **2021**, *18*, x FOR PEER REVIEW 9 of 15

#### **Figure 2.** The structural model results. **Figure 2.** The structural model results.

The proposed associations were tested. As expected, halal food performance exercised a significant influence on destination trust (*β* = 0.461, *p* < 0.01), destination attach-The proposed associations were tested. As expected, halal food performance exercised a significant influence on destination trust (*β* = 0.461, *p* < 0.01), destination attachment

evaluated. Our finding showed the significant linkages between destination trust and destination attachment (*β* = 0.539, *p* < 0.01) and between destination trust and Muslim traveler retention (*β* = 0.439, *p* < 0.01). Hence, Hypotheses 4 and 5 were found true. In addition, as anticipated, destination attachment was a significant predictor of Muslim traveler retention. Hence, Hypothesis 6 was supported (*β* = 0.379, *p* < 0.01). Muslim traveler retention was satisfactorily accounted for by its antecedents (R2 = 0.765). Moreover, about 37.2% and 21.3% of the total variance in destination attachment and destination trust were de-

The indirect influence of research constructs was observed. As shown in Table 2, our result showed that trust significantly affected retention indirectly through destination attachment (*β* = 0.204, *p* < 0.01). In addition, halal food performance encompassed a significant indirect impact on destination attachment (*β* = 0.248, *p* < 0.01) and Muslim traveler retention (*β* = 0.346, *p* < 0.01). This finding indicated that both destination trust and attachment played a critical mediating role within the proposed model. Our further investigation showed that destination trust had the strongest total impact on Muslim traveler retention (*β* = 0.643, *p* < 0.01), halal food performance (*β* = 0.590, *p* < 0.01), and then destina-

scribed by their predictors, respectively.

tion attachment (*β* = 0.379, *p* < 0.01).

*4.4. Baseline and Structural Invariance Model Results* 

(*β* = 0.131, *p* < 0.05), and Muslim traveler retention (*β* = 0.244, *p* < 0.01). This outcome supported Hypotheses 1, 2, and 3. The hypothesized influence of destination trust was evaluated. Our finding showed the significant linkages between destination trust and destination attachment (*β* = 0.539, *p* < 0.01) and between destination trust and Muslim traveler retention (*β* = 0.439, *p* < 0.01). Hence, Hypotheses 4 and 5 were found true. In addition, as anticipated, destination attachment was a significant predictor of Muslim traveler retention. Hence, Hypothesis 6 was supported (*β* = 0.379, *p* < 0.01). Muslim traveler retention was satisfactorily accounted for by its antecedents (R<sup>2</sup> = 0.765). Moreover, about 37.2% and 21.3% of the total variance in destination attachment and destination trust were described by their predictors, respectively.

The indirect influence of research constructs was observed. As shown in Table 2, our result showed that trust significantly affected retention indirectly through destination attachment (*β* = 0.204, *p* < 0.01). In addition, halal food performance encompassed a significant indirect impact on destination attachment (*β* = 0.248, *p* < 0.01) and Muslim traveler retention (*β* = 0.346, *p* < 0.01). This finding indicated that both destination trust and attachment played a critical mediating role within the proposed model. Our further investigation showed that destination trust had the strongest total impact on Muslim traveler retention (*β* = 0.643, *p* < 0.01), halal food performance (*β* = 0.590, *p* < 0.01), and then destination attachment (*β* = 0.379, *p* < 0.01).

#### *4.4. Baseline and Structural Invariance Model Results*

A metric invariance test was carried out to uncover the proposed effect of a halalfriendly destination image. The obtained responses were split into high and low image groups. The high group contained 151 cases, whereas the low group included 175 cases. This group was completed on the basis of the K-means cluster analysis result. A baseline model comprising these two groups was created. The baseline model assessment results are shown in Table 4. The model contains a satisfactory level of goodness-of-fit statistics (χ <sup>2</sup> = 376.699, *df* = 168, *p* < 0.001, χ <sup>2</sup>/*df* = 2.242, RMSEA = 0.062, CFI = 0.926, IFI = 0.927, TLI = 0.907). Within the model, all loadings were constrained to be equivalent across groups. We conducted a Chi-square test subsequently.


**Table 4.** Baseline and invariance model assessment results.

Note. Goodness-of-fit statistics for the baseline model: χ <sup>2</sup> = 376.699, *df* = 168, *p* < 0.001, χ <sup>2</sup>/*df* = 2.242, RMSEA = 0.062, CFI = 0.926, IFI = 0.927, TLI = 0.907, \*\* *p* < 0.01.

> The result of the comparison between the baseline model and the constrained model indicated that the path from halal food performance to trust was meaningfully different between the high and low groups of halal-friendly destination image (∆χ 2 [1] = 4.164, *p* < 0.05). This result supported Hypothesis 7a. However, the linkages from halal food performance to attachment (∆χ 2 [1] = 0.286, *p* > 0.05) were not meaningfully different between the high and low groups. Thus, Hypothesis 7b was rejected. Figure 2 and Table 3 include the specifics about the metric invariance test results.

#### **5. Discussion**

#### *5.1. Higher-Order Framework of Halal Food Performance and Implications*

One of the meaningful points in the present research is the higher-order framework of halal food performance. The four first-order variables, such as (1) availability, (2) health/nutrition, (3) accreditation, and (4) cleanness/safety/hygiene, belong to one inclusive latent factor of halal food performance. This means that the commonality underlying the four first-order variables was wholly extracted by its second-order construct. This empirical result and finding enrich the halal food literature by providing a hierarchical approach, which clearly apprehends the halal food performance. The parsimonious higherorder structure framework enlightens academics and practitioners about the competence of theorizing intricate halal food performance factors in a more succinct manner in the Muslim tourism sector.

Food cleanness/safety/hygiene and accreditation were two main factors of halal food performance. Therefore, for practitioners, assuring that halal foods served in restaurants and available in tourist sites are clean, safe, and hygienic is critical. Displaying a halal logo clearly and providing halal certified/accredited food/service is also essential. Such efforts would fulfill many crucial facets of overseas Muslim travelers' needs. In addition, food availability and health/nutrition were the other crucial dimensions of halal food performance. Boosting the availability of halal food and enhancing the healthy and nutritious facets of existing halal food are hence imperative for a non-Islamic destination product to appeal to Muslim visitors.

More than 20.0% of the food industry in the world is related to halal foods, and its volume is increasing with the constant growth of the international Muslim traveler population [20]. Many non-Muslim countries can also use halal foods as a tactic of their Muslim tourism development. As demonstrated in this research, halal food performance ultimately results in Muslim traveler retention. Improving the performance of halal food by centering on its cleanness/safety/hygiene, accreditation, availability, and health/nutrition can elicit approach behaviors for destinations, eventually increasing business opportunities, creating more jobs, and bringing monetary investment/benefit to the destinations. Theoretically, this research successfully explored halal food performance and its potential influence, which was weakly known. Accordingly, diverse aspects of halal food performance should be actively utilized when developing/building a theoretical framework for explicating international Muslim traveler responses and behaviors at non-Muslim destinations.

#### *5.2. Implications Related to the Role of Destination Trust and Attachment*

Prior research in the literature asserted that the influence of cognitive variable(s) on traveler post-purchase behaviors is likely to be strengthened by the mediating effect of trust or attachment [12,29,30,37]. In line with these studies, the present research finding demonstrated that destination trust and destination attachment significantly mediated the impact of halal food performance on Muslim traveler retention. This means that both destination trust and destination attachment acted as intensifiers of Muslim traveler retention within our proposed theoretical framework. Our results offer tourism academics and destination practitioners crucial information about the importance of escalating destination trust and enhancing destination attachment in order to induce the maximum impact of halal food performance on Muslim visitor retention. Given the elaborate theoretical mediating mechanism unearthed in the present research, it is imperative to deal with such mediator variables for the effectual increase in Muslim visitor approach behaviors for a non-Islamic tourism destination.

#### *5.3. Moderating Effect of Halal-Friendly Destination Image and its Implications*

Findings of our metric invariance test indicated that the relationship between halal food performance and destination trust is moderated by a halal-friendly destination image. In particular, the association strength was greater in the high group of destination image than in the low group (high group: *β* = 0.312, *p* < 0.01 vs. low group: *β* = 0.227, *p* < 0.01). This

result implies that at a similar level of halal food performance, Muslim visitors who have a strong halal-friendly image of a non-Islamic location more heavily rely on the destination and its tourism environment than those who have an unfriendly image. Theoretically, this finding has a strong value as the present study is the first empirical research that provides evidence regarding the significance of a halal-friendly destination image in determining the magnitude of the influence of halal food performance on destination trust. Our evaluation and finding of the convoluted associations among food performance, destination image, and destination trust, which are especially crucial in the international Muslim tourism context, contribute to escalating academics' understanding of Muslim visitors' post-purchase formation regarding non-Islamic destination products. Our finding is also practically meaningful. As a halal-friendly image about a destination is decisive in Muslim visitors' retention process, practitioners should be more aware of its criticality. Offering superior services and developing/providing new products, which are entirely friendly for Muslim visitors, could generate a positive halal-friendly destination image.

#### **6. Conclusions and Limitations**

#### *6.1. Conclusions*

The rapid growth of Muslim tourism is evident in many Islamic and non-Islamic destinations [4,5,10]. Yet, our understanding of halal food performance and its influence on Muslim traveler approach behaviors for a destination was lacking. The present research has filled this gap. The hypothesized conceptual framework was wholly supported. Halal food performance was revealed to be a determinant of destination trust, destination attachment, and Muslim traveler retention. Destination trust and attachment contributed to making the best use of halal food performance in the retention process. A Halal-friendly destination image strengthened the influence of halal food performance on destination trust. Our findings help practitioners at non-Islamic destinations invent useful strategies to retain international Muslim visitors by utilizing halal food, trust, attachment, and image as important tools. Indubitably, a theoretical base pertinent to Muslim traveler behaviors at non-Islamic places is in the infant stage. From this perspective, our research that helps academics and practitioners increase their understanding of such behaviors contains high originality and value.

#### *6.2. Limitations and Future Research Arena*

Although these research findings have presented both theoretical and conceptual frameworks, this research had some limitations that provide some directions for potential studies. First, the present study centered on Muslim traveler behaviors at a non-Islamic destination. Their behaviors can possibly differ at an Islamic destination. Future research should conduct an empirical comparison of the Muslim traveler retention process and behavior across Islamic and non-Islamic destinations, which would be a meaningful extension of this study. Second, it would be true that a normative process such as social norms and moral/ethical obligation is also crucial when explicating Muslim traveler approach or avoidance behaviors. Indeed, some research denoted the criticality of normative factors in traveler behaviors [51]. Thus, future research should broaden the proposed conceptual model by integrating normative influence in order to improve the comprehensiveness and explanatory power of the model. Lastly, future research should consider the changes in travel options. For example, the accommodation option of Airbnb and/or other rental properties will allow travelers to cook their own meals during their travel so that they do not have to consider the halal-friendly options.

**Author Contributions:** Conceptualization, H.H. and L.H.L.; methodology, A.R. (Aleksandar Radic); writing—original draft preparation, H.H.; writing—review and editing, L.H.L. and (António Raposo); visualization, A.H.N. and A.R. (António Raposo); supervision, H.H., L.H.L. and A.R. (Aleksandar Radic); project administration, H.H., A.R. (Aleksandar Radic) and A.H.N. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Data Availability Statement:** The dataset used in this research are available upon request from the corresponding author. The data are not publicly available due to restrictions i.e., privacy or ethical.

**Acknowledgments:** The authors would like to thank Lorna Darelius for the meticulous review of the manuscript.

**Conflicts of Interest:** The authors declare no conflict of interest.

**Ethics Statement:** Because of the observational nature of the study, and in the absence of any involvement of therapeutic medication, no formal approval of the Institutional Review Board of the local Ethics Committee was required. Nonetheless, all subjects were informed about the study and participation was fully on a voluntary basis. Participants were ensured of the confidentiality and anonymity of the information associated with the surveys. The study was conducted in accordance with the Helsinki Declaration.



#### **References**

