**Physicochemical and Techno-Functional Characterization of Native Corn Reintroduced in the Andean Zone of Jujuy, Argentina †**

#### **María Alejandra Giménez, Cristina Noemí Segundo, Manuel Oscar Lobo and Norma Cristina Sammán \***

Facultad de Ingeniería, CIITED-CONICET—UNJu, Ítalo Palanca 10, San Salvador de Jujuy 4600, Argentina; malejandragimenez@gmail.com (M.A.G.); segundocristina@gmail.com (C.N.S.); mlobo58@gmail.com (M.O.L.)


Published: 5 August 2020

**Abstract:** The chemical and techno-functional properties of nine maize races from the Andean zone of Jujuy, Argentina, in the process of reintroduction, were determined. Principal component analysis (PCA) was applied to establish the differences between them. The breeds studied showed high variability in their chemical and techno-functional properties, which would indicate that their applications in the food industry will also be differentiated. The PCA analysis allowed us to group them into four groups, and the Capia Marron and Culli races showed unique properties, mainly in the formation of gels.

**Keywords:** Andean; native corn; physicochemical; race; techno-functional

#### **1. Introduction**

The native corn of the province of Jujuy, Argentina, has been the foundation of the alimentary culture of the Andean region for centuries. However, the way of feeding has changed with the progression into modernity, and this has led to the loss of numerous maize races, affecting the biodiversity of this crop. Currently, there are very few communities that are suppliers of corn seeds that were cultivated in the past [1]. However, the Puna, Quebrada and Valles regions are considered amongst the most important in situ Andean maize germplasm banks in the country.

The functional properties of corn flours indicate their possible uses in the food industry [2]. For example, the soft endosperm hydrates much better because starches are easily reached by water, as they have fewer bodies of zein surrounding the endosperm [3]. Likewise, the amylose–amylopectin ratio in starches explains the differences in the granular structure, the physico-chemical properties, the swelling power, the viscosity, and the gelatinization temperature, the firmness of the gel, the retrogradation and the susceptibility to enzymatic attack [4]. The incorporation of starches with high amylopectin content into flour has a beneficial effect in bakeries, as higher moisture delays retrogradation and extends shelf life [5]. The same does not occur in pasta, since it produces less firmness and greater stickiness [6]. There are also certain characteristics of the corn that make it suitable for producing specific foods, and for their use in beverages, as they are 85% grain and 15% cob [7].

The re-insertion of native breeds is of great importance for biodiversity, and the knowledge of their technological aptitudes is fundamental in determining their possible industrial applications. The objective of this work was to analyze the nutritional composition and the techno-functional properties of the integral flours of nine Andean maize races, and to group them by applying principal components analysis (PCA).

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

#### *2.1. Raw Materials, Sowing, Pollination and Harvest*

The genetic material was provided by the INTA-Pergamino germplasm bank. The identification and origin of the genetic material is described in Table 1.

The sowing, pollination and harvesting was carried out in the experimental field of the Research Institute for Family Farming (IPAF INTA, Tilcara, Jujuy, Argentina) for two consecutive years (2017 and 2018). The ear corn were dried in the sun on metal sheets for 7 days (average temperatures: daytime 26 °C and nighttime 10 °C), then they were transported to the laboratory for analysis.

#### *2.2. Chemical Composition, Amylose Content and Endosperm Hardness*

The macronutrients of the different races were determined by Official Methods of Analysis [8]: humidity at 105 °C (AOAC 930.15), lipids by acid hydrolysis (AOAC 922.06), total nitrogen and proteins (AOAC 984.13), and ash by carbonization at 550 °C (AOAC 925.10). The amylose content was determined via the colorimetric method [9]. The hardness of the endosperm was determined by the hectoliter weight technique [3].

#### *2.3. Properties of Hydration, Absorption of Oil and Thermal*

The water holding capacity (WHC) at 30 °C and the oil holding capacity (OHC) at 70 °C were determined by the method of Ahmed et al. (2016). Both properties are expressed as g/g flour.

The thermal properties of the flours were analyzed by differential scanning calorimetry (DSC Q2000). The samples were prepared directly in capsules, with a final solids concentration of 25%, and they were heated from 20 to 130 °C at a rate of 10 °C/min in the presence of nitrogen. The initial temperature (To), peak temperature (Tp), final temperature (Tf) and enthalpy (̇H/g) were determined from the area corresponding to each peak.


**Table 1.** Origin and identification of plant material.

#### *2.4. Firmness of Gels and Stability in Refrigeration*

The gels were prepared from a flour/distilled water dispersion (3.5 ± 0.01 g flour in 25 ± 0.01 g water). The dispersion was heated to boiling with constant stirring for 3 min with a consistent heating plate temperature (temperature about 93 °C). They were then poured into cylindrical containers (3.5 m internal diameter, 4 cm high), allowed to stand for 25 min at room temperature and stored at 4 °C for 24 h for stabilization of the gel. The texture analysis was performed at room temperature on a texture analyzer TA.XT plus (Stable Micro Systems Ltd., Surrey, UK) equipped with Texture Exponent Lite software for Windows. A compression cycle was performed at a constant speed of 0.5 mmsƺ1 to a depth of 8 mm of the sample, followed by a return to the original position. The force-time curve was obtained, and was used for the determination of firmness (the maximum force observed before the fracture). The stability of the gels was determined at 4 °C by measuring the syneresis for 96 h [10].

#### *2.5. Statistical Analysis*

All measurements were in triplicate. Data were analyzed using XLSTAT software (V2008.1.50162). Linear correlations between any two samples were estimated by Pearson correlation analysis. Principal component analysis (PCA) was carried out to reduce the dimensions of variables and to visualize the similarities among different samples.

#### **3. Results and Discussion**

#### *3.1. Raw Materials*

The nine races of corn planted were identified as Capia, Culli, Morocho, Garrapata, Perlita, Brown Capia, Red, Crystalline Yellow and Cuzco (Figure 1). For the identification of the different breeds, the manuals provided by the germplasm bank INTA-Pergamino were used.

#### *3.2. Chemical Composition, Amylose Percentage and Endosperm Hardness*

Table 2 presents the chemical composition and hardness of the endosperms of the different races. According to the endosperm hardness, the races were ordered from the hardest to the softest, as follows: Perlita, Morocho, Rojo, Cristalino amarillo, Culli, Capiamarrón, Capia, Garrapata and Cuzo. The moisture varied between 9.01% and 10%. The protein content varied between 7% and 12%. The Morocho and Capia Marron breeds had the highest and lowest protein contents, respectively. Culli and Perlita maize had the lowest (3.8%) and highest (5.7%) lipid content respectively. No correlation was observed between the hardness of the endosperm and the protein or ash content. However, a positive correlation was observed between lipid content and hectolitre weight. The amylose content varied between 15 and 29 mg/100 g. A tendency to increase the content of amylose was observed with the increase in hardness of the endosperm [11].

**Figure 1.** Races identified during the harvest.

#### *3.3. Technological and Thermal Properties of Whole Meal Flours*

The values of WHC were between 2.3 at 30 °C and 3.6 at 70 °C (Table 2). The Perlita race showed the lowest values, which could be attributed to the low fiber, starch and protein contents. WHC values, in general, increased at 70 °C due to the swelling of the starch associated with the gelatinization process. The Perlita race had the lowest OHC, which was significantly different from the rest of the samples, possibly due to the higher lipid content and lower protein content [12]. The peak gelatinization temperature for the different corn races varied between 67 and 69 °C. There were no significant differences in enthalpy of gelatinization between the starches of the different maize races, indicating that similar energies are required for gelatinization. The temperature range of gelatinization (̇T) varied between 13 °C (Cuzco) and 25 °C (Culli), which suggests a wide diversity in gelatinization properties. The wholemeal flours are a very complex matrix; the presence of proteins and fibers hinders the access to water of the starch, increasing the Tf and ̇T. The gels presented a wide variation in firmness (16–81 Kp), and the lowest firmness corresponds to the gels of Cuzco (very soft endosperm) and the greatest to the Perlita (hard endosperm). However, no correlation was observed with endosperm hardness. The stability of the gels over 96 h in refrigeration was represented by syneresis between 4% and 32%; the greater stability was found for the Culli, and the least for Capia Marron. The percentage of syneresis correlated positively with the amylose content.

#### *3.4. Principal Component Analysis (PCA)*

Figure 2a shows the PCA applied to the chemical composition and techno-functional properties. The F1 factor explains 28.3% of the variability of the chemical composition, attributed mainly to the contents of ash and lipids, while F2 (21.09%) is attributed to the amylose content. The sample with the highest positive F1 score was the Culli race, and the highest F2 was Perlita. The main techno-functional properties that contributed to F1 were WHC and firmness. In F2, the variability was contributed by the OHC and syneresis. Only the variable ̇H is close to the crossing of the axes, which suggests its low contributions to the variability of the properties. It corresponds for F1 to the race Culli, and for F2 to Perlita. In Figure 2b, two groups of races with similar characteristics are distinguished: one composed of the Capia, Cuzco and Rojo races, with high endosperm hardness and protein content; and the other composed of the Perlita, Cristalino Amarillo and Morocho races, which formed firm gels. The Capia Marron and Culli breeds showed distance from the other two groups, suggesting that their properties are unique.


(**b**)

**Figure 2.** PCA of properties of maize races; (**a**) Chemical composition and techno-functional properties; (**b**) Grouping of maize races.


**Table 2.** Physicochemical and techno-functional properties of Andean corns.

the same column mean significantly different (*p* < 0.05). 

#### *Proceedings* **2020**, *53*, 7

#### *3.5. Principal Component Analysis (PCA)*

Figure 2a shows the PCA applied to the chemical composition and techno-functional properties. The F1 factor explains 28.3% of the variability of the chemical compositions, attributed mainly to the contents of ash and lipids, while F2 (21.09%) is attributed to the amylose content. The samples with the highest positive F1 score correspond to the Culli race, and the highest F2 to Perlita. The main techno-functional properties that contribute to F1 are WHC and firmness. In F2, the variability was contributed by the OHC and syneresis. Only the variable ̇H is close to the crossing of the axes, which suggests its minimal contribution to the variability of the properties. It corresponds for F1 to the race Culli, and for F2 to Perlita. In Figure 2b, two groups of races with similar characteristics are distinguished: one composed of the Capia, Cuzco and Rojo races, with high endosperm hardness and protein content; and the other composed of the Perlita, Cristalino Amarillo and Morocho races, which formed firm gels. The Capia Marron and Culli breeds showed distance from the other two groups, suggesting that their properties are unique.

#### **4. Conclusions**

A great variability in the chemical composition and technical-functional properties has been observed among the nine integral flours of the Andean corn races. According to their broad techno-functional behaviors, they could be used in different technological processes to produce integral foods. The analysis of the main components revealed that Culli and Capia Marron differ from the other races, mainly due to the formation of gels of intermediate hardness, and the high stability of Culli. The recovery of these races through the revaluation of their technological properties will contribute to the maintenance of biodiversity and the food security of rural families in the Andean region of Jujuy, Argentina.

**Acknowledgments:** This work was supported by grant Ia ValSe-Food-CYTED (Ref. 119RT0567) and Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) and Secretaría de Ciencia y Técnica y Estudios Regionales (SECTER), Universidad Nacional de Jujuy (Argentina).

#### **References**


© 2020 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 (http://creativecommons.org/licenses/by/4.0/).

### **Enrichment of Protein and Antioxidants of Cupcake with Moringa (***Moringa oleifera***) Leaf Powder and Sensorial Acceptability †**

#### **Alejandra Chinchilla, Susana Rubio-Arraez, Marisa L. Castelló and María Dolores Ortolá \***

Institute of Food Process Engineering for Development, Universitat Politècnica de València, Camino de Vera s/n, 46022 Valencia, Spain; alechinchita2193@gmail.com (A.C.); suruar@upvnet.upv.es (S.R.-A.); mcasgo@upv.es (M.L.C.)


Published: 5 August 2020

**Abstract:** *Moringa oleifera* plants have an extensive range of bioactive compounds (carbohydrates, phenolic compounds, lipids and fatty acids, proteins and functional peptides). These molecules may be included in several food matrices, such as bakery products, to improve their nutritional values. For that, the aim of this study was to replace the part of wheat flour with 1%, 2.5%, 5% and 10% of moringa leaf powder in cupcakes, assessing their antioxidant capacity, protein content and sensorial acceptability. The results showed that proteins and antioxidant capacity directly increased with moringa content. However, according to the tasters, these moringa-rich cupcakes were too dark.

**Keywords:** antioxidant capacity; cupcakes; moringa; proteins; sensorial analysis

#### **1. Introduction**

Moringa is a plant grown in the north of India, Spain, Africa, the Middle East and South America, being *Moringa oleífera* the most cultivated species. Their leaves contain several nutrients such as vitamins, minerals, amino acids, Ά-carotenes, antioxidants, fiber and proteins (19–29%) with low caloric levels [1–3]. Due to their nutritional components, dried leaves have been used to fortify different food products such as soups, pasta, breads, cakes and cookies [4].

In this regard, the aim of this study was to evaluate the level of wheat flour replacement by dried moringa powder (0%, 1%, 2.5%, 5% and 10%) on the water, protein and antioxidant capacity in cupcakes. Furthermore, a sensorial assessment was carried out to estimate the acceptability of these products.

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

#### *2.1. Materials*

Dried moringa leaves, grown in the Valencia region, were ground in a blender (Thermomix, TM31, Vorwerk, Wupertal, Germany) for 3 min at maximum speed (10,000 rpm). Then, the powder was passed through a 0.1 mm mesh sieve and it was stored at room temperature in a sealed glass jar protected from light.

#### *2.2. Preparation of Cupcakes*

Cupcakes were prepared with the following components (*w*/*w*): 25% of eggs, 25% of sucrose, 25% of wheat flour and/or leaf moringa powder, 12% of sunflower oil, 12% of milk and 2% of baking powder. Firstly, eggs were beaten in an electrical blender (Kenwood Ltd, KM240 serie, New Lane, Havant, UK) for ten minutes at maximum rate. After that, sucrose was added, and the mixture was blended for 5 more minutes. Then, milk and oil were incorporated, and the batter was mixed for 2 min at a low rate. Finally, wheat flour/moringa and baking powder were aggregated in the batter, and it was blended for 5 min at a low rate. The batter was left to stand in a refrigerator for 30 min. Next, muffin paper cups (60 × 35 mm) were filled with 65 g of batter and they were baked at 145 °C for 23 min in a semi industrial oven (Rational AGD-86899, Landsberg am Lech, Germany).

Depending on the degree of wheat flour replacement, five formulations were prepared: M0% (without moringa), M1%, M2.5%, M5% and M10% when the degree of replacement was 1%, 2.5%, 5% and 10%, respectively.

#### *2.3. Analytical Determinations*

Moisture content was obtained by means of the gravimetric method [5]. Protein content was determined by the Kjeldahl method [6]. An adaptation of the spectrophotometric DPPH method [7,8] was used to analyze the antioxidant capacity. For that, the percentage of free radical DPPH inhibition was registered according to the following equation:

$$1\% \quad DPPH \quad\_{reduction} = 100 \cdot \left[\frac{A\_{control} - A\_{sample}}{A\_{control}}\right]$$

where: *Acontrol* = absorbance of initial *DPPH* (without sample) and *Asample* = absorbance after 30 min of sample addition [9].

#### *2.4. Sensorial Analysis*

Acceptance of cupcakes formulated with different percentages of moringa powder (M1%, M2.5% and M5%) was analyzed with a panel composed of 30 panellists between 18 and 60 years of age. This test was performed in a sensorial room according to the rule ISO 4121:2003 [10]. On one hand, a hedonic scale was considered to find out the scores that the taster gave to the formulations depending on the attributes analyzed. On the other hand, a just about right (JAR) scale was used in order to know if the intensity of the attribute should be higher or lower.

#### **3. Results and Discussion**

Percentages of antioxidant capacity, water and proteins of the cupcakes are shown in Table 1. As can be seen in the table, moringa powder contains a high antioxidant capacity, which comes from compounds such as vitamin C, E and Ά-carotene. The antioxidant capacity of cupcakes increased linearly with respect to the percentage of moringa used (% DPPH inhibition = 7.4568 + 7.1074% Moringa, R2 = 0.9301), showing that the antioxidant power of moringa powder persists after baking.

**Table 1.** Percentages of water, protein and DPPH inhibition in cupcakes (M) depending on the amount of dried leaf moringa powder (0%, 1%, 2.5%, 5% and 10%) and in moringa powder.


Equal letters mean homogeneous groups obtained in the ANOVA analysis.

The persistence of the antioxidant activity of moringa after baking may be related to the interaction between the components of the cupcake (mainly proteins) and the active compounds (phenols) [11]. As was expected, protein content increased with the increase in moringa percentage in the product following a linear fitting (% Protein = 5.8946 + 0.2264% Moringa, R² = 0.9864) in coherence with the results found by other authors [12]. Bear in mind that in each formulation, for the theoretical protein content of the traditional components [13] and the protein obtained in the moringa powder (Table 1), no loses were found after baking in these conditions.

The relationship between water and protein content may be related to the strong ability of the dried leaf moringa powder to bind to water, due to its high amount of proteins [14,15]. The moringa powder protein has several polar aminoacids such as serine, treonine, proline and glutamine [1]. These polar aminoacids interact with water molecules, so cupcakes that contain moringa powder showed a higher water retention ability.

The lower scores obtained in the attributes of flavor, aroma, aspect and color when the percentage of moringa increased were probably due to the lower height reached in these cases and the great intensity of the green color, although the mechanical properties were well assessed without significant differences, irrespective of the level of moringa in the formulation (Figure 1).

**Figure 1.** Hedonic scores of cupcakes formulated with moringa. (\* significant level > 95%, significant level > 99%).

.

According to the results shown in Figure 2, the greater darkening of cupcakes with the moringa determined the purchase intention.

**Figure 2.** Just about right assessment (JAR) of cupcakes formulated with moringa.

#### **4. Conclusions**

It is feasible to formulate cupcakes with moringa leaf powder, increasing their antioxidant capacity and protein content. However, more studies should be carried out in order to improve their aspect, flavor and aroma since tasters penalized these attributes as the moringa concentration increased.

**Acknowledgments:** This work was supported by grant Ia ValSe-Food-CYTED (Ref. 119RT0567) and by the project "New Crops Addressing Climate Change: Moringa and Stevia" (Ref. AGCOOP\_A/2018/026 AVFGA— Generalitat Valenciana).

#### **References**


*Proceedings* **2020**, *53*, 8


© 2020 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 (http://creativecommons.org/licenses/by/4.0/).

#### *Proceedings*

### *Plinia peruviana* **"Yvapurü" Fruits and Marmalade from Paraguay: Autochthon Products with Antioxidant Potential †**

#### **Lourdes Wiszovaty, Silvia Caballero, Cristian Oviedo, Fernanda Ozuna and Laura Mereles \***

Universidad Nacional de Asunción, Facultad de Ciencias Químicas, Dirección de Investigaciones; Departamento Bioquímica de alimentos, P.O. 1055, San Lorenzo, Paraguay; lourdesw@qui.una.py (L.W.); scaballero@qui.una.py (S.C.); cristian\_ovi\_ro@hotmail.com (C.O.); andita21ozuna@hotmail.com (F.O.)


Published: 6 August 2020

**Abstract:** In this study, we aimed to describe the antioxidant content and physicochemical characteristics of the marmalade and fruits of *Plinia peruviana* "Yvapurü", harvested in Paraguay. The morphological characteristics, moisture, pH, vitamin C, total phenols, and anthocyanins were analyzed in mature wild and cultivated fruit samples. The values of anthocyanins (282–288 mg of cyanidin 3-O-glucoside/100 g) and total phenols in fruits and marmalades (214–224 and 719–817 mg GAE/100 g, respectively) make this fruit and its marmalade byproduct potential sources of phenolic compounds of interest to the dye, flavoring, and antioxidant industries.

**Keywords:** *Plinia peruviana;* antioxidants; total phenols; marmalade; anthocyanins; Yvapurü

#### **1. Introduction**

The systematic investigation of native fruits and their derived products promotes their reevaluation and contributes to a better exploration of the national species, which motivates new economic activities [1]. The biodiversity of fruits in Paraguay is considerable; however, the limited information on their composition results in a lack of use on the agronomic, industrial, and medicinal levels. *Plinia peruviana* (Poir.) Govaerts "Yvapurü" is a perennial tree of the Myrtaceae family that is distributed in the Southern Cone of America in the regions of Central Department, Cordillera, Ñeembucu, and Paraguarí in Paraguay. This species is currently accepted as *Eugenia guapurium* DC., *Guapurium peruvianum* Poir., *Myrciaria guapurium* (DC.) O. Berg, *Myrciaria cauliflora* auct. non (DC.) O. Berg, *Eugenia cauliflora* Miq., hom. illeg., *Plinia trunciflora* (O. Berg) Kausel, *Myrciaria trunciflora* O. Berg and *Myrciaria peruviana* (Poir.) Mattos var. trunciflora synonyms [2]. In the region, the chemical composition and biological activities of these fruits have been characterized and studied, highlighting a high total phenol content in the fruit with antioxidant activity. The content of phenols varies with the environment, plant growth, genetic variety, and the stage of maturation of the fruit factors, among others [2–4]. One of the most traditional products that uses all the parts of the fruit is marmalade. We aimed to describe the antioxidant content and physicochemical characteristics of *Plinia peruviana* "Yvapurü" fruits harvested in Paraguay, as well as determine the physicochemical characteristics and content of total phenols in marmalade (Figures 1 and 2).

**Figure 1.** Fruit of *Plinea peruviana.*

**Figure 2.** Batches of Yvapurü marmalade.

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

#### *2.1. Sampling*

Samples of wild and cultivated fruits were collected in the ripe state from Emboscada, Cordillera, Paraguay (Cabaña ITAPÉ) (Sample 1) and Caacupé, Coordillera, Paraguay (Sample 2) from the Paraguayan Institute of Agrarian Technology (IPTA), respectively. The handmade wholefruit marmalades were elaborated from the Sample 1 collection by traditional washing, slicing, cooking, and sieving without additives in three different batches.

#### *2.2. Processing of Samples*

For the determination of the morphological and physicochemical characteristics and vitamin C content in the fruit, whole fruits were used. To analyze total anthocyanins and total phenols, the peel and seeds of the pulp were separated. All determinations were made in triplicate; the data obtained are expressed as the mean ± standard deviation.

#### *2.3. Analytical Methods*

For the morphological studies, 30 fruits were taken for each sample, their weight was measured in analytical balance (AYD, model HR 120, Bradford, England), longitudinal and transversal diameter (measured in cm), and pH was measured with a potentiometer (Accurate pH 900, Horiba, Kyoto, Japan) at 25 °C. For humidity and vitamin C analysis, official A.O.A.C. techniques were used [5]. All reagents used were analytical grade. All determinations were made in triplicate. The determination of total anthocyanins by the differential pH method [1] was based on monomeric anthocyanin color loss at pH 4.5 and the presence of color at pH 1. The absorbance was measured at 510 and 700 nm.

#### *Proceedings* **2020**, *53*, 9

Total phenols were determined using the Folin–Ciocalteau method with some modifications based on a colorimetric oxide reduction reaction. The extraction was carried out as described by Rufino et al. [6].

#### *2.4. Statistical Analysis*

The data were recorded and processed in a form of the GraphPad Prism 5.0 program (GraphPad Software Inc., San Diego, CA, USA). To determine significant differences, *p* ǂ 0.05 was considered.

#### **3. Results and Discussion**

#### *3.1. Yvapurü Fruit Characteristics*

No significant differences were observed in the morphological characteristics of weight and longitudinal and transversal diameter (Table 1) between the fruit samples. This result showed that the analyzed fruits harvested in Paraguay are smaller than those of synonymous species fruits in the state of Paraná, Brazil. These fruits weigh between 6.4 and 11.4 g and their diameter is near to 2.65 cm [7,8].


**Table 1.** Physicochemical characteristics of *Plinia peruviana* "Yvapurü" fruits.

Results are expressed as mean ± SD of three independent assays. Values in the same row with the same superscript letter are not significantly different (*p* > 0.05) as measured by Student's *t*-test.

The pH values in the fruits are acidic and differ from the results reported by other authors (pH = 3.6–4.3) for the synonymous species of *Plinia peruviana* harvested in Brazil [7] *P. cauliflora* and *P. trunciflora*. These characteristics are explained by soil type and different environmental conditions, as well as genetic variations in the varieties distributed at different latitudes [9]. Thus, this indicated that the characteristics and composition of native fruits vary with soil type, genetics, and environmental conditions during the development of the species [7].

The moisture values in whole fruits were lower than 80%, with a significant difference between the average and the lower percentage observed by other authors (85.9%) in Brazil [6]. These values, however, are similar to the values observed by Seraglio et al. [10] for whole fruits of "Jaboticaba" (79.63%). Significant differences were observed in the vitamin C content between the fruits (Table 1). The values were lower than those reported for whole fruit in Brazil for *Myrciaria cauliflora* (238 mg/ 100 g) by Rufino et al. [6].

#### *3.2. Anthocyanins and Total Phenol Content in Fruits*

Significant differences in anthocyanins and total phenol content in different parts of the fruit were observed. Total phenols were highest in the peel (Table 2). Anthocyanins in the Sample 1 collection peel were smaller than in the Sample 2 collection. It was reported that this fruit has up to 58.1 mg/100 g of anthocyanins in fresh whole fruit [6] and 298.8–426.3 mg/100 g in peel, which agrees with the values observed in the present work. In the pulp, they reported lower values, 0.071–2.024 mg/100 g [8], than what was observed in pulps and seeds, which are used for the preparation of handmade marmalade in Paraguay. The values obtained in the pulp and seed were higher than those reported by other authors for *Plinia cauliflora* pulp in Brazil (32.4 mg GAE/100 g), and lower than the values reported in fruit peel harvested in Minas Gerais, Brazil [8].


**Table 2.** Anthocyanins and total phenols in fruits of *Plinia peruviana* "Yvapurü".

Results are expressed as mean ± SD of three independent assays. Values in the same row with the same superscript letter are not significantly different (*p* > 0.05) as measured by Student's *t*-test.

#### *3.3. Yvapurü* Plinia peruviana *Marmalade Results*

Significant differences in the titratable acidity were observed between batches 2 and 3 (ANOVA and Tukey's post-hoc test, *p* ǂ 0.05) as shown in Table 3.

**Table 3.** Characteristics of the fruit marmalade of *Plinia peruviana* "Yvapurü".


Results are expressed as mean ± SD of three independent assays. Values in the same row with the same superscript letter are not significantly different (*p* > 0.05) as measured by ANOVA and Tukey's post-hoc test, *p* ǂ 0.05.

The total phenol content did not show statistically significant differences (ANOVA and Tukey's post-hoc test, *p* ǂ 0.05). The results showed that the "Yvapurü" marmalade, with its acidic pH, its organic acid content (titratable acidity 0.828–0.937 g citric acid/100 g fw), and sugar content (66.2– 68.9° Brix), allows for the natural conservation of the product without the addition of artificial additives.

The marmalade has about 27–30% fewer total phenols than the pulp + seed and peel fruits, and provides about 22 mg of the total phenols per 10 g serving (one tablespoon of marmalade). Major polyphenols described for these species are quercetin, gallic acid, cyanidin-3-O-glucoside, isoquercetin, 3,4-dihydroxybenzoic acid, and kaempferol. These polyphenols give the product its antioxidant potential and other bioactive properties, such as anti-inflammatory, antibacterial, antifungal, antiproliferative, antimutagenic, hypoglycemic, and hypolipidemic activities [9,10]. The pomace, obtained as a byproduct (skin and seeds), can be of use in the food industry.

#### **4. Conclusions**

The fruits of *Plinea peruviana* "Yvapurü" are important sources of vitamin C, anthocyanins, and phenolic compounds. Anthocyanins are found mainly in the peel; however, phenols are distributed in the peel, pulp, and seeds. Phenolic compounds may be of interest to the food industry, as colorants, antioxidants, and flavorings. The marmalade provides polyphenols that give it added value. Studies on native fruits and their elaborated products should be furthered to characterize their unique chemical properties, with a possible denomination of their origin.

**Acknowledgments:** This work was supported by a grant from the Ia ValSe-Food CYTED Project (119RT0567). The authors are especially grateful to Cabaña Itapé and IPTA for the provision of the samples and the Facultad de Ciencias Químicas of the Universidad Nacional de Asunción for providing their facilities.

#### **References**


http://www.darwin.edu.ar/Proyectos/FloraArgentina/DetalleEspecie.asp?forma=&variedad=&subespecie =&especie=peruviana&genero=Plinia&espcod=21619 (accessed on 28 July 2020).


© 2020 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 (http://creativecommons.org/licenses/by/4.0/).
