Effect of A Moringa Oil–Beeswax Edible Coating on the Shelf-Life and Quality of Fresh Cucumber

Abstract

Cucumbers are a popular vegetable consumed worldwide and are known for their nutritional value, containing carbohydrates, antioxidants, vitamin C, etc. The abundance of a high moisture content is correlated to cucumber perishability, which encourages investigation into ways to maintain its quality and increase shelf-life. This study was carried out to determine the effect of a moringa oil–beeswax coating on the quality of fresh cucumber at different storage temperatures for 27 days of storage. Freshly harvested cucumbers were divided into two groups: the first group was coated with the moringa oil–beeswax edible coating, while the other one was not coated (control). Each group was divided into three other subgroups, for storage at 4, 10, and 22 °C. Different quality parameters, including weight loss, color change, firmness, total soluble solid (TSS), vitamin C, and pH, were evaluated. The findings showed that the weight loss of cucumber was highly increased in non-coated samples stored at high temperature. After 27 days of storage, the highest and lowest weight reduction % were recorded for non-coated cucumbers stored at 22 °C (38.09%) and moringa oil–beeswax-coated cucumbers stored at 10 °C (12.35%), respectively. Color analysis revealed that coating had a significant impact on color values, with distinct patterns in lightness, redness-greenness, and yellowness values for both treatments at various temperatures and days. The lightness values showed minimal fluctuations and stabilized at 13.65 at both 4 °C and 10 °C. Temperature and coating had a significant impact on pH levels, with the coating potentially exhibiting a protective effect on pH stability, particularly at lower temperatures (4 °C). Additionally, both groups’ total acidity levels held steady over time and at various temperatures, with the coating having a highly significant effect on total acidity levels. The amount of vitamin C varied significantly with temperature and storage period, but the coating did not affect vitamin C content. At 22 °C, there were notable variations in the vitamin C content over the storage period, with a final value of 37.7 mg/L on coated samples. Temperature and the duration of storage (p < 0.05) had a significant impact on the levels of total soluble solids (TSS), whereas firmness values changed significantly over the storage period only. Moringa oil–beeswax edible coating has the potential to preserve the nutritional value and quality attributes of cucumber.

1. Introduction

Cucumber is from the Cucurbitaceae family; it is one of the most well-known members, and a popular vegetable worldwide [1]. Cucumber production and trading have been substantial agricultural activities [2]. Cucumbers are grown in a variety of areas around the world, with China, Turkey, Russia, Ukraine, and Mexico being among the biggest producers. In 2021, the global cucumber output volume was 93.52 million tonnes, and China contributed 81 percent of the global production [3]. Cucumbers are a common pickling, salad, and cooking ingredient. While the consumption of pickles has been waning, the use of cucumbers as a fresh vegetable has been increasing [4]. It is a helpful food for obese patients as it has a low sugar content and is low in calories, thus helping obese patients to burn excess fats and quit burning sensations [5]. Cucumbers contain approximately 95% water, 3.6% carbohydrates, and 0.65% protein, and are low in calories (150 kcal kg⁻¹). They are a good source of many nutrients like pantothenic acid (B5) (0.026 mg kg⁻¹), vitamin C (0.28 mg kg⁻¹), and magnesium (1.3 mg kg⁻¹) [5].

Since cucumbers are a highly perishable product, the environmental circumstances in which they are grown, transported, and distributed have a big impact on the produce’s shelf-life and decay [6]. The shelf-life of cucumber is approximately 14 days. The recommended storage temperatures and relative humidity for cucumber are 7.2–10 °C and 85–98%RH [7]. Fresh cucumber post-harvest losses are a result of elevated transpiration and respiration following harvest, as well as insufficient storage facilities to reduce these effects. The temperature range in which cucumbers can be stored is restricted because they are sensitive to cold. When stored at 15 °C (59 °F), there is rapid yellowing and a loss of quality, while storage below 10 °C (50 °F) can cause chilling injury in as little as two to three days [8]. Physical and chemical activities such as respiration, moisture loss, yellowing, hardness, barrier, optical, mechanical changes, physiological damage, shriveling, and microbial growth can all have an impact on cucumber quality [9]. Firmness, color, and size are important quality characteristics that influence cucumbers’ economic and market value [10]. As a result, developing long-term preservation strategies is critical for minimizing/preventing rotting and increasing cucumber usage duration during off-seasons [9]. Therefore, employing edible coatings is one solution to this issue.

Andriani and Handayani [11] stated that food preservatives and edible coatings can be utilized to prolong shelf-life, minimize the growth of microorganisms, retain food-important compounds, and maintain the quality of fresh produce. Edible coatings are thin coats of natural or synthetic compounds placed on the surface of fresh fruit to establish a barrier between the product and its surroundings [12]. Edible coatings can be made from starches, proteins, and lipids, whereas synthetic coatings are made from cellulose derivatives and polyvinyl alcohol [13]. Edible coatings are defined as substances that provide a barrier of protection. The edible coating can be brushed, sprayed, or dipped directly onto the food surface [13,14]. It can slow the rate of respiration, reduce moisture loss, limit microbiological development, and increase the shelf-life of vegetables [12]. Also, the use of edible coatings has the benefit of reducing packaging waste, extending the shelf-life of fresh and minimally processed food, and insulating it from adverse environmental effects by ensuring that oxygen, carbon dioxide, moisture, scent, and flavor compounds are transferred into and out of the food system [15]. Indeed, edible coatings are a non-polluting method that increase fresh produce’s shelf-life during storage, and are also low-cost, and this has made edible coatings a popular option [16].

Some of the natural edible coatings will vanish during washing and cleaning procedures, and are replaced with waxes, which reduce water loss during handling and marketing [5]. Beeswax is a lipid-based coating material that is rich in hydrophobic qualities [17]. The free fatty acids, diesters, and exogenous materials that make up beeswax have a very low affinity for water [18]. Aly et al. [19] studied the influence of several waxing procedures on mango postharvest quality. Waxing dramatically reduced weight loss, decay incidence, and physiological diseases such as internal disintegration, stem-end rot, and spongy tissue in mangoes. Also, an investigation into the effect of edible coatings on mango shelf-life was carried out by Eshetu et al. [14]. Different concentrations of beeswax and chitosan coatings (0.5%, 1.5%, and 2%) were applied to two varieties of mango (Apple and Tommy Atkins). The results showed that 2% concentrations of beeswax and chitosan significantly reduced physiological weight loss and disease incidence and index, maintained the desired levels of pH, titratable acidity (%), and total soluble solids (°Brix), and preserved fruit firmness. Currently, beeswax coating has attracted a lot of interest in preserving fresh produce quality for extended storage times, because lipid-based coatings are hydrophobic and serve as a barrier against moisture loss and gas exchange, providing fruit with a glossy appearance [20].

Another edible coating is moringa oil, which is extracted from the moringa seeds. Moringa oil includes several compositional attributes like phenolic and antioxidant contents, proteins, etc. [21]. Moringa oil is considered a promising low-cost material used to decrease/eliminate undesirable microorganisms from food products [22]. The use of an edible coating like moringa extract reduces decay and increases the marketability of tomatoes [23]. The application of moringa oil coating prolonged the postharvest quality and shelf-life of the Tommy Atkins mango by controlling the physical and physicochemical properties during 12 days of storage at room temperature when compared to the control treatment. In addition, moringa oil coating slows down the degradation of pigments, allowing the coated fruit to gain shine.

The potential impact of coating cucumbers with a combination of beeswax and moringa oil on shelf-life is not well known due to the lack of research on this topic. Thus, this study aims to investigate the effect of a moringa oil–beeswax edible coating on the shelf life and quality of fresh cucumbers stored under different conditions.

2. Materials and Method

2.1. Experimental Material Collection

A locally produced moringa oil was purchased from a local trader in Nakhal, Al-Batinah Governorate, Oman. Fresh cucumbers (Cucumis sativaus L.) were harvested from a farm located in the same area and then transported to the Postharvest Technology Laboratory at Sultan Qaboos University, Oman. The samples were washed with tap water and then dried. For analysis, cucumbers with the same ripeness stage, a uniform size, and an absence of physical damage were chosen. The cucumbers were then divided equally into two groups. The first group was coated with moringa oil–beeswax edible coating, and the second group was not coated (control). Each of these groups was further divided into three other subgroups for storage at temperatures of 4, 10, and 22 °C. The total number of treatments was 6 (Figure 1).

Per day, a total of three replicates were used per treatment. The cucumbers were subjected to physical (weight, color, firmness), chemical (acidity, pH), and nutritional (sugar content, vitamin C) quality analyses at 3-day intervals over a 27-day storage period to assess changes that occurred during storage due to coating and storage temperatures. For day 0, a total of 3 samples were utilized. For this experiment, a total of 165 cucumber samples were used.

2.2. Coating Formulation and Application

A total of 80 mL of moringa oil and 20 g of beeswax [24] were taken in a beaker and then melted in an oven at a temperature of 120 °C (Model: ED-53, Blinder) for 5 min to produce a clear, homogenized mixture (beeswax–moringa oil). The melted beeswax solution/mixture was cooled to room temperature (22 ± 5 °C) prior to coating the fruit, following Dadzie et al. [25]. A brush [26] was used to coat the cucumbers gently once with the clear homogenized moringa oil–beeswax mixture and then stored directly at different storage temperatures for further quality assessment (Figure 2).

2.3. Weight Loss (%)

The weight of the samples was measured using a digital balance (Model: GX-4000, A & D Company, Tokyo, Japan). The same samples were used to detect weight loss through the period of storage. Equation (1), described by Al-Dairi et al. [27], was used to calculate the percentage of cucumber weight reduction.

$$Weight loss \%=\frac{\left(W_i-W_f\right)}{W_i}\times 100$$

(1)

• $W_i$ = the initial mass of banana fruit (g) before storage.
• $W_i$ = the banana fruit mass measured every 3 days.

2.4. Color

The method mentioned by Al-Dairi et al. [28] was followed to determine the color intensity of the coated and uncoated samples. A computer vision system based on RGB color measurements was used to collect 9 readings per color parameter from three cucumber samples per group at three-day intervals. A cardboard box was placed over the entire system to prevent backscattering effects, while a white background was placed to increase the contrast between the cucumber sample and the background. Two 36 W fluorescent lamps (Model: Dulux L, OSRAM, Milano, Italy) mounted parallel to the cucumber platform supplied uniformly bright lighting. The RGB color camera (Model: EOS FFOD, Canon Inc., Tokyo, Japan) was positioned vertically 0.26 m away from the cucumber sample to take the image. The images were saved in JPG format and processed with ImageJ software (https://imagej.net/ij/). Each sample was placed and aligned by hand for processing.

2.5. pH

Cucumber juice was made by extracting the juice from the cucumber using a blender (Model: LM2201, Moulinex, Jianmen, China). A total of 10 mL cucumber juice was poured into a clean and dry beaker, and the pH meter probe (Model: EUTECH Cyberscan pH 11, Singapore) was inserted and gently stirred for a few seconds [29]. A total of three readings were recorded per treatment.

2.6. Titratable Acidity (TA)

The titration method described by Al-Dairi et al. [29] was used to determine the cucumber’s titratable acidity (TA). A total of 10 mL of the prepared cucumber juice was diluted with 100 mL of distilled water, and phenolphthalein was also added as an indicator. By titrating 10 mL of cucumber juice against 0.1 N NaOH, the TA of the juice was determined. Equation (2) was used to calculate titratable acidity, which is given as a percentage of citric acid.

$$Titratable acidity (\%)=\frac{ Volume of NaOH \ast Normality of NaOH \left(0.1\right) \ast 0.064}{( ml of juice)}$$

(2)

Here, 0.067 = the citric acid milli-equivalent factor.

2.7. Ascorbic Acid

A total of 100 mL of boiled water was added to 1 g of starch and then placed aside to cool. A 0.01 N iodine solution was then produced by mixing 800 mL of distilled water with 16.6 g of potassium iodide and 1.269 g of iodine. Three samples of cucumber were divided into smaller pieces and 100 g was taken. Later, a blender was used to extract the juice and a mesh was used to filter it. A total of 10 mL of juice and 2 mL of starch solution were combined for titration. The iodine solution was titrated to the mixture until a uniform light gray color was observed. The amount of vitamin C was determined using Equation (3) [30].

$$Ascorbic acid (AA)=\frac{S\times N\times F\times 88.1\times 100}{10}$$

(3)

• A: Content of L-Ascorbic acid in the sample (mg L⁻¹);
• S: The amount of iodine solution consumed (0.05 M) at the end point of titration (mL);
• N: Normality of iodine solution in mol L⁻¹ (0.01);
• F: Consumed iodine solution factor (0.885).

2.8. Total Soluble Solid (TSS)

The total soluble solid was determined by using a hand-held refractometer (Model: PR-32 α, ATAGO Co., Ltd., Tokyo, Japan). One or two drops of clear juice were poured on the prism of the refractometer. To standardize the refractometer before usage, a few drops of distilled water (0 °Brix) were added. One reading was taken for each sample [1].

2.9. Firmness

The cucumber’s firmness was conducted according to the methodology of Al-Hadrami et al. [1]. The firmness was measured using a hand penetrometer (model: FHP-803, LLC., Franklin, ME, USA). The device’s probe (8 mm) was inserted into the sample, and the gauge meter reading was obtained and expressed in N. Three measurements were taken by penetrating the upper, lower, and middle regions of each sample. Per treatment, 6 readings were taken.

2.10. Statistical Analysis

SPSS 20.0 (International Business Machine Corp., New York, NY, USA) software was used to conduct statistical analyses. Three-way analysis was performed to evaluate the effect of three assessment factors like coating, storage temperature, and storage duration on the weight loss, firmness, total soluble solids, color, titratable acidity, pH, and vitamin C of fresh cucumbers at a 95% level of significance.

3. Results and Discussion

3.1. Weight Loss (%)

Critical p-values from the statistical analysis of the weight loss data provided the importance of different factors influencing the weight loss of the coated and the non-coated cucumbers. Temperature variations had a highly significant effect on weight loss in both groups (p < 0.001). Moreover, the documented weight loss results were highly influenced by the coating used, as well as the duration of storage (p = 0.001). This suggests that the observed weight loss trends were significantly impacted by temperature, coating, and number of days (Figure 3). The moringa oil–beeswax-coated cucumbers showed progressive weight loss over time at different temperatures. The trend lines at lower temperatures (4 °C and 10 °C) demonstrated a steady, rapid increase in weight loss, while a slightly more accelerated rate of weight loss was noted at a higher temperature (22 °C). A comparison of the two groups revealed the efficiency of the coating. The moringa oil–beeswax group exhibited a generally slower rate of weight loss progression in comparison to the control group, suggesting that coating had a moderating effect on weight loss. The highest weight loss % was observed in non-coated cucumbers on day 27 of storage at 22 °C, 10 °C, and 4 °C, with values of 38.1, 24.4, and 21.4, respectively. The lowest reduction in weight loss (12.4%) was recorded in coated cucumbers stored at 5 and 10 °C. This indicates that the non-coated group was more sensitive to changes in temperature than the moringa oil–beeswax cucumbers.

The overall reduction in cucumbers’ weight during storage is attributed to the probable changes in the cell wall tissue permeability, resulting in a higher rate of transpiration during storage, particularly at higher temperatures [1]. Similarly, Al-Dairi et al. [27] recorded a significant decline in weight in banana fruit stored at ambient temperatures due to due to respiration and water dehydration processes after 12 days of storage, when compared to storage at 13 and 5 °C. Regarding coating, Al Lawati et al. [26] stated that coating significantly reduces weight loss because of the decline in moisture content, as weight loss occurs due to the loss of water through transpiration and the loss of carbon dioxide reserves during the process of respiration.

The results are in agreement with findings published by Amin et al. [31], who used beeswax coatings in combination with chitosan–aloe vera and noticed comparable weight loss in mangos. They claimed that the addition of beeswax increased the coating’s hydrophobicity. As a result, there was a decrease in moisture removal, which in turn caused a reduction in fruit weight loss. The study by Silva et al. [22] found that moringa oil-coated fruits with 0.5 and 1% showed minor differences in weight loss during the storage period, indicating that the moringa oil coatings protected the fruits against excessive water loss. Dadzie et al. [25] reported a reduction in weight loss in beeswax-coated eggplant fruit, probably because lipid-based coatings are good barriers to water vapor. Generally, consumer acceptance of cucumbers can be affected by reductions in their weight, since the weight is correlated with external appearance, freshness, and crispness, which show wilting and shrinkage upon weight loss, thus reducing the fruit’s marketability.

3.2. Color

Changes in lightness (L*), redness and greenness (a*), and yellowness and blueness (b*) values of the moringa oil–beeswax and uncoated cucumbers at 4 °C, 10 °C, and 22 °C during 27 days of storage are shown in Figure 4. The L* values of color for both the moringa oil–beeswax and control cucumbers were found to be significantly influenced by the coating and day of storage (p < 0.05). The influence of temperature was not found to be significant (p > 0.05). Notable variations in the L* value of color within each group were caused on particular days and at particular temperatures (Figure 4). Throughout storage, distinct patterns were revealed by the trends in the L* value of color changes for the oil–beeswax and control groups at various temperatures. The L* values in the moringa oil–beeswax cucumbers started consistently at 29.95 at all temperatures and then gradually decreased over time. L* values showed minimal fluctuations and stabilized at 13.65 at both 4 °C and 10 °C. However, there was a more noticeable drop at 22 °C, with a minimum of 6.07 on days 9, 12, and 15. The non-coated (control) samples fluctuated more during the experiment.

At 4 °C and 10 °C, the L* values fluctuated around the initial level, with minimum values of 11.03 and 12.54, respectively, on day 3. Interestingly, at 22 °C, fluctuations were more pronounced, resulting in a minimum L* value of 11.61 on day 3 and a maximum of 31.00 on day 27. On day 3, the L* values at 4 °C and 10 °C varied around the initial point, falling to minimum values of 11.03 and 12.54, respectively. Variations were more noticeable at 22 °C, with a minimum L* value of 11.61 on day 3 and a maximum of 31.00 on day 27. At higher temperatures, the moringa oil–beeswax treatment tended to preserve higher L* values of cucumbers compared to the control treatment. These patterns highlight how the L* values of color changes for both treatments behave differently over time and at different temperatures, indicating how coating and temperature affect color measurements within the storage period.

Regarding the a* value, the statistical analysis showed that temperature and coating application had a significant impact on color values for both the moringa oil–beeswax and non-coated treatments, whereas storage duration had no noticeable effect on coated and non-coated cucumbers. There was a clear pattern in the trends in the color changes for both the moringa oil–beeswax and non-coated treatments at different temperatures and on different days (Figure 4). Starting with initial a* values that were identical at −12.77 on day 0, both groups showed variations throughout the experiment. The a* values in the moringa oil–beeswax group were comparatively constant at 4 °C and 10 °C, varying within the initial values and showing irregular decreases. Day 18 was a particularly noteworthy day for all temperature variations. However, at 22 °C, there was a discernible decrease to a minimum of −9.09 noted on several days, indicating a more noticeable fluctuation. However, the non-coated group exhibited variability in its values as well, with drops documented at different days and temperatures. Notably, on day 18, values decreased as low as −17.37 at 10 °C.

The findings indicated that coating, temperature, and storage day had a significant impact on the b* value of both coated and non-coated cucumbers. The observed trends in the b* value of color changes for both the moringa oil–beeswax and non-coated control at different temperatures and days revealed intriguing patterns in their behavior (Figure 4). Commencing with identical initial b* values of 15.34 across all temperatures, coated and non-coated cucumbers displayed fluctuations over the experimental period. In cucumbers coated with moringa oil–beeswax, the b* values demonstrated varying trends; at 4 °C and 10 °C, the values generally exhibited a consistent pattern, around 9.16 for several days, occasionally showing peaks and reaching a maximum of 23.83 at day 27 at 10 °C. However, at 22 °C, the fluctuations were more pronounced, showing a consistent reduction of around 9.16 from day 6 to 18, with a peak of 14.70 observed on day 27. Conversely, the control group also showed fluctuations in b* values over time, displaying a decline and increment at different days and temperatures, notably reaching a peak of 27.78 on day 27 at 22 °C. Both groups maintained their initial maximum b* value of 15.34 at certain intervals. These observations underscore the varied behaviors in the b* value of color changes, suggesting the influence of coating type and temperature variations on color measurements within the experimental context. The higher storage temperature accelerates the degradation of chlorophyll and tends to degrade the greenish color of the cucumber. The good visual perception of the coated cucumber’s color enhances the overall appearance and reflects the freshness and quality of the cucumber, leading to a shift in the purchasing decisions of the consumer towards the coated one.

Al-Hadrami et al. [1] observed similar findings; the color properties of cucumber were affected by the storage temperature and storage period after 24 days of storage. The changes in color in cucumbers are due to the conversion of the cucumber surface from a green to a more yellowish color [32]. The study by Silva et al. [22] did not show any significant interactions between color and moringa oil coating in mango. They observed variations in the color of the fruits, specifically for those in the control treatment (without bio-based coating). Differences in the color of the mango fruit peel could be attributed to ethylene production, since such a transformation is closely related to ethylene biosynthesis, which encourages an increase in the activity of chlorophyllase enzymes that are responsible for the degradation of chlorophyll and induces the synthesis of new enzymes responsible for carotenoid biosynthesis [33]. Dadzie et al. [25] found a delay in color change in beeswax-coated eggplants stored at cold temperatures for 18 days.

3.3. pH

Figure 5 illustrates the mean values of pH in coated and non-coated cucumber groups at 4 °C, 10 °C, and 22 °C during 27 days of storage. The results of the statistical analysis indicated that temperature (p < 0.001) and coating (p = 0.022) had a significant effect on pH values, indicating that these independent variables are important in changing the pH during storage. However, the day factor did not show a significant influence on pH variation (p = 0.239), suggesting that there was no statistically significant change in pH over the storage period.

The initial pH level was 6.3 for the non-coated (control) and moringa oil–beeswax-coated groups at all temperatures. At lower temperatures, the moringa oil–beeswax-coated cucumber showed comparatively stable pH levels. Compared to the control cucumbers, the pH gradually decreased at 4 °C and 10 °C. The pH decreased more slowly in the coated samples, suggesting that moringa oil–beeswax may have a protective effect on pH stability. The pH of coated and non-coated cucumbers is noticeably reduced by higher temperatures. Both the moringa oil–beeswax coated and control samples showed a significant pH reduction at 22 °C, particularly in the non-coated samples. This indicates that the reduction in pH was more significantly impacted by higher temperatures than by lower ones. Low pH in the moringa oil–beeswax-coated samples, especially at lower temperatures, implies that moringa oil–beeswax could potentially have a protective effect by slowing down pH changes over time. This might be the result of organic acid breaking down as a substrate during respiration, where the O₂ level increased [19]. The results conflict with the findings published by Wani et al. [34], who found that total acidity may decrease during the ripening process or storage period and increase the fruit pH.

3.4. Titratable Acidity (TA)

The data from the total acidity (TA) statistical analysis showed that the coating (p < 0.05) had a highly significant impact on total acidity in both groups. Storage days and temperature were found to have no significant effect on Total Acidity levels in the coated and non-coated group (Figure 6). The TA of coated and non-coated cucumbers showed consistent measurements over time at various temperatures. Total acidity levels remained mostly constant, ranging from 0.01 to 0.03 for the moringa oil–beeswax cucumbers and from 0.02 to 0.06 for the non-coated cucumbers, regardless of changes in temperature or the number of days.

Overall, neither temperature changes nor the number of days had an obvious effect on the observed total acidity measurements, although the type of coating applied had a significant impact on total acidity levels in both groups. These results are consistent with Eshetu et al. [14]’s research, which hypothesized that fruit coating concentrations higher than the fruit could potentially slow down the fruit’s respiration rate. This would reduce the fruit’s use of respiratory substrates like organic acids, which would ultimately result in lower fruit acidity. In addition, our findings showed that neither temperature changes nor the length of storage significantly impacted the levels of TA in the samples examined. This is in contrast to the findings of Doreyappa Gowda and Huddar [35] in several mango fruit varieties, which showed that titratable acidity decreased with extended storage time because of the respiration-induced use of organic acids.

3.5. Vitamin C

The statistical findings show that storage days (p = 0.043) and temperature (p = 0.004) had a significant impact on vitamin C levels. Nonetheless, there was no impact of the coating treatment on the variation in vitamin C content (p = 0.257). At the beginning of the experiment (day 0), the vitamin C levels of the moringa oil–beeswax-coated and non-coated cucumbers were 33.3 mg/L at all temperatures. Variations in vitamin C levels were then observed as the duration of storage increased (Figure 7).

Vitamin C levels in the moringa oil–beeswax-coated samples varied up until day 18, at 4 °C, and then increased to a peak value of 44.4 mg/L on day 21. Later, a decrease was noted, with a value of 33.8 mg/L on the last day of storage. The vitamin C content fluctuated at 10 °C, peaking at 64.7 mg/L on day 24, and then declined to reach 49.1 mg/L at the end of the storage period. At 22 °C, there were notable variations in the vitamin C content over the storage period with a final value of 37.7 mg/L.

The vitamin C levels in the non-coated samples showed variations based on storage time and temperature. At all three temperatures, there was an increase in vitamin C until the end of the storage period. On days 12 and 21, there were noticeable increases in vitamin C content in cucumbers, in non-coated cucumbers stored, particularly, at 10 °C. At 10 °C, the vitamin C content in moringa oil–beeswax cucumbers ideally increased from day 18 to day 24 of storage. This increase in vitamin C might be a sign of fruit enzymatic activity that has been stored. Also, Flores-López et al. [36] recorded a constant level of vitamin C in coated tomatoes during 15 days of storage. The activation of ascorbate oxidase enzymes during the storage period affects the decomposition of ascorbic acid. In addition, Jahan et al. [37] stated that changes observed in cucumbers’ vitamin C during storage are possible because of the oxidative breakdown of the compounds.

3.6. Total Soluble Solids (TSSs)

Total Soluble Solid (TSS) values were evaluated for 27 days at three different temperatures (4 °C, 10 °C, and 22 °C) in both the moringa oil–beeswax-coated and non-coated (control) cucumbers (Figure 8). The results of the statistical analysis show that the temperature (p = 0.017) and storage duration (days) (p = 0.046) had statistically significant effects on TSS values, while the coating treatment (p = 0.250) showed no effect in cucumbers. The initial value of TSS was 5.3 °Brix, as shown in Figure 8. As the storage time increased, significant differences in TSS levels were noted in both coated and non-coated samples at all temperatures. Variations in TSS values were observed for the moringa oil–beeswax-coated samples over time and at all three temperatures. The TSS values showed a low decline at 4° C, falling to a minimum of 4.2 °Brix by day 24 and rising to 4.7 °Brix by day 27.

TSS values gradually decreased at 10 °C during the storage period, going from 5.3 °Brix to 3.6 °Brix, initially. At 22 °C, TSS values varied between 3.7 and 5.9 °Brix, showing no discernible trend, but the values were comparatively constant. Similarly, TSS readings varied in the non-coated samples over the 27 days and at various temperatures. TSS values increased slightly at 4 °C until day 6, when they stabilized between 4.6 and 5.1 °Brix. The TSS values showed a progressive decrease at 10 °C, starting from day 3 until the last day of storage (3.90 °Brix). TSS values showed no trend and varied between 4.3 and 5.5 °Brix in non-coated samples stored at 22 °C. It was found that the moringa oil–beeswax coated cucumbers stored at 10 °C had the lowest TSS content, while the highest TSS values were obtained at 4 °C for both coated and non-coated samples. In general, as fruit ripens due to biosynthesis processes or polysaccharide degradation, the amount of sugars increases [14,38]. Similar results were found by Muddather and Abu-Goukh [39], who reported that the delay in TSS accumulation was further enhanced by the wax treatment. Coating mango with 0.5 and 1% moringa oil showed the best results for TSS values, as they presented the highest mean values [22]. El-Gioushy et al. [40] found that the TSS content of 10% Gum Arabic-coated guava was lower compared to non-coated. The observed reduction in the TSS content of some treatments is due to the depletion, degradation, and consumption of sugar during the ripening and respiration processes of the fresh produce, particularly on the last day of storage [26].

3.7. Firmness

The firmness values in the moringa oil–beeswax-coated and control cucumbers during 27 days of storage at different temperatures (4 °C, 10 °C, and 22 °C) are shown in Figure 9. According to the statistical analysis, firmness values were not significantly affected by temperature (p = 0.184) or coating (p = 0.871). However, a statistically significant effect on firmness (p = 0.002) was shown by the storage period. Day 0 of the study began with comparable firmness values for the control and coated samples, with a value of 6.8 N. Alterations in firmness values were noted over the storage period in response to different storage conditions. In comparison to other temperatures, the moringa oil–beeswax coated samples showed less reduction in firmness from day 0 to day 27 at 10 °C, while the coated samples kept at 22 °C showed the highest reduction in firmness. On day 27, the firmness values of moringa oil–beeswax-coated cucumbers at 4 °C and 10 °C were greater than the control cucumbers. In comparison to the beeswax-coated samples (3.8 N), the control cucumbers showed somewhat higher firmness readings at 22 °C (4 N).

Significant increases in firmness were recorded on day 9 in the coated cucumbers stored at 4 °C, whereas the control cucumbers showed clear increases in firmness on days 3 (8.9 N) and 9 (7.5 N) at 22 °C. Moringa oil–beeswax coating can maintain the firmness of fruits by inhibiting the activities of enzymes that break down cell walls, such as cellulose, pectin methylesterase, and polygalacturonase, which are particularly active during high storage temperatures [19]. Other studies found that the breakdown of mango fruit cell walls by various enzymes during ripening is responsible for fruit firmness reduction. The starch and pectin found in the cell wall are hydrolyzed by enzymes like pectin esterase [41]. According to Baswal et al. [42], the beeswax coating was also successful in preserving the reduction in the firmness of Kinnow mandarin fruit during low-temperature storage. Amin et al. [31], El-Gioushy et al. [40], and Al Lawati et al. [26] found that several coating substances were able to control the firmness of mango, guava, and zucchini and maintain a reasonable water content to avoid cell wall degradation and inhibit starch hydrolysis.

4. Conclusions

The study investigated the effectiveness of a moringa oil–beeswax mixture as an edible coating to maintain the quality of cucumbers while they are being stored. The outcomes showed that this coating preserved vital nutrients like vitamin C, slowed pH reduction, maintained color intensity, and significantly reduced weight loss. Cucumber quality was significantly impacted by variations in temperature, with lower temperatures having more beneficial effects. The firmness status of cucumber was affected by coating, particularly at lower storage temperatures. Color changes were highly maintained at higher at 13 °C. The changes of color from green to yellow were highly observed in non-coated (control) cucumbers. Overall, the study indicates that the moringa oil–beeswax coating has potential benefits for improving the preservation of cucumber quality characteristics like weight, firmness, color, sugar content, acidity, and vitamin C, and in prolonging the shelf-life, as well. Moringa oil–beeswax is a promising safe, effectively bridgeable, and eco-friendly strategy to replace the preservatives and packaging materials that are used to control the shelf-life of cucumber. Also, more effective cucumber shelf-life extension strategies could be advanced by more research into the optimization of coating formulations. This study can confirm the usage of such natural and edible coating solutions for other fruits and vegetables at the industrial level. This can help to maintain quality during the long journeys of the postharvest supply chain.