Low calorie nutrtaceutical beverage from snap melon and gac fruit

Abstract

In a balanced human diet, vegetables are essential because they are abundant in vitamins, minerals, carbohydrates, protein, and dietary fiber. To provide necessary micronutrients (particularly calcium, iron, iodine, vitamin A, and zinc) and avoid chronic diseases (particularly heart disease, cancer, and diabetes), the World Health Organization (WHO) advises a minimum intake of 400 g of vegetables per day. India is among the best places in the world for growing vegetables throughout the year for various reasons, including crop diversification, soil, availability of labour, and technology. The health benefits of vegetables belonging to the Cucurbitaceae family are well-established. Numerous studies have shown that cucurbit vegetables possess purgative, anti-inflammatory, anti-diabetic, and antioxidant qualities. Snap melon (Cucumis melo var. momordica) is one of the major crops of Cucurbitaceous vegetables grown worldwide and is vital to global trade. Ripe fruits of snap melon have a specific characteristic of splitting (cracking), leading to high perishability of fruits, resulting in substantial post-harvest losses, the imperative is to process them into value-added products. Momordica cochinchinensis Spreng, also known as Gac in Vietnam, is an underutilized variable Cucurbit species that grows widely in India, Malaysia, and Southeast Asia. This fruit is unique in terms of its nutritional properties as it contains carotenoids, particularly lycopene and β-carotene, in the flesh surrounding the seeds (aril). Stevia rebaudiana Bertoni is a native shrub of Paraguay that belongs to the Asteraceae family. For more than a century, people have used the leaves of this plant as sweeteners. Stevia plant produces a set of closely related, highly potent sweeteners known as steviol glycosides in its leaves. The increasing prevalence of diabetes and obesity has created a critical need for natural and low-calorie sweeteners to replace sugar. The study was undertaken under three experiments: The first experiment was conducted to determine the physicochemical constituents of snap melon and gac fruit in their horticulturally mature stage as per standard procedures. The highest level of moisture content (95.38%) and titratable acidity (0.64%), was recorded in snap melon whereas higher TSS (7.5°Brix), pH (5.78), ascorbic acid (44.8 mg100g ), total phenolics (95 mg100g ), β carotene (1.23 mg100g ), lycopene (1.63 mg100g ), and antioxidant activity (IC50 Values) (8.94 μg mL-1) was recorded in gac fruit. In the first part of the second experiment optimum proportions of snap melon juice, gac fruit aril, acid lime (Citrus aurantiifolia L.) juice, and steviol glycosides extract was determined. Various proportions of snap melon and gac fruit aril (25:75, 50:50, 75:25) and pure snap melon juice was combined with same amount of acid lime juice, and steviol glycosides extract. From this, ideal blend was selected based on organoleptic qualities on a nine-point hedonic scale. Although the treatment with 25% snap melon juice, 75% gac fruit aril juice, steviol glycosides, and acid lime juice recorded the highest levels of ascorbic acid (40.00 mg100 g ), total phenolics (66.75 mg100g ), β-carotene (1.01 mg100g ), lycopene (1.20 mg100g ), antioxidant activity (IC50 value of 3.44 μgmL-1), and an energy value of 183.15 kcal, the blend selected for development into nectar was the one with 75% snap melon juice, 25% gac fruit aril juice, steviol glycosides, and acid lime considering sensory and nutritional benefits. This blend also contained ascorbic acid (28.00 mg100 g ), total phenolics (33.75 mg100 g ), β-carotene (0.50 mg100g ), lycopene (0.62 mg100g ), antioxidant activity (IC50 value of 6.41 μgmL-1), an energy value of 99.42 kcal with an overall acceptability score of 6.4. In the second part of the second experiment, with the selected juice blend from the previous experiment nectar was developed. Low-calorie nectar was developed with 20% juice (75% snap melon juice, 25% gac fruit aril juice) with steviol glycosides and acid lime. 20% juice (75% snap melon juice, 25% gac fruit aril juice) with 15° Brix TSS with sucrose and 0.25% citric acid was used to develop conventional nectar. Nectar from pure snap melon was also made with 15 ° Brix TSS with sucrose and 0.25% citric acid. The developed low-calorie nectar was compared with the ones sweetened with sucrose (FSSAI) in terms of physico-chemical, microbial and organoleptic qualities. Based on the observations, it was observed that the nectar containing 20% juice (75% snap melon juice and 25% gac fruit aril juice) and acid lime sweetened with steviol glycosides was superior in terms of ascorbic acid (41.14 mg100g ), total phenolics (57.14 mg100g ), β-carotene (0.135 mg100g ), lycopene (0.189 mg100 g ), antioxidant activity (IC50 value of 2.47 μgmL-1), lowest energy value of 56.16 kcal with 10.85 g100 g carbohydrate, 0.55 g100g protein and 0.92 g100g fat content and without any microbial population. The highest overall acceptability score (7.76) on sensory evaluation was obtained for the nectar containing 20% juice (75% snap melon and 25% gac fruit aril) with 15° Brix (sucrose) and 0.25% citric acid. The nectar containing 20% juice (75% snap melon juice, 25% gac fruit aril juice) and acid lime sweetened with steviol glycosides obtained lowest overall acceptability score (5.56). The third experiment was undertaken to evaluate the changes in the nectar under different storage conditions. The three formulations of nectar were filled into 200ml glass bottles and pasteurized at 84°C–88°C for 20 minutes. These were stored for a period of three months under ambient (34±2°C) as well as refrigerated (5±2°C) conditions. Observations were recorded at 1MAS, 2MAS and 3MAS. From the observations, it was concluded that the nectar which was held under refrigerated (5±2°C) conditions retained bioactive constituents significantly better than those held under ambient conditions. The highest retention of bioactive constituents (ascorbic acid, phenols, β-carotene, lycopene) along with the highest antioxidant activity and lowest energy value was observed in the nectar made up of 20% juice (75% snap melon juice, 25% gac fruit aril juice) and acid lime sweetened with steviol glycosides stored under refrigerated condition during the storage period of three months with lower microbial population (fungi, bacteria, yeast). Significant variation among organoleptic scores was observed during the three-month storage period. The highest overall acceptability scores were obtained in sucrose-sweetened nectar combinations than steviol glycosides-sweetened ones. The nectar can be kept both at ambient conditions and as well as refrigerated conditions for up to ninety days. Both gac fruit and snap melon are underutilized, seasonal vegetables that contain high levels of bioactive components. The current study verified that these vegetables can be used to create value-added products such as nutraceutical nectars. By adding value, farmers can increase their income and thus guarantee the year-round availability of products from these underutilized vegetables.