Sophie E. Parks

Optimized aqueous extraction of saponins from bitter melon for production of a saponin-enriched bitter melon powder.

UNLABELLED Bitter melon, Momordica charantia L. (Cucurbitaceae), aqueous extracts are proposed to have health-promoting properties due to their content of saponins and their antioxidant activity. However, the optimal conditions for the aqueous extraction of saponins from bitter melon and the effects of spray drying have not been established. Therefore, this study aimed to optimize the aqueous extraction of the saponins from bitter melon, using response surface methodology, prepare a powder using spray drying, and compare the powders physical properties, components, and antioxidant capacity with aqueous and ethanol freeze-dried bitter melon powders and a commercial powder. The optimal aqueous extraction conditions were determined to be 40 °C for 15 min and the water-to-sample ratio was chosen to be 20:1 mL/g. For many of its physical properties, components, and antioxidant capacity, the aqueous spray-dried powder was comparable to the aqueous and ethanol freeze-dried bitter melon powders and the commercial powder. The optimal conditions for the aqueous extraction of saponins from bitter melon followed by spray drying gave a high quality powder in terms of saponins and antioxidant activity. PRACTICAL APPLICATION This study highlights that bitter melon is a rich source of saponin compounds and their associated antioxidant activities, which may provide health benefits. The findings of the current study will help with the development of extraction and drying technologies for the preparation of a saponin-enriched powdered extract from bitter melon. The powdered extract may have potential as a nutraceutical supplement or as a value-added ingredient for incorporation into functional foods.

Bitter Melon ( Momordica charantia L.) bioactive composition and health benefits: A review

ABSTRACT Bitter melon (Momordica charantia L.) has traditionally been used as a medicinal food in many developing countries. It is a tropical fruit claimed to have therapeutic effects due to its content of bioactive compounds. The present review is an attempt to highlight the bitter melon varieties, bioactive composition that is linked to its therapeutic effects, especially antidiabetic effect, in vitro and in vivo models, and understanding of the mechanisms of actions of bitter melon that are associated with epidemiological evidences. This paper also outlines a proposed processing scheme aiming to fully utilize bitter melon and add further value to this fruit.

Gac Fruit: Nutrient and Phytochemical Composition, and Options for Processing

Momordica cochinchinensis Spreng or Gac fruits are rich in nutrients, including carotenoids, fatty acids, vitamin E, polyphenol compounds, and flavonoids. Medicinal compounds are also found in the seeds, but the benefits of traditional preparations from these need to be clarified. The plant has the potential to be a high-value crop, particularly as parts of the fruit can be processed into nutrient supplements and/or natural orange and yellow colorants. However, the plant remains underutilized. There is limited information on its requirements in production, and the processing of health products from the fruits is a relatively new area of endeavor. The versatility of the fruit is highlighted through processing options outlined for fruit aril, seeds, pulp, and skin into powders and/or encapsulated oil products. These Gac fruit products will have the potential to be utilized in a range of foods such as pasteurized juice and milk beverages, glutinous rice, yogurt, pasta, and sauces.

An Optimised Aqueous Extract of Phenolic Compounds from Bitter Melon with High Antioxidant Capacity

Bitter melon (Momordica charantia L.) is a tropical fruit claimed to have medicinal properties associated with its content of phenolic compounds (TPC). The aim of the study was to compare water with several organic solvents (acetone, butanol, methanol and 80% ethanol) for its efficiency at extracting the TPC from freeze-dried bitter melon powder. The TPC of the extracts was measured using the Folin-Ciocalteu reagent and their antioxidant capacity (AC) was evaluated using three assays. Before optimisation, the TPC and AC of the aqueous extract were 63% and 20% lower, respectively, than for the best organic solvent, 80% ethanol. However, after optimising for temperature (80 °C), time (5 min), water-to-powder ratio (40:1 mL/g), particle size (1 mm) and the number of extractions of the same sample (1×), the TPC and the AC of the aqueous extract were equal or higher than for 80% ethanol. Furthermore, less solvent (40 mL water/g) and less time (5 min) were needed than was used for the 80% ethanol extract (100 mL/g for 1 h). Therefore, this study provides evidence to recommend the use of water as the solvent of choice for the extraction of the phenolic compounds and their associated antioxidant activities from bitter melon.

Greenhouse‐grown bitter melon: production and quality characteristics

BACKGROUND Bitter melon (Momordica charantia L.) is a medicinal fruit reported to have antidiabetic properties. To grow this tropical fruit year-round in temperate climates, greenhouse production is necessary, sometimes without insect pollinators. Suitable high-yielding varieties with good bioactivity need to be identified. This experiment evaluated the yield of six varieties of bitter melon under greenhouse conditions and their bioactivity in terms of total phenolic and saponin compounds and total antioxidant activity determined using four assays. RESULTS The larger varieties (Big Top Medium, Hanuman, Jade and White) were more productive than the small varieties (Indra and Niddhi) in terms of total fruit weight and yield per flower pollinated. The bioactivity (total phenolic and saponin compounds and antioxidant activity) of the two small varieties and Big Top Medium was significantly higher than that of the other three large varieties. Two antioxidant assays, 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric-reducing antioxidant power (FRAP), were shown to provide the strongest correlations with phenolic and saponin compounds of bitter melon. CONCLUSION Preliminary research has identified Big Top Medium as the most suitable variety for greenhouse production. The rich source of phenolic and saponin compounds and their associated antioxidant activity highlight bitter melon as a valuable food.

Effects of four different drying methods on the carotenoid composition and antioxidant capacity of dried Gac peel

BACKGROUND Gac fruit (Momordica cochinchinensis Spreng.) is a rich source of carotenoids for the manufacture of powder, oil and capsules for food, cosmetic and pharmaceutical uses. Currently, only the aril of the Gac fruit is processed and the peel, similar to the other components, is discarded, although it contains high level of carotenoids, which could be extracted for commercial use. In the present study, four different drying methods (hot-air, vacuum, heat pump and freeze drying), different temperatures and drying times were investigated for producing dried Gac peel suitable for carotenoid extraction. RESULTS The drying methods and drying temperatures significantly affected the drying time, carotenoid content and antioxidant capacity of the dried Gac peel. Among the investigated drying methods, hot-air drying at 80 o C and vacuum drying at 50 o C produced dried Gac peel that exhibited the highest retention of carotenoids and the strongest antioxidant capacity. CONCLUSION Hot-air drying at 80 o C and vacuum drying at 50 o C are recommended for the drying of Gac peel.

Effects of maturity on physicochemical properties of Gac fruit (Momordica cochinchinensis Spreng.)

Abstract The aril around the seeds of Gac fruit is rich in fatty acids and carotenoids (lycopene and β‐carotene). Understanding how these qualities are affected by fruit maturity at harvest may identify indices for quality assessment. Some physical and chemical properties of Gac fruit were determined for fruit harvested between 8 and 16 weeks after pollination (WAP). Fruit respiration rates and ethylene production rates were assessed after harvest and up to 20 days in storage at 20°C. Fruit harvested at 14 WAP had the highest oil (0.27 ± 0.02 g/g DW), lycopene content (0.45 ± 0.09 mg/g FW), and β‐carotene content (0.33 ± 0.05 mg/g FW) which declined by 16 WAP. External skin color and aril TSS were indicative of oil and carotenoid contents in aril. Skin color, TSS and potentially firmness were good indices of fruit quality. Harvesting less mature fruit at 12 WAP would be practical as the fruit were firmer and more capable of transport; however, quality during postharvest ripening may be limited. Fruits continued to ripen after they were harvested and an ethylene peak in the least mature fruit may reflect a climacteric behavior but this needs further investigation.

Optimisation of the Microwave-Assisted Ethanol Extraction of Saponins from Gac (Momordica cochinchinensis Spreng.) Seeds

Background: Gac (Momordica cochinchinensis Spreng.) seeds contain saponins that are reportedly medicinal. It was hypothesised that the extraction of saponins from powdered Gac seed kernels could be optimised using microwave-assisted extraction (MAE) with ethanol as the extraction solvent. The aim was to determine an appropriate ethanol concentration, ratio of solvent to seed powder and microwave power and time for extraction. Whether or not defatting the Gac seed powder had an impact on the extraction of saponins, was also determined. Methods: Ethanol concentrations ranged from 60–100% were used to compare total saponins content (TSC) extracted from full-fat and defatted Gac seeds. Ratios of solvent to Gac seeds ranged from 10 to 100 mL g−1 and microwave conditions ranged from 1–4 cycles at power levels ranged from 360–720 W, were examined successively to evaluate their efficiency in extracting saponins from full-fat Gac seeds. Results: A four-fold higher of TSC was obtained in extracts from full-fat Gac seed powder than from defatted powder (100 vs. 26 mg aescin equivalents (AE) per gram of Gac seeds). The optimal parameters for the extraction of saponins were a ratio of 30 mL of 100% absolute ethanol per g of full-fat Gac seed powder with the microwave set at 360 W for three irradiation cycles of 10 s power ON and 15 s power OFF per cycle. Conclusions: Gac seed saponins could be efficiently extracted using MAE. Full-fat powder of the seed kernels is recommended to be used for a better yield of saponins. The optimised MAE conditions are recommended for the extraction of enriched saponins from Gac seeds for potential application in the nutraceutical and pharmaceutical industries.

Optimising the Encapsulation of an Aqueous Bitter Melon Extract by Spray-Drying

Our aim was to optimise the encapsulation of an aqueous bitter melon extract by spray-drying with maltodextrin (MD) and gum Arabic (GA). The response surface methodology models accurately predicted the process yield and retentions of bioactive concentrations and activity (R2 > 0.87). The optimal formulation was predicted and validated as 35% (w/w) stock solution (MD:GA, 1:1) and a ratio of 1.5:1 g/g of the extract to the stock solution. The spray-dried powder had a high process yield (66.2% ± 9.4%) and high retention (>79.5% ± 8.4%) and the quality of the powder was high. Therefore, the bitter melon extract was well encapsulated into a powder using MD/GA and spray-drying.

Bioactive Composition, Antioxidant Activity, and Anticancer Potential of Freeze-Dried Extracts from Defatted Gac (Momordica cochinchinensis Spreng) Seeds

Background: Gac (Momordica cochinchinensis Spreng) seeds have long been used in traditional medicine as a remedy for numerous conditions due to a range of bioactive compounds. This study investigated the solvent extraction of compounds that could be responsible for antioxidant activity and anticancer potential. Methods: Defatted Gac seed kernel powder was extracted with different solvents: 100% water, 50% methanol:water, 70% ethanol:water, water saturated butanol, 100% methanol, and 100% ethanol. Trypsin inhibitors, saponins, phenolics, and antioxidant activity using the 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and the ferric reducing antioxidant power (FRAP) assays; and anticancer potential against two melanoma cancer cell lines (MM418C1 and D24) were analysed to determine the best extraction solvents. Results: Water was best for extracting trypsin inhibitors (581.4 ± 18.5 mg trypsin/mg) and reducing the viability of MM418C1 and D24 melanoma cells (75.5 ± 1.3 and 66.9 ± 2.2%, respectively); the anticancer potential against the MM418C1 cells was highly correlated with trypsin inhibitors (r = 0.92, p < 0.05), but there was no correlation between anticancer potential and antioxidant activity. The water saturated butanol had the highest saponins (71.8 ± 4.31 mg aescin equivalents/g), phenolic compounds (20.4 ± 0.86 mg gallic acid equivalents/g), and antioxidant activity, but these measures were not related to anticancer potential. Conclusions: Water yielded a Gac seed extract, rich in trypsin inhibitors, which had high anticancer potential against two melanoma cell lines.