Green extraction and biological activity of phenolic extracts from cashew nut testa using a combination of enzyme and ultrasound-assisted treatments.

BACKGROUND: A combination of enzymes and ultrasound treatment was employed to extract bioactive compounds from cashew nut testa, a by-product of the food industry. The total catechin, flavonoid, and phenolic content of extracts was investigated together with their biological activity. RESULTS: Enzyme and ultrasound-assisted extraction (E-UAE) was performed by incubation with Viscozyme L (20 mL kg-1 of testa powder, v/w) for 60 min before sonication for 40 min. Ultrasound and enzyme-assisted extraction (U-EAE) was carried out using sonication for 40 min before incubation with Viscozyme L (20 mL kg-1 of testa powder) for 60 min. Under appropriate conditions, the total phenolic, flavonoid, catechin, and epigallocatechin gallate content of the extracts from cashew nut testa obtained from a combination method (U-EAE or E-UAE) was significantly higher than that obtained using a single method (EAE or UAE). Extracts of cashew nut testa obtained from E-UAE displayed significantly higher antioxidant and α-amylase inhibitory activity than those from the U-EAE. The E-UAE extract at a concentration of 100 µg mL-1 had a greater impact on the cell viability of MCF-7 after treatment (22% cell viability) than did the doxorubicin (DOX) at 4 µg mL-1 (39% cell viability), and the E-UAE extract at 100 µg mL-1 was considered to be safe for healthy cells because the viability of the bovine aerotic endothelial cells treated with this extract was 91%, which was similar to the DOX treatment. CONCLUSION: The extract of cashew nut testa obtained from E-UAE is valuable and promising for the development of anti-inflammatory therapeutic drugs. © 2023 Society of Chemical Industry.

Physicochemical properties and in vitro digestibility of mung-bean starches varying amylose contents under citric acid and hydrothermal treatments.

In this study, starches of three mung bean cultivars (Vigna radiata) having different amylose contents were isolated and modified using a combination of citric acid and heat-moisture treatment (CA-HMT) or a combination of citric acid and annealing treatment (CA-ANN). Physicochemical properties and in vitro digestibility of native and treated mung bean starches were investigated. Resistant starch (RS) contents of the high-amylose, medium-amylose and low-amylose starches treated with CA-ANN were 41.1%, 35.7% and 27.1%, respectively, being higher than those treated with CA-HMT or native starches in the same variety. The CA-ANN did not affect the morphology and crystallinity of the starches. However, the starches treated by the CA-HMT were partly gelatinized and had higher degree of relative crystallinity as compared to the native starches. The DP¯s, swelling power, and viscosity of the treated starches were significantly lower than those of the native starches. The high-amylose mung bean starch was greatly affected by the treatments rather than medium- or low-amylose mung bean starch.

Effect of heat-moisture treatment of unpolished red rice on its starch properties and in vitro and in vivo digestibility.

Changes in physicochemical and digestible characteristics of starches isolated from untreated and heat-moisture treated unpolished rice grains were investigated in this study. Heat-moisture treatment (HMT) at moisture content of 20%, 25% or 30% and heating temperature of 100 °C or 120 °C were applied for treating unpolished rice grains. The results indicated that granular morphology and crystalline structure of starches remained almost unchanged. However, a significant difference in the format and degree of agglomeration of starches of the rice grains treated at moisture content of 30% was observed. The HMT also suppressed the swelling and breakdown of the starch granules when treating at high moisture content and heating temperature. After HMT, amounts of resistant starch (RS) in the treated rice grains significantly increased as compared to that in the untreated rice grains. Moreover, the rice grains were heat-moisture treated with higher moisture contents or heating temperatures had higher RS contents. As a result, the rice grains treated at moisture content of 30% and heating temperature of 120 °C contained the highest amount of RS (49.1%), released the lowest blood glucose level and had GI value of 55, which is considered as low GI food.

Physicochemical characteristics and in vitro digestibility of potato and cassava starches under organic acid and heat-moisture treatments.

A combination of acid (citric acid or lactic acid) and heat-moisture treatment was used to modify cassava and potato starches in this study. Changes in physicochemical properties and in vitro digestibility of the treated starches were investigated. The cassava starch contained 17.0% amylose and possessed A-type crystallinity, whereas the potato starch had 27.4% amylose and possessed B-type crystallinity. After acid and heat-moisture treatment, the crystalline structure of the cassava starch remained unchanged (A type), while the crystalline structure of the potato starch changed from B type to the C (B+A) type. The acid and heat-moisture treatment increased gelatinization temperature, peak and final viscosities of cassava starch but reduced peak and breakdown viscosities of the potato starch. After acid and heat-moisture treatment, rapid digestible starch contents of the treated cassava and potato starches were significantly reduced. However, resistant starch (RS) contents of the treated starches significantly increased as compared to the native starches. Citric acid was found to have high impact on formation of RS in starches. The RS contents of cassava and potato starches obtained under the citric acid and heat-moisture treatment were 40.2% and 39.0%, respectively, two times higher than those of the native starches.

In vitro digestibility and in vivo glucose response of native and physically modified rice starches varying amylose contents.

The native and physically modified rice starches with varying amylose contents were subjected to investigate the in vitro digestibility and the in vivo glucose tolerance in mice. The amylose and resistant starch (RS) contents of five native rice starches ranged in 4.7-30.6% and 6.3-11.8%, respectively. The RS contents of rice starches increased to 18.5-23.9% after heat-moisture treatment (HMT) and to 19.5-26.9% after annealing treatment (ANN). The heat-moisture and annealing treatments significantly reduced glycemic index (GI) values of the rice starches. GI values of the native, heat-moisture treated and annealed rice starches ranged in 68.9-100, 61.2-88.9 and 21.2-43.9, respectively. There was no correlation between amylose contents and the RS contents or GI values, while a strong negative correlation between RS contents and GI values was found (R(2)=-0.747, P<0.01).

Comparison of antifungal activities of Vietnamese citrus essential oils.

Citrus essential oils (EOs) are volatile compounds from citrus peels and widely used in perfumes, cosmetics, soaps and aromatherapy. In this study, inhibition of citrus EOs extracted from Vietnamese orange (Citrus sinensis), mandarin (Citrus reticulata Blanco), pomelo (Citrus grandis Osbeck) and lime (Citrus aurantifolia Swingle) on the growth of plant pathogenic fungi, Mucor hiemalis, Penicillium expansum and Fusarium proliferatum was investigated. The EOs of the citrus peels were obtained by cold-pressing method and the antifungal activity of EOs was evaluated using the agar dilution method. The results show that the EOs had significant antifungal activity. Lime EO was the best inhibitor of M. hiemalis and F. proliferatum while pomelo EO was the most effective against P. expansum. These results indicate that citrus EOs can be used as antifungal natural products in the food, pharmaceutical and cosmetic industries.