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Author: search.filters.author.Loan, Le Thi KimSubject: search.filters.subject.polyphenol

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    ULTRASOUND-ENZYME ASSISTED EXTRACTION OF POLYPHENOL AND AMYLASE ENZYME FROM VIETNAMESE RAMIE LEAVES: PREDICTIVE MODELING DEVELOPMENT AND OPTIMIZATION STUDY
    (2024-01-01)
    Loan, Le Thi Kim
    ;
    Vinh, Bui The
    ;
    Van Tai, Ngo
    Ramie leaves are rich in antioxidant polyphenols and amylase enzyme, which could be a good source for food applications. This study investigated the impact of combined ultrasound-enzyme treatment (U-EAT), including ultrasound intensity (10-30%), content of Viscozyme L. enzyme addition (0.5-1%) and extraction time (5-15 min) on polyphenol recovery, antioxidant activity, and amylase activity. The result revealed that U-EAT could enhance the efficiency of extraction, with a significantly higher yield of bioactive compounds and antioxidant capacity, and amylase enzyme activity compared to an untreated sample. Multiple regression analysis was applied to predict the efficacy of extraction through the values of total phenolic content, antioxidant activity and enzyme activity. The established models shown high accuracy in predicting the effect of the extracted conditions on the yield of the extraction of antioxidant and enzyme amylase. It was found that the maximum yield of extraction could be obtained when the operation conditions were ultrasound intensity of 26.5%, enzyme concentration of 0.87% and extraction time of 10.88 min. Under these optimal conditions, the highest values were found (TPC of 99.047 mgGAE/100 g, antioxidant activity of 65.02% and amylase activity of 45.36 U/mL). In summary, the findings indicate that the utilization of ultrasound combined with the enzymatic extraction process of polyphenol and amylase enzyme from ramie leaves holds potential for enhancing both the extraction yield and bioactivity of the extract. Further study should be concerned with the process of producing food ingredients or products from this extract.
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    MICROWAVE-ASSISTED EXTRACTION OF “CẨM” PURPLE RICE BRAN POLYPHENOL: A KINETIC STUDY
    (2023-01-01)
    Loan, Le Thi Kim
    ;
    Tai, Ngo Van
    ;
    Thuy, Nguyen Minh
    Background. “Cẩm” rice bran has been considered a waste product; however, it possesses rich bioactive compounds. These compounds could be utilized to make value-added products, using microwave-assisted extraction. Materials and methods. This study aimed to investigate and establish the kinetic extraction for “Cẩm” rice bran under different conditions of microwave-assisted extraction. Five levels of microwave power (90, 150, 300, 600, and 800 W) were used for extraction at a time range from 0 to 30 minutes. The extraction yield (%) and total phenolic compound (mg gallic acid equivalent per g, mgGAE/g) were determined. The experimental data were fitted with five empirical models to find the best fit model. Results. The power of irradiation greatly influenced the extraction yield and phenolic compounds in rice bran extract. The fast rate of extraction was found at the initial stage (after 5 minutes of extraction), then remained unchanged or slightly declined. Among the five models, the first-order model showed the best fit between the actual and predicted data. Conclusions. Based on the extraction rate constant from the first-order model, 500 W was considered the appropriate power level for extracting polyphenol from rice bran with a high yield of extraction and total polyphenol content. These conditions could be further optimized and upscaled for use in the food industry.