Technology for Extraction of Polyphenols from Inner Seed Coat of Red Kernel Walnut
Red kernel walnuts are an important economic crop in China,known for their rich nutritional val-ue and market potential.The inner seed coat of the red kernel walnut contains a high amount of phenolic sub-stances.This study aims to optimize the extraction process to achieve a higher yield of polyphenols.Initially,single-factor experiments were conducted,followed by an orthogonal experiment to refine the extraction process.The Folin-Ciocalteu method was used to measure the total phenol content,with the polyphenol yield as the evaluation index.Through orthogonal analysis of four factors,the optimal extraction conditions were deter-mined.The results showed that the regression equation for the standard curve of gallic acid,established through experiments,was A=1.039 3C+0.019 8,R2=0.991 4,indicating a good linear relationship between mass concentration and absorbance value within the experimental range.The optimal conditions identified through sin-gle-factor experiments were 70℃ as the extraction temperature,a liquid-solid ratio of 60:1,an extraction time of 2 hours,and a 45％ethanol concentration.Based on these single-factor experiments,four factors were selected for further examination:ethanol volume fraction,liquid-solid ratio,extraction temperature,and ex-traction time.A three-level orthogonal experiment was designed.The order of influence of the four factors was found to be:extraction temperature>liquid-solid ratio>ethanol volume fraction>extraction time.The op-timal extraction conditions were identified as 45％ethanol volume fraction,60:1(mL)liquid-solid ratio,70℃extraction temperature,and 2 hours extraction time.Under these conditions,the extraction rate of polyphenols from the inner seed coat of the walnut was 27.93％.In conclusion,the extraction method optimized in this study yields a high extraction rate and ideal extraction effect,providing a valuable reference for extracting polyphenols from the inner seed coat of red kernel walnuts.
Red kernel walnutEndotestaPolyphenol extractionSingle-factor experimentOrthogonal experiment
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