Distribution Characteristics Of Phytic Acid And Its Degradation Products In Soybeans And Their Mineral Bioaccessibility

Due to the anti-nutritional properties of phytic acid and its degradation products,such as chelating mineral ions,its research in food has received more and more attention.However,there is a lack of systematic investigation on phytic acid content in food in China at present.The measured phytic acid content is total phytic acid including degradation products,which overestimates the content of phytic acid in the sample,and its impact on the effectiveness of mineral elements is unknown.Therefore,it is urgent to accurately determine phytic acid and its degradation products in food.In this thesis,soybean was taken as the research object,and an ultra high performance liquid chromatography tandem mass spectrometry method was established for rapid analysis of phytic acid and its degradation products,including 6 kinds of inositol phosphate.The distribution characteristics of phytic acid and its degradation products in 62 samples from three major soybean producing areas in China were analyzed,and the bioavailability of 7 mineral elements(Ca,Mg,Zn,Fe,K,Cu and Mn)in vitro digestion simulation process of stomach and gastrointestinal tract,and the following results were obtained:(1)A method for simultaneous and rapid analysis of phytic acid and its degradation products,including 6 kinds of inositol phosphate,was established.The sample was extracted with 0.50 M hydrochloric acid as the extractant.Phytic acid and its metabolites were extracted by ultrasonic assisted method.Purification of extract using SAX anion exchange column.After vacuum freezing and concentration,pass the purified extract through 0.22 μM membranethe,separated by gradient elution of Waters PREMIER BEH Amide chromatographic column,and detected by triple quadrupole mass spectrometer in series with atmospheric pressure chemical ion source(APCI)using negative ion scanning multi reaction monitoring mode.The results show that the detection limit of this method is 0.002-3.773 μg/kg,LOQ 0.006-12.575 μg/kg,the recovery rate is 80.07%-102.33%.It can be used for the trace detection of phytic acid and its degradation products in soybean.(2)The distribution characteristics of phytic acid and its degradation products in62 soybean samples from Huanghuaihai,Northwest and South China were studied by the established method.The total concentration range of six kinds of phosphoinositol(Ins P1-Ins P6)was 0.000004-12.82 mg/g,the detection rate is 0.03%-100%.In soybeans,Ins P6 and Ins P5 are mainly found,with the detection rate of 100%.Ins P6 has the highest content of 0.92-12.82 mg/g(median 4.49 mg/g),followed by Ins P5,with the concentration range of 0.05-1.51 mg/g(median 0.34 mg/g),and Ins P1-4 has a relatively low content.The content of phytic acid and its degradation products in different production areas and varieties varies greatly,and the highest concentration of Ins P6 is12.82 mg/g(C 1),which is planted in the Huanghuai Sea area,the lowest concentration of Ins P6 is 0.92 mg/g(H 32),which is planted in the south,the highest concentration of Ins P5 is 1.51 mg/g(61),which is planted in the Huanghuai Sea area,and the lowest concentration of Ins P5 is 0.05 mg/g(S 51),which is planted in the south.Distinguish local varieties and bred varieties through examination and approval,the content of Ins P1,Ins P2 and Ins P3 in local varieties was lower than that of the bred varieties,and the other two degradation products Ins P4,Ins P5 and Ins P6 in local varieties were higher than that of the bred varieties.(3)The total contents of 7 mineral elements in 62 soybean samples were determined by ultrasonic assisted acid extraction.Physiological extraction test(PBET)was used to establish an in vitro digestion model to study the bioavailability of seven mineral elements in soybean in gastric and gastrointestinal metaphase digestion simulation,and to analyze the correlation between the content of phytic acid and its degradation products and the bioavailability.The results showed that in vitro simulated bioavailability of seven mineral elements in soybean,the bioavailability of stomach was higher than that of the middle gastrointestinal tract(p<0.01),and [Ins P6]/[Fe],[Ins P6]/[Cu],[Ins P6]/[Zn] showed extremely significant negative correlation(p<0.01).