Functional Properties Of Indigestible Fraction From Okara And Its Effect On Lipid-Lowering In Mice

Some chronic diseases such as hyperglycemia,hyperlipidemia,obesity increase rapidly recently.It is because of the change of people’s lifestyle and dietary structure that they become one of the serious threat to public health problem in many countries,therefore,indigestible carbohydrates containing low heat and rich in dietary fiber have become the first choice food for patients with chronic diseases.Dietary fiber is known as"the seventh nutrient"with important physiological function.But previous studies reported that the concept of dietary fiber should be expanded to the stage that material composition which can reach the cecum,and defined it as the indigestible fraction(IF),on the nutrition point of view,the research makes more sense.Okara,the main byproduct in the production of traditional soybean foods,is rich in dietary fiber,total about 62.92%.But,at present okara is mostly used as animal feed and fertilizer or be discarded as wasters,it not only fails to make full use of the resources,but also contaminates the environment.Therefore,in this study,in order to improve the utilization rate and nutrition value of okara,fresh okara was used as raw materials,and IF was obtained through simulating human gastrointestinal digestion system in vitro,then the main differences between IF and fresh okara in essential nutrients,physicochemical properties,physiological features,and effect on blood sugar,blood lipid and the control of obesity in mice ware analyzed.The main results of the study are as follows:1.Okara is rich in IF about 90.64%,of which the insoluble IF(iIF)accounts for most,about 94.92%,and soluble IF(sIF)is only 5.08%.The DF content is as high as 56.54%of the whole content of the IF,and the SDF content of IF is 23.75%,significantly higher than the SDF content of okara,in addition,IF is rich in resistance of protein,about 18.21%,and other ingredients such as resistant starch,minerals are about 20.03%.Moreover,condensed tannin content of okara is higher,while IF is rich in hydrolysis polyphenols,which means that the bioavailability of condensed tannins was higher than hydrolysis polyphenols in the small intestine.2.The temperature has a significant effect on water retention capacity(WRC)of okara and IF,their WRC under the condition of 37 ℃ is significantly higher than 25 ℃,but temperature has no significant effect on swelling capacity(SC)and water binding capacity(WBC).At 37 ℃,the oil retention capacity(ORC)of IF increased significantly,but the ORC of okara is not affected by temperature.From the point of chromaticity index,L*value of IF is significantly higher than okara,while a*and b*values significantly less than okara,it shows that the color of IF is more bright and more white than okara,and IF has the better sensory effect.3.IF and SDF with different modification treatment can improve bile-acid absorption ability and cholesterol absorption ability(CAA)to some extent,and in addition to the high pressure homogeneous modified SDF,the CAA at pH 2 of other samples is significantly greater than at pH 7.And in terms of anti-oxidation ability(AOA),all samples can significantly decrease the AOA except the high pressure homogeneous-enzyme modification SDF.4.Soybean dietary fiber,especially for SDF has a significant effect on lowing the body weight,fasting blood sugar levels,the content of TC,TG,HDL-C and AI,and improving the content of HDL-C,also it can obviously control the body fat level in mice,which can effectively reduce the risk of hyperlipidemia,diabetes and atherosclerosis.