The Screening Of Low Glycemic Index Of Beans And Application In Its Flour Products

A notable increment in the incidence of diabetes, resulting from unregualr diet, lack ofexercise and high life stress, has attracted more and more attention. Researches have shownthat rational formula diet is a helpful prevention and adjuvant therapy for diabetes. Aimed atselecting the formula staple food including legumes suitable for diabetes prevention andtreatment, this study has worked on the following issues: in vitro digestion of availablecarbohydrates in legumes, effects of legumes and legumes products on the postprandialplasma glucose, effects of legumes on alpha-glucosidase activity, relationships betweenlegumes and glycemic index (GI) and postprandial plasma glucose.It revealed from in vitro simulated digestion that the GI value is100for the referencesteamed bread while the GI values for legumes were significantly less than100(P<0.05). Theblack bean (green kernels), black bean (yellow kernels), green soybean, all have a GI of lessthan55, could be regarded as low GI food.Results of diabetic rat model experiment are as follows:1hour postprandial plasmaglucose of type I diabetic rats fed by adzuki bean (red bean), black bean (green kernels),soybean (small particle, Heilongjiang), black bean (yellow kernels) were2.73±1.40mmol/L,3.87±1.25mmol/L,2.13±2.39mmol/L and2.50±2.70mmol/L, respectively, which aresignificantly lower than that of common diet (P <0.05). For the area under postprandialplasma glucose curve of type II diabetes, the value of diabetic rats fed by red bean steamedbread, soybean steamed bread was significantly lower than that of wheat steamed bread (P<0.05). Area under2hour postprandial plasma glucose curve of type I diabetic rats fed bybuckwheat noodles (buckwheat flour to wheat flour ratio4to6), oat noodles (oat flour towheat flour ratio4to6), chickpea noodles (chickpea flour to wheat gluten95to5) were6.23mmol.h/L,6.56mmol.h/L and6.60mmol.h/L, respectively, which were significantlylower than that of wheat noodles14.07mmol.h/L (P <0.05). There was no significantdifference for the2hour postprandial plasma glucose curve between other formula noodleswith wheat noodles (P>0.05).Results from human experiment showed that area under2hour postprandial plasmaglucose curve of buckwheat noodles3.33±1.85mmol.h/L and oats noodles3.37±1.34mmol.h/L, respectively, were significantly higher than that of wheat noodles2.18±0.80mmol.h/L (P <0.05). There was no significant difference for the area between other formula noodles with wheat noodles (P>0.05).Legumes addition has the following effects on the activity of α-glucosidase. Enzymeinhibition effect was of irregular changes with the increase of soybean addition from0to4%.Inhibition of defatted soybeans on the activity of α-glucosidase were stronger than full-fatsoybean with the addition from5%to20%; enzyme inhibitory effect of defatted soybean onthe activity of α-glucosidase increased with the higher addition, the same thing happened tored beans and cowpeas. There existed significant correlations between α-glucosidase activityinhibition effect and defatted soybean GI value with the addition from5%,10%to15%(thecorrelation were0.9134、0.8634and0.8695, respectively. P <0.05); with one certain GI value,enzyme inhibition effect increased with the addition from5%to20%. When the addition was20%, There were significant negative correlations between inhibition effect of several high-fatlegumes on enzyme activity and1hour postprandial plasma glucose (the correlation was-0.8405. P <0.05). There were no correlations between inhibition effect of the low-fat soybeanon enzyme activity and GI value as well as postprandial plsma glucose.