| Resistant starch (RS) is defined as the sum of starch and products of starch degradation that can not be digested in healthy individuals’small intestine. It can play a lot of physiological function after RS has entered into human body, such as regulating the blood sugar level, preventing colon cancer, reducing cholesterol levels, controlling weight, promoting absorption of vitamin and minerals.The most important type of RS is the type Ⅲ (RS3), which has stronger heat-resistant ability and higher security in food used than others, had made it the focus of reseach in recent years. In this subjects, wheat starch was selected as the raw material to produce RS3 by combination of microwave processing and amylase effecting. Then the physicochemical properties of RS3 has determined, including water-holding capacity, resistance to hydrolysis, viscosity, microstructure, and in vitro analysis. Besides, the tests of postprandial blood glucose in normal mice and its comprehensive influence on the alloxan-inducing diabetic mice were carried out to determine the physiological function of RS3. Furthermore, RS3 was added to wheat flour to produce functional biscuits and the quality of products were studied. The main research contents and results were as follows:1. Amylose and amylopectin of wheat starch were successively separated repeatedly n-butanol recrystallization,when they were respectively separated after 7 times and 10 times, the purity of amylose and amylopectin can reach 98 percent.2. The results showed that the optimum conditions of combination treatments to process wheat RS3 is that the concentration of starch 20%(W/V), microwaves processing(780W,150s), the adding amount of thermostable a-amylase 5 U/g dry starch, enzymolysis time 30 min, enzymolysis temperature 95 "C, retrogradation in condition of 4℃,24h. After centrifugation, smash and sift the sediment. Under this condition, when the content of amylose is 85%, The yield of RS3 reaches 39.8%.3. The physicochemical properties of RS3 were studied. The results showed that compared with native wheat starch, the water-holding capacity of RS3 increased; viscosity will not change under 95℃ as a result of no gelatinization happened at this tempreture; RS3 was highly resistant to digestion by amylase. The wheat granule structure was destroyed mostly and transformed into irregular pieces, which have rough surface and layer stucrure of crystal. The crystalline structure changed from A-type to a mixture of B and V-type when native starch changed to RS3, and no generation of new chemical groups occured during the formation of RS3. Simulative digestive experiment in vitro showed that the digestibility of RS3 was very low in artificial gastric and intestinal juice.4.The RS3 tests of postprandial blood glucose in normal mice and its comprehensive influence on the alloxan-inducing diabetic model mice showed that a proper amount of RS3 in diet can be effectively adjust animals’blood sugar level, which represented it has the function of peak load shifting.5. The results showed that the best formula of RS3 functional biscuits were as follows:the adding amount of RS3 20.0%, sugar 25%, vegetable oil 32%, swelling agent 1.6%. The biscuits with this formula had uniform colour and luster, and tasted delicious; and RS3 retention rate could reach 88% after high tempreture baked, which showed it had good processing stability. The application of RS3 in paste food had certain practical significance, and the product had better healthy functions. |
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