Study On Preparation Of Resistant Digestion Sweet Potato Starch By Steam Explosion

In the process, steam explosion technology only need high temperature steam and don’t need to add any chemicals, and it can cause that materials occur a variety of chemical and physical changes. So, it is a more secure pretreatment method. In this study, it has researched molecular structure of sweet potato starch that was processed by steam explosion treatment. Based on single factor test, the response surface methodology was used to optimize the process conditions of product resistant starch by steam explosion treatment and the Study factor was anti-digestible starch. Then, analyzed the digestive characteristic of resistant starch that process by different treatments. Details are as follows:1. The electron microscope was used to scan sweet potato starch granule morphology that processed by steam explosion technology and we can know: a significant increase in particle size of sweet potato starch, formed many different sizes of block, starch particle shape almost disappeared, many cracks and ravines on particle surface and presented a very irregular lump or slug. The high performance gel filtration chromatography was used to detect sweet potato starch that processed by steam explosion technology and we can know: the molecular weight of treated starch will decrease with the increase of the pressure of steam explosion treatment and the time of steam explosion treatment. The peak area of the branched starch with longer chain length was gradually reduced. The short chain starch peak area of the chain is gradually increased. The infrared scanning pattern was used to analysis sweet potato starch granule morphology that processed by steam explosion technology and we can know: Sweet potato starch of being processed did not produce a new absorption peak, but the crystallization index of sweet potato starch was gradually increased with the increasing of pressure and steam explosion treatment. The laser particle size analyzer was used to analysis sweet potato starch granule morphology that processed by steam explosion technology and we can know: The diameter of sweet potato starch of being processed was significantly increased.2.Through single factor experiment, the process parameters of sweet potato starch of being processed by steam explosion technology processed resistant starch by autoclave method are as follows: Steam explosion treatment pressure2 MPa, Steam explosion pressure maintaining time is 60 s, hot pressing and starch concentration is 20 %, hot press time of 20 min, cold retrogradation time is 18 h. Through Box-Behnken central composite design and response surface, the optimum conditions steam burst pressure of sweet potato starch of being processed by steam explosion technology processed resistant starch by autoclave method is 2.1 MPa, The pressure time of steam explosion treatment was 62.37 s, and the heat treatment time was 21.35 min. Under the conditions for preparation of sweet potato starch resistant was 18.24 %±1.1 %.3. To research the Sample digestion characteristics through different methods of treatment showed that: in SE-SPS samples, the content of RS increased to 13.8 %, the content of RDS decreased to 57.8 %, the content of RS in AC-SE-AC-SPS sample increased to 30.1 % and the content of RDS decreased to 53.5 %. Experiments show that the nutritional quality of AC-SE-AC-SPS sample was improved greatly. SE-SPS sample rises more slowly than the rate of hydrolysis SPS samples. The rate of rise of more flatten after 30 min. This is because the resistant starch content of the starch samples after heat treatment increased significantly, so its anti digestion is stronger. SPS, SE-SPS sample and AC-SE-SPS sample prediction glycemic index are 70 or more, are high glycemic index foods, but the prediction of glycemic index of the SE-AC-SPS samples and AC-SE-AC-SPS samples. They belong to moderate glycemic index foods that can be added to foods for diabetics.