Optimization On Process Of Soybean Protein Peptide-Corn Starch Compound By Autoclave-Enzymatic Method And Its Properties

Resistant Starch(RS₃),also known as regenerated starch,is widely used in the food industry in recent years because of its low digestibility and similar function to dietary fiber,which can achieve the effect of reducing fat and losing weight.Moreover,it has a good market prospect because of its unique excellent processing quality.Due to the limited function of starch,and the rapid rise of human blood sugar value and other shortcomings,the preparation of resistant starch and the compound of polypeptide can improve the physicochemical properties of starch,reduce the digestibility of starch,make up for the deficiency of natural starch.In this paper,using corn starch as raw material,the resistant starch was prepared by pressing thermal-enzymatic method,in the process of the formation of resistant starch,it was synthesized with soybean protein peptide to form the soybean protein peptide-corn starch compound,and the changes in the properties of the compound were investigated.The main research results are as follows:1.Through single factor experiment and response surface optimization experiment,the best technology for preparation of corn resistant starch by autoclave-enzymatic method was determined.The results showed that:starch emulsion concentration was 5.10%,enzymatic hydrolysis temperature was 56.00?,p H value was 5.60,and enzyme dosage was 7.10U/g.Under these conditions,the yield of resistant starch was 58.15%.2.The soybean protein peptide-corn starch compound was prepared under the optimum technological conditions.The results of scanning electron microscopy showed that the appearance of corn starch was mostly ellipsoidal or polyangular,while the morphology of soybean protein peptide-corn starch compound was seriously damaged,which was a sheet structure of different sizes.The infrared spectrum results showed that the-OH of the infrared spectrum of the compound moved towards the low wave number,indicating that the molecular order of the compound was higher than that of the original starch.The results of XRD and solid state NMR showed that the crystal structure of corn starch was A-type,and the crystal structure of the compound changed to B+V type obviously after treatment.3.DSC results show that the melting temperature of the compound is up to126.81?,which indicates that the crystal disintegration temperature of the compound is very high,the crystalline structure is compact and the thermal stability is higher,and a very high temperature is needed to destroy the crystallization zone.The experimental results showed that the main interaction force between soybean protein peptide and corn starch was hydrogen bond.The results of in vitro digestion showed that the digestibility of the treated compound was significantly decreased,the content of resistant starch was significantly increased,and the resistance to enzymatic hydrolysis was gradually increased with the addition of soybean peptide.4.Solubility and swelling rate the experimental results showed that the solubility and swelling rate of corn starch at the same temperature were higher than that of compound,and the swelling rate was much higher than that of compound.The results of freeze-thaw stability showed that the water separation rate of the compound was significantly higher than that of corn starch,and the water separation rate of the compound tended to decrease with the increase of the addition amount of soybean protein peptide,which indicated that the soybean protein peptide had the properties of parents and could reduce the frozen water content in the system.The results of RVA test showed that the viscosity characteristic value of the compound was much lower than that of the original corn starch,and the RVA curve showed a straight line of approximately zero,which indicated that the structure of the compound was obviously different from that of the original corn starch,and it lost the gelatinization characteristics of the original corn starch.The results of iodine absorption curve and average degree of polymerization showed that the maximum absorption wavelength of the compound was smaller than that of corn starch,and the average degree of polymerization was significantly reduced.