Preparation, Physicochemical Properties And Application Research Of Chinese Chestnut Starch

RS3, which is called dietary fiber, has been a major ingredient of our diet. And its functions in human body and excellent food processing characteristics in food processing make it valuble in research. The study used Chinese chestnut starch as materials, modifying them in the way that pressure-heating treatment recombined pullulanase enzymatic hydrolysis for deep development and utilization. It begined with optimizing the processing parameter of RS3, and then evaluated the samples’difference on structure, physicochemical properties and digestibility. Considering the application, this study discussed the addition of resistant starch in noodles.Based on the content of modified resistant starch, Box-Behnken response surface method was used to optimize pressure-heating treatment recombined pullulanase enzymatic hydrolysis. The optimum preparation conditions were achieved as follows:starch suspension mass fraction of 11.00%, pullulanase adding amount of 9 PUN/g, enzymatic hydrolysis time of 10 h and cooling time of 15 h. Under above conditions, the yield of the chestnut resistant starch reached 64.90%, which was close to the predicted value(65.70%). The anti-enzymatic property of resistant starch was measured and the results showed that the degestbility of resistant starch in stomach is 2.18%, compared with the native starch, fell by 2.42%. It is 2.68% in small intestine, fell by 7.92% in comparision with native one. Above the results, we can com firm that RS3 symbolized certain anti-enzymatic function.Observed by scanning electron microscope (SEM), Chinese chestnut starch granule showed round, elliptical, irregular, kidney and oval shape with smooth surfaces. Which are mainly concentrated in the range of 6.0～7.2 μm diameter. But after modification, its structure resembled spongy structure without rules, leading to adhesion and the loss of granular appearance, we could clearly see the pore channels on the surface. By X-ray diffraction analysis (XRD), we found strong peaks at diffraction angles of 2θ= 5.65°,17.2°,22.0° and intermediate intensity peaks at 2θ=15.0°, 24.0°, indicating a C-type crystallinity. After modification, diffraction angle and diffraction peak position were changed, we found a single peak at diffraction angles of 2θ=17.2°, and a small peak at 2θ=22.2°, indicating a B-type crystallinity. By the Differential Scanning Calorimeter (DSC). It suggested that there was a strong endothermic peak at 64.8℃. The onset temperature(To) was 61.0℃, peak temperature (Tp) was 64.8℃, conclusion temperature(Tc) was 69.5℃, the enthalpy was 1.3 J/g. After modification, the To, Tp, Tc and □H of RS3 changed a lot. There were 2 peaks in the range of 30 to 100℃, including an exothermic peak at 40.8℃ and an endothermic peak at 97.3 ℃. The exothermic transition of To, Tp, Tc and △H was 38.4℃,40.8℃,43.6℃ and-0.8 J/g, while the endothermic transition of To, Tp, Tc and AH were 96.5℃,97.4℃,99.3℃ and 0.1 J/g, incredible higher than native one. This indicated RS3 has a higher stability when standed heat.In terms of physical and chemical properties. Swelling power, transparency, freeze-thaw stability and viscosity property of starch paste were studied.The results showed there was a decrease of RS3 in swelling power, water solubility index and freeze-thaw stability due to the hydrolysis and thermal process. But the transparency of RS3 increased as a result of the destruction to the integrity of linear and branched chain. Besides the above results, under certain conditions of temperature, the apparent viscosity of chestnut starch and resistant starch solution are negative correlated with its speed, but after modification, resistant starch viscosity is lower than the original starch.According to the above features, the resistant starch was added to the noodles. And the fomula was as follows:wheat flour 100 g, chestnuts RS34 g, distilled water 50 g, salt 1 g. Simple formula can reduce the interference of other factors on the experiment. Compared with samples without adding them, the noodles with 4% RS3 was measured in the properties of sensory evaluation of the quality, texture profile analysis(TPA), as well as blood glucose measurement index.The results showed noodles with RS3 obviously lowered EGI and benefit patients of obesity and diabetes.Therefore it can be added in foods.