| Thisarticle is talking about taking Castanea henryi starch as raw material, use superfine grinding, enzyme and heat-moisture combine treatment,or autoclave method to produce the denatured starch, and defining its main properties, focusing on the relationship of the composition, structure and physiological functions in the process of vitro digestion and fermentation and the changes of composition, structure and digestive properties in the process of produce and storage.(1) Effects of superfine grinding on physicochemical properties of Castanea henryi starch were studied. The results demonstrated that, along with prolonging the superfine grinding time, particle diameters, crystallinity degrees, dilatations, gelatinization temperature ranges and gelatinization enthalpies of C. henryi starches decrease, while their solubilities and enzymatic hydrolyzation rates increase. When the superfine grinding time is up to 60 min, starch granules are shattered to limit and their crystalline structures destroyed all become amorphous structures, which the gelatinization temperature ranges are from 35℃ to 62℃ and enzymatic hydrolyzation rates are beyond 70%. Moreover, when the superfine grinding continue to 75 min, more fine particles occur together, particle size of 0～5 μm of particulate matter decrease significantly, and particle size greater than 25 μm of large particles increase. Superfine grinding can also destroy the apparent structure and crystalline structure of starch granules into the amorphous type, which benefits the hydrolysis of various kinds of amylase. Therefore, the abilities of saccharification and alcohol fermentation of superfine grinding starch have been greatly improved.(2) Compound modified starches from Castanea henryi were made by enzyme and heat-moisture combine treatment, and the effects of enzyme dosage and reaction time on their physicochemical properties were studied. The results demonstrated that crystal types of compound modified starches belong to A type, they are low expected glycemic index (pGI) foods because of most pGI below 55%. By in vitro digestion dynamics analysis, scanning electron microscope (SEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), high performance anion-exchange chromatography with pulsed ampere detection (HPAEC-PAD), resistant starch (RS) content, molecular chain average degree of polymerization (DP), relative crystallinity and melting enthalpy of composite modified starches along with the change of enzyme dosage and debranching time characterize by three phases. Especially in the second phase, namely the enzyme dosage in 50-60 U/g and the reaction time within 12-16 h, RS content, relative crystallinity and melting enthalpy are maximum due to the molecular chain of DP value suitable to reaggregate to form stable crystalline structure.(3) Recrystallized starch from Castanea henryi was made by heat-moisture treatment, and the effects of storage conditions on its physicochemical properties were studied. The results demonstrated that, at storage temperature of 4℃, in vitro digestion kinetic parameters are obviously influenced, more resistant starch can be formed, average degree of polymerization of recrystallized starch arrives at the maximum at the fourteenth day, crystal type of recrystallized starch transits from type A at zero day into type V at the third and seventh day, type B at the fourteenth and twenty-first day, and the changes of relative crystallinities of recrystallized starch are very remarkable. At storage temperature of 25℃, larger influences of in vitro digestion kinetic parameters are achieved, more rapidly digested starch can be formed, average degree of polymerization of recrystallized starch reaches the top at the third day, crystal type of recrystallized starch always keeps type A, and the changes of relative crystallinities of recrystallized starch are not obvious. As comparison with the storage temperature of 4℃, there only arises the low temperature melting region, the melting enthalpies reduce more and the melting peak temperature differences decrease more prominent. At temperature-cycled retro gradation of 4/25℃, in vitro digestion kinetic parameters also are obviously effected, more slowly digested starch can be formed, average degree of polymerization of recrystallized starch attain the maximum at the seventh day, crystal type of recrystallized starch transforms from type A at zero day into type V at the third, type B at the seventh and fourteenth day, and tye V at the twenty-first day, and the changes of relative crystallinities of recrystallized starch are rapider. Compared with the storage temperature of 4℃, peak and conclusion temperatures of high temperature melting zones decrease more.(4) Resistant starches from Castanea henryi before and after in vitro digestion were made and purified. Their probotic functions and structural changes were intensively studied. The results demonstrated that these resistant starches before and after digestion have good proliferative effect (P<0.05) on bifidobacterium and lactobacillus, have significant inhibitory impact (P<0.01) on Escherichia coli and Clostridium perfringens, and have no obious influence (P>0.05) on Enterococcus faecalis and Corynebacterium fusifome. The increasing total acidities of fermentation liquids demonstrated that these resistant starches before and after digestion can be used by intestinal probiotics. Compared with resistant starch, digested resistant starches have increasing specific surface areas, and have more greater specific surface areas after in vitro anaerobic fermentation. In comparison with native starch, average degree of polymerization of resistant starch decrease significantly (P< 0.05). After fermentation, average degree of polymerizations of resistant starches before and after digestion decrease. Crystal type of resistant starch is type V, then turn into type B after digestion in vitro. After fermentation, crystal types of resistant starches before and after digestion all become type A, the degrees of microcrystalline, submicrocrystal and total crystallinity obviously decreased (P<0.05) compared with before fermentation. |
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