Preparation Of V-type Porous Starch And Its Application In The Inclusion Of Curcumin

Porous starch is a kind of modified starch with porous structure and excellent adsorption and slow-release properties.However,the traditional porous starch is generally prepared by enzymatic hydrolysis of raw starch,which is inefficient and insoluble in water,which restricts the application of porous starch.V-type granular starch(VGS)is soluble in cold water,has granular morphology and V-type single spiral cavity structure.It is a potential good raw material for preparing porous starch.Therefore,the catalytic activities of?-amylase and glucoamylase in ethanol solution were studied first,then VGS was prepared by ethanol aqueous heat treatment,and a new type of V-type porous starch(VPS)was prepared by enzymatic hydrolysis of VGS in ethanol solution.The reaction conditions were optimized,and the optimized VPS was used to encapsulate curcumin.The research results are as follows:Firstly,the optimum reaction temperature and temperature stability of?-amylase and glucoamylase in ethanol aqueous solution with different concentrations were studied.The results showed that the catalytic activity of?-amylase and glucoamylase in ethanol aqueous solution was inhibited to some extent.Under the lower alcohol concentration(40%,50%,60%),they could keep more than 80%of enzyme catalytic ability,and with the further increase of ethanol concentration,the enzyme activity continuously decreasesd.When the ethanol concentration reached 90%,the enzyme activities of the two enzymes could only keep about 30%.When the ethanol concentration was more than 60%,the optimum reaction temperature increased from 25?to 45?.After incubation for 6 h at the optimum reaction temperature,both enzymes had high stability.Secondly,VGS was prepared in 50%,60%and 70%ethanol respectively,and the reaction conditions were optimized with the adsorption capacity of VGS as an index.The results showed that the oil absorption rate of starch was positively correlated with the relative crystallinity of V-type crystals.With the increase of ethanol concentration,higher ethanol concentration might inhibit the formation of starch-ethanol complex,and the relative crystallinity and oil absorption rate of V-type crystals decreased.The optimum conditions for preparing VGS under three kinds of alcohol concentrations were 50%ethanol,reaction temperature 100?,the highest oil absorption rate of VGS(VGS-E50%)was 176.23%.In60%ethanol,130?,the highest oil absorption rate of VGS(VGS-E60%)was 150.62%.In70%ethanol,reaction temperature 140?,the highest oil absorption rate of VGS(VGS-E70%)was 149.79%.Then,the optimized VGS with 50%,60%and 70%ethanol concentration were hydrolyzed to explore the effects of hydrolysis time,temperature and reaction speed on the hydrolysis degree and adsorption performance of the prepared porous starch.With oil absorption rate as the index,the orthogonal experiment was carried out to optimize and verify the best process of preparing VPS with different ethanol concentrations.The optimized result showed that VPS(VPS-E50%)prepared by enzymatic hydrolysis of VGS prepared from VGS-E50%at 300 r/min,25?and 4 h had the highest oil absorption rate of 550.28%.The VPS(VPS-E60%)prepared by enzymatic hydrolysis of VGS-E60%at 200 r/min,40?for 5h had the highest oil absorption rate of 420.56%.The VPS(VPS-E70%)prepared by enzymatic hydrolysis of VGS-E70%at 500 r/min,40?and 12 h had the highest oil absorption rate of 289.36%.The properties of VPS optimized under three kinds of alcohol concentrations were analyzed and compared,and A-type porous starch(APS)prepared by traditional methods was used as control.X-ray diffraction images showed that V-type crystals were retained and the relative crystallinity increased after VGS enzymatic hydrolysis.The results of SEM showed that the holes on the surface of VPS were dense and irregular,showed a honeycomb network structure.Through the comparative analysis of oil absorption rate,specific surface area and bulk density,it was found that VPS-E50%showed the highest oil absorption rate(550.28%),specific surface area(39.94 m~2/g)and the smallest bulk density(0.19 g/cm~3),which was far superior to APS.Finally,porous starch curcumin inclusion complex was prepared by loading of curcumin on porous starch with 50%ethanol concentration.The effects of adsorption time,ethanol concentration and curcumin addition on the properties of the inclusion complex were studied.The orthogonal test was carried out with the loading capacity and loading adsorption rate as the preparation method.The optimal preparation process of the inclusion complex was obtained as follows,2 h,10%ethanol concentration,52 mg curcumin was added,the loading capacity and loading adsorption rate of V-type porous starch for curcumin reached the maximum value,namely 49.06 mg/g and 94.32%.The results of optical property analysis,SEM,DSC and FTIR showed that the binding mode of V-type porous starch to curcumin was both adsorption and embedding,and the adsorption capacity was much greater than the embedding ability.Curcumin coule be released slowly in the inclusion complex by simulating the release of SGF and SIF.DPPH radical scavenging ability showed that porous starch could retain its antioxidant capacity after curcumin adsorption.