Study On The Hydrolysis Mechanism Of Starch Granule And Its Application In Microencapsulation Of Lycopene

Corn starch was hydrolyzed by α-amylase and glucoamylase mixture belowgelatinization temperature. Porous starches with similar degree of hydrolysis (DH) wereprepared by controlling hydrolysis time and enzyme concentration, and the different effects ofhydrolysis time and enzyme dosage on their physicochemical properties and structures wereanalyzed. Porous starches were used to embed the lycopene. The effects of differentembedding methods on stability of lycopene were compared. The stabilities of lycopeneembedded with the different porous starches were compared and analyzed.The capacities of oil absorption and the degree of hydrolysis were taken as indexes tooptimize the ratio of α-amylase and glucoamylase, and obtained the best ration was1:3. Bycomparing the capacities of oil absorption of these starches with similar DH, it was found thattheir capacities of oil absorption were different.By comparing the physicochemical properties of the starches with similar DH, the resultsindicated that the amorphous ring and the inner part of the starch granules hydrolyzed withlonger time were hydrolyzed more heavily and appeared a big cavity inside the granules. Theporous starches with more enzyme dosage were broken more seriously, and itssemi-crystalline region was hydrolyzed more than the former. With the DH increasing, theenthalpy and amylose content of those starches hydrolyzed with longer time were lower thanthe others.Methods, including vacuum filtration, dissolving by organic solvent, and spray dryingwere used to embed the lycopene. After one month, it was found that the products prepared bydissolving the lycopene in organic solvent showed the best stability, while those prepared byvacuum filtration showed the worst when they stored at room temperature and in scatteredlight. However, when they were kept at4℃andin dark conditions, the methods of vacuumfiltration and dissolving by organic solvent showed no obvious difference, and the method ofvacuum filtration even showed a better heat stability. It was probably that when the productsplaced at room temperature and in scattered light, the better stability of the products prepared by dissolving the lycopene in organic solvent was due to the preventive function of the porousstructure from the light.By comparing the protective effects of those porous starches with similar DH on thestability of lycopene, it was found that the starches with longer hydrolysis time showed abetter effect. Through the determination of the specific surface area, pore volume and porediameter, it was found that the specific surface areas of these samples with longer hydrolysistime were greater than the other group. This trend was contrary with that of the pore diameter.In conclusion, it was deduced that these starches with longer hydrolyzing time gave abiggerabsorption area for the lycopene. The structures of those starches with more enzyme dosagewere broken more heavily than the former. Those reasons may lead to the above results.