Effects Of Main Non-starch Nutrients In Acorns On Physicochemical And Digestive Properties Of Starch

Acorn is a general term that refers to the obsolete family of chestnuts except chestnut shells.Acorn lacks effective development and utilization,and there are few studies on the multi-scale structure of acorn starch and the effects of non-starch nutrients in acorn on the physicochemical properties and in vitro digestibility of starch.In this paper,liaodong oak(Quercus wutaishanica.Bl.)and variabilis(Q.variabilis.Bl.)were selected as raw materials to explore their related properties,which provided theoretical basis for the development of acorn food.The main results are as follows:(1)In terms of main nutritional components,except for the fat content of Q.variabilis,which was higher than that of Q.liaotungensis,the contents of total starch,protein and dietary fiber showed insignificant difference.The average chain length distribution of amylopectin from Q.liaotungensis was DP27.3,significantly higher than DP22.1 from Q.variabilis.The amylose content of Q.liaotungensis and Q.variabilis was 25.91%and32.70%,respectively.The molecular weight dispersion of acorn starch is at a very low level among vegetable starches.There is no obvious difference in the morphology of the two acorn starch particles,and the particle size of the particles is ranged between 3～30μm.Both acorn starches are C-type and the relative crystallinity are 24.31%(Q.liaotungensis)and 25.92%(Q.variabilis).(2)Deprotein treatment increased the amylose content,while degreasing and dedietary fiber treatment decreased the amylose content.The aggregation phenomenon between starch particles and the adhesion of the particle surface have been changed obviously after different treatments.The degreasing,deproteinization or dietary fiber removal did not cause changes in the acorn crystal form,but the relative crystallinity decreased to varying degrees.In terms of thermodynamics,the onset temperature(T_o)is the most sensitive to different treatments,and the trend of change is consistent with decrease of crystallinity.(3)Acorn endogenous fat,protein,and dietary fiber inhibit starch digestibility to a certain extent,and follow the order of fat?protein?dietary fiber.The correlation analysis also showed that there was a significant positive correlation between crystallinity and peak temperature(T_p)(r=0.724,P?0.05);there was a significant negative correlation between amylose and resistant starch(r=–0.691,P?0.05).RS also showed a significant negative correlation with the enthalpy of gelatinization(r=–0.783,P?0.01)and transition temperature(r=–0.864,P?0.01).