Accumulation Of Storage Substances In Endosperm Of Adlay (Coix Lachryma-Jobi L.) Caryopsis And Its Effects On Starch Physicochemical Properties

Adlay,a medicine food homology plant,contains abundant nutrient components such as starch,protein,and fat,and while contains active compounds such as phenolics and coixin.In contrast to other cereals,adlay seeds are characterized by difficulty in gelatinization,which limits its applications on foods.Here,we used Adlay caryopsides as materials to study the accumulation of storage substances in the endosperm of Adlay.And we explored its effects on physicochemical characteristics of Adlay starch by removing protein and lipids.Then,the enzyme modification was carried out to improve the physicochemical and functional properties of starch.It was suggested that there were differences in accumulation period of starch,protein and crude fat.And the primary storage substances are the dominant factor leading to difficulty in gelatinization of starch.Additionally,enzyme modification affected the structural property and physicochemical property of Adlay starch to some extent.The following are the main contents and results:1.During endosperm development of caryopsis in adlay,the total starch,protein and crude fat content gradually increased.All three storage substances began to accumulate from 7 days after pollination.The content of total starch increased most from 14 to 21 days after pollination.Protein content increased at a constant rate during the whole development period,but was relatively slow from 21 to 28 days after pollination.And the content of crude fat increased most from 7 to 14 days after pollination.After 21 days of pollination,the endosperm of caryocephaly of Adlay was basically established and symmetrical.The microstructure showed that starch grains and proteins were increased with the extension of developmental time during endosperm development of adlay.There was the transition of starch grains from round to irregular shaped.And protein formed membrane-like structures that wraps around the starch grains during late development.2.The onset gelatinization temperature（To）,rapidly digestible starch（RDS）and resistant starch（RS）were decreased and slowly digestible starch（SDS）,gelatinization enthalpy（ΔH）were increased by removing protein in Adlay flour.The RDS,SDS content were increased and peak gelatinization temperature（Tp）and RS content were decreased by removing crude fat in Adlay flour.The solubility,swelling power,peak viscosity（PV）,trough viscosity（TV）,final viscosity（FV）and setback viscosity（SV）were increased and pasting temperature（PT）was decreased by removing protein and crude fat in Adlay flour.The swelling power,solubility,RDS and SDS were significantly increased and the ratio of the peak intensity of 1045/1022 cm^-1,PV,TV,breakdown viscosity（BV）and RS were significantly decreased by removing SGAPs and lipids in Adlay starch.The gelatinization transition temperature（ΔT）andΔH were significantly increased and the To was significantly decreased by removing SGAPs in Adlay starch.The effect of the removal of SGAPs on the short-range ordered structure and digestibility of starch was greater than that of the removal of lipids in Adlay starch.The thermal properties of adlay starch were not significantly affected by the removal of lipids,and the crystal type of starch was not significantly affected by the removal of SGAPs and lipids in Adlay starch.3.The morphology showed hollow porous structure and very weak Maltese cross of enzyme-modified starches.The results revealed the increase of amylose content,swelling power,solubility,transparency,SDS content and the decrease of relative crystallinity of enzyme-modified starches.Moreover,the hollow and fragmented phenomenon of starch granules was serious at TG-12 h.TG-12 h had highest relative crystallinity and SDS content and lowest enthalpy value and RS content.The ratio of 1045/1022 cm^-1 of enzyme-modified starches showed a generally increasing tendency,peaking at TG-16 h,whereas 1022/995 cm^-1 reached its lowest at TG-16 h.There was little overall change at average chain length of amylopectin.The relative proportion of A chain and B1 chain were reduced,while that of the B2 chain and B3 chain were relatively higher.Overall,there was little overall change at average chain length of amylopectin.