The Functionalities And Analysis Of Arabinoxylan And Starch Composite Polysaccharides

Native starches do not generally have ideal properties for the preparation of food products.Their unpredictable viscosity change and swelling during gelatinization,degradation of gel texture and mouth-feel during retrogradation are important factors in starchy food industrialization.Arabinoxylan is a hemicellulose mainly found in cereal grains,and it is consumed as low value-added forage for many years.To improve the viscosity and textural properties of starch gelatinization and retrogradation,in present study,the composite system of starch and arabinoxylan(AX)was studied.Different ratios and molecular characteristics of AXs were mixed with com starch,wheat starch and waxy com starch.Starch/AXs mixtures were studied in the systems of gelatinization,retragradation and film-forming.The combination and interaction of two polysaccharides were elucidated to understand the functions of AX in starch-based foods,and show the potential of AXs in food industry.Main results are as follows,1.The effect of different concentrations of CFG on the gelling and rheological properties of con starch:Comparing with the reference,CFG addition contributed to smaller peak viscosity and breakdown,but larger final viscosity in RVA measurement.The swelling power and the amount of leached amylose of maize starch gels were reduced as the addition concentration of CFG increased.Rheological parameters,inculuding storage modulus(G’)and loss modulus(G"),of the corn starches were observed to increase when CFG was present,supporting the hypothesis that the interaction between CFG and amylose could happen in the composite system.2.During the long-term storage,the addition of CFG significantly lowered the hardness and thermal retrogradation degree of the composite starch gel,restrained the syneresis of the starch system.The X-ray crystallization peak of starch containing 0.5-1.0%CFG was quite diminished.The starch gel alone showed the lowest rapidly digestible starch(RDS)content and the highest resistant starch(RS)content in comparison to starch/CFG composite gels.3.The effect of different molecular characteristics of CFG on the gelling and retrogradation properties of corn and wheat starch:CFG addition lowered peak viscosity and breakdown of com and,and increase of breakdown of wheat starch.The changes in RVA characteristics were more pronounced as the Mw of CFG increased.The amount of leached amylose of corn/wheat starch gels decreased as the Mw of CFG increased.CLSM confirmed changes in gel microstructure as starch components tended to be inhibited from leaching out of the granules.The inhibition was more obvious as the MH,of CFG increased.4.As for the blends of CFG/WCS,the addition of CFG lowered the peak viscosity of WCS.CFG slightly weakened the visco-elasticity of WCS gels,as either G’ or G" was decreased.Compared to corn starch film,the tensile strength of sarch/CFG composite film was less and the percentage of elongation at break was larger.The addition of CFG increased the solubility and water vapor permeability of starch film.The better hydrophilic ability of CFG/starch film indicated that composite film was more susceptible to water.5.Three carbohydrate-rich fractions were isolated and compared:Hemicellulose A(Heli A),Hemicellulose B(Hemi B)and cellulose-rich residue(CRF)from sorghum bran(SBR),sorghum bagasse(SBA)and sorghum biomass(SBI).Higher Ara/Xyl values in the Hemi.A and Hemi.B from SBR indicated a more branched structures.During the water holding capacity(WHC)measurement,both the drum and spray dried CRF from all three sorghum sources show high WHC.The emulsification study in oil-in-water emulsion system showed that the Hemi.B from all three sorghum sources had a better emulsion stability than the well-studied corn fiber gum(CFG).