挤压物料水分对白酒糟醇溶蛋白性质的影响

Extrusion Material Moisture on the Property of Prolamins from Distiller's Grains

本文通过单螺杆挤压机改性白酒糟(Distiller's grains,DGs),研究了挤压物料水分(21%、24%、27%、30%、33%)对白酒糟醇溶蛋白(Prolamins from distiller's grains,PDGs)理化(溶解度、表面疏水性、巯基和二硫键含量)、功能(持水、持油能力)和二、三级结构等性质的影响。结果表明,不同挤压物料水分对PDGs改性效果具有显著影响,随物料水分增加,挤压对PDGs天然结构的破坏程度逐渐增大,分子构象的改变促进内部亲水基团的暴露和二硫键的生成,物料水分为27%时,溶解度提高了1.56倍,达到34.75%,表面疏水性降低了56.11%,增强了持水能力,热变性温度由96.79℃增大到102.53℃,热稳定性更强,PDGs经变性重排后,蛋白聚集体有序程度增加。而物料水分过高时(高于27%),挤压造成PDGs过度变性,稳定聚集态的破坏反而会弱化其亲水、热特性、有序程度等,说明挤压物料水分对PDGs性质的改变具有十分重要的调控作用。

In this study,a single-screw extruder was used to extrude distiller's grains(DGs)and the effect of extrusion material moisture(21%,24%,27%,30%,33%)on prolamins from DGs(PDGs)was studied by measuring the physicochemical(solubility,hydrophobicity,sulfhydryl and the disulfide bonds contents),functional(water and oil holding capacities)and secondary and tertiary structure properties.The results showed that the modification effect of PDGs was significantly affected by different extrusion material moisture.The damage degree of the natural structure of PDGs was increased gradually with the increase of extrusion material moisture,and the change of molecular conformation promoted the exposure of internal hydrophilic groups and the formation of disulphide bonds.The solubility was increased by 1.56 times to 34.75%,the surface hydrophobicity was reduced by 56.11% at 27% extrusion materials moisture,and the water holding capacity was enhanced accordingly.The thermal denaturation temperature was increased from 96.79℃ to 102.53℃,indicating the thermal stability was stronger.The order of protein aggregates increased after the denaturation rearrangement of extruded PDGs.Extrusion led to excessive degeneration of PDGs when the material moisture was too high(higher than 27%),and the destruction of the stable aggregation state would weaken the hydrophilicity,thermal property and order degree of PDGs,indicating that the extrusion material moisture played a very important role in regulating the variation of PDGs properties.