pH值碱性偏移结合热处理对米糠蛋白结构和功能性质的影响

研究pH值碱性偏移（pH 11）结合热处理（50、60 ℃）对米糠蛋白结构和功能性质的影响。结果表明，pH值碱性偏移促使米糠蛋白二级结构由有序向无序转化，pH值碱性偏移结合热处理使得米糠蛋白二级结构呈现折叠-去折叠-复折叠的复杂变化，并伴随巯基氧化。pH值碱性偏移促使米糠蛋白展开，随着处理时间的延长，米糠蛋白重新聚集，热处理会加剧聚集程度。pH值碱性偏移使得米糠蛋白持水性、起泡性、泡沫稳定性、乳化性和乳化稳定性显著下降，仅持油性显著改善；随着处理时间的延长，米糠蛋白持水性、起泡性、乳化性和乳化稳定性逐渐上升，其中乳化性上升幅度最大。pH值碱性偏移结合热处理可显著改善米糠蛋白的持水性、起泡性、泡沫稳定性和乳化稳定性，同时也会降低米糠蛋白的持油性和乳化性。

Effect of Alkaline pH-Shifting Combined with Heat Treatment on the Structural and Functional Properties of Rice Bran Protein

The effects of alkaline pH-shifting(pH 11)combined with heat treatment(50 and 60℃)on the structural and functional properties of rice bran protein were investigated.The results indicated that the secondary structures of rice bran protein were transformed from an ordered state to a disordered one by alkaline pH-shifting treatment.Alkaline pH-shifting combined with heat treatment led to complex changes in the protein’s secondary structures from folding to unfolding to refolding,which was accompanied by oxidation of sulfhydryl groups.Alkaline pH-shifting treatment resulted in unfolding of rice bran protein.As the treatment time increased,the protein re-aggregated,which was aggravated by heat treatment.Alkaline pH-shifting treatment resulted in a significant decrease in the water-holding capacity,foaming capacity,foam stability,emulsifying activity,and emulsion stability of rice bran protein,but a significant improvement in the oil-holding capacity.As the treatment time increased,the water-holding capacity,foaming stability,emulsifying activity,and emulsion stability gradually increased,with the emulsifying activity showing the most significant increase.Alkaline pH-shifting combined with heat treatment could significantly improve the water-holding capacity,foaming capacity,foam stability and emulsion stability of rice bran protein while reducing its oil-holding capacity and emulsifying capacity.