关键词: 米谷蛋白, 热聚集, 高压微射流, 理化性质, 乳化性能

Abstract: In this study, natural rice glutelin was modified by acid-heat treatment (pH 2.0, 90 ℃ for 30 min). As a result, we obtained fibrous protein aggregates, and we further treated the protein aggregates by high pressure microfluidization (HPM) at different pressure levels (35, 70, 105 and 140 MPa). The samples without heat or high pressure treatment were used as a control. The effects of high pressure treatment on physicochemical properties were investigated by comparing the morphology, particle size, ζ potential, surface hydrophobicity, sulfhydryl content, thermal properties, rheological properties, emulsifying properties and secondary structure of the treated and untreated samples. The results showed that after HPM treatment, the structure of the protein aggregates became loose, and the particle size increased from (146.93 ± 1.04) to (184.77 ± 4.82) nm. The total sulfhydryl content increased first and then decreased, and so did the emulsifying capacity and emulsion stability, at 70 MPa reaching a maximum of (30.08 ± 0.75) m2/g and (150.58 ± 2.03) min, respectively. Small changes were observed in ζ potential and surface hydrophobicity, but thermal stability and apparent viscosity were affected by HPM treatment. The secondary structures of α-helix and β-turn increased, while β-sheet reduced. Lower pressure could result in further protein aggregation, and higher pressure could lead to depolymerization. The sample modified by 70 MPa treatment had good emulsifying properties and thermal stability.

Key words: rice glutelin, thermal aggregation, high pressure microfluidization, physicochemical properties, emulsifying properties