The mechanism of alkali-induced rice protein gel formation: Effect of alkali concentration and temperature
The mechanism of alkali-induced rice protein gel formation: Effect of alkali concentration and temperature
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DOI：
10.1016/j.foodhyd.2023.109335
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发表时间：
2023-10
影响因子：
10.7
通讯作者：
Yaoyao Lian;Ya Li;Ruyan Lv;Lifeng Wang;Wenfei Xiong
中科院分区：
文献类型：
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作者：
Yaoyao Lian;Ya Li;Ruyan Lv;Lifeng Wang;Wenfei Xiong
大米蛋白（RP）是一种优质的低过敏性植物蛋白，但其极差的水溶性使其难以应用于液体食品体系。因此，深入探索其凝胶特性是拓宽RP应用场景的有效途径。在这项工作中，首先发现在25 °C下通过RP形成凝胶的速率和强度强烈依赖于碱浓度的增加（从0.05 M到0.125 M），即，高于0.075 M的碱浓度足以诱导10%（w/v）RP在0.5小时内形成稳定的凝胶。在碱诱导的RP凝胶形成期间增加温度（50 °C，80 °C）大大增加了凝胶形成的速率，而延长（>30分钟）的热处理导致凝胶液化。一个更深入的分析表明，碱能够在其天然状态下的团聚体内的谷蛋白脱乙酰化，从而在较低的碱浓度（CNaOH= 0.075 M）谷蛋白分子之间形成凝胶网络，主要是通过疏水相互作用。然而，较高的碱浓度（CNaOH= 0.125 M）导致暴露的游离巯基迅速转化为二硫键，从而发挥了主要贡献的凝胶网络，其次是氢键。此外，热诱导的凝胶液化的现象主要是由于谷蛋白亚基的解离，并伴随着在酰胺III区的蛋白质的无序结构的增加。这些研究结果可为大米蛋白凝胶食品的开发提供科学依据。
Rice protein (RP) is a high-quality hypoallergenic plant protein, but its extremely poor water solubility makes it difficult to be applied in liquid food systems. Therefore, in-depth exploration of its gel properties is an effective way to broaden the application scenarios of RP. In this work, it was first found that the rate and strength of gel formation by RP at 25 °C strongly depended on the increase in alkali concentration (from 0.05 M to 0.125 M), i.e., alkali concentrations above 0.075 M were sufficient to induce the formation of a stable gel by 10% (w/v) of RP in 0.5 h. Increasing the temperature during alkali-induced RP gel formation (50 °C, 80 °C) greatly increased the rate of gel formation, whereas prolonged (>30 min) heat treatment resulted in liquefaction of the gel. A more in-depth analysis revealed that the alkali was able to depolymerize glutelin within the agglomerates in its native state, thereby forming a gel network among glutelin molecules at lower alkali concentrations (CNaOH= 0.075 M) mainly through hydrophobic interactions. Whereas, higher alkali concentration (CNaOH= 0.125 M) resulted in the rapid transformation of exposed free sulfhydryl groups into disulfide bonds, thus exerting a major contribution to the gel network, followed by hydrogen bonding. Furthermore, the phenomenon of heat-induced gel liquefaction was mainly attributed to the dissociation of glutelin subunits and was accompanied by an increase in the disordered structure of proteins in the amide III region. These findings may provide a scientific basis for the development of rice protein gel foods.