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• Food Chemistry •     Next Articles

L-Histidine Modifies the Structure thereof and Heat-induced Gel Properties of Whey Protein

2, 2, 2,Mei-gui Huang   

  • Received:2020-01-28 Revised:2021-01-15 Online:2021-03-25 Published:2021-03-22

Abstract: L-Histidine (L-his) used as a functional enhancer of protein gels, was added to whey protein isolate in aqueous solutions to prepare heat-induced gels. The effect of L-his on the structure thereof and gel properties of whey protein were investigated. The results show that the protein aggregates with a size of ~1700 nm and a smaller specific surface area were formed at the isoelectric point (pI 5.2) of whey protein. However, the aggregate size was ~400 nm when pH was diverted from the pI. L-His inhibits whey protein aggregating, suppresses aggregate size but dramatically increases its specific surface area, and also promotes the unfolding of whey protein single molecules when the pH of samples beyond pI. Whey protein formed a heat-induced white gel at the pI with a low water holding capacity (WHC), whereas the gels formed at other pHs were yellow and the tendency towards yellowness was increased as pH far away from the pI, and the WHC was also significantly improved (P<0.05). L-His effectively enhanced the textural properties of gels. Typically, the elasticity and chewiness of the gel that formed at pH 7.59 and pH 9.74 were significantly improved (P<0.05). These changes of gel functional properties could be mainly ascribed to L-His impelling the rearrangement of hydrogen bonds, disulfide bridges and hydrophobic interactions involved the gel matrix. Overall, L-His changes the structure of whey protein and improves the gel properties but also was affected by pH.

Key words: whey proteins, pH, L-histidine, structure, gel properties

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