| Lactylation is a type of protein post-translational modification mediated by lactate.At present,the research of lactylation mainly focuses on histone,which has not been applied in food protein modification.Wheat gluten is a vegetable protein with high nutritional value produced during wheat processing.Its special three-dimensional network structure gives dough strong plasticity and occupies an important position in the food industry market.Therefore,in this paper,lactate and sodium lactate were used to modify wheat gluten by lactylation,so that the lactate group was connected to the lysine side chain of protein.Secondly,the effects of lactylation on typical functional properties of whrat gluten were analyzed.Then,from the perspective of microscopic conformation,the change trend of different structural properties was compared to explore the internal mechanism of lactylation on wheat gluten.Finally,in view of the important role of it in stabilizing the properties of dough,lactylated wheat gluten was applied to provide a new strategy for improving the quality of frozen dough’s deterioration.The main research contents are as follows:Firstly,lactate and sodium lactate were used to modify wheat gluten.The results of western blot showed that the modification sites mainly focused on gliadin and low molecular weight glutenin subunits(LGW-GS).After the lactylation,the solubility of wheat gluten increased from 0.05 mg/m L to 0.19 mg/m L and 0.21 mg/m L,respectively.Simultaneously,based on the the increase in solubility,the emulsifying property and foamability were significantly improved.The oil holding capacity of the lactylated wheat gluten increased from 0.83 g/g to 1.25g/g and1.44 g/g,respectively.The interaction between hydrophobic groups and lipids significantly enhanced the oil holding capacity.The viscoelasticity of gluten protein was significantly improved,and the storage modulus(G′)and loss modulus(G″)were significantly increased.After the lactylation,the weight loss rate of wheat gluten decreased from 78.73% to 71.53%and 72.58%,respectively,so wheat gluten formed a stronger and tighter network structure.Then,the structural properties of wheat gluten after lactylation were studied.After lactylation,β-turns were partially transformed into β-sheets.The contents of β-turns decreased by 5.86% and 12.94%,respectively,and the contents of β-sheets increased by 10.15% and11.49%,respectively.Tryptophan residues were in a more polar environment,with maximum absorption wavelength redshifted and fluorescence intensity reduced.The content of disulfide bond increased by 23.92% and 36.20%,respectively.The UV absorbance significantly increased and the tertiary structure of proteins obviously changed.The hydrophobic groups were buried and the surface hydrophobicity was reduced.The protein bands in high molecular weight regions were deepened,and wheat gluten molecules formed aggregates.The noncovalent interaction between the lactylated wheat gluten was enhanced,which promoted the formation of a more stable network structure.Finally,according to the deterioration of network structure in frozen dough by freezingthawing,lactylated wheat gluten was used to strengthen the gluten network.Compared with wheat gluten,the specific volume of steamed bread prepared with lactylated wheat gluten increased significantly.Specifically,after three freeze-thaw cycles,the specific volume of steamed bread with sodium lactate treated gluten increased by 18.34% compared with blank group and 5.73% compared with control group.The results of LF-NMR demonstrated that the lactylated wheat gluten could slow down the downtrend of the water-solid interaction caused by freeze-thawing,thus reducing the water mobility.Based on the observation of dough microstructure by CLSM,it could be seen that the protein-protein interaction in dough was enhanced by adding lactylated wheat gluten.A denser gluten protein network structure was formed. |
