Effects of glucose glycation on structural and functional properties of limited enzymatic hydrolysates from brown-striped mackerel scad (Decapterus maruadsi) protein isolate

In order to explore the extended application of fish proteins and promote the high value utilization of brown-striped mackerel scad (Decapterus maruadsi), taking the brown-striped mackerel scad protein isolate limited enzymatic hydrolysate (BPILH) as raw material, we used glucose to conduct a glycation reaction to investigate the effects of different reaction time on the structural and functional properties of BPILH. The results show that glucose underwent glycation reaction with BPILH, and the degree of glycation reaction was positively correlated with reaction time and chromaticity. Structural properties results show that the glycation reaction reduced the α-helix and irregular coil content of BPILH and decreased its endogenous fluorescence intensity. In addition, high temperature treatment with long time during glycation reaction exposed the hydrophobic groups inside the protein molecules and increased their surface hydrophobicity. The solubility of glycation BPILH firstly increased and then decreased with the reaction time under acidic and alkaline conditions, in which the glycation solubility of product reached the highest value of (90.49±0.01)% at pH of 10 after 8-hour reaction. The emulsification of glycosylated BPILH increased with the reaction time. Comparied with the original mixture before reaction, the emulsification of the glycation product after 12-hour reaction increased by 24.28%, and both emulsification stability and oil-holding capacity showed an increase-decrease tendency with the reaction time, with the highest value of emulsification stability of (17.51±0.13) min at 1^st hour and oil-holding capacity of (2.19±0.21) g·g⁻¹ at 2^nd hour. The emulsification stability of glycation product increased by 24.28% with the reaction time. Therefore, long reaction time may have some negative effects on the functional properties, and this study provides theoretical references for the application of brown-striped mackerel scad protein isolate in food industry.