Effects of single-mode microwave heating and dextran conjugation on the structure and functionality of ovalbumin-dextran conjugates.

The proteins modified with carbohydrates through the glycation reaction are capable of changing and improving the functional properties of proteins. In this study, dextran was conjugated to ovalbumin (OVA) by traditional wet heating (WH) or single-mode microwave heating (MH) to improve the functional properties of OVA. Compared with traditional WH, MH for 15-60 min significantly increased the grafting degree (GD). The emulsifying activity and emulsion stability of the OVA-dextran conjugates improved under both traditional WH or MH (p < 0.05), especially under MH at 90 ℃ for 20 min. Correlation analysis showed that the emulsifying activity was positively correlated with surface hydrophobicity (p < 0.05), and emulsion stability was significantly positively correlated with surface hydrophobicity (p < 0.01) and positively correlated with the β-sheet contents (p < 0.05). Moreover, traditional WH and single-mode MH treatment could decrease tan δ, especially MH at 90 °C for 20 min. High GD and long MH treatment (≥25 min) resulted in a significant decrease in ⍺-helix and an increase in β-turn and γ-random coil. The secondary structure of OVA became loose, which was disadvantageous to the thermal stability of the OVA-dextran conjugates. In conclusion, compared with traditional WH, dextran conjugation with OVA via single-mode MH was an effective and safe way to improve the utilization value of OVA.