Design, synthesis and characterization of lysozyme–gentisic acid dual-functional conjugates with antibacterial/antioxidant activities

Both microbiological and chemical food spoilages remain to be the major challenges in the food industry's efforts to combat food waste and loss because of the lack of high efficacy food preservatives. In this study, dual-functional conjugates that simultaneously suppress both lipid oxidation and microorganism growth are fabricated by covalently conjugating natural antioxidant gentisic acid (GA) on native antibacterial lysozyme (Lys). The mixing ratio of Lys and GA determines the particle size, morphology, antioxidant activity, and antimicrobial performance of the ensuing conjugates. With more of GA being grafted, a drastic decrease in the net surface charge with the concomitant occurrence of aggregations are observed in the conjugates. The maximum antioxidant activity and antibacterial performance of the conjugates is achieved when Lys:GA molar ratio is 1:112. The findings could guide the rational design of future functional food ingredients that combine multiple natural bioactive compounds to effectively intervene food waste and loss.