Optimization of wet heat conjugation method for heat stability improvement of whey protein

Whey protein is known for its excellent emulsifying capacities. However, its industrial application is still limited due to the instability of heating treatment. Dry heat conjugation of whey protein with carbohydrate improved its heat stability. Nevertheless, the method required hours to days of incubation. Hence, it is considered less efficient industrially. Wet heating generally boosts the conjugation of protein and carbohydrates by providing more water to allow protein-sugar interaction. This study aims to investigate the effectiveness of the wet heat conjugation technique to enhance the heat stability of whey protein with shorter incubation time than the dry method. To this end, whey protein concentrate was wet heat incubated with its innate lactose at different temperatures and durations. The incubated WPC was then applied in oil-water-emulsion, followed by heating the emulsions to evaluate their heat stability. The results indicated that the wet heat conjugation method was only capable of increasing the heat stability of whey protein to a limited extent. The particle size of the heated emulsions was smaller than that of control (native WPC), although it was still higher than the unheated emulsions. The wet conjugation technique used in this study was more effective at inducing protein aggregation compared to protein-lactose conjugation.