Combined effect of acidification temperature and different acids on microstructure and textural properties of heat and acid-induced milk gels

Heat and acid-induced milk gels, such as Indian Paneer cheese, can serve as a meat substitute in various cuisines due to their non-melting and cookable features. This study investigated the effects of acidification temperature (60, 70, 80, or 90 °C) and different acidifiers (citric, lactic, or hydrochloric acids) on the composition, texture, and microstructure of these gels. Across all acids, increasing the acidification temperature reduced the yield of gel due to lower moisture retention. However, the hardness, springiness, and cohesiveness of the gels increased with temperature, influenced by the rate of protein aggregation and calcium recovery. At high temperatures (e.g., 90 °C), gels prepared by citric acid exhibited greater hardness and cohesiveness, but lower springiness compared to those made with lactic or hydrochloric acid. This effect may be attributed to the formation of a more compact gel network, characterized by fewer pores, and lower water mobility.