ACID GELATION OF HYBRID MIXTURES OF RECONSTITUTED MILK AND ALMOND PROTEIN

Developing fermented hybrid dairy products depends on the acid gel-forming ability of dairy and plant proteins mixtures. In this context, using glucono-delta-lactone (GDL) is an interesting strategy to explore the gelation behavior of protein mixtures during slow acidification, similar to the fermentation process. This study aimed to evaluate the gelation profile of mixtures of whole milk powder (WMP) and almond protein flour (APF) under slow acidification. WMP and APF were mixed maintaining 13% solids, with different ratios of WMP:APF protein content (100:00, 75:25, 50:50, 25:75 and 00:100). These mixtures were dispersed in water, homogenized (55°C, 200 bar), heat-treated (85°C/30 min), and cooled (30°C). After the addition of GDL (1.3%, w/v), the mixtures were placed in a water bath (30°C) and the acidification profile was monitored. The gels obtained were evaluated for water holding capacity (WHC) on the following day (representing firm yoghurt) and after stirring and stabilization for 24 hours (representing a stirred yoghurt). Additionally, the stirred gels were evaluated regarding the texture profile for consistency, firmness, viscosity index, and cohesiveness parameters. The results indicated that all mixtures (except 00:100, excluded from the study because it formed thermal gel at 85°C/30 min) had the same acidification profile, reaching pH around 4.9 after 300 minutes and forming firm gels. Firm gels had higher WHC than stirred gels, which decreased with the reduction of the dairy proportion in the protein network. Firmness, consistency, cohesiveness, and viscosity index were higher for the 25:75 mixture than the other mixtures. This behavior may be related to the lower WHC of the matrix with higher almond protein content. The results suggested that hybrid mixtures with different proportions of dairy and almond proteins have the potential to form acid gels. Future studies are needed to evaluate the fermentation of hybrid mixtures by lactic acid cultures.