Impacto da suplementação de farinhas roxas no processo fermentativo de iogurte de leite de cabra

Abstract

Goat milk yogurt, in particular, offers unique nutritional benefits and greater digestibility, making it an attractive product for consumers seeking alternatives to cow milk yogurt. The global demand for functional dairy products has driven innovations in yogurt formulations, including the incorporation of plant-based additives to enhance nutritional and sensory properties. In this context, this study evaluates the effects of adding purple flours (açaí, beetroot, and hibiscus) on the fermentation dynamics, growth kinetics of lactic acid bacteria (LAB), acidification, apparent viscosity, and sensory acceptance of goat milk yogurts. Four formulations were prepared: a control yogurt without flour (CGY) and yogurts enriched with açaí flour (AGY), beetroot flour (BGY), and hibiscus flour (HGY). The results demonstrated that beetroot and hibiscus flours significantly increased the maximum cell concentration of LAB, accelerating fermentation efficiency and acidification. Regarding pH, açaí flour (AGY) resulted in a more basic pH or one equal to the control. However, its stability provided a yogurt comparable to the control for most of the fermentation period, finishing with a less viscous product than the control. Meanwhile, HGY exhibited the lowest pH (4.53 ± 0.07), and BGY displayed the highest apparent viscosity (187.23 ± 2.96 mPa·s), indicating improved fermentation processes and enhanced textural properties. Through the growth curves, substantial LAB growth was observed in all treatments analyzed. Considering microbial counts, AGY showed lower values compared to the control in the final product. Thus, açaí flour (AGY) was not suitable for improving the microbial and physical quality of the yogurt compared to the control. The differences between treatments indicate that, by using these flours, it is possible to adjust both the acidity and texture of the yogurt according to formulation preferences, where hibiscus contributes more to acidity, beetroot to firmer texture, while açaí worsened microbial and rheological parameters in the final yogurt. The sensory evaluation highlighted the acceptance of açaí flour yogurt due to its balanced flavor and visual appeal, while beetroot and hibiscus flour yogurts offered superior textural improvements. These findings suggest that purple plant flours, particularly beetroot and hibiscus, can serve as functional ingredients in goat milk yogurts, improving microbial growth, acidification, and texture, while offering innovative opportunities to meet consumer demand for functional dairy products.