Development and acceptance of freeze-dried yogurt “powder yogurt”

Yogurt is the most popular fermented milk product all over the world, but its shelf life is still relatively low when compared to other dairy products. In this context, freeze dryingis a suitable toolto extend yogurt shelf life. This technology consists of drying the product through sublimation at low temperature and pressure, maintaining the nutritional, microbiological, and sensory characteristics, and resulting in a dry product that rehydrates easily.This study aimed to make a comparative study of the physicochemical, microbiological, and sensory characteristics of the traditional yogurt and rehydrated freeze-dried yogurt. The samples were characterized for moisture, aw, ash, acidity, pH, carbohydrates, texture, lipids, protein, and metabolizable energy, they were also analyzed microbiologically to detect lactic bacteria survival and sensorial acceptance analyzes, the Tukey’s test at 5% of significance level was used for the detection of differences between means. The results showed a higher concentration of nutrients in the rehydrated product,since a lower amount of water was usedfor rehydration when compared to the water lost duringfreeze drying,aimed to obtain a more nutritious product with similar texture to the traditional yogurt.The microbiological results showed that the rehydrated yogurt kept the number of lactic acid bacteria above the values required by Brazilian law. Finally, the results of sensory evaluationevidenced that the rehydrated yoghurt had greater acceptance than the traditional yogurt, possibly due to the concentration of compounds which positively affected aroma and flavor. Therefore,it can be concluded that the rehydrated freezedried yogurt produced in this study met all recommendations of the Brazilian legislation for fermented milk products, and can be a promising marketing alternative for the dairy industry, since it is a differentiated product with greater acceptance, nutritional value, and shelf life when comparedwith the traditional yogurt.