Physicochemical and microbial changes in yogurts produced under different pressure and temperature conditions

Variations on fermentation conditions (temperature, pressure, etc.) can bring novel characteristics to fermentative processes and the respective final products. Regarding yogurt, both bacteria metabolism and physical properties of gel may be affected, resulting in different yogurts. Therefore, lactic acid fermentation was performed under different combinations of pressure (0.1, 10 and 30 MPa) and temperature (35, 43 and 50 degrees C), and microbiological and physical properties of the yogurts obtained were analyzed. Fermentation conditions affected the microbial growth, with Streptococcus thermophilus being more sensitive to the combination of high temperatures and pressures than Lactobacillus bulgaricus. Regarding physical properties, both syneresis and texture were influenced by fermentation conditions. Yogurts fermented at 10 MPa presented interesting features, with syneresis similar to control yogurts and a firm texture. Therefore, the feimentative conditions can be changed not only to regulate the fermentation kinetics, but also to produce a final product with different properties. Therefore, this approach opens the possibility of applying this type of strategy to a wide range of food fermentative processes, with potential to improve food quality and to create and develop food products with novel characteristics.