(335c) Production of Yogurt from Goat Milk in Agitated Conditions

Yogurt is traditionally produced in non-agitation conditions, mainly to allow a proper gel formation. The classic process involves milk fermentation by lactic acid bacteria in the vessels were the product will be finally sold. The use of non-agitated small vessels is also possible. For liquid formulations, or mixed with fruit formulations, mixing is applied after fermentation. Nowadays, most of the yogurt produced is consumed in a liquid form. For this product presentation, gel formation is not critical characteristic. In this communication, we report a process for fermentation of goat milk to produce yogurt in agitated conditions in a 5 L stirred tank bioreactor. Lactobacillus lactis and Streptococcus thermophilus were used as fermenting bacteria. Two different temperature and agitation levels in the laminar regime are tested. Curves of pH, viscosity, and lactic-acid bacteria population are presented for each one of the four process conditions tested. Results are compared versus those observed for non-agitated conditions. Mixing reduces considerably processing time, without apparent sacrifice of organoleptic properties.