High Pressure Homogenization as alternative to thermal treatment to improve the microbial safety, shelf-life and functionality of milk and milk products.

High pressure homogenization (HPH) is one of the most promising alternatives to traditional thermal treatment for food preservation and diversification. In order to evaluate de potential of milk treated by HPH for the production of fermented milks carrying probiotic bacteria, four types of fermented milks were manufactured (using Streptococcus thermophilus and Lactobacillus delbruekii subsp. bulgaricus as starters): HPH- (from HPH treated milk), P- (from pasteurized milk), HPH-P- (HPH treated milk plus probiotics) and P-P- (pasteurized milk plus probiotics) fermented milk. Microbiological, physicochemical and organoleptic analysis was carried out during the refrigerated period (35 d ) at 4ºC. The use of HPH applied to milk did not modify, with respect to the traditional products, the viability of the probiotic cultures whereas increased the cell loads of the starter cultures (ca. 1 log order). The coagula from HPH treated milk resulted significantly (P < 0.05) more compacted (higher firmness) than the one obtained with only pasteurized milk, and it was characterized by the highest values of consistency, cohesiveness and viscosity indexes with respect to the fermented milks produced from milk without HPH treatment. In relation to the sensory analysis, all the samples received high scores for each descriptor considered, and were judged then of presenting high quality. The HPH treatment of milk can have a potential of diversifying the market of probiotic fermented milks, especially in terms of texture parameters