Effect of dynamic high pressure on milk fermentation kinetics and rheological properties of probiotic fermented milk

This work studied the fermentation kinetics and the rheological behavior of gel formation during fermentation and storage. The milk (2% v/v fat) was subjected to conventional homogenization (15/5 MPa, control treatment) and dynamic high pressure (50/5 MPa, 100/5 MPa, 150/5 MPa and 180/5 MPa), and fermented by Streptococcus thermophilus in co-culture with Lactobacillus acidophilus. The results showed that dynamic high pressure (DHP) did not alter the fermentation kinetics (p > 0.05). However, the rheological behavior during fermentation showed that higher pressures increased the consistency. During storage, an increase of 15% in the consistency index (K') and a reduction of 31% in the gel syneresis were observed for samples processed at 180/5 MPa, as compared to the control ones (124.67 Pa.s(n'); 13.5%). After the 28th day, these differences increased up to 27% and 40%, respectively. It is concluded that DHP promotes an increase in consistency and reduction syneresis of fermented milk without changing the fermentation. Industrial relevance: The use of DHP allows to increase the consistency of probiotic fermented milk without the addition of any additive. Thus, the product would attend to the probiotic's consumer market which demands high quality products, with a reduced amount of fat (2%), high consistency and without addition of other ingredients. Furthermore, the DHP does not affect the product fermentation, which would facilitate its direct implementation in the industry. (C) 2014 Elsevier Ltd. All rights reserved.