Evaluation of aroma production and survival of Streptococcus thermophilus, Lactobacillus delbrueckii subsp. bulgaricus and Lactobacillus acidophilus in fermented milks.

摘要

The fat, SNF and inoculum size of L. acidophilus IPVR 224 were modulated according to a Central Composite Design. The aim was to evaluate the effects of these variables and their interactions on the decrease in pH during fermentation, the qualitative and quantitative composition of the aroma profile, as well as the loss in viability of S. thermophilus IPVR 161, L. delbrueckii subsp. bulgaricus IPVR 132 and L. acidophilus IPVR 224 strains during 5 weeks of storage. In addition, the overall acceptability of the cultured milks was assessed by means of a sensory panel. The polynomial quadratic equations obtained allowed the variables that significantly affected the aroma profile, organoleptic properties and microbiological counts of the various cultured milks to be determined. The survival of the L. acidophilus strain during storage was higher at low concentration of SNF and its presence did not affect the acetaldehyde content of cultured milks. From the response surfaces analysis it was possible toselect optimum conditions for enhanced positive organoleptic traits and for improved survival of the probiotic culture.