Viability of lactic acid microflora in different types of yoghurt

BIROLLO, G.A.; REINHEIMER, J.A.; VINDEROLA, C.G.

FOOD RESEARCH INTERNATIONAL

ELSEVIER SCIENCE BV

Año: 2000 vol. 33 p. 799 - 805

0963-9969

The suitability of three culture media (Skim milk agar,M17 agar and MRS agar, incubated under aerobic and anaerobic conditions) to obtain total and di€erential counts of yoghurt bacteria, was assayed. A total of 25 samples of di€erent yoghurt types (set, skimmed set, drinking, and set with ``dulce de leche'') obtained with the culture IA, were used. The lactic micro¯ora viability was studied at 6C and 12C. Skim milk agar (aerobiosis) was the most useful medium for total and di€erential counts of Streptococcus thermophilus andC and 12C. Skim milk agar (aerobiosis) was the most useful medium for total and di€erential counts of Streptococcus thermophilus andC. Skim milk agar (aerobiosis) was the most useful medium for total and di€erential counts of Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus. Cell viability depended on the yoghurt type and the storage temperature. On the basis of a minimum value of 107 CFU gÿ1, the shelf life of yoghurts at 6C was longer than 60 days, with the exception of the drinking type (45 days). At 12C, shelf life was identical for the skimmed drinking yoghurt but lower for the other yoghurt types. Both the storage temperature and the yoghurt type should be taken into account when shelf life is speci®ed on the basis of the lactic micro¯ora content.subsp. bulgaricus. Cell viability depended on the yoghurt type and the storage temperature. On the basis of a minimum value of 107 CFU gÿ1, the shelf life of yoghurts at 6C was longer than 60 days, with the exception of the drinking type (45 days). At 12C, shelf life was identical for the skimmed drinking yoghurt but lower for the other yoghurt types. Both the storage temperature and the yoghurt type should be taken into account when shelf life is speci®ed on the basis of the lactic micro¯ora content.7 CFU gÿ1, the shelf life of yoghurts at 6C was longer than 60 days, with the exception of the drinking type (45 days). At 12C, shelf life was identical for the skimmed drinking yoghurt but lower for the other yoghurt types. Both the storage temperature and the yoghurt type should be taken into account when shelf life is speci®ed on the basis of the lactic micro¯ora content.C, shelf life was identical for the skimmed drinking yoghurt but lower for the other yoghurt types. Both the storage temperature and the yoghurt type should be taken into account when shelf life is speci®ed on the basis of the lactic micro¯ora content.