Abstract

Probiotic yoghurt belongs to a group of products known as functional foods and has an increasing importance in human nutrition nowadays. The chemical and physical properties of raw cow's milk for production of probiotic yoghurt had the following average values: milk fat (3.70%), proteins (3.25%), lactose (4.45%), non-fat dry matter (8.37%), freezing point (-0.517 °C), titratable acidity (6.12 °SH) and pH (6.65). After the standardization of milk fat and addition of skim milk powder, the milk was with the following parameters: milk fat (1.00%), proteins (3.47%), lactose (4.51%), non-fat dry matter (9.00%), freezing point (-0.520 °C), titratable acidity (6.32 °SH) and pH (6.64). The paper examined the dynamics of titratable and active acidity, as well as the sensory properties of probiotic yoghurt using 3 types of starter cultures (ABT 6, ABT 10 and ABT 21), produced in Chr. Hansen, Denmark. These starter cultures, were composed of bacteria Lactobacillus acidophilus LA-5, Bifidobacterium ssp.BB-12 and Streptococcus thermophilus ST, in different ratios. The studies were conducted on the 1, 7, 14 and 21 day. The titratable acidity of the yoghurt ranged in intervals between 28.55-29.18 °SH on the first day of the trials and reached values of 34.29-36.10 °SH after a 21 day storage. The pH value ranged between 4.45-4.48 (1 day) and reached 4.04-4.14 units (21 days). The lowest post-acidification and best sensory properties of the final product were determined in the variant yoghurt produced with the starter culture ABT 10.

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