Production of lactose-free probiotic yoghurts for lactose-sensitive people

Fermented milk products, for example yoghurts contain less lactose than the ordinary milk, however, this quantity of lactose can cause lactose intolerance. The aim of the work was to produce lactose free fermented milk products based on the lactose hydrolysed milk. Products were fermented with Streptococcus thermophilus, Lactobacillus delbrueckii subsp. bulgaricus (N 71) and Bifidobacterium bifidum (N 1), Lactobacillus helveticus (N 43), Lactobacillus acidophilus (N 42).The growth characteristics, the acidity, the most important aroma productivity and the lactose content were measured. Products were evaluated with organoleptical test. Products were lactose free, so they are suitable for people suffering from lactose intolerance. There were differences among the acid content at the end of fermentation. In case of normal yoghurt culture acid content was 29.6 SH° and in case of probiotic cultures 30.4 SH° and 37.5 SH°, respectively. According to the results of sensory evaluation, the product made with traditional yoghurt bacteria (Streptococcus thermophilus, Lactobacillus delbrueckii subsp. bulgaricus)was better than products made with probiotic species because of the higher alcohol and lower acetic acid content.