Use of a selected multi-strain potential probiotic culture for the manufacture of set-type yogurt from caprine milk

Abstract

Set-type low-fat yogurt from goat's milk, prepared by using yogurt starter bacteria and potential probiotic lactobacilli, was studied for physicochemical, microbiological and sensory characteristics. Selected isolates of Streptococcus thermophilus (2 strains), Lactobacillus delbrueckii subsp. bulgaricus (2) from goat's milk yogurt and Lactobacillus paracasei subsp. paracasei (1) and Lactobacillus acidophilus (1) from new born infant faeces were tested for their ability to grow and metabolize in goat milk and for their in vitro resistance to the specific conditions of the human gastrointestinal tract. Results revealed that L. paracasei subsp. paracasei and L. acidophilus strains were distinguished for their potential probiotic properties (resistance to low pH, tolerance to 0.15% bile salts, cholesterol removal from the medium, resistance to 100ppm lysozyme), as well as for high diacetyl production. The synergistic growth of selected strains was shown by growing six single-strain cultures and one multi-strain culture in goat milk, so the later one was used to produce a set-type yogurt from goat milk. The product was characterized by high numbers (∼108cfu/g) of potential probiotic lactobacilli; it contained carbonyl compounds and had a satisfactory consistency with good organoleptic characteristics. This study depicted the ability to successfully produce set-type yogurt from caprine milk by implementing beneficial lactobacilli strains.