IMPACT OF Bifidobacterium befidium ON VITALITY AND QUALITIES OF BIO-YOGHURT MADE WITH DIFFERENT STRAINS OF LACTIC ACID BACTERIA

Abstract

Four strains of lactic acid bacteria as the following I- Str. thermophilus + Lactobacillus acidophilus + B. befidium (1:2:1) treatment (B). II- Str. thermophilus + Lactobacillus helveticus + B. befidium (1:1:2) treatment (C). Str. thermophilus + Lactobacillus bulgaricus + B. befidium (1:2:2) treatment (D) were evaluated to their abilities at viability and growth rate when grown with Bifidobacterium befidium to produce bio-yoghurt as compared to traditional yoghurt made by traditional yoghurt starter IV- Str. thermophilus + Lactobacillus bulgaricus (1 : 1) treatment (A). Resultant yoghurt chemically, rhiologically, microbiologically and sensory evaluated when it was fresh or during storage period. Results showed that pH values in all treatments were higher than those in control and the acidity was in inverse trend to the pH in all treatments and control. T.V.F.A. values were increased in all treatments and control with the progress in storage periods as well as, treatment (B) gained the highest T.V.F.A. value among other treatments and control. Curd syneresis was in a correlation with the progress of acid content. Also, total bacterial count was increased with progress in storage until 3 days followed by a decrease but treatment (D) gained the highest growth rate among other treatments and control yoghurt. The strains were enhanced when they grown in a combination with Bifidobacterium befidiumallexcept Lactobacillus acidophilus. No growths on macconkey agar media, no molds and yeast in all treatments and control yoghurt in fresh or stored product. The presence of proteolytic and lipolytic bacteria was increased with the progress in storage periods. Sensory evaluation data showed the consumers acceptance of all treatments except treatment (B) where it was weak in body and texture and more flat in aroma. From these results we can concluded that bio-yoghurt with healthy properties can be made with a combination with Bifidobacterium befidium to enhance its viabilities and to achieve the probiotic dose number (106 cfu/gm) without any aroma, body and texture defects. Also, these results orientate the future research works to enhance the properties of bio-yoghurt contains Streptococcus thermophilus, Lactobacillus acidophilus and Bifidobacterium befidium as starter culture.