Four strains of the dry yeast Saccharomyces cerevisiae were obtained from different sources.
The identification of yeasts was confirmed by morphological and physiological properties.
Mannan extracts from yeast cell walls ranged between 25.80-34.40% of the dry weight of yeast
cells. Five different concentrations of mannan extract were mixed with buffalo milk, to be
used for bio-yogurt production. Probiotic starter culture contained Lactobacillus acidophilus,
Bifidobacterium sp. and Streptococcus thermophilus used. After fermentation, pH values
decreased to 4.6-4.8, while total acidity was 0.89-1%. The cells viability of Lactobacillus
acidophilus was 6.8-7.85 Log CFU/g, 5.8-7.15 Log CFU/g of Bifidobacterium sp. and 6.74-
7.22 Log CFU/g of Streptococcus thermophilus after fermentation. At 28days (the end of the
storage period), pH values decreased to 3.7-4.2, while total acidity increased to 1-1.3%, The
cells viability of starter bacteria decreased with Streptococcus thermophilus being affected.
Consequently mannan extract added to the yogurt increase the viability of probiotic bacteria
after production.
علاء كريم نعيمة | Alaa Kareem Niamah | 5395