The objective of the present study was to improve the quality of the
Egyptian hard cheese (Ras type) by adding some Lactobacillus spp. as probiotic
adjunct cultures. Strains of Lb. acidophilus, Lb. helveticus and Lb. casei were
used and the chemical, microbiological and sensory characteristics of the cheese
during 90 days of ripening were evaluated. The obtained data indicated that pH
values and moisture content were decreased, while the total nitrogen (TN), fat,
fat/dry matter, titratable acidity and salt contents were increased significantly
during the ripening period in all treatments. For the ripening indices, significantly
higher content of soluble nitrogen (SN), SN/TN, soluble tyrosine, soluble
tryptophan and total volatile fatty acids were found in the experimental cheese
compared to the Control cheese. Higher Lactobacilli count were observed in the
adjunct treated cheeses, which reflects the positive retention of Lactobacilli in
the experimental cheeses. Also, the use of probiotic adjunct cultures reduced the
growth of fungi and prevented the coliform bacteria on Ras cheese. There was
higher acceptability for the experimental cheeses than for the Control. Ras cheese
was considered a good carrier for Lactobacillus probiotic strains since they were
found to survive during cheese manufacture, ripening and storage.