Food & Nutrition

Arab Journal of Food & Nutrition
98. Developing A Lactic Acid Bacteria/Yeast Starter Culture and Its Use in
Jameed Production (2008)
Abed Hammad Abdullah Al-Slaihat\ University of Jordan
Supervisor: Dr. Mohammed Isam Yamani
Cultures of Saccharomyces cerevisiae, Kluyveromyces marxianus var bulgaricus
and Lactobacillus delbrueckii subsp. bulgaricus, Lactococcus lactis subsp. lactis.
Streptococcus salivarus subsp. thermophilus which had been isolated from fermented
milk used in jameed production in previous studies, were inoculated into cows’ milk
separately and as co-cultures to determine their growth and interactions with the aim
of developing a starter cultures to be used in jameed production. The inoculated milk
samples with different combinations were incubated at 30°C for 72h.
In addition to the five cultures of the single strains, ten combinations of one
yeasts, and one LAB or two LAB were done. These combinations were Lb. bluigaricus
and Sc. cerevisiae, L. lactis subsp. lactis and Sc. cerevisiae, St. thermophilus and Sc.
cerevisiae, Lb. bulgaricus and K. bulgaricus, L. lactis subsp. lactis and K. bulgaricus,
St. thermophilus and K. bulgaricus, Lb. bulgaricus and St. thermophilus and K.
bulgaricus, Lb. bulgaricus and St. thermophilus and Sc. cerevisae, Lb. bulgaricus and
L. lactis subsp. lactis and K. bulgaricus, and Lb. bulgaricus, L. lactis subsp. lactis and
Sc. cerevisiae. Titratable acidity and pH were recorded every 24h, and both yeasts and
LAB were enumerated by selective culturing. A1so sensory evaluation was done for
the inoculated fermented milk with the different combinations. Both alone and in coculture,
there was a significant increase in the microbial counts, a sudden drop in the
pH and increase in acidity of the fermented milk after 24h of incubation. Increase in
counts and acidity (and drop in the pH) were more prominent where microorganism
was cultured with other microorganisms than when in single culture. The higher the
number of microorganisms in the culture, the higher is significant in the changes.
There were significant differences between the different combinations in flavour
and overall acceptability parameters. Evaluations for the best combination in sensoric
quality (Lb. bulgaricus, St. thermophilus and Sc. cerevisiae,) were 8.2 for flavour and
8.2 for overall acceptability. Jameed was produced by inoculating 20L cow milk with
this combination following the developed method.
This study showed that the interaction between chosen yeast and LAB within the
fermented milk indicates synergistic interaction where both microorganisms will
benefit from the other. The developed starter culture could be considered as a
prototype culture. This is why further studies are needed to make the use of this starter
culture on commercial bases possible. This includes propagation and preparation of the
mixed starter culture for use in dairy plants and optimization conditions of
fermentation and preparation of substrate. This study suggests that the combination
composed of Lb. bulgaricus, St. thermophilus and Sc. cerevisiae is the best starter
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