Food & Nutrition

Arab Journal of Food & Nutrition
3. In Vitro Studies of the Effect of a Fermented Dairy Product Containing
Probiotic and Neutraceuticals on Different Characteristic of Intestinal Microflora
(2003)
Saddam Sh. Awaisheh\ University of Jordan
Supervisor: Dr. Malik S.Y. Haddadin
Three isolates of probiotics were selected from 79 isolates of lactic acid bacteria
(LAB) and bifidobacteria, derived from the feces of breast fed infants, and used with a
combination of three neutraceuticals for the production of therapeutic yogurt.
The probiotic potential of these 79 LAB and Bifidobacteria isolates were
examined against resistance to pH 2 and 0.3% bile acids (oxgall), autoaggregation
sensitivity (adhesion capabilities), antibacterial activities against enteric pathogens,
and cholesterol assimilation. Nine of these isolates were found to have potential for
use as probiotics. Weak short chain fatty acids (SCFA) production was found among
these isolates in both milk and MRS broth.
The effect of different concentrations (0.0, 0.1, 0.3, and 0.5mg/ml) of the
neutraceuticals, isoflavons, stigmasterols, and -3-fatty acids on the viability of these
potential probiotics, was determined. Great variation was found regarding the effect of
different concentrations of the neutraceuticals on probiotic viability. The effect of a
combination of each neutraceutical concentration, which had produced the maximum
effect on the counts of these potential probiotics, was investigated.
An in vitro coculture technique was used to study the effect of the probiotic and
neutraceutical interaction on the main microbial flora of human gastrointestinal (GI)
tract, by using a sample of human feces. A 100 fold reduction in bacterial counts were
observed for both Enterobacteriaceae, coliforms and Staphylococcus aureus.
Also, a 10 fold reduction was observed in the total facultative aerobes,
Clostridium and Bacteroides.
From the results obtained above, the physiological, biochemical, and
morphological characteristics of probiotic isolates with maximum potential, were
further identified.
From the 9 isolates, Lactobacillus casei, L. gasseri, and Bifidobacterium infantis
and the neutraceuticals combination were chosen for yogurt preparation. A two-step
fermentation technique was used, in which a 2% probiotic inoculum with the
neutraceuticals combination were added to pasteurized milk, which was then incubated
at 37ºC for two hours. This fermentation was followed by the addition of traditional
yogurt starter culture (L. bulgaricus and S. thermophilus) for 3 hours at 44ºC.
Probiotics yogurt sensory evaluation criteria (including appearance, texture,
flavor, odor, and overall acceptability) were studied against regular yogurt as a control.
Probiotic yogurt obtained higher, but statistically insignificant scores, over those of the
control yogurt. The survival rate of these selected probiotic strains, during storage of
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Volume 311 11, No. 25, 2011