Food & Nutrition

Arab Journal of Food & Nutrition
The chemical changes of lipids were generally accelerated with the severity of
the heat treatment and duration of storage. The CLA content of cheese heated in a
microwave oven for 5 min decreased by ca. 21%, while microwave for 10 min caused
a decrease of ca. 53% as compared to that of freshly boiled cheese.
2. The Inhibitory Effect of Selected Plant Extracts on Growth and Enterotoxin
Production by Clostridium perfringens (2003)
Sharaf S. Omar\ University of Jordan
Supervisor: Dr. Khalaf S. AL-Delaimy
310
This study aimed to isolate and characterize Clostridium perfringens from
different sources of Jordan environment and to investigate the effect of different
concentrations of selected aqueous and ethanol plant extracts on growth, sporulation,
and enterotoxin production by C. perfringens.
Forty samples of animal dung, soil, water basin, and minced meat were cultured
and thirty-four isolates out of fifty isolates were identified as C. perfringens. Two
isolates were tested to be enterotoxin positive. Among the twenty-two different
aqueous and ethanol plants extracts used Salvia officinalis L. (Sage), Rosmarinus
officinalis L. (Rosemary), Origanum syriacum L. (Oregano), Allium sativum L.
(Garlic), and Allium cepa L. (Onion) were found to be the most effective plant extracts
against growth, sporulation and enterotoxin production of C. perfringens. However,
aqueous and ethanol extracts of Capsicum frutescence L. (green hot pepper) stimulated
the growth of C. perfringens.
The effect of aqueous plant extracts (0.35, 0.40, 0.45, 0.50, 0.55, 0.60 0.65, 0.70,
0.75, 0.80 mg/ml) on growth, sporulation and enterotoxin production were relatively
higher than ethanol extracts (0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70 0.75, 0.80 mg/ml).
S. officinalis, R. officinalis were the most effective plant extracts while A. cepa had
the lowest inhibitory activity. The minimum inhibitory concentration (MIC) of 0.1
mg/ml of aqueous extracts was determined for both S. officinalis and R. officinalis for
the C. perfringens ATCC 13124 and C. perfringens J1 and J3 used. Double and four
times of the MIC of the extracts were observed for both A. sativum and A. cepa,
respectively.
In general, the concentrations of aqueous and ethanol plant extracts needed to
inhibit sporulation of all three C. perfringens were higher than the concentrations
needed to inhibit the growth. S. officinalis and R. officinalis inhibit the enterotoxin
production at 0.45 mg/ml plant extracts, the rest of extracts required 0.50 mg/ml or
higher up to 0.75 mg/ml to inhibit enterotoxin production by C. perfringens ATCC
13124 and the local isolate J1.
The variation in the effect of different extracts on the enterotoxin formation had
Volume 309 11, No. 25, 2011