STUDYING THE EFFECT OF CHITOSAN ON BACILLUS CEREUS PRODUCING CEREULIDE TOXIN IN MILK AND SOME DAIRY DESSERTS

Abstract

A total of 150 samples of raw milk and two types of refrigerated processed dairy desserts dishes (cooked rice with milk and Mehalabia dishes) (50 for each) were collected from dairy shops and local restaurants in Assuit City, Egypt. ISO7932 method was used for enumeration of B. cereus, afterwards a PCR was performed to confirm the presence of cereulide toxin (ces) gene. In addition, the effect of different concentrations of chitosan and chitosan nanoparticles (CNPs) (0.05, 1%) on B. cereus was studied in pasteurized milk.The shelf life was evaluated by clot on boiling test and Ph value. Their pathological effect was detected by orally administration to experimental rats to investigate their adverse effect on rats liver and intestine using histopathological examination. The most prominent potent bactericidal effect was observed inCNPs 1%, B. cereus count reached to undetectable level at 5th day of refrigerated storage. The pasteurized milk inoculated with B. cereus, chitosan and CNPs showed some pathological lesions in rats treated with B. cereus,while the chitosan 0.5% had antibacterial activities without cytotoxic effect on rat tissues, alternatively to CNPs 1%, which exist edematous tips of intestinal villi and mild kupffer cells activation in liver.Therefore, our results contribute data that are primary to indicate the risk of food poisoning due to B. cereus and trials to control that in food by careful using of nanotechnology. However, the additional researches are needed to safe using of this technology even on natural nano-materials as it at nano-size gain new qualities.