Bacteriological contamination of salad vegetables and the effect of biological sanitizer (EM) on the contaminants

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Nada Abdel Wahed Suleiman
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University of Khartoum
Abstract Introduction:- Vegetables which are eaten raw in a form of fresh salad as a source of minerals, vitamins and fibers should be fresh and wholesome. Salad vegetables can be contamin ated with a range of microbial contaminants. Therefore, they may act as a vehicle for transmition of infectious microorganisms when eaten raw. Objectives:- This study was conducted in Elsoge Elmarkazy at Khartoum North for fruit and vegetable in May- 2009 to clarify the load and types of bacterial contaminant, and the effi ciency of the biological sanitizer Effective Microorganism (EM) solutio n (it’s specific group of naturally occurring beneficial microorganisms such as phototrophic bacteria, yeast, it’s composed of warm water (chlor ine free), molasses, natural vinegar, EM liquid concentrates, on e of it’s functions is Production of antibiotics and other bioactive compounds) on the contaminants. Material and Methods:- Total of 60 samples of six sala d vegetables (10 samples of each) namely lettuce, rocket; as leafy ve getables, green onions, carrots, cucumber and tomato as fleshy t ypes were chosen and collected randomly. The load and types of bact erial contaminants were detected before and after washi ng with EM solution by using serial dilution technique and culturing on nutrient and Macconkey,s medium. Results:- VII The bacterial load was more in leafy salad vegetable samples (10 4 can be acceptable more than this ca n not be acceptable). It is average from (2.1×104) to (2.1×10 5) for lettuce and from (1.7×10 4) to (2.3×10 4) for rocket (in countable samples and the most of them uncountable). The load was decreased from (2.1×10 4) to (0.4×10 4) in lettuce and from (1.7×104) to zero in rocket when the EM. Solution was used as surface sanitizer. For fleshy salad vegetables th e bacterial load was more in cucumber, it is average from (2.9×10 4) to (1.6×10 5) followed by tomato (0.5×104) to (2.1×105), green onion averaged from (0.3×10 4) to (9.1×104) and carrot from zero to (1.6 ×104) in countable samples. A total of 80 types of isolates were obtained. Staphylococcus spp represent the most dominant isolates (30%) followed by Escherichia coli (20%), Klebsiella pneumoniae (17.5%), Pseuomonas aeruginosa and Proteus mirabilis (10%), Salmonella spp (5%), Shigella spp and Alcaligenes spp (3.75%). The higher percentage of Staphylococcus spp was presented in rocket (60%), cucumber (50%), carrot and lettuce (40% for each), tomato (30%). Whereas, Escherichia coli predominant in lettuce and rocket (60% for each), Pseuomonas aeruginosa (30%) on tomato, Klebsiella pneumoniae (50%) on green onion and Proteus mirabilis (40%) on green onion. Conclusion:- The study concludes that, salad Vegetables were contaminated with pathogenic microorganism. Also the study had clarified the ef fect of EM solution in reducing bacterial load on leafy salad vegetables (lettuce and rocket). Furthers studies are recommended rinse all vegetables under running tap water and wash with sterile EM solution
A thesis submitted in partial fulfillment for the requirements of the degree of MPEH Department of Food Hygiene and Safety
University of Khartoum Bacteriological contamination salad vegetables biological sanitizer contaminants Food hygie
Nada Abdel Wahed Suleiman, Bacteriological contamination of salad vegetables and the effect of biological sanitizer (EM) on the contaminants. – Khartoum : University of Khartoum, 2010. - 72 P. : illus., 28 cm., M.Sc.