Science Essay: Investigation of the microbial contamination of food and the effects of storage, cooking and hand washing on microbial load

The consequences show that nutrients tested varied well both in the grade of microbic taint and the types of bacterium nowadays. Bile salts in the MacConkey agar allow selective growing of bacteriums adapted to turn in the mammalian enteric piece of land ( Heritage et al. 1996 ) .The bulk of these are Enterobacteriacae ( enteral bacterium ) , including pathogens such as Escherichia coli ( coliforms ) and Salmonella spp. , many of which are causal agents of human nutrient toxic condition ( Murray et al. 2002 ) .

Bacterial settlements present on the alimentary agar are likely to be a mixture of non-pathogenic and spoilage bacteriums, Staphlococcus spp. every bit good as infective enteral species ( Beuchat 2002 ) . Analysis of microbic burden on the MacConkey agar is hence a more dependable indicant of whether a nutrient is contaminated with potentially infective bacteriums ( although some non-enteric bacteriums such as Staphlococcus aureus besides do nutrient poisoning ) .The bulk of these bacteriums are destroyed by equal cookery ( Murray et al. 2002 ) .

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The determination that some nutrients, such as salad and cheese, had a high microbic burden of enteral bacteriums is worrying as these are intended to be eaten natural. The high degree of bacterial growing on the alimentary agar is non needfully as much of a wellness concern, as many of these bacteriums are likely to be non-pathogenic spoilage bacteriums normally found on veggies and fruit, such as species of Pseudomonas, Corynebacterium and Streptomyces ( Adams & A ; # 038 ; Moss 2000 ) . These will non normally cause disease but may diminish the storage life of the nutrient.Other surveies have besides found salad to be contaminated with infective bugs, such as Salmonella, Listeria and E.coli ( Sagoo et al. 2003, Viswanathan & A ; # 038 ; Kaur 2001 ) and 19 instances of S.

Newport were traced to eating contaminated salad.The determination of high degrees of enteric and other bugs on cheese was non as predictable, as the cheese-making procedure normally decreases microbic burden as cheese has a lower H2O content and pH than many other dairy merchandises ( Adams & A ; # 038 ; Moss 2000 ) . The high burden could hold resulted from taint at the cheese devising works or subsequent handling in the kitchen/laboratory.The high degree of enteral bacteriums in flour was besides non predictable. The dry nature of flour normally limits bacterial growing and molds are normally more of a job for grain merchandises, instead than bacteriums ( Adams & A ; # 038 ; Moss 2000 ) .

Again, this may hold resulted from cross-contamination of the flour in the kitchen/lab following handling of extremely contaminated nutrients, such as meat, or during the research lab processs. All of the nutrient types should be retested with freshly purchased points to look into these consequences, with rigorous isolation of each nutrient and managing hygiene protocols.
The enteral bacteriums isolated on the selective agar could hold arisen from a figure of beginnings of taint throughout the nutrient production procedure ( Hobbs & A ; # 038 ; Roberts 1993 ) . Meat, domestic fowl and eggs are often contaminated with bacteriums such as coliforms and Salmonella spp. on the farm or butchery. Inadequate storage or subsequent cookery so allows the bacteriums to multiply and is more likely to bring on disease when eaten. Enteric bugs can besides be spread from individual to individual, via the faecal-oral path, due to inadequate hygiene following contact with fecal matters.

Managing natural nutrient so cooked nutrient and unequal chilling and reheating of cooked nutrient are besides common causes of high bacterial growing on nutrient. Contaminated H2O, flies and pets may besides distribute bacteriums.The presence of such infective bacteriums in nutrient is a wellness hazard, and although it increases the hazard of going ailment, there are other factors involved. One of these is the sum of bacteriums on the nutrient and the morbific dosage for each bacterium.

Bacterial strains such as E. coli 0157: H7, which causes nutrient poisoning that can come on to serious complications such as kidney failure and decease, has an morbific dosage of around 100 bacteriums. Speciess of Salmonella require at least 100,000 bacteriums to be ingested before nutrient toxic condition symptoms are seen ( Murray et al. 2002 ) , so really low Numberss of feasible beings are improbable to do disease.Immunocompromised people, such as babes, the aged and those with immunodeficiencies are at increased hazard of going ailment following consumption of smaller doses of bacteriums. There is besides assortment in the susceptibleness of healthy persons to disease, which was highlighted by Parry and co-workers ( 2005 ) who found similar degrees of Salmonella taint on dish fabrics and icebox swabs in the kitchens of people who had suffered Salmonella nutrient toxic condition and controls that had non.

Although most people are able to contend off infection from really low doses of ingested bacteriums, the purpose of nutrient manufacturers and animal trainers should be to extinguish bacterial taint to cut down the hazard of disease. This can be achieved through the HACCP system ( Hazard Analysis of Critical Control Points ) at the farm and industrial phases of nutrient production ( Hobbs & A ; # 038 ; Roberts 1993 ) and through suited storage, cooking and managing in the domestic kitchen.
The consequences from our survey of meat storage show that stop deading had the greatest consequence in cut downing feasible enteral bacteriums, but still did non wholly extinguish them, which is consistent with other findings ( Bolton et al. 2001 ) . Refrigeration resulted in a lower enteral microbic burden, which although still significantly better than storage at room temperature is still likely to present a hazard to wellness. The microbic burden of the meat prior to storage was non recorded, so it can non be determined if there had been any growing whilst in the icebox or if it had remained changeless, which would be in maintaining with old findings of E.

coli growing between 6 and 45oC ( Tamplin et al. 2004 ) , but non at the normal fridge temperature of 4oC ( Berry & A ; # 038 ; Koohmarie 2001 ) . Many people do non cognize the existent temperature of their kitchen electric refrigerator, which means that they could be hive awaying nutrient above the 6oC at which coliform growing occurs ( Kennedy et al. 2005 ) , thereby increasing the hazard of unwellness.Adequate cookery is normally stated as a certain manner to kill enteral bacteriums in contaminated nutrient ( Hobbs & A ; # 038 ; Roberts 1993 ) , but the consequences of our survey inquiry this. Although all the hamburger cooking governments reduced the microbic burden significantly, feasible beings remained even after 14 proceedingss grilling on each side.

Although another survey besides found that grilling hamburgers on one side with infrequent turning did non extinguish all E. coli bacteriums ( Rhee et al. 2003 ) , the experiment should be repeated to guarantee there was no cross-contamination during the research lab processs.Another of import method of diminishing the hazard of human unwellness due to consumption of contaminated nutrient is to better hygiene whilst managing nutrient. Hand rinsing after managing natural meat is a simple, speedy process and the consequences show that it reduces the microbic burden on the custodies.

It did non, nevertheless, extinguish bacteriums, which could therefore still be transferred to subsequent nutrients handled. Equally good as bacteriums from any natural nutrients handled, there are likely to be other bacteriums on the custodies which can take to food-borne unwellness, such as Staphlococci spp. , enteral bacterium following defaecation and dirt bugs such as Clostridrium perfringens. Contamination from custodies could besides be spread to other countries of the kitchen, such as chopping boards, which so act as beginnings of taint themselves ( Wachtel et al. 2003 ) , or may distribute straight to the oral cavity.

Haas and co-workers ( 2005 ) used quantitative microbic hazard appraisal to find the benefits of manus rinsing in the kitchen and found that rinsing with normal, non-germicidal soap reduced the microbic burden, which agrees with this survey, and is hence good, if non ideal. The most effectual manner to cut down the bacterial burden further was to utilize intoxicant based topical merchandises.