Microbiological properties on ready-to-eat food

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The ready-to-eat food provides nutrients for us every day. However, the cases of food poisoning outbreaks world-wide has increased public awareness about food safety (Mead et al., 1999; Nguz, 2007). The possible factors such as processing and handling can affect the composition of microorganism on ready-to-eat food. Besides that, this can definitely increase the presence of E. coli and S. aureus in foods (Legnani, Leoni, Berveglieri, Mirolo, & Alvaro, 2004). Therefore, quality of the ready-to-eat-food has been examined by investigator worldwide (Johannessen et al., 2002).

Furthermore, food poisoning related to ready-to-eat foods have been found to associate with different kinds of microorganism such as E. coli, Staphylococcus Aureus, B. cereus, coliforms and Pseudomonas spp. (Gibbons, Adesiyun, Seepersadsingh, and Rahaman,2006; Gilbreth et al., 2005). Besides that, bacteria normally multiply very fast as the nutrient provided is enough for them. Isolation of microorganism can be easily done in some foods such as milk, meat and cheese (Le Loir, Baron, & Gautier, 2003).

In addition, the aim of this study is to determine the microbiological properties of a variety of ready-to-eat food in Wangsa Maju area. Therefore, the results obtained provide the basic information about the microbiological quality of these food samples. After that, I will compare the total plate count of the bacteria to the microbiological standard guideline. The guideline identifies four categories of microbiological quality for ready-to-eat foods ranging from satisfactory to potentially hazardous.  Besides that, this reflects the high level of microbiological quality that is achievable for ready-to-eat foods in Australia and New Zealand and indicates the level of contamination that is considered to present a significant risk to public health.

Objective :

To identify the microorganism on ready-to-eat food

To perform total plate count

Literature review :

Different types of bacteria

Staphylococcus Aureus

Staphylococcus aureus is a Gram positive bacterium. It has a spherical shape. It can cause food borne intoxication. They are able to produce heat-stable enterotoxins. It was found to be one of the predominant The production of SE by this food-borne problems causing gastroenteritis worldwide such as Vietnam and developed countries like the USA, Japan, etc. About 185,000 people suffered from this food poisoning including thousands people died in the year 1997 (Mead et al., 1999).

1.2 Escherichia coli

Escherichia coli is the family of Enterobacteriaceae. It is a Gram-negative bacterium which has a rod shape. Besides that, some of the strains are known to be pathogenic. It is a common bacteria found in the lower gut (Levine, 1987; Holland, 1990). Enterotoxigenic E. coli strains cause some diseases such as diarrhoea and toxemia (Fairbrother, 1993). Enterotoxigenic E. coli strains synthesize heat-stable and heat-labile (LT) enterotoxins. It can colonize the small intestine by using fimbrial and adhesins ( Gaastra and De Graaf, 1982; Fairbrother, 1993 ) .

1.3 Salmonella spp.

Salmonella genus are the members of the Enterobacteriaceae family. It is gram-negative bacteria. They are pathogenic to animals and humans (Holt et al., 1994). The infection of the Salmonella spp. is usually due to the consumption of contaminated food. Therefore, Salmonella spp.can be isolated from chicken meat. Besides that, it is an vital pathogen to the food industry and known as an etiological agent of foodborne outbreaks (Siqueira et al., 2003).

1.4 Pseudomonas aeruginosa

Pseudomonas aeruginosa is the members of the Enterobacteriaceae family. Pseudomonas aeruginosa is a Gram-negative bacterium. It can utilize a wide range of organic compounds such as food sources. This is because, it can produce a number of toxic proteins which not only cause extensive tissue damage. Besides that, it can interfere with the human immune system's defense mechanisms (Holt et al., 1994).

1.5 Bacillus cereus

Bacillus cereus is a gram positive bacterium. It was found to be spore-forming bacteria. Bacillus cereus can be isolated from different types of food, including rice, spices, meat, eggs and dairy products. Besides that, It can produce some types of enterotoxins namely, haemolysin BL and non-haemolytic enterotoxin (NHE) are three-component proteins, while Ent FM, CytK and BceT are one-component toxins (Granum and Lund, 1997; Hansen et al., 2003).

2.0 Incident of food-borne poisoning

On 17 June 1999 in Japan, there was an incident of staphylococcal food poisoning because of an egg yolk reaction- negative strain. In this case, Twenty-one of 53 dam construction workers were affected due to the consuming of boxed lunches prepared at their company cafeteria. They became ill and eight of them required hospital treatment. They showed the symptoms of staphylococcal food poisoning such as vomiting and diarrhoea. Staphylococcal enterotoxin produced by Staphylococcus aureus was isolated from four fecal specimens of eight patients (Miwa et al., 2001).

Besides that, another case happened in Madhya Pradesh, India. It was found that, more than children and adults suffered from the typical symptoms of staphylococcal food poisoning such as vomiting and diarrhoea after eating of a snack called "Bhalla" which made up of potato balls fried in vegetable oil. Besides that, large number of enterotoxigenic Staphylococcus aureus were found from the food samples (Nema, V., et al., 2007).

Methodology Review :

Food samples from different 5 food categories were purchased for bacteriological examination. The food samples were collected and transported to the laboratory. They were analyzed within 24 hours. First, 25g of food samples were homogenized for 90 seconds in 180ml of sterile saline solution using a stomacher. After that, foods were tested for aerobic and coliform bacteria. Serial dilution was performed by using 1ml of the homogenate and 9ml of MRD. The sample was serially diluted in MRD to 10-3.

Besides that, streak plate procedure was performed. First, ChromocultR coliform agar plate (Merck, Darmstadt, Germany) were used for the enumeration of E. coli and coliforms. Next, Baird-Parker Agar was used for Staphylococcus Aureus (Fang et al., 1999). Furthermore, B. cereus agar plate was used for B. cereus (Vanderzant and Splittstoesser, 1992). In addition, Pseudomonas agar F (Oxoid) plates were used for Pseudomonas spp. All plates were incubated under 37 °C for 48 hours. Total plate count was performed.