Evaluation of Ready-Made Food Sold for Human Consumption at City Local Market

Received: 23-Jul-2021 Accepted Date: Aug 24, 2021 ; Published: 31-Aug-2021

Introduction

Food supplies the body with nutrients, but at the same time, it conveys a lot of microorganisms that cause diseases and food poisoning. Food is usually contaminated via soil, water, sewage, and air, or contaminated during harvesting of raw materials, storage, transport, handling, and processing [1].

Food-borne illness is a major international public health problem and there are several outbreaks of food-borne diseases that have been documented everywhere. Food-borne diseases seriously affect children, pregnant women, and the elderly besides [2].

FAO and WHO stated that up to be one-third of the population of developed countries may be affected by food-borne diseases each year, and the figures are more than that in developing countries [3]. Many outbreaks of food-borne diseases are due to a poor investigation of early-warning cases [4].

There are several microbiology protocols used in the detection of food-borne pathogens. One of these important groups’ pathogens is Enterobacteriaceae [5].

Objective

To evaluate the safety of food to the consumer through determining the bacterial load, coliform bacteria, and E coli presence comparing with the standard.

Food-borne Diseases as a Public Health Problem

Food-borne diseases can be caused by bacteria, viruses, or parasites. Natural (physical) and manufactured chemicals in food products also can harm people. Some diseases are caused by toxins from the disease-causing organism (germ), others by bodily reactions to the organism itself. Food-borne diseases may have no symptoms or develop symptoms ranging from mild intestinal discomfort to severe dehydration and bloody diarrhea [6-10].

The World Health Organization (WHO) reported that food-borne diseases became a major public health problem and had increased in the last years affecting populations in both developed and developing countries. The intensity of foodborne illnesses increases every year; CDC estimates that 76 million people suffer from food-borne illnesses each14 year in the United States [11].

The major factors that contribute to contamination of food are food handlers, equipment, through contact with raw foods and utensils, air, water, soil, clothes of the workers, packaging materials, distributing and retailing [12].

The useful indicators of unsanitary food and food processing are the presence or contamination with the bacterial family Enterobacteriaceae. Their presence is often considered as an indicator of unhygienic practices in production processes, their presence in high numbers (>10⁴ per gram) in ready-to-eat foods indicates that an unacceptable level of contamination has occurred during food processing [13,14].

Some bacteria that belong to Enterobacteriaceae are called coliforms. They are traditional indicators of food contamination [15]. Regulatory agencies have used Enterobacteriaceae, coliform, or E. coli counts as microbiological criteria to reflect the safety of a particular food product [16].

Codex Alimentarius Commission and FDA stated that the personal hygiene of food handlers would give greater assurance of food safety than clinical examination [17,18]. World Trade Organization (WTO) described the need for regulations governing international trade in foods to be based on science and risk assessment.

According to Bryan survival of bacteria, which contaminate food, can be controlled by heat treatment and acidification [19].

Applicable control measures during production, adequate hygiene standards, and fitting cooking during final preparation should ensure that the end products are being of good quality to the consumers [20]. In addition to that, an International Food Safety Standard (IFSS) has advised farmers to change their production and marketing practices [21].

To prevent foodborne diseases associated with Enterobacteriaceae, WHO reported that Hazard Analysis Critical Control Points System (HACCP) has to be implemented to assess hazards and to establish a control system that focuses on enhancing food safety throughout the food production chain [22].

The safety of food is important for everyone-food manufacturers, catering businesses, organizations for the supply and distribution chain, retailers, and people preparing meals at home, and consumers. Recent legislation now requires a food safety management system, such as Hazard Analysis Critical Control Point (HACCP) intending to reduce the toll of death and ill-health associated with unsafe food [23,24].

WHO established a strategy to reduce the public health hazards of food-borne disease includes developing surveillance systems of food-borne diseases, improvement of risk assessments, developing methods for assessing the safety of the products of new technologies, and strengthening the role of science and public health [25].

FDA stated that only ten cells from E. coli O157:H7 could cause illness. This E. coli O157:H7 became widespread and caused food poisoning in developed countries [26].

In Sudan, E. coli among other species were isolated by Hussein from fresh meat samples; Abd ElRahman isolated E. coli from 17% of minced meat samples; Ahmed investigated E. coli in ready to eat a beef burger in Khartoum State and declared that total coliform bacteria were observed in 48.8% of samples and 9.3% of them were positive for E. coli, Hassan, NA isolated E. coli and other’s bacteria from restaurant’s food, worker’s hands and dishes in Khartoum State [27-29]. Abdalla, et al. surveyed to determine food safety knowledge of street food vendors in Khartoum city [30]. CDC Bulletin reported the incidence of Salmonella in Australia and linked them with a traveler from some countries, including Sudan [31]. Mustafa and Abdallah detected E. coli and Salmonella spp. in 6.6%, and 5%, respectively from Street-Vended Um-Jingir near industrial areas in Khartoum State [32]. Elfaki, et al. detects total coliform bacteria and total bacterial count of (Shawerma) and ice cream in Khartoum State to ensure the safety of two foods [33]. Ali and Abdelgadir estimated the incidence of E. coli, in raw cow’s milk in Khartoum State at 63% of the samples [34].

The diarrheal disease was the second major disease during the years from 2003-2007 in Sudan as reported in an annual health statistical report of the Federal Ministry of Health (FMH) (National Health Information Centre (NHIC) Table 1 [35].

Materials and Methods

Study Area

This study was conducted at Khartoum State, Locality of Khartoum in the period from January 2014 to December 2015.

Inspection of Food Samples from the Market

A total of one hundred forty-five different food samples (Table 2) were collected from the Khartoum locality randomly.

Food samples were placed in a sterile plastic bag, labeled, and transported to the laboratory in the portable cooler at 4°C. Samples were investigated directly in the laboratory.

Most Probable Number (MPN)

MPN means a statistical estimate of the number of bacteria per unit volume and is determined from the number of positive results in a series of fermentation tubes.

Twenty-five grams of the samples were placed into a stomacher bag with 225 ml of buffer peptone water and blended for 2 min at 230 rpm using a Stomacher (Stomacher 400, Seward, and Norfolk, UK). From the homogenized samples, sufficient diluents were made.A series of nine sets of MacConkey’s broth medium containing Durham’s tubes were divided into three parts and each was inoculated with 10 mL, 1 mL, and 0.1 mL of aliquot sample, then incubated at 37ºC for 48 ± 2 h. Productions of gas and turbidity bubbles were observed after incubation. The number of organisms in the original culture was estimated from an MPN Determination Chart to determine the MPN index per gram [36].

Confirmatory Test

From each positive gassing tube, a loopful of suspension was transferred to a tube of Brilliant Green LB broth, incubated at 35°C for 48 ± 2 h, and examined for gas production. Calculation of the Most Probable Number (MPN) was done [36,37].

Results

Most Probable Number (MPN) of Coliform Bacteria

In this study coliform count was detected in different proportions in food samples. The highest unsatisfactory concentration of coliform bacteria was found in red meat and their products followed by white meat and their products, while egg and milk samples were less contaminated than other types of food in both cooked and uncooked food samples (Table 3, Figure 1, Figure 2 and Figure 3).

Figure 1. Percentages of total coliform bacteria for cooked food samples

Figure 2. Percentages of total coliform bacteria for uncooked food samples

Figure 3. Percentages of total coliform bacteria for (cooked and uncooked and total food) of food samples

In Figure 4 the safe and hygienic food samples (satisfactory) were approximately only half of the samples (47%).

Figure 4. Percentages of total coliform bacteria for a total of food samples

In the comparison between cooked and uncooked food, Figure 1 and Figure 2 show unsatisfactory coliform levels in uncooked food more than in cooked food, especially in white and red meat and its products (Figure 5). The same MPN result for total samples was shown in Figure 3.

Figure 5. Total coliform bacteria from different types of food samples

E. coli was found in 9% of the total samples (Figure 6). The incidence of E. coli in cooked food samples was 14% (Figure 7) and in uncooked samples was 7% (Figure 8).

Figure 6. E. coli bacteria from total food samples

Figure 7. E. coli bacteria from cooked food samples

Figure 8. E. coli bacteria from uncooked food samples

The Salmonella typhi detection result was shown in Figure 9, it was found in 7% of total samples.

Figure 9. Salmonella typhi bacteria from total food samples

In all food samples analyzed for bacterial contaminants; the (E. coli, Salmonella typhi, and Shigella dysentery) bacterial species were not found in egg samples (Table 4). 57.1% of positive E. coli results were detected in red meat, equal positive Salmonella typhi results were obtained from PCR analysis of white and red meat (50%) Figure 10.

Figure 10. Percentage of E. coli and Salmonella typhi in food samples

Eggs and milk were less contaminated than white and red meat, no presence of Shigella dysentery was detected in these food samples (Figure 10).

From total Escherichia coli positive samples, 71.4% were identified in cooked food. Salmonella typhi positive results were divided equally among cooked and uncooked samples (Table 5 and Figure 11).

Figure 11. Presence of three bacteria in cooked and uncooked food samples

Discussion

Coliform bacteria are used as indicator organisms. In this study coliform bacteria were found at levels that are cautionary and unsatisfactory in 53% of the samples (≥ 1000/g), this was closely identical to a study done by Charles, et al., who found coliform bacteria in 51% of the samples [40]. In the present study, coliform bacteria were encountered in various types of food similar to results obtained by Odu and Akano who analyzed the microbial quality of shawarma purchased in Port Harcourt city, Nigeria, and found the total coliform count ranged from 1.9 × 10³ to 9.4 × 10⁵ [41].

In this study, the highest concentrations of coliform were detected in red and white meat. This confirms the high probability of the presence of food-borne bacteria in red or white meat. The contamination may be from personal activities, the meat itself, during the slaughtering process or manufacturing, working tables, or displays for sale.

Eggs samples analyzed showed the lowest total coliform bacteria (there was no unsatisfactory level detected), this may be due to the nature of the egg which has good protection by their intrinsic parameters that minimize the entry of microorganisms. These intrinsic parameters include the outer waxy shell membrane, lysozyme in egg white, avidin which forms a complex with biotin making this vitamin unavailable to microorganisms, conalbumin which forms a complex with iron making it unavailable to microorganisms and a high pH (about 9.3) of egg white [42].

Unlike previous studies carried in Sudan, milk samples showed a low level of total coliform bacteria. This might be because the milk samples contain inhibitory substances such as residues of antibiotics used in animal treatment or for preservation purposes. If so, it has health hazards. The use of antibiotics in food leads to an increase in the number of antibiotic-resistant microorganisms which is not responding to traditional antibiotic treatment. Also cause a mutation and plasmid in microorganism which may harm the human and animal [43-45].

The presence of total coliforms bacteria in the samples is considered a hazardous result not only their amounts in food as mentioned before by the Connecticut Department of Public Health-CDPH [46].

In the present study, coliform was detected in uncooked foods more than cooked foods especially in white and red meat and their product. This is obvious as heat treatment destroys all coliform bacteria. Any coliform bacteria that occur after heat treatment is referred to as cross-contamination.

In this study, the presence of E. coli, Salmonella typhi, and Shigella dysentery by PCR were detected in samples that had coliform more than cautionary. E. coli was found in 6 out of 7 at the level of cautionary and unsatisfactory. All Salmonella typhi were at an unsatisfactory level. It indicates that total coliform is a good indicator for pathogenic bacteria.

Conclusion

This study investigated a total coliform count as the traditional method to evaluate the safety of ready-to-eat food. Coliform is an indicator organism was found at the level cautionary and unsatisfactory in 51% of the samples in the different types of food. Their presence was varying from type to type of food. The highest presences of coliform were in red meat and white meat. While the hygienic food samples were eggs which have the lowest total coliform bacteria, this may be due to the nature of the egg. Milk was also having lower total coliform bacteria and this might be due to the addition of antibiotics during milk production. Coliform was detected in uncooked foods more than cooked foods especially in white and red meat and their product. E. coli was found in 9.2% of the samples, while Salmonella typhi was found in 3.9%, and no presence of Shigella dysentery. E. coli was identified 71.4% in cooked food from total positive samples. Salmonella typhi divided (50%) in cooked and (50%) in uncooked positive samples. Cooked food was more contaminated, especially with E. coli.  That means the contamination or cross-contamination was coming to food due to food handlers, utensils, or unsafely ways of food preparations. The presence of E. coli, Salmonella typhi, and Shigella dysentery were detected in samples that had coliform of more than 1110/gram.

Declarations

Conflicts of Interest

The authors declared no potential conflicts of interest concerning the research, authorship, and/or publication of this article.

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