Microbiological evaluation of certain fruits and vegetables marketed in the city of Kenitra-Morocco

Fruits and vegetables are essential for human health due to their nutritional qualities, but the consumption of raw foods leads to food safety problems as they are recognized as sources of transmission of infectious diseases. The objective of this work is to assess the microbiological quality of some fruits and vegetables marketed in the Kenitra city. The samples were purchased at the fruit and vegetable markets during the period from April to July 2018.The detection of microorganisms in the samples requires several steps which are weighing, dilution, isolation, enumeration and 'identification. The results of the microbiological analysis of fruits and vegetables studied show significant concentrations of the total aerobic mesophilic flora varies between 2.25 and 8.48 log10 CFU / ml, Concerning total coliforms the contamination rates vary between 1.92 and 8.42 log10UFC / ml, as well as the presence of fecal coliforms between 1.13 and 8.05 log10UFC / ml, in the same samples analyzed, strains such as: Escherichia coli, staphylococcus aureus and a total absence of salmonella and shegilla. In order to improve the safety and hygienic quality of fruits and vegetables, the application of good hygienic practices as well as continuous microbial quality control is necessary to protect the health of consumers.


INTRODUCTION
=@4?> ,9/ A020?,-70> ,=0 0>>09?4,7 1:= 3@8, 9 30    Was made according to the AFNOR method (French Normalization Agency) in 4 steps: pre-enrichment to recover bacteria that have undergone stress; then a selective enrichment, favoring the multiplication of salmonella in relation to the competing flora; followed by isolation on specific selective media and biochemical and molecular identification [18]. The dish is incubated at 37 ° C. for 24 hours. Then the characteristic colonies are picked and seeded on the nutrient agar. For confirmation tests, either enterotubes or API galleries are used. According to Standard V 08-052 (May 1997) [19].

Gram stain [20]
Coloring with gentian violet or crystal violet.leave to act for 30 seconds, rinse with demineralized water Spread the lugol and let it act for 1 minute. Rinse with deionized water Ethanol decoloration pour dropwise, and monitor the decoloration (5 to 10 seconds). The net should be clear at the end of the discoloration. Rinse with demineralized water, Recolouring with safranin or fuchsin. Leave on for 30 seconds to 1 minute,Wash gently with demineralized water in progress. Dry the slide on a hot plate at 40 ° C, 10 to 15 minutes. Observe with a drop of objective 100 immersion oil (magnification x1000).

Microscopic observation [21]
Studying microbial morphology under a light microscope means researching the shape of bacteria and their grouping mode.

Kligler test, Citrate and Mannitol [21]
For the three environments in fact: Inoculate using a Pasteur pipette loaded with suspension of the culture to be studied: -the slope in streaks (without reloading the pipette between the slope and the pellet).Incubate 24 hours at 37 ° C.  [21]: You must first have developed a bacterium in isolated colonies in a Petri dish to identify Gram -bacilli belonging to the ENTEROBACTERIACEAE family.Gallery of 20 ready-to-use microtubes for performing 23 biochemical tests. We create an anaerobiosis in the ADH, LCD, ODC, URE, H2S tests by filling their well with paraffin oil.Close the incubation box and place it in the incubator at 35-37 ° C for 18-24 hours.

Confirmation by Galleries [21]
Microtube cup containing the dehydrated medium the bacterial suspension introduced into the tube dissolves the dehydrated substrates. Combine the bottom and lid of an incubation box and distribute approximately 5 ml of water in the cells to create a humid atmosphere.

Results and discussion
The results of our study to assess the microbiological quality of the most consumed fruits and vegetables are noted above:

Microscopic observation
From our microscopic observation we found bacterial strains. Among them E. Coli, Shegilla, Salmonella which presents a bacillus in the form of elongated rods with gram negative, the same for Clostridium but with gram positive. While Staphylococcus aureus is a gram positive bacterium that presents in the cocci form.

Example of E. coli
Escherichia coli is a mobile enterobacterium characterized by the fermentation of glucose +, the production of indole +, TDA-, indole ++, VP-, does not have urease, does not produce H2S and is unable to assimilate citrate as the only aerobic carbon source.
Image 1: Gallery of E. Coli

Biochemical characters
The study allowed us to determine the real discriminating power of the biochemical methods used to identify lactobacilli. In addition, we evaluated the importance of nutritional characteristics in these results.
We have also shown a method associating the requirements for amino acids and bases with certain fermentable characteristics of carbohydrates would allow a satisfactory identification of strains of the genus Lactobacilli.

Enumeration of FMAT (ISO standard 4833) and coliforms (ISO 4832; February, 2006).
We observe a presence of FMAT, CT and CF in most vegetables with percentages deferred from one vegetable to another. On the other hand, a total absence of the three for potatoes and carrots (Table 4).
Regarding the fruits, FMAT, CT, CF are present in all the fruits studied with the exception of the pastic, one also notices a total absence of CT and CF in the banana (Table 5).

Determination of the bacterial load of vegetables and fruits
Fresh fruits and vegetables can be carriers of pathogenic microorganisms which come from organic fertilizers, contaminated irrigation water and this also depends from region to another [22]. So it is necessary to assess the risk and determine which criteria will be applied. The bacterial loads (Escherichia. Coli, Streptococci, Staphylococcus aureus, Pseudomonas) are very high at the level of certain vegetables and fruits, while onion, potato, tomato, lemon and orange show a total absence of these bacteria. Moreover, all these products studied have a bacterial load that does not exceed 10 log10 CFU / ml and a total absence of Salmonella spp and Shegilla for all the foods studied (Table 6 and 7).
In this context, a study of lemon "published in the Journal of Environmental Health" was made by researchers from New York University, the results of their work indicate a wide variety of microorganisms even if it is considered to be an antibacterial [23]. According to a study of the Microbiological Assessment and the Origins of Contamination of 4th Range Products Sold in Abidjan Markets, Cote D'ivoire analysis of the survey sheets shows that vegetables and fruits constituting the raw materials of 4th range products manufactured are not subject to control and no health certificate is admitted to traders. In some cases, fruits and vegetables that are injured, overripe, sore or attacked by microorganisms are used. In general, the material comes from the fruit port and is composed of nonconforming products [24]. CT

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The 20 samples of vegetables and fruits analyzed, 15 showed a bacterial load. These high levels of microbial contamination and the presence of pathogenic bacteria reflect the poor hygienic quality of vegetables and fruits marketed which could be due to the poor production and transport conditions of these foods on the production and distribution circuits. The results of the microbiological analyzes indicate that 75% of the samples analyzed are unfit for consumption.
This testifies to unhygienic and incorrect handling of vegetables and fruits. Great vigilance is required for the consumer vis-à-vis salads, especially when it is consumed raw. Vegetables and fruits are generally exposed to microbial contamination through contact with soil, dust, water and various harvesting methods or postharvest treatments. Therefore, they harbor different types of pathogenic microorganisms for humans and for the plant itself [25]. Study says that the cause of contamination may be through irrigation water, transport and individual management by retailers may be the cause 16. Potential sources of these pathogens are soil, faeces (animal and humans), water (irrigation, cleaning), animals (including insects and birds) [26]. In fruit and vegetable markets, staff should first be sensitized to hygiene and the problem of food poisoning. The prevalence of the most important bacterial load in vegetables, is that of pumpkin and turnip with four strains (E. coli, staphylococcus pseudomonas and   1). Regarding fruit prevalence of bacterial loads, we find the strawberry by three strains such as E. coli, staphylococcus and pseudomonas (figure 2).

Fig 1: Prevalence of strains in vegetable deferens
The prevalence of the most important bacterial load in vegetables, is that of pumpkin and turnip with four strains (E. coli, staphylococcus pseudomonas and streptococcus) and three strains (E. coli, staphylococcus and pseudomonas) respectively (( figure 1). Regarding fruit prevalence of bacterial loads, we find the strawberry by three strains such as E. coli, staphylococcus and pseudomonas (figure 2).

Conclusion
The microbiological analysis of vegetables and fruits ready for public consumption shows contamination by various germs (Clostridium, Staphylococcus aureus, E. coli), which poses a risk for the consumer. This contamination problem can be caused by various factors such as environmental problems (pollution of water resources) and the use of animal fertilizers for treatments. Therefore, it is necessary to define good hygiene practices for the purchase of fruits and vegetables.
To avoid poisoning by fruits and vegetables, wash your hands before and after handling a raw food afterwards, it is essential to adopt certain practices, in particular the passage of raw fruits and vegetables under lukewarm water before to eat or cook them, it is also advisable to wash what has touched the raw food to avoid crosscontamination from hands, countertops, kitchen utensils or the refrigerator to other food.