Bacteria Contamination of Freshly Cut/ Sliced Water Melon and Eggplant Sold in Meat Market (Abakaliki) Metropolis

Fruit and vegetables are rich in vitamins, minerals, antioxidants and many phytonutrients. Fruit and vegetables are essential parts of people’s diet and are vital for health and well-being. They help to reduce the risk of several diseases (Kalia and Gupta, 2006). Fruits are also an extraordinary dietary, source of nutrients and fiber for human well balanced diets, rich in fruits are especially valuable for their ability to prevent vitamin C and vitamin A deficiencies.

Sliced fruits of freshly –cut fruits refer to fruits that have been cut open, sliced into bits, but remain in the fresh state and displayed for sale in retail outlet for consumption. These sliced fruits are bought directly from the street vendors or hawkers or at local market without necessarily having to undergo any further treatment before consumption. Consumption of sliced fruits has been on the increase since they are easily accessible, convenient and most especially cheaper than the whole fruit (Nwachukwu et al., 2008). Sliced fruits are commonly processed and sold by unlicensed vendors with poor educational levels and untrained in food hygiene (Muinde and Kuria 2005, Barro et al., 2007). Vended fruits have been on the increase in many developing countries due to lack of formal jobs for the working age groups. Sales of sliced fruits can contribute significant income for house holds and at the same time providing a source of in expensive nutritious meal (Mosupye and Von Holy 1999).
Outbreak of illness caused by consumption of fruits had been reported (Abdul-Raouf et al., 1993, Bean and Grifjin 1996).

The increase in consumption of sliced fruits has been linked with a parallel increase in food borne illness (Mensah et al., 2004). Fruit produce is known to carry a natural non-pathogenic microflora, and have an epidermal layer of cells which provides a barrier for penetration of microorganisms. Cutting and slicing can eliminate the protections and microbes can invade the internal tissue (Barro et al., 2007). Unsanitary processing and preservative methods could increase the possibilities of contamination. Open display of stress food produce encourages sporadic visits by flies, cockroaches rodents and dust (Bryan et al., 1992).
Poorly processed street vended produce have been identified as an important cause of death in developing countries (Mensah et al., 2002).

Bacteria causing gastroenteritis can contaminate the sliced produce, thus exposing consumers to greater risk (Jolaoso et al., 2010). Bacteria like Salmonella sp, Shigella sp, Campylobacter species and Escherichia coli can contaminate sliced fruits through contact with sewage and contaminated water (Tredlund et al., 1987, Beuchat 1995, Gayler et al., 1995).
There are different sources of microbial invasion of sliced produce. Pathogens may invade the interior surfaces of the produce during washing, feeling, slicing, trimming, packaging, handling and marketing (K.B Mazhar at al., 1994, N. Bario et al., 2007). This study is designed to assess the microbial contaminants of ready to eat sliced water melon and garden egg sold in meat market Abakaliki, Ebonyi State Nigeria, in order to highlight the health implications of consuming such unwholesome ready to eat fruits.

JUSTIFICATION OF THE STUDY
Quite often, very many people patronize marketers of fruits and vegetables which they mostly eat raw or cooked owing to the high nutritional values. However care should be taken when harvesting, storage, and distribution of these items on one hand and in the consumption of these items on the other. Improper handling of fruit and vegetables will significantly increase its bacterial load. This is the basis of this study as the extent of bacterial contamination will not only expose a basic poor handling each right but will also give a clue into the inherent dangers associated with their consumption especially where cooking may not be needed.

 

AIMS AND OBJECTIVES
This work is intended to;
1. Determine the extent of bacterial contamination of freshly – cut/ sliced water melon and eggplant sold in meat market Abakaliki metropolis

2. Isolate the different bacterial contaminates found in freshly-cut water melon and eggplant, sold in meat market Abakaliki metropolis.

3. To advice freshly cut fruits and vegetable retailers of the best practices that will help control microbial contaminates associated with the processing of fresh cut fruits and vegetables.

CHARACTERISTIC OF SOME BACTERIAL PATHOGENS THAT HAVE BEEN LIKED TO OUTBREAKS OF PRODUCE-ASSOCIATED ILLNESS

Microorganism Typical incubation period Symptom Source
BACTERIA

 

Escherichia coli 2-5 days Blood diarrhea, abdominal pain, can lead to hemolytic uremic syndrome and kidney failure especially in children and the elderly Animal faces especially cattle, deer and human, cross contamination from raw meat
Salmonella 18-72 hours Abdominal pain, diarrhea, fever, nausea, vomiting Animal and human faces cross contamination from raw meat, poultry or eggs.
Shigella species 1-3 days Abdominal pain, diarrhea, fever, vomiting Soil, food processing, environments
Listeria monocytogenes 1-5 or more weeks Febrile gastroenteritis in healthy adults, may lead to spontaneous abortion or still birth in pregnant women, mortality may be 20-40% Environments, food processing

 

COMMON BACTERIA FOUND IN FRUITS AND VEGETABLES

The   minimum   processing   required   for   fresh   and   fresh-cut produce, which omits any effective microbial elimination step, results in food products that naturally would carry microorganisms, some of which may be potentially hazardous to human health. Although can neither be routinely practiced, nor effectively inculcated in the norms of the majority of famers in Abakaliki (mainly illiterates), the FDA opines that efforts should be made to effectively isolate disease causing pathogens in fruits and vegetables.

A wide variety of bacteria have been linked to outbreaks of illness associated with fresh produce (Guzewich and Ross, 1999). Although these microorganisms are physiologically diverse, they share some common features. Common disease causing bacteria found in vegetables and fruits include Clostridium botulium, Esherichi coli, Salmonella typhi, Shigella dysenteriae, and Listeria monocytogenes, Staphylococcus aureus.

Bacterial factors like temperature of incubation, rate of multiplication etc contribute to the postharvest longevity of bacteria in fruits and vegetables. Food borne bacteria that are frequently associated with fresh produce originate, for the most part, from enteric environments       that is, they are found in the intestinal tract and fecal material of humans or animals. Exceptions include C. botulinum, which is usually isolated from soils, water and decaying plant or animal material, and Listeria monocytogenes, which can be readily isolated from human and animal feces, as well as from many other environments including soil, agricultural irrigation sources, decaying plant residue on equipment.

Contamination of raw fruits and vegetables with pathogenic organisms of human health significance can occur directly or indirectly via animals or insects, soil, water, dirty equipment, and human handling. For example, fruit flies have been shown to transfer Escherichia coli O157:H7 to damaged apples under laboratory conditions (Janisiewicz el al, 1999).

The survival and/or growth of pathogens on fresh produce is influenced by the organism, produce item, and environmental conditions in the field and thereafter, including storage conditions. Beattie and Lindow in 1999 asserted that environmental conditions, however, can greatly influence bacterial populations – such conditions including the presence of free moisture on leaves from precipitation, dew, or irrigation. Survival of food borne pathogens on produce is significantly enhanced once the protective epidermal barrier has been broken either by physical damage, such as punctures or bruising, or by degradation by plant pathogens (Snowdon, 1990).

SOURCES   OF   BACTERIA   FOUND   ON   FRUITS   AND

VEGETABLES

The sources of bacteria found in fruits and vegetables may be grouped into the following:

  • Production and harvesting procedures
  • Postharvesting activities
  • Distribution

Production and Harvesting Procedure

          In an effort to achieve to low burden of bacteria on fruits and vegetables, more attention should always be given to identifying the steps in the process of harvesting where pathogens might be introduced, controlled, or eliminated. Relevant hazard control points include: field worker hygiene, field sanitation, equipment sanitation, container sanitation, water sanitation, truck sanitation, and temperature control.

Field worker hygiene is an important consideration in the harvest and post-harvest processing of fruits and vegetables due to the widespread use of human hands as part of the process. Although this varies with items, some item like melon will need hand touch in almost all stage of its processing.

Water    

          Water used for in production and harvest operations may contaminate vegetables and fruits if there is direct contact of water containing human pathogens with the edible portions or by means of water-to-soil and soil-to-lettuce/leafy greens contact (Solomon et al., 2003). In addition, irrigation could possibly introduce human pathogenic bacteria or promote their multiplicity. It is also worthy to state that the spraying of water (contaminated.) during machine harvest to prevent product dehydration of the fruits and vegetables may pre-dispose the products to contamination by bacteria should there be a direct contact of the water with the edible portions of the vegetables.

Soil Treatment

Soil treatment is also a contributing factor. The most common way of increasing soil productivity in this part of the world is by use of manure, which is mostly composed of animal debris. Human pathogens may persist in animal manures for weeks or even months (Gagliardi and Karns, 2000).

Proper composting of animal manures via thermal treatment will reduce the risk of potential human pathogen survival. Field soil contaminated with human pathogens may provide a means of fruit and vegetable contamination; however, human bacterial pathogens mostly do not persist for long periods of time in high UV index, low relative humidity conditions but may strive for longer periods of time within aged manure or inadequately composted soil amendments. Therefore, establishing suitably conservative pre-plant intervals, appropriate for specific regional and field conditions will effectively minimizing chances of contamination (Suslow, 2005).

Encroachment by Animals

Fruits and vegetables are generally grown in rural areas that may have adjacent wetland and/or parks harboring wildlife. Fenlon in 1985 acknowledged the economic importance of many wildlife species (deer, pigs, birds, insects, amphibians and snakes) as potential carriers of human pathogens. In the areas where these organisms are grown, there is usually an increased chance of the encroachment of the farms by domestic animals that may not only defecate indiscriminately therein, but also cut open the fruits and vegetables as they graze.

Equipment Facilitated Cross-Contamination

Farm equipment that has direct contact with soil, manure, or water that is likely to contain microorganisms of significant concern to public health and may spread microbial contamination to other production lands or water sources.

Distribution

After harvesting and other  post harvesting   activities,   another possible source of bacteria found on fruits and vegetables arise in the process of distributing the produce  from one  location  to  another, Several modes of transportation (air containers, refrigerated van and containers, marine containers, etc) are used to move harvested fruits and vegetables   from  production   areas   to   packing   or   processing facilities, to shipping points, and to destination markets Tompson et al., 2000).

Equipment used by short-haul and local distribution carriers is generally of lower quality and refrigeration capacity, while long distance transportation more often takes into consideration issues of quality and safety of fresh produce. Air carriers, railcars, marine vessels, (bulk and container), highway trailers, and intermodal combinations such as  trailer-on-flatcar (TOFC) and container-on-flatcar (COFC), are used to transport fresh, perishable commodities, Categorically, transportation should also focus on the prevention of food borne illness by Good Sanitation Practices, maintaining appropriate temperature and humidity   management,   and   minimizing   damage   potential   to   the product.

Diseases Caused by Vegetables and Fruit Borne Bacteria

The greatest concern caused by vegetables and fruits of high bacterial load is the diseases they cause man to suffer following their consumption. Such nonspecific clinical symptoms like nausea, vomiting, fatigue, dizziness, dryness of mouth and throat, muscle paralysis, difficulty swallowing, double or blurred vision, drooping eyelids, breathing difficulties, bloody diarrhea, abdominal pain, hemolytic uremic syndrome, kidney failure (especially in children and the elderly) and so on, mostly result from the pathogenic activities of fruits and vegetables borne bacteria ( US FDA, 2001).

Salmonella contamination is associated with bacterial soil rot of fresh fruits and vegetable in the market place. Wash with water from 66%, 401 samples of fresh fruits and vegetable collected in the market­place and affected by bacterial soft rot were positive for suspected strains of salmonella (Al-Hindawi and    Rihab-Rised,   1979).   The diseases can be found on crop in the field, in transmit and in storage or during marketing resulting in a great economic loss that causes greater loss of products than any other bacterial disease that enters through wounded areas often created by insect feeding or bruising at harvest. Insect and water are effective modes of spreading the bacteria that cause the disease. Once the fruits and vegetables are ready for harvest, they were handled by several different hands in the field and orchards, then in de warehouse, and finally in the grocery store.

Bacteria like Listeria, Salmonella and E. coli may all be found on the fruits and vegetables were they grow. These bacteria all cause food born illness and need to be washed away from produce (Garcia-Villanova et al., 1987). Generally speaking, poor handling, storage, or sanitation, should also be a warning for possible enteric bacteria while that can be assumed as salmonella and other fecal E.coli forms that may be present in commercially handling of fresh produce at base levels, any factor that favour multiplication of bacteria before consumption could result in a public health problem. Precautions should especially be observed if there is evidence of bacteria decay in foods when prepared.   Handling   practices   that   lead   to   bruising   and   mechanic damage the predisposing factor   for bacterial soft rots, should   be controlled.  Finally, salmonella survive and grow on contaminated, fresh- cut surfaces of tomato and other vegetables (Wood et al,. 1991).

Reduction of Fruit and Vegetable Bacterial Load

Owing to the current public health concerns with the microbiological safety of fruits and vegetables, researchers have investigated the efficiency of numerous physical, chemical, and biological methods for reducing the microbiological load of these produce. Pathogenic microorganisms associated with whole or fresh- produce can cause disease outbreaks, thus, demonstrating the need for improved mitigation efforts to reduce risks associated with these products. While there have been numerous methods proposed to be effective in the reduction of microbial load of fruits and vegetables, FDA opines that the ultimate method remains the prevention of bacterial contamination in the first place. However, this is not always possible and the need to wash and sanitize many types of produce remains of paramount importance to prevent disease outbreaks. Some of the suggested methods of sanitizing fruits and vegetables include physical methods, refrigeration, chlorination, use of iodophorcs, quaternary ammonium compounds, peracetic acid, hydrogen peroxide, ozone, irradiation, and the use of alkaline compounds.

Refrigeration

Fruits are commonly refrigerated in a bid to preserve their original taste and value in one hand, while they are kept from decaying or spoiling in the other. Refrigerated temperatures cannot be relied upon to prevent growth of pathogenic microorganisms on produce. According to Farber and his colleagues (1998), the populations of Listeria monocytogenes remained constant or grew on a variety of whole and cut produce stored at refrigerated temperatures, saying that under certain chilled storage conditions, spoilage of the product by the native micro flora might not occur until after pathogen populations reach levels capable of causing disease.

While growth of some pathogens may be inhibited by chilled temperatures, survival can be enhanced under certain conditions. To support this, Parish el al (1991) asserted that Salmonella and E coli O157:H7 survive for a longer time period in fruit juices under refrigeration than at room temperature. Hot water is also effective in reducing microbial load, although adverse effects on color, texture  and flavor limit the usefulness of this treatment, as Pao and Davis  (1999) determined that immersion of oranges in hot water (70 OC For 2 min, or 80 °C for I min) effectively reduced Escherichia coli on overall fruit surfaces by 5 log CFU/cm2.

Chlorination

Perhaps the most widely used sanitizer in the food industry. Chlorine has been used for sanitation purposes in food processing for several decades (Cherry 1999). Chemicals that are chlorine based are often used to sanitize produce as well as to reduce microbial populations in water used during cleaning and packing operations. The use of chlorine as a sanitizer is not only convenient but cheap in food services and household levels against food borne pathogens. Liquid chlorine and hypochlorites are generally used in the 50 to 200 ppm concentration range with a contact time of 1 to 2 min to sanitize produce surfaces and processing equipment.

Beuchat 1999. Showed   that   those   chlorine   concentrations   traditionally   used   with produce (<200 ppm) are not particularly effective at reducing microbial populations on lettuce. Survival of E coil O157:H7 on cut  lettuce pieces after submersion for 90 s in a solution of 20 ppm chlorine at 20 or 50 °C (68 or 122 °F) was not significantly different from the non chlorine treatment (Li et al, 2001). Contrarily, Eseudero et al 1999 opined that chlorine resulted   in   bacterial   population reductions of roughly 2 to 3 log. Treatment of fruits and vegetables with higher concentrations of chlorine (>500 ppm) has been studied. Jaquette et al (1996) stated that chlorine concentrations up to 100 ppm reduced populations of pathogens on alfalfa seeds. Enterobacteriaceae populations on tomato surfaces decreased when chlorine levels of process water were raised from about 115 to 225 ppm populations (Pao  and Davis, 1999).

Iodine

The use of iodine-containing solutions as direct contact sanitizers for produce is limited due to a reaction between iodine and starch that results in a blue-purple color. Despite these limitations, iodine solutions such as iodophors (combinations of elemental iodine and nonionic surfactants or carriers) are commonly used as sanitizers for food contact surfaces and equipment in the food processing industry (Lacey 1979). lodophors have a broad spectrum of antimicrobial activity, are less corrosive than chlorine at low temperatures, and are less volatile und irritating to skin than other types of iodine solutions (Lawrence et al., 1957). lodophors might have some usefulness for treatment of items that are peeled  before consumption,  although  they  are  not approved for direct food contact.

Hydrogen peroxide

H2O2 possesses bactericidal and inhibitory activity due to its properties as an oxidant and due to its capacity to generate other cytotoxic oxidizing species such as hydroxyl radicals Ukuku, 2004). Its sporicidal activity coupled with rapid breakdown makes it a sterilant of choice for some food contact surfaces, and packaging materials in aseptic filling operations (Juven and Pierson, 1996). The use of H2O2 on whole and fresh-cut produce has been investigated in recent years. Salmonella populations on alfalfa sprouts were reduced approximately 2 log CFU/g after treatment for 2 min with 2% H2O2 (Beuchat and Ryu 1997).

Quaternary ammonium compounds

These are cationic surfactants that are odorless, colorless, stable at high temperatures, non-corrosive to equipment, nonirritating to skin, and able to penetrate food contact surfaces, more readily than other sanitizers (Walker and LaGrange 1991). Quat sanitizers form a residual antimicrobial film when applied to most hard surfaces and are relatively stable to organic compounds. They are most effective when used at pH 6 to 10, and are not compatible with acidic environments, soaps or anionic detergents. Listeria monocytogenes is more sensitive to quaternary ammonium compounds than coliforms, Salmonella spp., pathogenic E. coli, or pseudomonads – their mechanism of activity possibly involving a breakdown of the cell membrane or wall complex Marriott 1999).

 

Ozone

Ozone is an effective treatment  for drinking  water and  will inactivate bacteria, fungi, viruses, and protozoa. Bacterial pathogens such as Salmonella Typhimurium, Y. enterocolitica, S. aureus, and L. monocytogenes are sensitive to treatment with 20 ppm ozone in water (Restaino  et al.,   1995).   Salmonellae  and  E,   coli  populations   was reportedly reduced 3 to 4 log/g in ground black pepper after 60 minutes treatment with ozonated air (Zhao and Cranston 1995). Treatment with ozonated water can extend the shelf life of apples, grapes, oranges, pears, raspberries, and strawberries by reducing microbial populations and by oxidation of ethylene to retard ripening, besides, since it has excellent penetrating ability and does not leave a residue, ozone may have usefulness for treatment of process water, food contact surfaces, or whole produce.

Ozone can also cause corrosion of metals and other materials in processing equipment. It is capital intensive and may be difficult to monitor and control in situations where highly variable organic loads are likely to occur. Due to its strong oxidizing activity, ozone may cause physiological injury of produce. Also, since ozone produces toxic vapors, adequate ventilation is necessary for employee safety.

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