ISOLATION AND IDENTIFICATION OF MICROORGANISM ASSOCIATED WITH VEGETABLE SALAD

ABSRACT

Fresh samples of vegetable salad collected from different food outlet in Ilorin metropolis were evaluated for bacteria loads, at a temperature of 25⁰c and the PH of the samples which is 3.7 using spread plate agar dilution method, the bacteria load ranges from 1.6×10⁴cfu/g to 11.5×10⁴cfu/g and faecal coliform ranges from 1.6×10⁴cfu/g to 4.6×10⁴cfu/g associated with the salad from majority of the samples. Microorganism associated with vegetable salad include,Bacillus anthracis mycobacterium spp, Brucella spp, Listeria monocytogenis, Yersima enterolytia, clostridium perfringens, Klebsiella spp and M. Paratuberculosis

CHAPTER ONE

1.0 INTRODUCTION

        Vegetables are most consumed as salads or cooked in savory or salty dishes. While culinary fruits are usually sweet and used for deserts, but it is not the universal rule (Harri Vaino, Franca Bianchini, 2003).Some vegetable can be consumed raw, some may be eaten cooked and some must be cooked to destroy certain natural toxins or microbes in egg plant, unripe tomatoes, day lily, winter melon, fiddle head fern, and most kinds of legume/beans (such as common beans)

        The yellow/orange colors of fruits and vegetable are due to the presence of carotenoids, which are also affected by normal cooking processes or changes in pH. Chlorophyll is affected by the pH and it changes to olive green in acid conditions, and to bright green in alkaline conditions. Some of the acids are released in steam during cooking without a cover. The red/blue coloring of some fruits and vegetables (e.g., blackberries and red cabbage) are due to anthocyanins, which are sensitive to changes in pH. When the pH is natural, the pigments are purple, when acidic, red, and when alkaline, blue. These pigments are quite water-soluble. This property can be used in rudimentary testing of pH.

        Vegetables, as it name implies, is an edible plant or part of a plant, other than a fruit, planned for cooking or eating raw (Harri Vainio, Franca Bianchini,2003).

        During harvesting and transportation, raw vegetables may be bruised resulting in the release of plant nutrient, and thereby, providing substrates for microorganism present on the surface of the vegetables to grow. With a view of such exposure to pathogens, vegetables have been associated with the outbreaks of food borne disease in many countries (Alice, 2001).

        Bacteria are commonly found on raw foods like salads, eggs, beef, vegetables, cheese,  ice cream, unpastaurized milk, fish, fresh fruits, canned foods mushrooms etc(Noah,2009;Fry et al., 2005)

        Outbreaks of staphylococcus aureus, Bacillus and proteus food poisons after eating in a restaurant have been reported by some researchers in 2001, Norinaga Miwa reported on outbreak of staphylococcus aureus food poison due to the consumption of eggs in boxed launches prepared at their company cafeteria.(Norinaga et al). Aerobic colony counts, coliform and enterococci enumeration are useful and most often used means of accessing overall sanitation in the environments of food service establishment. (Collins, 1964; Jay, 1978, Moyo and Baudi, 2004).

        Effective cleaning is of prime importance since it not only removes gross contaminations but also any residues that could support the subsequent survivals and growth of microorganisms.(Clark,1965).As  a result of inadequate cleaning microorganism may persists on utensil and work surfaces and build in numbers(Fraizer and Westhoff,1988).The main objectives of sanitations is to minimize the access of microorganisms in food from various  sources    at    all      stages    of handling  (Marrioat,1989,cords and Dychdala,1993)

        Salad may be served at any point during a meal, such as: appetizer salads, light salads to stimulate the appetite as the first course of the meal, Dessert salads, sweet version often containing fruit, gelatin and or whipped cream

        In recent years, salad has become a very popular components of menu served in birthdays and wedding parties; they are also sold in fast food outlets in most major cities in Nigeria.

        Examples of different parts of plants used as vegetables are: coriander leaf, stem, flower bulbs, Leaves, leaf sheaths, leek, Tuber, Roots stem shoots, stem bulbs etc