ASSESSMENT OF MICRO ORGANISMS IN MINIMALLY PROCESSED FRUITS AND VEGETABLES: A CASE STUDY OF NASARAWA TOWN.

ASSESSMENT OF MICRO ORGANISMS IN MINIMALLY PROCESSED FRUITS AND VEGETABLES: A CASE STUDY OF NASARAWA TOWN.

Abstract

Vegetables and fruits that have been physically altered from their original states but remain in fresh states are considered minimally processed. Minimally processed fruits and vegetables are good media for growth of microorganisms, they habour potential pathogens. Four fruits and three vegetables (water melon, pineapple, paw-paw, Orange, Pumpkin leaf, Spinach and Cabbage) were assessed for microbial loads. The microbial loads were: water melon, 9.5 x10³; Pineapple, 4.53 x10³; Pawpaw, 5.52 x10³, Orange, 3.46 x10²; pumpkin leaf, 8.47x10³; spinach,8.41 x10³;and  cabbage, 9.32 x 10^3.  After washing with tap, distilled and salted water, the microbial loads were reduced significantly. Washing with salt water  proved to have the highest effect in reducing the microbial loads to: water melon, 4.5 x10¹; Pineapple,6.14 x 10¹; Pawpaw, 2.68 x 10¹, Orange, 2.2 x10¹; pumpkin leaf, 3.36 x10¹; spinach,3.56 x 10¹;and  cabbage,4.1 x 10¹  . Also, microorganisms isolated were mostly Salmonella spp. Shigella spp. and E. coli. Sensitivity tests were conducted using some selected antibiotics in other to treat some of the disease that can arise as a result of the consumption of the contaminated food but Ciprofloxacin, Gentamacine, Streptomycin and Chloramphenical were the most sensitive.

CHAPTER ONE

1.1 INTRODUCTION

Vegetables and fruits that have been physically altered from its original state but remain in its fresh state are considered minimally processed. Fresh fruits and vegetables are an important source of nourishment and a vital ingredient in healthy and balanced diets. Minimally processed fruits and vegetables are products that undergo some industrial or manual processing (such as peeling, slicing, chopping, shredding, trimming, washing or packaging) which make them ready for consumption. However, in this dicing step occurs the release of internal cellular fluid rich in nutrients, which allow microorganisms to multiply rapidly increasing the initial microbial load and thus reducing considerably the shelf life of these products.  Packaging in modified atmospheres, together with refrigeration, slows down air flow and consequently the respiration of the vegetables. Bacterial growth is also inhibited, and the shelf-life of the product is enhanced (Fallik and Aharoni, 2004).

What the consumer perceives as the most appealing attribute of this products include: their fresh-like appearance, taste and flavor, in addition to convenience.

There are few factors that increase the risk associated with minimally processed fruits and vegetables above that of their non-processed counterparts. First, the more a product is handled and the longer between production and consumption, the more opportunity there is for contamination of the product. Secondly, most minimally processed or ready-to-eat products are meant to be taken home and eaten with no further washing or processing needed. The lack of any step that will kill or reduce the level of contamination before consumption increases the risk of consumer’s exposure to pathogens. Thirdly, in processing the peel or rind is often disrupted by cutting or peeling. The peel or rind can act as an effective barrier to microbial or chemical contaminants, so when it is disrupted, it leaves the fruits more vulnerable to contamination. (S.Demelo Silva, 2001)

1.2 OBJECTIVES

The aim of this project work is to assess the microorganisms in minimally processed fruits and vegetables and to provide a systematic review of the potential food safety risks from pre-processing to sale in the market as well as to proffer solution on better ways of prevent contamination and ways of decontamination.

1.3 SCOPE AND LIMITATION

The scope of this project is to assess micro organisms in minimally processed fruits (citrus, pineapple, water melon, and paw-paw) and vegetables (cabbage, spinach, pumpkin) in the local market of Nasarawa with special interest on Samolnella spp  Shigella dysenteriae and Escherichia coli and to also perform an antibiotics susceptibility test in order identify the various antibiotics that can be used to combat the various diseases caused by these micro organism. The major limitation is the cost involved in running the analysis and the constraint involved in maintaining an aseptic condition throughout the period of the analysis.

1.5 JUSTIFICATION

The complete execution of this project work (assessment of microorganisms in minimally processed fruits and vegetables) will be of relevance in the production of micro-organism free fruits and vegetables for the teaming population as well as better ways of decontaminating and packaging the products.

CHAPTER TWO

2.0 LITERATURE REVIEW

2.1 INTRODUCTION

Fresh fruits and vegetables are considered for the sign of novel health and good source of nutritional supplement for the human body. Minimal processing helps to firstly keep the produce fresh and supply it in a convenient form, and secondly, extend shelf life and to facilitate its distribution to consumers. (Francis G.A 1999).

Removing the skin from the surface or altering the size leads to the loss of nutrients, rupture of cells accelerate the enzymatic reactions, rapid microbial growth, colour changes, textural changes and weight loss resulting poor quality of the produce. Minimally processing fruits and vegetables results in the release of internal cellular fluid, rich in nutrients, which allows microorganisms to multiply rapidly increasing the initial microbial load and thus reducing considerably the shelf life of these products. The Centres for Disease Control and Prevention (CDC, 2009) revealed that an estimated of 12.3% of total food borne diseases outbreaks from 1990 to 2007 were related to fruits and vegetables.

2.2 HEALTH AND NUTRITIONAL BENEFITS OF FRUITS AND VEGETABLES

Eating vegetables provides a lot of health benefits – people who eat more of vegetables and fruits as a part of an overall diet are likely to have a reduced risk of chronic disease. Vegetables provide nutrient vital for health and maintenance of the body, it may reduce the risk of heart disease, obesity, and type 2 diabetes.

2.3 METHODS OF PRESERVING MINIMALLY PROCESSED FRUITS AND VEGETABLES (FRESH CUTS)

The following are more natural ways of keeping the quality of minimally processed fruits and vegetables:

·        Temperature

·        Essential oil

·        Modified atmospheres

·        Packaging

 TEMPERATURE:

Is one of the most effective factors, controlling freshness and the decay of the fresh cuts products and maintains good quality control (the cool chain) is the first factor in extending shelf-life of high quality fresh cuts products. Low storage temperature is more effective in delaying the ripening and microbial growth while preserving sensory quality of fresh cuts mango slices.

ESSENTIAL OILS:

Methyl Jasmonate (Mj, C 13 H 2003) is natural occurring substance that is commonly found in plant tissues and is a part of the defence mechanism in plant which makes it more resistant to temperature changes and to attacks by insects, bacteria and fungi.

PACKAGING AND MODIFIED ATMOSPHERE

Packaging fresh-cut fruits products in polymeric films that help in creating a suitable passive modified atmosphere can also be an effective supplement to proper temperature management in maintaining their quality. However, oxygen level can get too low if the wrong poly bag is used and this can lead to off-flavor development as a result of anaerobic respiration. This challenge is to select a packaging material which will have low enough oxygen to assist in quality retention without leading to off-flavor development.

2.4 EFFECTS OF WASHING

The lack of an effective antimicrobial treatment at any step from planting to consumption means that the pathogens introduced at any point may be present on the final food product. Washing and rinsing some types of fruits and vegetables can prolong shelf-life by reducing the number of microorganism on the surface. Infiltration may also be enhanced by the presence of suffectants and when the temperature of the fruit or vegetable is higher than the temperature of a water suspension of cell.

By subjecting bacteria to a salty environment, it keeps them from growing. Some bacteria however, have adapted to living in salty environments, such as Staph. Salt will kill off bacteria from the fruits by creating a hypertonic environment.

2.5 KIRBY-BAUER ANTIBIOTIC TESTING (DISK DIFFUSION ANTIBIOTIC SENSITIVITY TESTING)

This is a test which uses antibiotics –impregnated wafers to test whether bacteria are affected by antibiotics. In this test, wafers containing antibiotic are placed on agar plates where bacteria have been placed, and the plate is left to incubate. If an antibiotic stops the bacteria from growing or kills the bacteria, there will be an area around the wafer where the bacteria have not grown enough to be visible. This is called the zone of inhibition. This information can be used to choose appropriate antibiotics to combat a particular infection. (Mohanty A et al; 2010)

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