ASSESSMENT OF THE EFFICACY OF VARIOUS SANITIZING AGENTS IN REDUCING MICROBIAL LOAD IN LEAFY VEGETABLES

ABSTRACT
Foodborne illnesses have been associated with the consumption of fresh produce, specifically leafy vegetables due to their soft texture and method of cultivation. As a safety precaution, these vegetables are usually cleaned with chemical sanitizers before consumption, hence the efficacy of various chemical sanitizers was tested on leafy vegetables to ascertain their potency. Lettuce, cabbage and spinach were collected aseptically in plastic bags from Kumasi central market to the laboratory. Samples were taken through pretreatment by washing with distilled water, sanitizing with 70% alcohol under Ultra Violet light to ensure complete sterility. Test organisms E. coli, Salmonella and L. monocytogenes inoculum were obtained from the microbiology laboratory of the Centre for Scientific Research into Plant Medicine (CSRPM), Akuapem Mampong and inoculated on samples using the dip method. Samples dried for an hour at 37oC and were sanitized with varying concentrations of peracetic acid, acetic acid, hydrogen peroxide, sodium hypochlorite and sodium chloride within varying exposure times. Microbial analysis were carried out at a temperature of 37oC for 48 hours on all samples using spread plate technique on plate count agar (PCA) for enumerating colonies that will grow on plates. Results showed that there was a significant difference (P˂0.05) between the loads on various test organisms. However, E. coli was chosen as a model organism. After inoculating cabbage, lettuce and Spinach, the results showed no significant difference (P>0.05) in the loads, thus cabbage leaves were selected for the assay. Inoculum sample of pretreated leaves showed 0 CFU/g and served as a control. Plate count before and after sanitizer treatment were also obtained and used to determine the potency of chemicals on microorganisms through the reduction in microbial population. All the sanitizers were found to have an efficacy of 99.99% except for sodium chloride which was 99.90%.


CHAPTER ONE
INTRODUCTION 
1.0 BACKGROUND
Food safety is a science that is concerned with handling, preparation, and storage of food in ways that forestall food borne unhealthiness. This entails the elimination of physical, chemical and biological hazards from food to make it safe for consumption ( o un a gi et al., 2011).

The objective of food safety is to eliminate food-borne disease outbreak and enhance consumer confidence in food by making food safe for human consumption (Jay et al., 1999). The application of pre-requisite programs such as good agricultural and sanitation practices from farm to fork through the implementation of Hazard Analysis for critical Control Point (HACCP) goes a long way to realize this objective.

Consumer food choices are made based on many factors such as satiety, taste, availability, convenience, age, health awareness, environmental influence, cost etc. One of such choices is the consumption of fruits and vegetables which form a vital aspect of peop e’ diet a round the world because of the health awareness created and increased urbanization (Cisse ,1997; Olayemi, 1997; Armar Klemesu et al.,1998 ; Niang 1999; Faruqui et al. 2004; Amoah et al.,2005). Vegetables form the basis for a healthy and balanced diet due to the nutritional components they possess such as vitamins, minerals, proteins, calcium, chlorophyll, carotene, potassium, dietary fiber and folate (Koffi-Nevry et al., 2012).

Vegetables also have a beneficial impact on general wellbeing and prevention of diseases (Remesy et al., 1998) by decreasing the risk of acquiring illnesses such as cancer, coronary heart disease, etc.

In Ghana and other developing countries, general sanitation and proper waste management remains a challenge and cropping practices of foods like vegetables cannot be assured to be pathogens free. Numerous studies in West Africa has revealed high levels of microorganism infection in irrigation water; on farms and market vegetables (Cisse ,1997) which surpasses the International Commission on Microbiological Specification for Food standards by far (ICMSF 19742 ).Other common sources of microorganisms are soil, air, farm pests, food handlers and irrigation containers used (Taura and Habibu, 2009).

According to markets and street food surveys conducted in Accra Ghana, about 200,000 urban residents consume foods containing raw vegetables treated by sewer water in urban and peri-urban agriculture (Obuobie et al. 2006; Amoah et al., 2007). These foods have been quoted as a serious explanation for the increasing diarrheic diseases (Tjoa et al. 1977; Mensah et al. 1999; King et al. 2003).

In a report given by the World Health Organization in 2015, the burden of food borne illness has been identified to be caused by 31 hazards which include bacteria, virus, toxins, chemicals and parasites. These cause an estimated number of 22 diseases with the most common agents being Escherichia coli, Salmonella, Norovirus and Campylobacter. These organisms cause 70% of the wor d’ food borne i ne with Africa and Southea tern A ian recording highest number of incidence and death followed by eastern Mediterranean region.

Due to the exposure levels of vegetables to bacteria, effective wastewater treatment using high-technology treatments and decontamination structures can be used. These processes are however difficu t and expensive to carry out as they need high energy, infrastructure and maintenance necessities, as well as skilled labor, which makes it less feasible in countries with low income (Carr & Strauss, 2001).

Another way of removing pathogenic microorganisms from fruits and vegetables apart from waste water treatment is the use of effective sanitization treatments to eliminate food borne diseases in connection with fresh vegetable consumption (Xu, 2005). This is more feasible and less expensive to practice.

An accepted and widely used sanitizer for fresh vegetables is hypochlorite at 50-200mg/L. Chlorine also produces 1-2 log reduction in microbial content at common concentrations although it raises safety concerns of its ability to form trihalomethanes which is a carcinogen (Delaquis et al.,2004). The utilization of acetic acid as a substitute to chlorine for sanitizing vegetables has also been explored especially as vinegar, an inexpensive acetic acid source and also used in household applications (Sengun and Karapinar, 2004; Chang and Fang, 2007).

The presence of pathogenic and spoilage bacteria in vegetables has already been established, hence this study seeks to determine the efficacy of common sanitizing agents in reducing these pathogenic organisms to tolerable levels before consumption to enhance food safety hence, consumer protection.

1.2 Problem Statement
In recent times, there has been an increasing demand for vegetable salads because of the assertion that vegetables are healthier. However leafy vegetables have been associated to foodborne illness because of pathogens like Escherichia coli O157:H7. In 2001, Salmonella spp, faecal coliforms, Shigella spp and E. coli were found in unacceptable levels in tomatoes and lettuce from farms and markets in Accra Metropolis (Mensah et al., 2001).

The incessant occurrences of food borne illnesses through the ingestion of fresh produce is caused by rise in alteration in production processes; science, harvesting; storage, distribution and ingestion routines and practices (Hedberg et al.,1999).As a safety precaution, consumers wash leafy vegetables in water together with sanitizers such as chlorine dioxide, salt, peroxyacetic, hypochlorite, hydrogen peroxide etc. before consumption.

However  re idua  concentration  in thi  food (vegetab e ) may fluctuate  becau e of  ac  of now edge regarding the  anitizer di infection efficiency and the microbia  contaminant  that remains on vegetables surface. This presents a task for researchers and food processors to identify and ensure the microbiological quality and safety of vegetables (Garcia et al. 2003).

1.3 Need for the Study
Vegetables are known to harbor pathogenic microorganisms due to their soft texture and mode of cultivation which causes food borne illnesses when consumed untreated. Vegetables are however of increasing demand due to the health benefits associated with them.

There is therefore the need to properly sanitize vegetables and rid them of these pathogens to acceptable levels in order to curb food borne illnesses and promote food safety.

1.4 Objectives 
Main Objective:
To assess the efficacy of common sanitizing agents in reducing microbial load in leafy vegetables at different concentrations and contact times.

Specific objectives:
To determine the microbiological load of pathogens inoculated on leafy vegetables.

To determine the concentration of the sanitizing agent capable of reducing the microbial load to acceptable levels.

1.5 Organization of Study
The thesis was organized in five chapters. Chapter one being the introduction entails the background, problem statement, need for the study and objectives.

Chapter two, the literature review discusses vegetables and their importance to man, microbial contaminations they are exposed to, common illnesses they cause, through to sanitizers that are used for treatment and factors that enhance their efficacy.

Chapter three outlines the protocol used to inoculate microorganisms of known concentration onto vegetables and the sanitizing treatment they undergo while chapter four highlights the figures and graphical representation of results obtained from the experiment conducted. Chapter five discusses into detail the results and recommendations to support and sustain the proper practice of chemical treatment of vegetables.

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Item Type: Ghanaian Project Material  |  Attribute: 74 pages  |  Chapters: 1-5
Format: MS Word  |  Price: GH50  |  Delivery: Within 30Mins.
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