ASSESSMENTS AND BACTERIOLOGICAL EXAMINATION OF ICE CREAM OFFERED FOR PUBLIC CONSUMPTION IN UMUAHIA

ABSTRACT

Ice-cream is a nutritionally enriched diary products consumed by all age groups most especially children particularly in summer as well as throughout the year. Its microbial quality has always been crucially important to the public health. The present study was constructed to assess the bacteriological quality of ice cream sold in Umuahia. A total of 14 samples were randomly purchased from the fast food joint, supermarket, school, market and street hawkers differentiated in 2 categories: industrially produced ice cream (IND1-IND7) and locally produced ice cream (LP1-LP7). The total heterotrophic count range from 3.0x10³-2.0x106 (cfu/g) with industrially variety (IND3-IND4) recording no bacterial growth and also some lowest count while locally produced ice-cream has the highest count. The total staphylococcus ranged from 1.0x10² (cfu/g) in the industrially produced variety (IND4) to 3.0x10³ (cfu/g) in the locally produced variety (LP5). For E. coli count, the range was from 1.0x10² (IND2)-2.0X105 (LP5) (cfu/g) in both industrially produced and locally produced. The Lactobacillus count range from 1.0x10² (LP1)-1.0X104 (LP4) (cf/g). Total isolates were eight bacteria (Staphylococcus aureus, Lactobacillus spp., Streptococcus spp., Proteus spp.,Escherichia coli, Klebsiellae and Pseudomonas aeroginosa). Lactobacillus has the highest incidence (7) with the percentage of 50% while Proteus spp, Klebsiella, Pseudomonas aeroginosa had the least incidence and percentage of (1) 7.1%, (2) 14.2% and (2) 14.2% respectively. The total heterotrophic count was further subjected to a t- test statistical analysis which showed no significant difference (p<0.05;) between comparing the bacteriological quality of locally produced ice cream and industrially produced ice cream fall into the same categories. Since in the bacteriological count of ice cream industrially produced, 2 out of 7 products show no bacteria growth which implies that if adequate preparation that is standard process are used it is possible for industrially produced ice cream to be safe to health and better than locally produced ice cream. The presence of pathogenic organism in the ice cream  sample should be viewed with concern by the consumes, producers, ice cream manufacturing industries and the government since food poisoning by Staphuyloccocus Aureus, Bacillus spp, is possible through consumption of contaminated ice cream.

TABLE OF CONTENTS

Title page                                                                                                                               i

Certification                                                                                                                          ii

Dedication                                                                                                                              iii

Acknowledgement                                                                                                                iv

List of tables                                                                                                                          v

CHAPTER ONE

1.0  Introduction                                                                                                              1

1.1 Aims and objectives                                                                                                        4

CHAPTER TWO

2.0 Literature review                                                                                                            5

2.1 Location of microbes                                                                                                      6

2.2 Manufacture of ice-cream                                                                                             7

2.3 Microorganisms in ice-cream                                                                                        7

2.3.1 Bacteria                                                                                                                        8

2.3.2 Mould                                                                                                                            8

2.3.3 Yeast                                                                                                                              8

2.4 Microbial community of ice-cream                                                                              8

2.5 Hygienic and microbial aspects                                                                                     9

2.6 Major diseases transmitted through ice-cream                                                           13

2.7 Microbiology of ice-cream                                                                                             15

CHAPTER THREE

3.0 Materials and Method                                                                                                    17

3.1 Study area                                                                                                                       17

3.2 Experimental design                                                                                                       17

3.3 Sample collection                                                                                                            17

3.4 Sterilization of materials                                                                                                18

3.5 Media                                                                                                                               18

3.6 Preparation of serial dilution                                                                                        19

3.7 Bacteriological examination                                                                                          19

3.8 Characterisation and identification of bacteria isolates                                             20

3.9 Gram staining                                                                                                                 20

3.9.1 Catalase test                                                                                                                 21

3.9.2 Coagulase test                                                                                                               21

3.9.3 Oxidase test                                                                                                                  21

3.9.4 Citrate test                                                                                                                    22

3.9.5 Motility test                                                                                                                  22

3.9.6 Indole test                                                                                                                     22

3.9.7 Statistical analysis                                                                                                        23

CHAPTER FOUR

4.0 Results                                                                                                                              24

CHAPTER FIVE

5.0 Discussion                                                                                                                        33

5.1 Conclusion                                                                                                                       36

5.2 Recommendation                                                                                                                        37

References

Appendix

CHAPTER ONE

1.0            INTRODUCTION 

Milk is a complex biological fluid and by its nature, a good growth medium for many microorganisms. As a result of the specific production, it is impossible to avoid contamination of milk with micro-organisms therefore the microbial content of milk is a major feature in determining its quality (Rogelj, 2003). Bacterial contamination of raw milk can originate from different sources: air, milking equipment, feed, soil, faeces and grass (Coorevits et al., 2008). Milk is an opaque white liquid produced by the mammary gland of female mammals. It provides the primary source of nutrition for newborn mammals before they are able to digest other types of food. The exact components of raw milk vary by species, but it contains significant quantity of saturated fat, protein and calcium as well as vitamin C. Cow milk has a pH ranging from 6.4 to 6.8 making it slightly acidic. Several animals produce milk for human consumption, although the cow is by far the most important in commercial terms (Adams and Moss, 1999). The milk is perishable thereby necessitating it’s immediate consumption as fresh milk and can be processed into other products like ice-cream, yoghurt, cheese, butter which have improved keeping qualities. Ice cream is a product of milk which consists of milk, sweetening and stabilizing agents together with flavoring and colouring matter (Malou and Uzochukwu, 1999). It is a product that has wide patronage from infants, youth, adolescent and adult (Akinuli, 1998). There are numerous variables that must be controlled accurately during processing to obtain a high quality ice cream with the required taste, flavor, viscosity, consistency and appearance. Handling and storage conditions are some of these variables because they affect the physical, chemical and microbial quality of the product. The methods employed in the sales of ice cream are of different categories. It could be sold in open containers at retail outlets or in packages which may then be distributed manually in satchets, scoops or cones across the counter (Marshall and Arbuckle, 1996) (Warke et al., 2000); (Champagne et al., 1994) and (Daniels et al., 2002). Most ice creams become contaminated with microbes during production, transit, and preservation. Disease outbreak in many countries of Asia, Europe, and North America is as a result of consumption of ice cream contaminated with microbial pathogens during the processing stage (Chung, 1996). In Previous reports, high microbial loads in ice cream samples obtained from patisseries in Turkey were observed (Digrak et al., 2000; Evrensel and Gunes, 1998; Kivanc et al., 1994). The consumption of ice-cream is higher among children of vulnerable age groups therefore there is a need to maintain a high microbiological safe standard. A relatively low storage temperature and pasteurization step during its processing are considered to eliminate most of the pathogenic microorganisms. However, the addition of contaminated ingredients, improper handling and the use of improper storage temperatures are factors that contribute to the potential hazard of the finished products especially during processing and after pasteurization processes. This is particularly of interest during soft ice cream preparation since the point of sale happens to be its final stage of production (Verma, 1992).

Other possible sources of microorganisms in ice–cream have been reported to include raw materials used for the composition of ice-cream mix such as separated milk and milk powder cream, flavoring and coloring substances and stabilizers (Gomez, 1999) and from air during processing (Pelzer and Michael, 2000). Food spoilage is a predominant problem in African countries, Nigeria inclusive. It is generally stored by refrigeration, but the original taste and flavor does not last very long. Proper handling and storage of ice-cream helps to prevent its spoilage and the incidence of food borne illness, thereby increasing its shelf life. Ice cream is considered a popular product consumed particularly in summer as well as throughout all year and continues to be a dominant interest of large segments of the population (Mann, 1988). It is a combination of milk, sweetener, stabilizer, emulsifier and flavoring agents, egg products, coloring additives and hydrolyzed products of starch (Marshall and Arbuckle, 1996). Many studies have measured the sensory properties of ice cream to evaluate the relationship among various ingredients and sensory characteristics such as flavor and texture (Hyvönen et al., 2003). The body and texture characteristics are closely associated and are important in influencing consumer acceptance of ice cream and related products. Microorganisms are transmissible to humans through milk and milk products (Samarzija et al., 2012). The microbiological quality of ice cream can be low, as it is a good growth-medium for microbes (Kanbakan et al., 2004), especially as a hawking product. Historically, ice cream has been responsible for numbers of outbreaks of food borne illness (Nichols et al., 1995).

The source of microbial contamination can be at various stages of manufacture from humans and environmental sources (Chukuezi, 2010). The high content of nutrients like lactose of ice cream, proteins and its neutral pH (6–7) makes it an excellent growth medium for microbes, some of which may cause serious diseases and outbreaks like cholera, typhoid and bacillary dysentery in human beings (Ahmed et al., 2009 and Lee et al., 2009). Coliforms (fecal types) were historically used as indicator microorganisms to serve as a measure of faecal contamination, and thus potentially of the presence of enteric pathogens in food (Osamwonyi et al., 2011). Although some of these coliforms are not pathogenic, their presence indicates possible faecal contamination and the corresponding presence of intestinal pathogens responsible for a variety of diseases (Cakir et al., 2002). Coliform organisms are commonly used to reflect hygienic statistics of final products and effectiveness of hygienic practice in production. Bacteriological quality of ice cream reflects the hygienic practice in production and is an indication of food safety.

1.1       AIMS AND OBJECTIVES

            i. To isolate, identify and characterize the microorganisms of different ice cream samples sold in Umuahia.

            ii. To determine bacteriological quality of ice-cream offered for public consumption in Umuahia and its potential to pose risk to the public.

            iii. To compare the bacteriological quality of industrially produced and locally produced ice cream sold in different areas of Umuahia.

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