Determination of Proximate Composition, Mineral Elements, Heavy Metal Levels and Microbial Quality of Kilishi From Selected Areas in Kaduna State, Nigeria

Determination of Proximate Composition, Mineral Elements, Heavy Metal Levels and Microbial Quality of Kilishi From Selected Areas in Kaduna State, Nigeria

Chapter One

Aim and Objectives

The aim of this research is to determine the proximate composition, mineral content, heavy metals composition and microbial contaminations of Kilishi samples, differently prepared from the same beef source, at some selected Kilishi selling spots in Kaduna State of Nigeria. This aim would be achieved through the following objectives:

To prepare Kilishi by commercial producers, from the same beef source, at six- selected Kilishi selling spots in Kaduna State of Nigeria viz: Kasuwan Mata- Sabon Gari in Zaria, Yan Awaki-Tudun Wada in Zaria, Durumi Maigarke-Zaria City in Zaria, Raba Road-Malali in Kaduna, Sultan Bello Road-Anguwan Sarki in Kaduna and Kasuwa-Jos Road in Kaduna.
To prepare Kilishi and raw beef in the oven as control samples, from the same beef source, in the
To determine the proximate composition (moisture content, ash content, fat content, protein content, fibre content and carbohydrate) in the prepared samples.
To determine the mineral content (Na, Ca, Mg, P and K) in the
To determine selected heavy metals (Fe, Cu, Zn, Co, Mn, Pb, Cd, Cr and Ni) level in the samples.
To determine the microbial quality (Mesophillic aerobic plate count, Staphylococcus count, Coliforms count and fungal count) and identify some selected bacteria and fungi species in the
To compare the results obtained of Kilishi prepared by Commercial producers from their respective production spots with values of the control samples prepared from the
To compare the results obtained with WHO and FAO standard limits for meat and meat

CHAPTER TWO

LITERATURE REVIEW

Meat and its Composition

Meat is generally define as the flesh from domesticated animals and generally includes the skeletal tissues or flesh of cattle, sheep and other animals (Sulzbacher and Gaddis, 1977; Potter, 1980). The Food Safety and Inspection Service (2001) defined meat as “All parts of an animal that are intended for, or have been judged as safe and suitable for human consumption.” Thus, meat is the edible portion of animals, which is suitable for use as food and consists of lean and fatty tissues. In many developing countries, especially Nigeria meat is widely consumed either cooked or processed into other forms to avoid associated spoilage (Olaoye et al., 2010).

Chemically meat is composed of four major components including water, protein, lipid, carbohydrate and many other minor components such as vitamins, enzymes, pigments and flavour compounds (Lamber et al., 1991). According to Beilken et al. (2007), every specie of meat has its chemical characteristics. Lawrie (1991) reported that chemical composition of meat comprises 56-72% water, 15-22% protein, 5-34% fat, and 3.5% soluble non-protein substances (including carbohydrates, organic salt, dissolved nitrogen substances, minerals and vitamins). Aberle et al. (2001) reported that meat contains 70% water, 19% protein, 5% fat, 3.5% non-protein substances, and minerals and other materials 2.5%. However, Rendle and Keeley (2000) reported that each species has different chemical characteristics. In their report, the chemical composition of meat changes after slaughtered due to the stiffness of the dead muscles, a process known as „rigor mortis.‟ Therefore, at this rigor mortis, the muscles glycogen would be converted into lactic acid that caused a falled in pH making the meat to lose some of its water- binding capacity a desirable feature that slows down the growth of microorganisms and enhances flavour, juiciness and colour of the meat to give an attractive saleable product.

Water

The moisture content of meats depend on several factors and varies considerably with age of the animal, species, fat contents and the particular tissue under consideration (Greenfield et al., 1987). Rendle and Keeley (2000) reported the water content in lean meat, beef and lamb of 75, 73 and 71% respectively.

Protein

Muscle protein is divided into 3 groups based on their solubility properties; firstly, sarcoplasmic protein (30%), myofibrillar protein (55%) and stromal protein or muscle tissue (15%) (Droulez et al., 2002). Williams (2007) reported that the sarcoplasmic proteins are mostly glycolytic enzymes (glucosidase, diastase, pepsin, trypsin, among others) and are involved in conversion of stored energy into muscles power. He also reported that the myofibrillar protein such as myosin and actin are responsible for the muscle‟s overall structure. Chan et al. (1995) reported that stromal protein such as collagen and elastin affects the meat quality by lowering the tenderness of the meat, which depends on its number and degree of its cross-linking to other stromal proteins. It also influences the meat emulsion capacity, due to its non-solubility in water and lowers water-binding capacity of the meat because of its low content of hydrophilic and charged amino acids.

According to Williams (2007), raw red muscle meat contained around 20 to 25 g protein per 100g, while cooked red meat contained 28 to 36 g per 100g due to the decreased in water content that makes its nutrients become more concentrated during cooking. Protein from meat provides all essential amino acids: lysine, threonine, methionine, phenylalanine, tryptophan, leucine, isoleucine, valine, and has no limiting amino acids. It performs a wide range of functions such as provision of energy (5.65Kcal/g) that contribute 15 – 20% of the total calories in the body for maintenance (Pushparajan et al., 2012).

Fat

Fat in meat is generally in triglycerides form that significantly determines the meat tenderness and roughness. It is an important energy source because the amount of energy produced can be double from that generated by proteins and carbohydrates. According to Lawrie (1991), other important substances such as vitamins: A, D, E and K are dissolved in fat. Kris (2013) reported that fat contains nine calories per gram, while protein contains four calories per gram. He reported that fatty meats tend to be higher in fat-soluble vitamins such as vitamins A, D, E and K₂ than in lean meats. Rendle and Keeley (2000) reported fat content in lean, beef and lamb meats of 3.0, 3.9 and 7.4% respectively.

Organic substances (soluble non-protein)

These substances fall into two categories: nitrogen-based substances such as free amino acids and vitamins, and carbohydrates such as lactic acid and glucose (Kris, 2013). According to Kris (2013), meat is a good source of essential amino acids, minerals and vitamins, and a good source of energy (on average, beef yields 510 kJ and lamb yields 630 kJ per 100 g) and all the essential amino acids required for life are present and highly bioavailable in raw muscle tissue. Most importantly, meat is a dietary source of both vitamins B₁ (thiamin) and B₂ (riboflavin).

CHAPTER THREE

METHODOLOGY

Study Area

The study areas are Zaria and Kaduna towns in Kaduna State of Nigeria. Zaria town town covers an area of approximately 563 km² and is bounded by latitude 11^o 04‟ 00” N to 11^o 07‟ 00” N and longitude 7^o 42‟ 00” E to 7^o 70‟ 00” E of Northern Kaduna State (Figure 3.1). The indigeneous Hausa predominantly occupy Zaria town neighbourhood. Kaduna town covers approximately 131 km² and the area is bounded by latitude 10^o 31‟ 23” N to 10^o 52‟ 30” N and longitude 70^o 26‟ 25” E to 70^o 44‟ 28” E (Figure 3.2). It is the state capital of Kaduna State in northwestern Nigeria. The town is an industrial centre of Northern Nigeria manufacturing products like textiles, petroleum products, etc. The study areas has tropical wet and dry (savanna) climate with a pronounced dry season that lasts from November to mid-April and a rainy season that lasts from mid-April to November. The State extends from the tropical grassland known as the Guinea Savannah to Sudan Savannah. These two climatic conditions greatly influenced activities of the predominantly occupied people, who are primarily based on agriculture. It also favours animal keeping. In addition, the population of Nigerians recorded in Kaduna and Zaria towns of 760,084 and 695,089 respectively (2006 census) influenced business activities. Thus, Kilishi business is prominent in Kaduna and Zaria towns of Kaduna State.

CHAPTER FOUR

RESULTS

Proximate Parameters of Dried Beef and its Kilishi Samples

The results of the proximate composition of moisture, crude fat, crude protein, ash content, fibre content and carbohydrate content are presented in Table 4.1.

Percentage moisture content was highest in Malali Kilishi having 9.23%, which is not significantly different from Zaria City Kilishi (8.83%), while it was lowest in dried beef having 6.46% that is not significantly different from Kilishi from Kasuwa (7.22%) and Laboratory (6.93%) at P < 0.05. The result for crude fat ranged between 17.07 – 22.42%. The highest crude fat value obtained was from Malali Kilishi and the lowest value was from the dried beef. For crude protein, the highest value was from dried beef with a value of 67.94% and the lowest value of 52.92% obtained was from Malali Kilishi. There is no significant difference of crude protein values observed in Kilishi samples from Anguwan Sarki, Laboratory and Sabon Gari (P < 0.05). The least percentage of ash obtained was from the dried beef (6.81%) while the highest percent ash was from Anguwan Sarki (9.42%). Tudun Wada Kilishi had the highest percent of crude fibre of value 3.42%, while the least value of 0.75% was from the dried beef. The highest percentage of carbohydrate of 8.32% was obtained in Kilishi from Zaria City which value has no significant difference from values obtained in Sabon Gari and Malali Kilishi (P < 0.05), while the dried beef had the lowest carbohydrate value of 1.72%.

CHAPTER FIVE

DISCUSSION

Proximate Compositions in Dried Beef and its Kilishi Samples

Moisture content

From the results in Table 4.1, it can be seen that percent moisture content ranged between 6.46 – 9.23%. According to Ingram and Simonsen (1980), meat with moisture content of 20 and 15% has the ability of inhibiting some bacteria and fungi species respectively. Following their opinion, it therefore implies that the studied samples can inhibit the growth of microbes (lower moisture content). Similarly, this result agreed with moisture content values in Kilishi samples (7.50% and 8.67 – 10.00%) reported by Igene et al. (1990) and Olusola et al. (2012) respectively. However, Isah and Okubanjo (2012) reported higher values of moisture content than the current results of 16.65% and between 19.75 and 23.30% in dried meat and Kilishi samples respectively. The higher moisture content in Kilishi samples could be attributed to the step-wise drying in their processing technique (Mbofung, 1993). It could also be as a result of the environmental conditions and the infusion ingredients paste used during its production.

CHAPTER SIX

CONCLUSION AND RECOMMENDATION

Conclusion

Commercial producers prepared six samples of sun-dried Kilishi, from the same beef source in the month of August. These samples were prepared and collected for analysis from their production spots in Kaduna State of Nigeria viz: Kasuwan Mata- Sabon Gari in Zaria, Yan Awaki-Tudun Wada in Zaria, Durumi Maigarke-Zaria City in Zaria, Raba Road-Malali in Kaduna, Sultan Bello Road-Anguwan Sarki in Kaduna and Kasuwa-Jos Road in Kaduna. From the same beef source, an oven-dried Kilishi and oven-dried beef sample were prepared from the laboratory and collected for the analysis. Standard methods by AOAC were used for the proximate and microbiological analysis with app.ropriate equipments. Flame photometer (PF9) and VARIAN AAS (AA500) were used in assessing the concentrations of the mineral contents and heavy metals in the samples respectively. The level of mineral elements, heavy metals and microbiological parameters in all the samples were determined and assessed by comparing the results with the permissible limits.

The study revealed that processing meat into Kilishi in Kaduna State of Nigeria improves the percent proximate parameters of the products thus making it nutrient dense. The results show that the profile of proximate parameters in the study samples is protein > crude fat > ash > moisture > carbohydrate > crude fibre. The high protein content results demonstrate the value and potential of Kilishi as a high protein food product. Kilishi from Kasuwa had the highest protein content and had the lowest values of fat, ash, moisture and carbohydrate. Kilishi prepared from the Laboratory that served as control seems to give the best results in trms of its effect on moisture and fat by lowering the moisture and fat contents, and had lower value of protein contents.

The present results showed that the mineral elements (Na, Ca, Mg, P and K) found were excessively in all the samples in the profile of K > P > Na > Mg > Ca. Kilishi samples contained the highest values of Na, P and K contents while the highest values of Ca and Mg contents recorded were from dried beef. The Laboratory (control) Kilishi had the lowest Ca, Mg and P contents. From the study samples, the highest Na and Mg contents were determined in Kilishi from Kasuwa, highest Ca content was determined in Kilishi from Tudun Wada and Kilishi from Malali had the highest P and K contents, while the lowest mineral contents were determined in Sabon Gari Kilishi. The study reveals that all the samples are good sources of macro elements that are safe for consumption except in cases where their deficiencies produce diseases.

The order of the levels of the heavy metals obtained from the six study samples is Fe > Zn > Ni > Pb > Mn > Cu > Co while Cd and Cr were below detection limits. Levels of each trace essential elements of heavy metals (Fe, Cu, Zn, Mn and Co) in both the study and in the Laboratory Kilishi samples differed significantly among the different samples except for Kilishi from Sabon Gari and Zaria City that Co concentrations were below detection limits. The concentrations of Fe and Zn in this study were above their threshold effects levels, which show that consumption of these samples have accumulated unsafe levels of Fe and Zn. Copper concentrations in this study shows that consumption of these ssamples is safe since they were below its threshold effects levels. The levels of Co contents were below its threshold effects levels in the Laboratory (control) Kilishi, while Co contents were below detection limits in Kilishi samples from Sabon Gari and Zaria City. Values of Mn concentrations show that only Laboratory and Malali Kilishi samples had Mn below its threshold effects levels, which indicates these samples are safe in respect to Mn hazards. From these results, Tudun Wada Kilishi had the highest value of Fe while Anguwan Sarki Kilishi had the lowest. It also shows that Sabon Gari Kilishi had the highest Cu and Zn values, Zaria City Kilishi had the highest Mn value and Anguwan Sarki Kilishi had the highest Co value, while the Laboratory (control) Kilishi had the lowest concentrations of Cu, Zn, Mn and Co, and it can be concluded that the study areas receive more of these metals. From the results of this study, the concentrations of Pb and Ni in this study exceeded their threshold effects levels, and this indicates that it is potentially harmful to consume these samples. The highest concentration of Pb found was in Zaria City Kilishi while the lowest Pb value found was in Malali Kilishi. Kilishi from Sabon Gari had the highest Ni content value while the lowest Ni value obtained was from Laboratory Kilishi.

The microbiological results revealed that the values of Staphylococcus counts in this study are above the threshold effects levels, and it indicates that it is unsafe to consume these samples. Again, comparison of values for Coliform counts with the FAO/WHO limits show that it is unsafe to consume Kilishi samples from Tudun Wada, Zaria City, Malali, Anguwan Sarki and Kasuwa due to their high Coliform counts levels. However, the results of Mesophillic aerobic counts and fungi counts were below the threshold effects levels, which show that consumption of these samples is safe. The presence of bacteria species of Staphylococcus aureus, Bacillus spp., Salmonella spp., Klebsiella spp. and Escherichia coli and fungi species of Aspergillus spp., Penicillium spp. and Geotricum candidum were confirmed in some samples with Staphylococcus aureus predominantly detected in all the samples. Nevertheless, the Laboratory, control Kilishi sample was found to be free from Salmonella spp., Escherichia coli, Aspergillus spp. and Geotrichum candidum, and thus had less microbial contaminants.

Recommendations

Further work should be carried out at the study area to investigate for mercury and arsenic heavy metals that might be present, known to be highly toxic metals to ascertain their concentrations.

Future studies to evaluate chemical contaminants such as pesticides and herbicides, and organic contaminants such as nitrates, phosphates, sulfates and chlorides, that are ubiquitous in the environment should be carried out to ascertain the levels of their contaminations in Kilishi products.

Again, studies to analyzed the spices and condiments used for the production of Kilishi meats should be carried out to ascertain their levels, whether they are the source of the Kilishi contaminants.

Kilishi produced in other areas in Nigeria where there is high traffic density should be evaluated for heavy metals concentrations and microbiological contamination because environmental pollution might be high in these areas.

Government should take measures to ensure good hygienic and sanitary standard at the various slaughtered houses, abbatoir and Kilishi processing spots as well as good hygienic practices by the producers that are probable contributors to the heavy metals and microbial contamination on the products.

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