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ABSTRACT

Additives used in food processing can be natural or synthetic in nature. The use of natural additives in food processing has been encouraged due to the health hazards, non-nutritiveness and high cost usually associated with their synthetic counterparts. Hence, this research work is aimed at determining the effects of three selected natural additives-spices (alligator pepper, cloves and ginger) on the quality attributes of kunun-zaki in order to encourage the use of natural additives and to establish their best concentrations for the production of kunnu –zaki. Kunun-zaki samples of different concentrations of spices: Cloves (Syzygium aromaticum), Ginger (Zingiber officinale) and Alligator pepper (Aframumom danielli) at 0% (control), 0.5%, 1.0%, 1.5%, 2.0% and 2.5% of each spice were produced. Samples were stored at room (RT) and refrigerated temperature (ReT) respectively. Chemical, mineral (heavy metals), pesticide residues, microbiological and sensory evaluations were carried out on the samples for four storage days using standard methods.  All the spices had various effects on the quality of Kunu-zaki produced. For the pH, specify gravity and sucrose, gradual decrease in values was observed during the first two storage days (ranging from 3.32-5.48 (RT); 6.00 -7.71(ReT); 1.0110-1.0255(RT), 2.5-1.0255 (ReT) and 0.20 - 0.15(RT), 0.77- 0.85 (ReT) respectively followed by increase in the values for the remaining storage days. For the titratable acidity, volatile acidity and free fatty acids, gradual increase in the values were observed (ranging from 0.51- 1.29(RT); 1.37 -1.40 (ReT) and 0.12 - 0.92 (RT); 0.12- 0.17 (ReT), 0.01-0.14(RT); 0.01-0.04(ReT) respectively. The control samples showed a higher rate of decrease and increase in each case. Chemically, 2.0% treated samples stored at refrigerated temperature gave better results (keep longer) than the other concentrations stored at room temperature. For the minerals (heavy metals): Lead, cadmium and Chromium were not detected but Zinc had values of 0.001 for the whole samples. Pesticide residues:  Hexachlorobenzene (HCB), Lindane, Dichloro Diphenyl Trichloroethane(DDT), Aldrin, Heptachlor, Endrin, Heptachlor Epoxide and Chlorodane ) though present in minute quantity, were found to decrease as the concentration of spices increased, with 2% and 2.5% being most effective on the average. The three spices were able to effectively control the microbial growth for the first three days, while visible growth were observed for the other days in samples stored at RT and less with the samples stored at ReT. Sensory evaluations showed that there were no significant difference in colour, taste and flavour with the samples but the mean values showed that sample treated at 1.5%, 2.0% and 2.5% were generally accepted with 2.0 % concentration mostly acceptable. Kunun-zaki produced at 2% concentration of the spices and stored at refrigerated temperature maintained the chemical constituents of the product and exhibits the neutralization of the heavy metals. There was also reduction of pesticide residues and suppression of microbial growth. Therefore, it can be concluded that kunun- zaki be produced at 2% concentration of these spices and be store at refrigerated temperature.

CHAPTER ONE     

INTRODUCTION

1.1     BACKGROUND OF THE STUDY          

Kunun-zaki is a traditionally fermented non-alcoholic beverage that originates from the Northern part of Nigeria which can be produced either from millet, sorghum or maize. Kunun-zaki is a Hausa word meaning “sweet beverage,” It is now widely consumed in several parts of Nigeria owning to its refreshing qualities (Osuntogun and Aboaba, 2004). The beauty of the acceptability of kunun-zaki is the fact that it is acceptable by the two dominants religious groups (Christians and Muslims). This is because it is used as substitute for alcoholic drinks. This beverage has been found to be highly nutritious and medicinal (Goffa and Ayo, 2002). Kunun-zaki can be consumed at anytime of the day by both the adult and children. It can be taken as breakfast drinks or food complement. It is also a refreshing drink that can be used to entertain visitors and serve as appetizer in social gatherings (Amusa and Ashaye, 2009). Kunun-zaki has poor keeping qualities which may be due to faulty processing and storage, since product is essentially a home based industry and at present, there is no large-scale factory production. This results to its proneness to microbial contamination by Lactobacillus fermentum and L. leichmannii which dominates its fermentation (Efiuvwevwere and Akoma, 1995).

Food additives are used for various technological functions like improving the nutritional qualities, organoleptic properties and general acceptability of food. They also perform a variety of useful functions in food that are often taken for granted. For example, it helps keep food wholesome and appealing en-route to market. Which can be some thousand of miles away from where it is produced or manufactured (US FDA, 1992)? Chemical or synthetic additives have been the major means of preserving foods for a long time. They are however limited in their ability to preserve foods without altering its quality parameters such as flavours, aroma and in many cases the chemical compositions. Complaints resulting from the use of synthetic additives ranges from mild one such as nausea, diarrhea and shortness of breath or even total shock after consuming such foods to life threatening disease such as cancer (US FDA, 1992).  As a result, the safety of some of these additives has become the public concern and the requirement for pre-market approval and monitoring of these substances has continued to make them issue of significance (Roller, 2003). There is a global concern about chemical residues in foods especially during storage. Consumers demand for food products with fewer synthetic additives and at the same time increased safety, quality and shelf life (Roller, 2003). Unlike in the past, consumers are more concerned about what they consume and the world is going more natural than it used to be. Many edible plants that contain complex compounds have been found to be having fungicidal and bactericidal properties, which can be extracted for use. Some have been identified and tests were conducted to establish their efficacy and suitability. There are high demands for minimally processed, fresh-like food products with high sensory and nutritional qualities. There is a growing interest in non thermal processes e.g. pulse field, dense gasses, high pressure technology for food processing and preservation (Ade-Omowaye, 2002).        

The quest for natural products has led to the introduction of ‘nutra ceuticals’ which is a term used for food or part of a food that allegedly provides medicinal or health benefits including the prevention and treatment of diseases. Stephen De Felice coined the term from ‘Nutrition’ and ‘Pharmaceuticals’ in 1989. The result is a word that refers to dietary or nutritional ingredients that promote optional health (Kalna, 2003). Quite a number of works has been done at maximizing the utilization of some natural additives, since they have been discovered to function quite well. The antimicrobial, antioxidative and preservative effect of a number of natural additives has been explored. Fruits, vegetable, spices, nuts, seeds, leaves, roots and bark have been exploited as natural sources of preservatives (Kalra, 2003).          

Spices are the dried, aromatic vegetable products used in food seasonings, they are usually of tropical or semi-tropical origin and include: barks (cinnamon), roots or rhizomes (ginger), flowers, buds (clove), fruits and seeds (pepper, cardamom). In most cases, spices are very aromatic and may contain large percentages of essential oil from which they derive their main flavorings character (Mau et al, 2001). The potent sources of natural antioxidants are spices and herbs. Spices have been known to impact flavor but it is now recognized that they fulfill more than this one function in food systems, certain spices prolong the shelf life of foods by their bacteriostatic activity, spices such as red chili, cinnamon leaf, clove, rosemary, sage, have been reported to have antioxidant properties. According to Pokorny (1991), when natural antioxidants are compared with synthetic ones, natural antioxidants were found to be readily acceptable by consumers as they are considered to be safer. Because they are from natural or biological sources, no safety tests are required by legislation for they belong to a component of food that is generally regarded as safe (Adegoke and Sagua, 1993).

Compounds having wide spectra of anti-microbial effectiveness have been found in thymol from thyme and iregano, allicin in garlic, engenol from cloves. Adegoke and Sagua (1993), reported, the inhibition of microbial growth in tomato ketchup using spices like Eeru (Xylopia aethiopica), Ariwo (Monodora myristica) and Atare (Aframomum meleguata). The mixed extract from Chinese chive, and cinnamon were reported to exhibit better inhibition on growth of Escherichia coli than potassium sorbate at 2% mg/ml. Mau et al, (2001), reported the inhibitory effect of selected Turkish spices and oregano component on some food borne fungi. Ginger and Aframomum danielli   were also found to inhibit some food spoilage yeast (Candida tropicalis, Torulopsis candida and Hansenula anomala).(Adegoke and skura,1994).

1.2     Justification

Spices have been used from pre-historic times not only as flavorant but also for medicinal purposes. According to the International Standard Organization (ISO), there are over Seventy (70) spices and herbs officially recognized, but more than 350 to 400 Spices are used in different Countries by people with different religion and Climate. They are mostly of no food value; they are only added to food as stimulant for the appetite and to aid digestion. The selection of a particular spice for food stabilization should be based on the type of quality desired in the food. The quantity of spice incorporated into the food must be minimized   because excess concentration might be ineffective and not serve the exact purpose for which it is applied. Aframomum danielli had been used to preserve Kunun-Zaki and is at its best at 2% concentration, (Adegoke and skura, 1994). However, the synergistic tendency of additives as found in synthetic \ chemical additives can also be explored in natural additive too hence, there is need to investigate the other spices synergetic effects on the quality of Kunun-Zaki. The result will provide appropriate data for food processors as well as investors in the beverage industry.    

1.3     Aim and Objectives          

The aim of this work is to study the effects of selected spices (Alligator pepper (Aframomum Danielli), Cloves (Syzygium aromaticum), and Ginger (Zingiber officinale) on the quality attributes of kunun-zaki, a non-alcoholic beverage with the following objectives

1. to carry out the chemical, nutritional and microbiological analysis on the produced kunun-zaki samples

2. to perform sensory evaluation on the produced kunun-zaki samples.

3. to establish the best concentration of the spices that can give the best quality.

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