CONTRIBUTIONS OF PACKAGING TO THE EXTENSION OF SHELF LIFE OF PROCESSED GRASSCUTTER MEAT (Thyronomys swinderianus).

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ABSTRACT

This research was carried out to assess the physico-chemical properties, storage stability and acceptability of cured grasscutter meat (Thyronomys swinderianus) products which were smoked and packaged with different plastic films (High Density Polyethylene and Polypropylene). Live grasscutter was slaughtered, dressed, cut-up and divided into three portions. One portion was treated with a solution of 5% salt; second portion was cured with a solution containing sodium nitrite, potassium sorbate, salt and Onion (Allium cepa) extract, while the last portion which was not cured served as control. They were all hot smoked for nine (9) hours at 78+20C. Following smoking and cooling, each portion was further divided into three sets.  One set was not packaged, while another set was packaged with High Density Polyethylene and the last set was packaged with Polypropylene. Following smoking and cooling, samples were analysed for physico-chemical, microbial and sensory properties before storage. During storage at ambient conditions for 92days, samples were withdrawn at 21day intervals for evaluation of quality changes. Results show that smoking, with or without salting and curing of fresh grasscutter meat appeared to be an effective means of preservation. Samples smoked after curing had the least microbial count and high chemical/anti-oxidative stability followed by the samples smoked after salting. The control had the highest microbial load and least anti-oxidative stability. Hot smoking reduced the moisture content and water activity, but increased per unit weight the protein, fat, ash, pH, vitamins (such as vitamin A and C) and minerals (such as iron, sodium and potassium), presumably due to concentration effect. The sensory analysis showed that the samples smoked after salting were generally preferred to the other two samples, based on the colour, flavour and general acceptability. Although no Significant difference (P > 0.05) were found among the samples. During storage, samples packaged in polypropylene were found to have more oxidative stability with the least TBARS, peroxide and acid values. The water activity values were low. Microbial analysis of these packaged samples during storage gave the least mould and total viable counts. Unexpectedly, the vitamin and mineral contents were retained more in the High Density Polyethylene packaged samples throughout the storage period compared to Polypropylene packaged samples. Also, sensory analysis during storage showed no significant differences due to packaging (P>0.05).

CHAPTER ONE

INTRODUCTION

1.1       BACKGROUND INFORMATION

             Meat products are processed animal tissues which are used as foods. They are complex biomaterials that are subjected to many biological, chemical and physical changes that affect quality and shelf life (Hotchkiss, 2006). Biological changes are caused by micro-organisms (spoilage and pathogenic), insects and rodents. Chemical changes result from environmental influences and include oxidation, flavour deterioration and colour loss among others. Physical changes include moisture gain or loss, textural changes and contamination by foreign materials.

Meat processing is little practiced in the tropics mainly because of crude technological base and entrepreneurial reluctance to take the risks, hence high demand for fresh (raw) meat. Consequently, fresh meat and traditional meat products are just wrapped with paper, and leaves (Obanu, 1986). Meat traditionally preserved by drying is sometimes, packaged in linen bags, baskets or pottery to facilitate storage and transport and to provide some kind of protection against dirt and insects. To extend the shelf-life of these meat products, some processing are necessary.

An aspect of processing in common use is packaging. Proper packaging precludes deteriorative changes in meat products.According to Hotchkiss (2006), the time it takes for a food product to deteriorate to an unacceptable degree (shelf-life) is dependent on processing method, storage conditions and form of packaging. Thus, food packaging significantly affects quality and safety related changes in food and has a profound impact on shelf-life (Bugusu and Bryant, 2006).

            Packaging can be seen as an enclosure or wrapping of products (IFIS, 2005). In view of this, food packaging therefore involves the creating of an inert, correct and suitable environment for food, protecting it from biological, chemical and physical changes by effectively acting as a barrier between the internal and external environments. This enables packaging to preserve and protect a product so that it reaches the consumer in the same condition as when it was first made. Packaging as a meat preservation technique operates on the principle of prevention (or reduction) of contamination and protection; its protective technique operates on protection against static and dynamic stresses imposed by storage and transportation (Brody, 1974).

            In addition to its preservative and protective function, packaging also performs overtly presentational/technical functions; by increasing sales through displaying what the product actually is and information regarding the product as well as creating brand awareness. It also aids to appeal to the consumer in terms of shape, size, colour and convenience (Fellows and Axtell, 1993).

1.2       PROBLEM STATEMENT

In most developing countries, processed meat products are handled and stored with minimal refrigeration. A fast-turnover system existed traditionally, ensuring that meat slaughtered in the morning are sold and consumed the same day. With higher concentrations of population, however, this traditional system now becomes obsolete and unsatisfactory because more time is needed between slaughtering and ultimate consumption (FAO, 1990). Meat products are highly perishable because of their high initial water content and nutritive content. Heat processed smoked meats have been observed to absorb moisture from the environment, develop objectionable odour and flavour and because they are not stored well, can be easily attacked by rodents, insects, flies and micro-organisms (Kramlich, et al., 1980).

            In order to check deteriorative changes in processed meat products to the point of consumption, certain methods of preservation technique have to be applied. Refrigeration is the obvious solution, but this is expensive and frequently unavailable in developing countries. Hence, it is observed that in industrialized countries, only 2% of products are spoilt before they reach the consumer compared to the staggering 30 – 50% in developing countries where the packaging chain is less well developed. Energy-saving storage methods are therefore particularly relevant (Anonimous, 2001; FAO, 1990).

            Nigeria is blessed with abundant sources of raw material for flexible film packaging material namely resins. Despite this abundance, packaging is in its infancy, consequently, inadequate packaging films are used to protect indigenous meat products and they fall short of providing maximum protection. For instance, extrusion technology is low, being available only for few extrusion operations. This may be because demand is low too. Odigbo and Ikeme (2008) noted that the cost of using polypropylene films for kilishi packaging added less than one naira to the cost of product. This is not much. It is, therefore, necessary to identify other factors than cost that contributes to low usage rate of appropriate film.

            A major contemplation is lack of knowledge of the application of the packaging films. Producers of meat products still prefer to use a selection of traditional packaging material such as leaves and papers among others in an attempt to preserve cherished characteristics.

            It is necessary to extend the knowledge that such cherished characteristics can be preserved by modern packaging materials if they are carefully chosen. Additionally, the modern packaging material can help to extend the shelf-life of their delicate meat product.

            This work is therefore aimed to assess the contributions of packaging to the shelf-life of grasscutter, an indigenous meat product.

SIGNIFICANCE OF STUDY

  •  To improve our traditional smoked meat packaging.
  •  Reduce Contamination and improve marketability of smoked grasscutter meat.

 1.3                         AIMS AND OBJECTIVES OF STUDY

The main aim of this research is to assess the suitability of selected packaging films in the extension of shelf life of smoked grasscutter meat product.

 The specific objectives are to:

A:  Package grasscutter meat with the selected films,

B:  Analyse the physicochemical and organoleptic qualities of grasscutter meat stored in the films,

C:  Assess the acceptability of the stored meat products.

      It is hoped that this study will help to lay the foundation for the desired improvement of our traditional smoked meat packaging technology.

CONTRIBUTIONS OF PACKAGING TO THE EXTENSION OF SHELF LIFE OF PROCESSED GRASSCUTTER MEAT (Thyronomys swinderianus).