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 During storage at ambient conditions for 92days, samples were withdrawn at 21day intervals for evaluation of quality changes.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).
