ABSTRACT

Microbial examination of spoilt avocado fruits was carried out to obtained the causal organisms, a total six(6) avocado from Nka market and Affiong Etuk market Eket were examined by culturing on nutrient agar and sabourand dextrose agar, for bacteria and fungi causing post-harvest spoilage on the fruits; three bacterial species and four fungal species was isolated. The bacteria include Erwinia spp, staphylococcus spp, pseudomonas spp fungi species includes Aspergillus species, Rhodotorula species, penicillium spp, fusarium spp, avocado fruits from Nka market were more contaminated than the avocado from Affiong Etuk market.

CHAPTER ONE

1.1   INTRODUCTION

The Avocado fruit, Persea americana is a tropical and sub-tropical fruit tree, originated in central America or adjoining regions of North or South America. It has now spread too much of the near tropical world. The avocado is limited especially by its climatic requirements, with race differences. It is also highly susceptible to drought injury. But excess soil moisture is equally fatal, encouraging the dread phytophthora root in most of the world, and where the fungus is unknown. Despite the high water activity of most fruits, the low PH leads to their spoilage being dominated by fungi, both yeast and molds. Other common diseases of pears include the black spot or scab caused by as comycetes. (Bezundenhouit J.J. 1992)

Avocado fruits has being estimated that one fourth of all produce harvested is not consumed before spoilage (Salulche, 1974), spoilage of fresh fruits usually occurs during storage and transport and while waiting to be processed unlike many other foods fruits after picking and before processing, microbiological spoilage problems are really market diseases of these products

Shape, varies from slightly obligate to highly elongate, an intermediate oval or pear shape is preferred, yellow to purple or black. (Sheperd J.S: 1990)

The composition of the fruit influences as the likely type of spoilage. Thus bacteria soft rot is widespread for the most part among the fruits is limited to those that are not highly acid. Because most fruits are some how acid and are fairy dry at the surface, and are deficient in B vitamins, moulds are the most common causes of spoilage. The compositions too, must determine the particular kind of moulds most likely to grow, thus avocado support a large, variety of fungal spoilage organisms and other kinds comparatively few. (Prusky and N.T. Keen 1993).

1.2   STATEMENT OF PROBLEM 

Micro-organisms are known to destroy fruits, thereby reducing the quantity for consumption and the profits desirable from fruits such as avocado. Many spot are noticed on pears which do change the taste when consumed.

Bacteria and fungi are harmful and useful living organisms. The spoilage of most fruits is always associated with bacteria and fungi, many diseases of plants are associated with bacteria and fungi (Micro-organisms).

The adverse effect of bacteria in plants and fruits has resulted in shortage of avocado fruits for consumption. Revenue is lost by farmers and industries that uses avocado fruits as raw materials for fruit juice due to the spoilage caused by micro-organisms. (Macmillam and Narayanam, 1990)

1.3   AIM AND OBJECTIVE OF THE STUDY     

Microbial examination of spoilt avocado fruits.

a.     To isolate and identify how micro-organism destroy avocado so as to guide producer and farmers on how to manage the fruits.

b.     To isolate and identify those micro-organisms that are responsible for the spoilage.

c.      To compare the extent of spoilage in the area of collection (tree) with that of market.

1.4   SIGNIFICANCE OF THE STUDY

This study will be useful to farmers, fruit juice industries and consumers of avocado fruits. The outcome of this research will guide users of avocado fruit on the best method of preserving to avoid spoilage. The research work also will add to the literature  and information existing about avocado for student and companies that uses avocado as raw materials for the production of fruit juice. (Debek A.J 1993)

1.5   LIMITATION OF THE STUDY

There are many different types of micro-organisms that cause spoilage in avocado fruit or fruits in general, focus is made only on fungi and bacteria because they are the major organisms associated with spoilage in avocado fruits.