Microbial Examination Of Spoilt Avocado Fruit

Project and Seminar Material for Science Laboratory Technology SLT

Microbial Examination Of Spoilt Avocado Fruit


Microbial examination of spoilt Avocado fruits was carried out to obtained the causal organism. A total of 60 avocado from Ogbete Main market and New market Enugu were examined by culturing on nutrient agar and sabourand dextrose agar (SM), for bacteria and fungi causing post – harvest spoilage on the fruits; six bacterial species and six fungal species were isolated. The bacteria include Erwinia SP (66.7%), Streptococcus sp, *25%), E. Coli (18.9%) and staphycoccus sp (33.3%), Pseudomonas sp(20%) and Chromobacterium sp (5%) has the lowest percentage occurrence, Erwinia sp, Pseudomonas sp and chromobacterium sp were found to be absent in the control. The fungi species, includes Aspergillus sp (50%), Pericillium sp (25%), Fusarium sp (16.6%), Rhisopus sp (13.3%), currularia sp (8.3%) and Rhoctorula sp (3.3%), were also kolated Avocado fruits from Ogbete main market were more contaminated than the avocado form the new market.

Table Of Contents

Preliminary Page(s)

  • Title page
  • Certification page
  • Dedication
  • Acknowledgement
  • Abstract
  • Table of content

Chapter One


  • 1.1 Background of study
  • 1.2 Statement of problem
  • 1.3 Aim and Objectives of the study
  • 1.4 Hypothesis
  • 1.5 Significance of the study
  • 1.6 Limitation of the study

Chapter Two

Literature review

  • 2.1 The origin of Avocado fruits
  • 2.2 Uses of avocado fruits
  • 2.3 Preservation of avocado fruits
  • 2.4 Ways avocado fruits can be prone to contamination
  • 2.5 Microbial spoilage of avocado fruit
  • 2.6 Control of bacterial and other disease of avocado fruits and fruits products
  • 2.7 Some biochemical test for bacterial isolates

Chapter Three

Materials and methods

  • 3.1 Sample collection
  • 3.2 Sterilization of media an material used
  • 3.3 Preparation of media
  • 3.4 Bacteria and fungi isolate from avocado fruits
  • 3.5 Bacterial isolation and identification
  • 3.6 Fungal isolation and identification
  • 3.7 Lactophenole blue staining technique for fungi isolates
  • 3.8 Staining techniques for bacteria isolates grains stain
  • 3.9 Biochemical test for identification of bacteria isolates

Chapter Four

Results and discussion

  • 4.1 Bacterial Examination
  • 4.2 Fungi, examination

Chapter Five

Conclusion and recommendation

  • 5.1 Conclusions
  • 5.2 Recommendation
  • Reference

List Of Table

  • Table I: Bacterial isolated and their frequencies
  • Table 2: Fungi isolated and their frequencies
  • Table 3: Sources of collection of the fruit and Bacteria isolate
  • Table 4: Sources of collection of the fruits and fungi isolates

List Of Figures

  • Fig. 1: Rate of occurrence of fungi
  • Fig. 2: Rate of occurrence of bacteria
  • Fig. 3: Fungi isolates according to sources
  • Fig. 4: Bacteria isolates according to source.

Chapter One

1.0 Introduction

1.1 Background Of Study

The Avocado pear, 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 to much of the near tropical world. The avocado is limited especially by its climatic requirements, with their race differences. It is also highly susceptible to drought injury. But excess soil moisture is equally fatal, encouraging the dread phytophthora root rot in most of the world, and where the fungus is unknown. Despite the high water activity of most fruits, the how PH leads to their spoilage being dominated by fungi, both yeast and moulds. Other common diseases of pears include the black spot or scab caused by as comycetes

Avocado fruits has being estimated that one fourth of all produced harvested is no consumed before spoilage (Salulche, 1974), spoilage of fresh fruits usually occurs during storage and transport and while wacting to be processed unlike many other foods fruits after picking and before processing are β€˜a live’ of the products plus the normal ripering process complicate an independent discussion of the 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.

The composition of the fruit influences 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 somewhat acid are fairly dry at the surface, and are deficient in B vitamins, mold are the most common causes of spoilage. The compositions too, must determine the particular kind of molds most likely to grow, thus avocado support a large, variety of fungal spoilage organisms and other kinds comparatively few.

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 bactera and fungi, many diseses 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 a raw materials for fruit juice due to the spoilage caused by micro-organisms.

1.3 Aim And Objectives Of The Study

Microbial examination of spoilt avocado fruits

  1. To isolate and identify how micro-organism destroy avocado so as to guide producer and farmers on how to manage the fruits
  2. To isolate and identify it those micro-organisms are responsible for the spoilage
  3. To compare the extent of spoilage in the area of colelction (tree) with that of market

1.4 Hypothesis

HO: Microbial organisms do not cause spoilage of avocado at either in the field or during exposure for sale.

Hg: Microorganisms (Fungi and Bacteria) are responsible for avocado spoilage.

1.5 Significance Of The Study

This study will be useful to farmers, fruit juice industries and consumers of avocado fruits. T he 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.

1.6 Limitation Of The Study

There are many or different type of microorganism that causes spoilage in avocado fruit or fruits in general, focus is made only on fungi and bacterial because they are the major organisms associated with spoilage in avocado fruits.

Chapter Five

5.0 Conclusion And Recommendation

5.1 Conclusion

Considering the data obtained from this work, bacteria and fungi spoilage of avocado will continue to increase. If not controlled. The percentage (frequencies) of occurrence of the various isolates showed that in the case of fungi isolates the Aspergillus sp, Penicillium sp. Rhizopus sp with Fusarium are the worst agents of spoilage of avocado in the study area, on the other hand in the case of bacteria Erwinia sp, chromobacter sp have been found to be pathogenia for man and animals, so can cause health problems to man. It therefore follows that any method used to control or reduce these micro-organism will drastically reduce the spoilage of fruits. When this fungi and bacteria spoilage is reduced, more of the fruits will be available for human consumption

5.2 Recommendation:

On health ground, it is advisable not to consume spoilt avocado fruits in order to avoid very fatal infections in human beings, example Chromobacterium sp can causes pyogenic infection in from infected avocado.

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