Comparative Study of Micro-organism Associated With the Spoilage of Banana
CHAPTER ONE
AIM AND OBJECTIVES
- it shows the amount of bacteria present in the decay of banana
- it also shows the amount of yeast and mold present in the decay of banana
- it provides a basic understanding of the physical, chemical and microbiological principles underlying the psreervation of foods and also provide as a basic understanding of the study of food microbiology from farm to consumer.
- It provide students with an understanding of the physical and chemical characteristics which influence the formation, stability and texture of food systems
CHAPTER TWO
LITERATURE REVIEW
MICROBIOLOGY OF BANANA(Musa musaceae)
WINE Banana wine was produced using each of industrial and wild yeast strains of scharomyces cerevisiae for pitcching. The wild yeast fermented the Banana must in 8 days while the industrial yeast strain gave the correspondence wine product in 6 days. Microorganisms isolated and characterised from the must included Bacillus subtilis, saccharomyces cerevisiae and candida mycoderma. B. substilis and saccharomyces cerevisiae in addition to lactobacillus Banarum and leuconostoc mesenteroides were all isolated from the fermenting must and the wine (Droby and Kotze, 1998).
Condida mycoderma was however not isolated from the two later sources. Biochemical parameters studies included pH using a digital pH meter (Corning pH meter 150, Type 3AG), titratable acidity by titration, alcohol content was calculated from initial and final specific gravity values and organic acid was by paper chromatograph on whatman paper. The Banana must initial pH was 5.07 + 0.01 the resultant wine had pH values of 4-16 and 4.14 for the industrial and wild yeast strains respectively initial specific gravity of must was 1.086. Industrial yeast caused a decrease to 0.999. Initial titratable acidity was low at 0.02%. This was significantly increased to 1.66% and 1.71% in industrial and wild yeast wines respectively. An alcohol content of 12% (v/v) was recorded with industrial yeast while a slightly lower value 11.8% (v/v) was obtained for the wild yeast fermentation product. Citric and malice acids were the organic acids from the must these two organic acids in addition to latic acid were found in the wine product irrespective of the yeast strain used. The occurrence of microorganisms in Banana wine suggests the need for microbiological quality treatment of banana wine before consumption. (Janisiewiez, etal 1997)
A total of fifty isolates of Bacillus species were compared for their amylase-producing ability on a solid medium containing 0.2% cassava starch as the substrate.
Two isolates, Bacillus subtillis G3 and Bacillus licheniformis B5.1 were the highest amylase producers. The two isolates were further grown in submerged culture in shake flasks in order to determine the effects of cultural conditions on their yields or amylase. The optimum concentration of cassava starch for amylase production was 3.5% for Bacillus subtilis G3 and 4.0% for Bacillus licheniformis B5.1. the two organisms produced highest yields of amylase when starch was used as the carbon source rather than when simpler carbohydrates (glucose, sucrose, or maltose) were used .(Kenwick, etal 1998)
However, cassava starch appeared to be a better inducer of the enzyme than soluble potato starch (Difco); yields of the enzyme for Bacillus subtilis G3 and Bacillus licheniformis B5.1 were 316.80 and 312.20 units/ml Banana just like most fruit has a pH between 2.5. The pH of a fruit is always a critical factor because it determines the kind(s) of microorganisms that attack the fruit. (Williamson, etal (1999). Usually low pH favors the growth of yeast and mold, both which are fungi, on banana fruit. Bacteria are also involved but come as secondary attackers after the fungi. In the case of bacteria, they get involved when the banana peel has a shit. (shepherd; 1990) This becomes a means of entrance into the banana fruit. The banana peel serves as a protective cover against microbial infestation. But these organisms are able to release some enzymes that are capable of breaking down the peel. All these microorganisms are capable of reducing the quality of what once was an attractive fruit. (kotze; 1992). Banana fruits are normally stored in a cool place. But when stored in an unfavorable condition result s in invasion of the fruit by micro-organisms. These micro-organisms now attach the stored frut decaying it more, thus resulting in making the fruit unattractive as well as giving it odor. These microorganisms include the following mold, yeast’s and some bacteria.
CHAPTER THREE
MATERIALS AND METHODS SAMPLE COLLECTION
Ripe and decay bananas were brought from new market and main market in Enugu and transported to the laboratory in a new clean polythene bag.
STERILIZATION OF MATEIRLAS AND MEDIA USED: sterilization of the glass materials used examples petri-dishes pipette, flask, test tubes etc is done by auto claving at 1210c for 15 minutes. The heat labile materials is also autoclaved at 1210c for 8 minutes. The culture media used include nutrient agar (NA) and sabraud dextrose Agar (SDA). This is obtained in the commercially prepared powered (Hydrated) forms and prepared according to the manufactures instructions. The specific quality was dissolved in specified volume of distilled water and sterilized by autoclaving at 1210c for 15 minutes in well stoppered conical flask. Each flask and its contents is allowed to cool for about 450c – 500c before dispensing into pre sterilized peri-dishes under sterilized conditions
The media is being poured into sterile bijoux bottle and left in slanting position to gel. 0.5mg of chloramphenical is added to SDA and mixed properly just before pouring into plates or bijoux bosttles in order to exclude the growth of bacterial that have the capability of growing in SDA
PREPARATION OF SABORAUD DEXTTROS AGAR (SDA):
The SDA will be prepared using:
Neutalised peptone agar – 1.5g
Glucose – 2.0g
Agar – 1.5g
Distilled water – 100ml
The above will be put in a sterile conical flask and shaked properly and capsules of choramphenical of 250mg was dissolved in 10ml of absolaute distilled water o.5ml of this solution was added to every 100ml of the SDA medium before autoclaving
PREPARATION OF NUTIRENT AGAR
The nutrient agar is being prepared in the laboratory as follows:-
Nutrient broth – 11g
Plain agar – 10g
Distilled water – 400ml
The above is being prepared and mixed in a conical flask and tightly plugged with cotton wool and autoclaved at 1210c for 15 minutes.
CHAPTER FOUR
RESULTS
In all, a total of 20 banana fruits were obtained from the two sources viz, New market and main market in Enugu. Each fruit were examined for fungi and bacteria associated with its spoilage by both physical examination and culturing chloramphenical.
In this work, six bacterial and five fungal species were isolated. The bacterial isolates were Erwinia sp, staphlococcus sp, pseudomonas sp, Eschierichia sp, streptococcus sp and charomobacterium sp, with pseudomanas species occurring 10 times (highest occurrence) and chromobacter having the least occurrence of 3 times. The fungal species observed were Aspergillus sp, penicillium sp, fusarium sp, Rhotorulla sp and Rhizopus sp.
Table I and II shows the various isolates and percentage of occurrence, with Aspergillus sp, having the highest occurrence of 10 in fungi examination.
CHAPTER FIVE
DISCUSSION
Banana is a rich, smooth, thick and attracted fruit, eaten as a nutritious fruits. It is enjoyed world wide.
In this study Banana from the new market Enugu had more of the spoilage microorganisms than the ones obtained from the main market Enugug. This can be attributed to the handling, transportation and storage problems. This corresponds to the work done by salunche, 1999. According to sommer (1993) the longer fruits are stored the more they are exposed to contamination and spoilage. It has been shown that some bacteria like Erwinic sp, and schromobacterium sp, can cause discolourarion of banana (seitz et al, 1992) Erwinia sp, has been incriminated as pathogen, saprophyte or constituent of epiphyic flora of plants.
This hence explains the high percentage of p[seudomonas and Erwinia species (66.7%) in this study. A lot of bacteria and fungi have been incriminated in fruit spoilage, also a lot of tropical conditions provides suitable conditions for their spoilage of fruit. These tropical conditions include the high temperature and high humidity. According to Debek (1985) the rates of growth of fungi and bacteria are markedly influenced by the storage environemnt and the lower the temperature and humidity, the slower the growth of microorganisms, and the smaller the likelihood of new infections. Not only storage environment is important in the spoilage of banana, but also the conditions under which the banana is held temporarily or offered for sale. In a very dirty condition the banana spoils faster than in a less dirty condition, example wounds on the fruit are especially likely to become infected if there is poor hygiene. The high occurrence of Aspergillus species, (50%) in the banana fruit can be attributed to its ability to contaminate the fruits while still on the plants in the farm from the result of this work, some of the fungal species isolated e.g. Aspergillus species, penicillium sp, and fusarium sp are pathogenic on health ground, it is not advisable to consume spoilt banana fruits
CONCLUSION
Considering the data obtained from this work, bacterial and fungi spoilage of Banana fruits will continue to increase, if not controlled. The percentages (frequencies) of occurrence of the various isolates showed that in the case of fungi isolates that Aspergillus species, pencillium species, Rhizopus species with fusarium are the worst agents of spoilage of banana in the study area. On the other hand in the case of bacteria Erwinia species, chromobacter species, pseudomonas species have been found to be pathogenic for man and animals. In order words it can cause health problems to man. It is therefore follows that any method used to control or reduce the spoilage of fruits. When this fungi and bacteria spoilage is reduced, more of the fruits will be available for human consumption.
On health ground, it is advisable not to consume spoilt banana fruits in order to avoid very fatal infections in human beings, example Chromobacterium species can cause pyogenic infection in man eaten from infection banana fruits. It is able to enter the banana fruits through wound on the body of bananas. (Zentmyer, 1993) proper method of transportation and storage has been able to reduce the problem of wounds on banana fruits, thus controlling spoil by fungi and bacteria
RECOMMENDATION
From the findings in the project, the following recommendation are hereby advocated.
That it is not proper to store banana with high temperature and high humidity because the rate of growth of fungi and bacteria organisms are markedly influenced by the storage environment and the lower the temperature and humidity is the slower the growth of microorganisms, and the smaller the likelihood of new infections on health ground, it is not advisable to consume spoilt banana fruits so as to avoid being infected by some microorganisms like Erwinia species, pseudomonas species, chromobacxterium species etc.
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