EVALUATION OF THE PERFORMANCE OF SECCHAROMYCES CEREVISAAE ISOLATE FROM PALM-WINE IN VINEGAR PRODUCTION FROM OR ANGE JUICE.
ABSTRACT
This project work aims at understanding the role of yeast in the vinegar production. This involves the breaking down of glucose molecule in the orange must into ethanol and carbon dioxide and water. The strains of the yeast used was sacharomyces cerevisiae isolated from palm-wine. The procedure and processes of isolating it which involves the palm-wine on the nutrient media after contrifugating the palm-wine and the supernatant was discarded. The isolated pure yeast cell was cultured with a selective yeast extract agar (YEA) to produce enough inoculum for the fermentation of the orange must. The yeast was inoculated into the orange must and the action of the yeast (seccharomyces cerevisiae) was careful examined to understand and observe the performance of the yeast in the production of vinegar from orange must. The activities which was examined daily by careful observation of the plated culture to evaluate the rate of changes from first day till the fifth day of the fermentation process.
Also, gram stain reaction was carried out to identify the possible contaminant of the inoculated culture. The result was tabulated and described based on the various test carried out and the colonies of the possible contamination was desecribed.
CHAPTER ONE
INTRODUCTION
Vinegar is an alcoholic liquid that has been allowed to allowed to sour. It is primarily use to flavour and preserve foods and ingredient in salad dressing and marinades. Vinegar is also use in a cleaning agent. The word is from the French vin (wine) an aigre (sour) costman et al, 2005).
Vinegar is made from the oxidation of ethanol in wine, cider beer, fermented fruit juice or nearly any other liquid containing alcohol. It is generally known to be made from a variety of diluted alcoholic products, the most common being wine, beer and rice. Commercially, vinegar is produced either by fast or slow fermentation process. Slow methods are generally used with traditional vinegars and fermentation proceeds slowly over the course of weeks or months. The longer fermentation proceeds slowly over for the accumulation of nontoxic slime composed of acetic acid bacterial and soluble cellulose, known as the mother of vinegar. Fast methods adds mother of vinegar ie bacterial culture to the source liquid and then add air using a venture pump system or a turbine to promote oxygenation to give the fastest fermentation. In fast production processes, vinegar may be produce in a period ranging from 20 hour to three days (Johnston et all, 2004).
However, micro organism perform a lot of important activities in the process vinegar production. The fermentation of orange juice into ethanol and subsequent oxidation to produce vinegar is carried out by a strain of yeast specie. There are thousands of yeast blowing in the wind and living in the soil on leaves, stems, vines and grapes. Amongst the 15 known genera, it was only one particular genus that are favourd in wine making. From Greek word for sugar (sakchar) and fungus (myke).
Sacharomyces is the genus that is favoured for the production of wine, bread and beer. The process of wine production furthermore to specify the particular specie of this genus, thus. Sacharomyces cerevisiae by a strain known as sacharomyces ellipsodeus (Kramer, 1966).
This yeast are unicellular eucaryetic fungi which can be isolated from various sugar rich source including palm wine (okafor, 1972; Okaghue, 1988). Where as palm wine is a local alcoholic beverage obtained from different kind of palm trees, such as the oil, raffia and date species. The species elacis guineesis is the most exploited because of its oil and sap, which are widely consumed in sourthen part of the country. Besides, its sap constitute a good growth medium, for numerous micro-organism, especially of yeast, lactic acid bacteria. Palm wine is also used locally as traditional raising agent in dough making and also to produce a local spirit by adding sugar. Nigeria palm wine yeast has been used to develop baking yeast (Ejiofor et al, 1994).
Presently, most of our industries depend on commercially isolated yeast in production of wine. Also, the process of transportation of commercial yeast can lead to the loss of it’s sensitivity. Again the cost of purchasing and transporting the commercially made yeast affect the production rate in the fermentation industries. This project work will therefore look for an alternatives approach on how to obtain yeast (sacharomyces cerevisia) by using local source (palm wine) which could give a large number of yeast.
The objectives of this work therefore are:
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