ALCOHOL FERMENTATION FROM FRUITS-WINE

 ALCOHOL FERMENTATION FROM FRUITS-WINE 

AIM: 

 To prepare consumable alcohol from grape juice using yeast. 

PRINCIPLE: 

 Grape is an important fruit found all over the world, It is used for eating and for production of wine. In China, the total annual production of grapes is about 50,00000 tons per where as production of wine is about 500000liter. The exact origin of wine is not cleared. However, used of the grape fruit for production of wine, was “domesticated” before 4,000 B.C. in Mesopotamia and Egypt. Any beverage derived from fermented fruit juice is considered wine. However, wine as we know it is still fermented grape juice from 6,000 years after its domestication. Contracy to common belief that wine making is a relatively simple process as compared to beer fermentation. The sugar-fermenting yeasts are present in the grape skins and naturally begin fermentation whenever there is a break in the grape skin. Where as ethanol is an alcohol made from the fermentation of the carbohydrate or sugar fraction of biomass (plant) materials. By Improving fermentation methods, the grape juice concentrate could allow fermentation of high alcohol (wines) which eliminate brandy fortification and provide an easier process to produce dessert wines. 

The strains of yeast (Saccharomyces cerevisiae) are mostly used for fermentations of sugar into alcohols. Red wine, as it is commonly produced with red berried grapes. Grape juice - of every grape, including the red berried ones. The wine maker could decide about adding specific yeast cultures in order to have a better control over fermentation as well as giving the wine particular organoleptic qualities. The main and fundamental role of alcoholic fermentation (or primary fermentation) consists in transforming the sugar contained in the must into alcohol and carbon dioxide - a job done by yeasts - however this process has the purpose of developing the secondary aromas of wine as well. The duration of fermentation and maceration depends on the style of wine to be made as well as on the varieties of grapes. In light bodied wines this phase can last three or four days - a sufficient time in order to extract color and some tannins - whereas in full bodied wines this time can also have a duration from one week to one month. The process of alcoholic fermentation will be completed in most of the cases, within one week.

Maturation is a the phase in which tannins and gustatory substances are being extracted, is a process that must be scrupulously controlled because excessively long times could result in the extraction of an excessive quantity of polyphenols therefore obtaining very astringent wines with a bitter and mediocre taste. At the end of maeration the wine is separated from the skins and transferred in the aging containers as opposed to white wines, in red wines malolactic fermentation (The process in which malic acid is converted into lactic acid and carbon dioxide) is always done. In red wines malolactic fermentation always plays a positive role because it makes the wine smoother and less astringent. Malic acid accentuates the astringent effect of tannins therefore its transformation into a “sweeter” acid, such as lactic acid, greatly contributes to the roundness of wine.

MATERIALS AND METHODS: 

Collection of Samples Samples of grape fruit (Jufeng) were collected from supermarket of Baoding city of Hebei, China. The samples were washed with dist. water to remove unwanted materials. The samples were kept in the plastic bags dully labeled with numbers and locations. Preparation of Samples The grape fruit (Jufeng) samples were processed to get juice (stum) with the help of juice machine. In order to prevent the possible oxidative reactions, 50 mg of SO2 and 10g of Ascorbic acids was added immediately after getting juice from juice machine. The reactions mixture was further added 90 g of Sucrose and NH4H2PO4 (300 mg/l) to supply Carbon and Nitrogen. The soluble solid contents were maintained up to21。Bix and pH was adjusted to 3.5. Activation of Microorganism In order to incline the culture media, the yeast ( Saccharomyces cerevisiae) was inoculated to the bean sprout juice at 28 in incubator. The process was repeated three times to get the growth up to 2×109cell/ml. 

PROCEDURE: 

High-activity of dry yeast (Saccharomyces cerevisiae) was inoculated with reactions mixture of stum. The yeast numbers up to 5×106cell//ml was achieved during this process, whereas fermentation process was carried out at 28o for overnight. Where as yeast numbers, the soluble solid contents and degree of liquor were measured after every day, in order to determine age of wine, the level of aromatic compound was measured with the help of the gas chromatography. The optimized condition like Temperature, Flow rate, N2, H2 and Air pressure was used during the experimental work, when the analysis of aromatic compounds was done with gas chromatography 

Qualitative analysis of Aromatic Compounds 

Equal volume (0.1ml) of butyl acetate, ethyl formate, ethyl acetate, ethyl butyrate, propyl alcohol, isobutyl alcohol, isoamyl acetate, isoamyl alcohol, ethyl hexanoate and ethyl lactate was taken in flask and volume was rised to 50 ml with absolute alcohol. The retention time was measured with gas chromatography to determine the peaks of aromatic compounds 

Analysis of Wine with Gas Chromatography. 

Twenty ml of grape wine was taken in 60 ml spherical flask and 10 ml of dichloromethane was added. The contents of flask were shaken, kept for 10 minutes to separate the organic layers and process was repeated three times. Further more volume of sample obtained was concentrated to 1 ml by the KD-concentration vessel. The sample was added with 0.1ml, butyl acetate as internal standard before injection into instruments. 

Analysis of Data:

The data obtained from experimental work was analyzed statistically by using Duncan multiple comparison test in the software minimum significance level 0.05. 

RESULT AND DISSCUSSION: 

Data obtained after analysis of various parameters are seen. The relationship between growths of yeast with time duration is given in the . It was observed that the growth of yeast increased during first 2 days followed by decrease during third and forth days but stabilized during 5th days of growing period. The soluble solid contents (13.5% ) obtained in this experiment after first day of fermentation. However, this contents were decreased up to 7.5% in the second day of experiment followed by further decreased up to 6%, during 5th days . It was observed that yeast (Saccharomyces cerevisiae) fermentation ability became strong when soluble solid contents were 6% at 28 because time for fermentation process was short and sugar contents were low. Data given is shows the changes in liquor degree with time period of fermentation during experiment. It was observed that liquor degree was 6.5% in the first day of fermentation followed by increased to 12% during fourth days of experiment. The liquor degree shows trend of escalation, before its stabilization.