Grapewine 2

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AN INVESTIGATION OF FERMENTATION RATE ON

SACCHAROMYCES CEREVISAEAND

SACCHAROMYCES SP.

Nguyen Thi Anh Thoa, Nguyen Ba NgocAbstract:

Red wine is a light wine which was fermentated by fruit juice with highlevel of nutrient, nice taste, and have good effect for the health when we useit with a right amount. In the World, specially in Europe, wine has beenmade a long time ago, and it was used very commonly. But in Vietnam, wineproducts have not been concerned much, pruducing scale is small and

artisanal; its efficiency is low.During the traditional wine making, wine is fermentated by naturaltypes of yeasts which stay in the grapes. To have a good quality of product,researches should be done to categorize and choose the best yeast genera.

Until now, there are lots of experiments in wine making process fromSaccharomyces.cerevisiae, which was sold in the market to make bread. Sothis thesis chose Saccharomyces.cerevisiae and Saccharomyces spp (yeaston the husky of grape) to do the reasearch of comparing speed offermentation as well as quality of product.

Introduction:Research about Saccharomyces Cerevisiae and Saccharomyces.spp

wether which type of yeast has the higher degree of activity, to make abetter kind of wine, is the essential demand to raise the fermentationefficiency and quality of product.

Purposes of this thesis are:examine developing speed of yeast,alcohol degree and the pH change of grape during fermentation bySaccharomyces.cerevisiae and Saccharomyces spp (yeast on the husky ofgrape); and compare developing speed, alcohol degree between those twotypes of yeast at different pH conditions.

Materials:1. Grape

Understanding the types of grapes used in wine and theircharacteristics is vital to make good wine. There are many kindsof grapes to choose from, depending on where you live. There aretwo main families: Vitis Vinifera - which is popular in Europe - and

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Vitis Labrusca - which is native to Canada and the eastern UnitedStates.The traditional and most popular type of grape for wine is the Vitisvinifera species. Belows are some of types in Vitis viniferaspecies:

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Auxerrois creates a neutral wine,fruity and soft. It is mainly grown

in Luxembourg and Canada.

Barbera is a low-tainnin grape

known for its tarry flavor. It is

widely planted in California.

Cabernet Franc is used in

Bordeaux added in smallamounts for flavor. It is mostly

used as an additive to blend with

other grapes.

Chardonnay is one of the mostpopular and easiest to grow whitegrapes. It is grown in Burgundy,

California, Australia and South

Africa.


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2. Wine yeastYeast is used in winemaking, where it converts the sugars present

in grape juice (ormust) into ethanol. Yeast is normally alreadypresent on grape skins.Most added wine yeasts are strains ofSaccharomyces cerevisiae,though not all strains of the species are suitable.Saccharomyces cerevisiae is a species ofyeast. It is perhaps themost useful yeast, having been instrumentalto baking and brewingsince ancient times. It is believed that it wasoriginally isolated from the skin of grapes.

All strains ofS. cerevisiae cangrow aerobically on glucose, maltose, and trehalose and fail to

grow on lactose and cellobiose. However, growth onothersugars is variable. Galactose and fructose are shown to betwo of the best fermenting sugars. The ability of yeasts to usedifferent sugars can differ depending on whether they are grownaerobically or anaerobically. Some strains cannot growanaerobically on sucrose and trehalose.Saccharomyces spp is a natural yeast. It is believed thatSaccharomyces.spp was founded in the skin grape when it isbeing fermentated.

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Pinotage is developed in the early

1900s and used primarly by South

Africa. Pinotage wine is heartywith a fruity and spice taste.
http://en.wikipedia.org/wiki/Winemakinghttp://en.wikipedia.org/wiki/Grape_juicehttp://en.wikipedia.org/wiki/Musthttp://en.wikipedia.org/wiki/Ethanolhttp://en.wikipedia.org/wiki/S._cerevisiaehttp://en.wikipedia.org/wiki/Specieshttp://en.wikipedia.org/wiki/Yeasthttp://en.wikipedia.org/wiki/Bakinghttp://en.wikipedia.org/wiki/Brewinghttp://en.wikipedia.org/wiki/Strain_(biology)http://en.wikipedia.org/wiki/Aerobic_respirationhttp://en.wikipedia.org/wiki/Glucosehttp://en.wikipedia.org/wiki/Maltosehttp://en.wikipedia.org/wiki/Trehalosehttp://en.wikipedia.org/wiki/Lactosehttp://en.wikipedia.org/wiki/Cellobiosehttp://en.wikipedia.org/wiki/Sugarshttp://en.wikipedia.org/wiki/Sucrosehttp://en.wikipedia.org/wiki/Trehalosehttp://en.wikipedia.org/wiki/Winemakinghttp://en.wikipedia.org/wiki/Grape_juicehttp://en.wikipedia.org/wiki/Musthttp://en.wikipedia.org/wiki/Ethanolhttp://en.wikipedia.org/wiki/S._cerevisiaehttp://en.wikipedia.org/wiki/Specieshttp://en.wikipedia.org/wiki/Yeasthttp://en.wikipedia.org/wiki/Bakinghttp://en.wikipedia.org/wiki/Brewinghttp://en.wikipedia.org/wiki/Strain_(biology)http://en.wikipedia.org/wiki/Aerobic_respirationhttp://en.wikipedia.org/wiki/Glucosehttp://en.wikipedia.org/wiki/Maltosehttp://en.wikipedia.org/wiki/Trehalosehttp://en.wikipedia.org/wiki/Lactosehttp://en.wikipedia.org/wiki/Cellobiosehttp://en.wikipedia.org/wiki/Sugarshttp://en.wikipedia.org/wiki/Sucrosehttp://en.wikipedia.org/wiki/Trehalose


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Different Saccharomyces yeasts have differing physiological andfermentative properties, therefore the actual strain of yeast

selected can have a direct impact on the finished wine.

3. Sodium bisulfite

While the related compound, sodium metabisulfite, is used in

almost all commercial wines to prevent oxidation and preserveflavor, sodium bisulfite is sold by some home winemakingsuppliers for the same purpose. In fruit canning, sodium bisulfite isused to prevent browning (caused by oxidation) and to killmicrobes.

In the case of wine making, sodium bisulfite releases sulfurdioxide gas when added to water or products containing water.The sulfur dioxide kills yeasts, fungi, and bacteria in the grape

juice before fermentation. When the sulfur dioxide levels havesubsided (about 24 hours), fresh yeast is added for fermentation.

It is later added to bottled wine to prevent the formation of vinegarif bacteria are present, and to protect the color, aroma and flavorof the wine from oxidation, which causes browning and otherchemical changes. The sulfur dioxide quickly reacts with oxidationby-products and prevents them from causing further deterioration.

Methods:

PH= 4.0-4.

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Taking out the grape skin

Presssing

Grapes

(Sugar), Citric acid

Saccharomyces spp Saccharomyces cerevisae
http://en.wikipedia.org/wiki/Sodium_metabisulfitehttp://en.wikipedia.org/wiki/Sodium_metabisulfite


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n

A1 A2 A3(B1, B2) (B1, B2) (B1, B2)

Grapes were fresh, clean before being take out the skin. Afterthat, grapes were pressed to take the juice. Grape juice waspasteurized by 122mg/l sodium bisulfate (NaHSO3) for 30minutes. The yeast was added to the sterilized juice. pH and Brixwere adjusted by pH meter and Brix meter. We added the yeastagain and the mixture war stirred thoroughly. The first sample N0was analysed. Then, grape juice was dealed to bottles which have

250ml volume.Each bottle was covered to be fermentated. We analysed thesample every 12 hoursto observe the fermentation process.

We investigated the effect of pH on the fermentation process fortwo yeast

A1 : pH = 3.1

A2 : pH = 4.1

A3 : pH = 4.5

We also observed the fermentation rate on two yeast

B1 : Saccharomyces sppB2: Saccharomycess cerevisae

RESULT AND DISCUSSIONCompare the development of 2 yeast genera:

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Stir

Pasteurizing (NaHSO3 122g/l)

Analysing

Fermentating Yeast

S.cerevisae

S.spp (B)

pH = 3.1 4.5Brix = 220Bx


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1. Effect of pH on the developing speed, Brix degree, Alcoholdegree by the time during the fermentation process usingSaccharomyces Spp. Alcohol

Degree(%V)

Time (hour)Figure 1. Effect of pH on developing speed of yeast

by the fermentation time

Time (hour) Time(hour)

Figure 1. Effect of pH on developing Figure 2. Effect of pH onAlcohol

yeast by the fermentation time degree by thefermentation time

(Counting bacteria by Petri plate)


Figure 3. Effect of pH on degradation speed of Figure 4. Effect pH todeveloping

Brix degree by the fermentation speed of yeast by thefermentation time

(Counting yeast cells by microsope)

2. Effect of pH on the developing speed, Brix degree, Alcoholdegree by the time during the fermentation process usingSaccharomyces Cerevisiae.

AlcoholDegree(%)

Time(hour) Time(hour)

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Figure 5. Effect of pH on developing Figure 6. Effect of pH on

Alcoholyeast by the fermentation time degree by the fermentation

time(Counting bacteria by Petri plate)


Figure 7. Effect of pH on degradation speed Figure 8. Effect pH to

developingof Brix degree by the fermentation time speed of yeast by thefermentation time


Follow those figures, we can see: in the first 24 hours of fermentationprocess, the amount of glucose dropped slowly because the amount ofyeast was low. In that time, alcohol formation was little because the yeastcell was focusing on creating the biomass.

After 24 hours, developing speed of yeast was very high and strong(developed with exponential function), which made Brix degree reducedstrongly. At the same time, Alcohol degree raised very fast. Figure 1 shows

us: the maximum developing speed is from 48 to 72 hours, strength of yeastcells was maximum (Nmax: 10

10 cfu/ml). The second reason is the amount inthe environment was very high, so it inhibited yeast cells. Therefore the aliveyeast reduced within 72 hours. At once, the amount of glucose also reducedslowly, so the amount of alcohol raised slowly.

Figure 2 shows us the Alcohol degree raised fastly from 48 to 72hours, then raised slowly because of the low gkucose amount, lots of deathyeast cells. The chart about the change of pH within the fermentationprocess shows the lowest pH at 48th hour, which can be explained by thereason: during the fermentation process, beside alcohol, there was also

organic acid. After 48 hours, pH raised because at that time, the amount ofglucose was very low, some microorganisms could use organic acid tocreate energy. After 96 hours, the amount of glucose was very low and pHraised fastly because of that reason.

The charts shows the developing speed and alcohol amount ofSaccharomyces.sp got the maximum rate at pH 3.7, and SaccharomycesCerevisiae got the maximum rate at pH 4.1.

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3. Compare the development of Saccharomyces.sp and Saccharomyces

Cerevisiae at different pH

Time(hour)Time(hour)Figure 9. Developing speed of Saccharomyces.sp Figure10. Degradation of Brix

between Saccharomyces Cerevisiae at pH 3.7 Saccharomyces.spand Saccharomyces (Counting bacteria by Petri plate)Serevisiae

Alcoholdegree (%V)

Time(hour) Time(hour)Figure 11. Alcohol degree between Saccharomyces.sp Figure 12.Developing speed ofSaccharomyces.spand Saccharomyces Cerevisiae Saccharomyces Cerevisiae at pH 3.7


pHBrix degree

Amount ofyeast cells(Counting byPetri plate)

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Amount ofyeast cells(Counting byMicroscope)

Table 1. Brix degree, developing speed of yeast at different pH by different

examining methods

According to the figures and tables, these 2 types of yeast developed slowlyin the beginning of fermentation process before hour 24th, then their speedraised fastly from 24 to 72 hours.with exponential function. The amount ofyeast cells raised fastly, the amount of glucose reduced rapidly, Alcoholdegree and pH reduced rapidly. But the difference between these 2 types ofyeast was less than 5% in different conditions.So grape wine fermentated by Saccharomyces cerevisiae andSaccharomyces.sp was different just a little.

Conclusion:After the experiment, we have conclusion:

_ Developing speed ofSaccharomyces.sp and Saccharomyces cerevisiaeewas different less than 5% in conditions of oH 3.1, 4.1 and 4.5. Themaximum rate of cells reached 1010 cfu/ml.

_ Maximum rate of Alcohol degree didnt have diffrence more than 5%at pH 31., 4.1 and 4.5.

_ May the genus of yeast in nature:Saccharomyces.sp is genus

Saccharomyces.cerevisiaee_ We can use the genus Saccharomyces.sp to make wine instead ofSaccharomyces.cerevisiae with the same high quality.

Suggestion:Because of the limited time, this thesis could just examineSaccharomyces.sp and Saccharomyces cerevisiaee at different pHconditions. During the examining period, 2 types of yeast didnt show thedifference.To have better result, we need:

_ Examine effect of Brix degree_ Examine effect of temperature

References:1. Fruit wine making at home Vu Cong Hau, 19932. Fruit Microbiology Ho Quang Tri, 19993. Microbiology Technology 1, 2, 3 Nguyen Duc Luong University

of Technology, 1996

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4. Biotechnology Experiments Nguyen Duc Luong, 20025. Microbiology Technology Luong Duc Pham, 19986. Fermentation Processing - Tri Nhan Minh, Teshome Edae Jiru,

Naznin Sultana, Michael Wawire, 2001

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