FOOD BIOTECHNOLOGY

ALCOHOLIC BEVERAGES

SUMBITED BY

R.YASOTHA

INTRODUTION

All alcoholic beverages involve the action of fungi.

Most involve the genus Saccharomyces. These yeasts covert six carbon

sugars such as glucose to ethanol and carbon dioxide and live under

anaerobic conditions. Yeasts can tolerate fairly high concentrations of

alcohol (up to about 14-18%) in the medium.

Alcoholic beverages are known from virtually all cultures. These beverages

are major social problems, but also sources of nutrition.

Many plants have been used to prepare alcoholic beverages. Mead is made

from fermented honey.

Plants often store nutrition as starch. Yeasts cannot use starch. The starch

is broken down by enzymes in the plant into sugars. The sugars are then

converted by the yeasts into ethanol and carbon dioxide.

Alcohol is a lipid and moves freely across membranes in the stomach.

Alcohol is broken down in humans, but also affects the neurons and is a

non-selective central nervous system depressant.

YEAST

In browing, alcoholic fermentation comprises the conversion of sugar into

carbondioxide and ethyl alcohol. This process is carried out by yeast enzymes.

In browning we use the sugar fungi form of yeast. These cells gain energy from

breaking down the sugar.

The product, CO2 bubbles through the liquid and dissipates into air. Alcohol

remains in the yeast cells die, when the level of alcohol exceeds beyond tolerance.

Brewers yeast tolerates about 5% alcoholic beyond this level the yeast can not

continue fermentation.

The overall process of fermentation aims to convert glucose sugar (C6H2O6) into

alcohol(CH3CH2OH)and carbondioxide.

The reaction with in yeast make this happen:

BREWER’S YEAST

Brewer’s yeast is dried, pulverized cells of saccharomyces cervisia, a

type of yeast that reproduce by budding.

They are hundreds of varieties and straing of this yeast in the past,

there were two types of beer yeast;

ale yeast : [ the “top fermenting type, saccharomyces cerviside ]and

large yeast: [the “bottom – fermenting “type, saccharomyces

uvarum,tormerly known as saccharomyces carlsbergensis].

ALE YEAST:

Ale yeast strains are best used at temperatures between 10 and 25*c though some

strains will not actively ferment below 12*c ale yeast is generally regarded as

top – fermenting yeast since it rises to the surface during fermentation,

creating a very thick, rich yeast head.

That why the lerm “top fermenting” is assosiated with ale yeast.

Ale yeast produce beer high in esters.

LARGE YEAST;

Large yeast strains are best used at temperature between 7and 15*C large yeast –

grow less rapidly than ale yeasts, and with less surface form they tend to settle to

the bottom of the fermenter at the and of fermentation.

This is why they are often refferred as “bottom” fermenting yeasts.

The final flour of beer will however, depend greatly on the strain of yeast and the

temperatures at which it is fermented.

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YEAST LIFE CYCLE;

Yeast is activated from dormancy as soon as it is added [pitched] to the wort.

yeast growth follows four phases:

The lag phase

Growth phase

Fermentation phase

Sedimentation phase

LAG PHASE:

Reproduction is the priority in pitching, and the yeast will not show any other

activity untill food reserves are built up this stage is marked by a drop in PH due to

untilyzation of phosphate and reduction in oxygen.

Glycogen,an intracelluler carbohydrate reserve. Is a prime energy sources for cell

activity since wort sugars are not assimilated early in the lag phase.low geycogen

levels produce abnormal levels of vicinal dixetones [ especialy diacetyl]and may

result in longer fermentation.

Growth phase

The growth phase aften refered to as the respiration phase,follows the log phase

once sufficient reserves are built up within the yeast.

In this phase the yeast cells use oxygen in worth to oxidize a variety of acid

compounds resulting in a significant drop of PH. In this connection, some yeast

strains will result in a much greater fall in PH than others with in the same

fermenting wort.

FERMENTATION PHASE:

The fermentation phase quickly follows the growth phase when the oxygen supply

was been depleted.

Fermentation is an anaerobic process. In fact any oxygen remaining in the wort is

stripped out of the solution by carbondioxide bubbles produced by yeast.

This phase is characterized by the reduction of wort gravity and the production of

carbondioxide. ethanol and beer flavours.

Most beer yeast will remain in suspension for 3or7days, after which flocculation

and sedimentation will commence.

SEDIMENTATION PHASE: The sedimentation phase is when the yeast flocclates and settles to the bottom of

the fermenter.

The yeast produces a substance called glycogen, wich will preserve its. Life as it

prepares it self for dormancy.

Glycogen is necessary for cell maintance during dormancy and is an energy source

during the lag phase.

Products of Alcoholic Fermentation

WINE FLOW CHARTSRipe grapes

Washing, removal of stem and crushing

Filling jar up to ¾

Addition of sugar

Adjustment of pH [0.6-0.8]

Addition of preservative [1.5g/10kg of fruit]

Addition of wine yeast [S.ellopodevs]

Fermentation [For 2 day]

Filtration

Fermentation[For 10 days]

Packing [siphoning of clear liquid]

Fining and filtration [bentonies]

Aging 6-8 [months]

Bottling

Crocon corking

Pasteurization[85*c for 20min]

Cooling

Storage

Wine fermentation tanks

BEER FLOW CHARTBarley grains

Washing

Soaking

Malting [involves soaking, steeping, germination, drying and crushing.]

Mashing [mixing of ground malt with water and heated at 70*C

Worting [inactivation of enzyme] and boiling with hops S.cervisiae S.carlbergenosfermentation

Maturing

Packaging

Barley fields in California

and Germany

BRANDY FLOW CHART Cashew apple fruits

Plucking and removing nuts

Transportation

Washing and weighing

Fruit-mill

Juice extraction

Sulphitation

Inoculation

Fermentation

Distillation

Adjusting the strength to 60%

Aging in wooden barrels

Dilution to 43% alcohol

Bottling

Labelling

VODKA FLOW CHART

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