Wine is an alcoholic beverage made from
Yeast consumes the sugar in the grapes
and coverts it to ethanol, carbon dioxide
Different varieties of grapes and strains of
yeast produce different styles of wine.
These variations result from the complex
interactions between the biochemical
development of the grapes, the reactions
involved in fermentation, the terroir, and
the production process.
Viticulture is the Science of Grape-
Enology is the science of wine (making)
3. History and Origin
Winemaking probably began as one of the
earliest of human enterprises (8000-3000
The wine grape was domesticated by at
least 4000 B.C. Wine was used for
Egyptian worship ceremonies.
Wine only became a popular beverage
about 2000-1000 B.C. in Greece.
Early microbiologists, such as Pasteur and
Muller observed the presence of bacteria
in wine, and any early 1900’s their
importance in winemaking was beginning
to be understood.
5. Major constituents of grape juice
Citric acid 0.01-0.05%
Tannins(catechol, chlorogenic acid, caffeic acid) 0.01-0.1%
Nitrogenous compounds(amino acids and proteins) 0.03-0.17%
Minerals(Phosphates, sulphites) Traces
B group vitamins (thiamine, riboflavin, pyridoxine, nicotinic
Vitamin C Traces
Volatile aroma constituents Traces
Color constituents Traces
6. Grape varieties
Wine is usually made from one or more
varieties of the European specie Vitis
vinifera, such as Pinot noir,
Chardonnay, Pamay and Merlot.
Wine can also be made from other
species of grapes or hybrids, created by
the genetic crossing of two species, V.
labrusca, V. aestivalis, V. rupestis, V.
rotundifolia and V. riparia.
When one of these varieties is used as
the predominant grape (minimum of
75%-85%), the result is a ‘varietal’ as
opposed to a ‘blended wine’.
7. Know your yeast:
The most common yeast generally associated with
winemaking is Saccharomyces cerevisiae which is also used
in bread making and brewing. Other genera of yeast include:
8. SACCHAROMYCES SPP.
Saccharomyces is a genus of fungi that
include many species of yeasts.
Unicellular and saprophytic fungi.
More specifically, it is a globular-
shaped, yellow- green yeast belonging to
The yeast can form symbiotic matrices
with bacteria, and are used to produce
Kombucha, kefir and ginger beer.
Natural strains of yeasts have been
found on the surfaces of the plants, the
gastrointestinal tracts and body surfaces
of insects, surface of fruits, storage
cellars and on the equipment used
during the fermentation process.
10. Stage I: Harvest and selection.
There are over 4000 varieties of grapes used in
the production of wine.
Grapes are usually harvested from the vineyard
from early September until early November in
the Northern hemisphere, and mid February until
early March in the Southern hemisphere
After the Harvest, the grapes are taken into a
winery and prepared for primary ferment
11. It starts in the vineyard at harvest:
It is important to wait until the grapes reach the proper
maturity for the variety of grape & style of wine being
As the grapes ripen, the sugar level increases and the
The sugar level is measured in units of “Brix”; wine
grapes are usually harvested at a Brix of 22 to 28.
Ripening will depend on many factors, such as the
temperature, amount of sun and rainfall, availability of
The grapes can be harvested manually or by mechanical
pickers. Manually picked grapes are typically higher
12. STEP II: Crushing and pressing
The grapes are transported to the winery where they
undergo destemming and crushing.
There are a variety of presses that are used to produce the
juice, which is called “must”.
The sugar in the wine is used by the yeast to produce ethyl
alcohol and carbon dioxide gas, thus making wine.
The type of yeast can affect the qualities of the wine as
will the other compounds in the wine - some naturally
occurring and some that are byproducts of the
13. STEP III: FERMENTATION
Must can begin fermenting
naturally within 6-12 hours when
aided with wild yeasts in the air.
However, many winemakers
intervene and add a commercial
cultured yeast to ensure consistency
and predict the end result.
Fermentation continues until all of
the sugar is converted into alcohol
and dry wine is produced.
Fermentation can take anywhere
from 10 days to one month or more
14. Principle of fermentation:
C6H12O6 + Yeast 2C2H4OH + 2CO2
The alcohol solution that results from fermentation contains
about 12%-15% ethanol.
This correlates to the conditions that yeast cells can survive in,
higher concentrations of ethanol will kill the yeast.
For every gram of sugar that is converted about a half gram of
alcohol is produced.
To achieve 12% alcohol concentration, starting material must
contain about 24% sugars.
16. TYPES OF YEAST:
WILD TYPE: The natural yeast
flora, found on grapes and in
wineries, play an significant role
during fermentation and are
particularly important during
spontaneous fermentation because
no additional wine yeasts are
introduced into the process.
The common wild yeasts found in
the vineyard or on the surface of
grapes are the genera of Kloeckera,
These genera of wild yeasts have
very low tolerance to both alcohol
and sulfur dioxide.
17. CULTURED TYPE: Winemakers select a
cultured yeast strain, i.e., Saccharomyces
cerevisiae that has been identified and
planted from wineries across the world.
They has a tendency to :
Quickly begin fermentation, out- competing
other ‘wild yeasts’ for nutrients in the most.
Completely utilize all fermentable sugars
with a predictable sugar-to-alcohol
Have an alcohol tolerance up to 15% or even
higher depending on the winemaking style.
Have a high sulfur dioxide tolerance but low
production of sulfur compound such as
hydrogen sulfide or dimethyl sulfide.
Produce minimum amount of residual
pyruvate, acetic acid and acetaldehyde..
18. FERMENTATION IN
ALCOHOLIC FERMENTATION: Process in which yeasts
metabolize grape sugars and produce alcohol, carbon dioxide
MALOLACTIC FERMENTATION: A bacterial conversion
occurring in most wines, this natural process converts sharper
malic acid into softer lactic acid. Total acidity is reduced; the
wine become softer and more complex. It stabilizes wine by
preventing the undesirable fermentation in the bottle.
19. SECONDARY FERMENTATION: The process that creates the
bubbles in sparkling wine. As the wine is bottled, a small amount
of yeasts and sugar crown cap. Known as BOTTLE
CARBONIC MACERATION: Also known as whole grape
fermentation where instead of yeast being added, the grapes
fermentation is encouraged to take place inside the individual
grape berries. Used in production of Beaujolais wine. The resulting
wine are usually soft and fruity.
20. STEP IV: CLARIFICATION
Clarification is a process in which
solids such as dead yeast
cells(lees), tannins and proteins
are removed through filtration.
Wine is transferred or racked into
a different vessel such as an oak
barrel or a stainless steel tank.
The wine is then prepared for
bottling and future aging.
21. STEP V: AGING AND BOTTLING
Final stage of wine making process.
The wine maker has two options:
bottle the wine right away or give the
wine additional aging.
Aging the wine in oak barrels will
produce a smoother, rounder and
more vanilla flavored wine.
It also increases wine’s exposure to
oxygen while it ages, which decreases
tannin and help the wine reach its
Steel tanks are commonly used for
zesty white wine.
After aging, wine are bottled with
either a cork or a screw cap.
22. Different types of wine
Champagne (Sparking) Wine
23. White Wine
White wine is a wine that is fermented without skin
Grapes for white wine are harvested and pressed.
The must is fermented in stainless steel tanks.
Some white wines, such as Chardonnay, is aged in
The wine is bottled
Most white wines are not bottle aged but
consumed with in 3 years of bottling.
However, an exception is particularly fine wines
made from Chardonnay and Champagne
24. Red Wine
Grapes for red wine are harvested, crushed.
The must is left with the skins during
fermentation to produce the red color.
The red color coming from the anthocyan
pigments( also called anthocyanins) present in
the skin of the garpes
Red wine is commonly aged in oak barrels for
6 to 24 months.
25. Rose Wine:
A rose wine is a type of wine that incorporates
some of the color from the grape skins, but not
enough to qualify it as a red wine.
Made with the skin contact method
Black-skinned grapes are crushed and the skin are
allowed to remain in contact with the juice for a
short period, typically 2-20 hours.
The must is then pressed and the skin are
discarded rather than left in contact throughout
26. Champagne (Sparking) Wine
It is a wine with significant levels of carbon
dioxide in it, making it frizzy.
The sparkling quality of these wines from their
carbon dioxide content and may be the result of
natural fermentation, either in a bottle , as with the
traditional method , in a large fermentation tank
designed to withstand the pressures involved, or
as a result of simple carbon dioxide injection in
some cheaper sparkling wines
27. Fortified Wine
Grapes for fortified wines are harvested like for other
Fortified wine is a wine to which a distilled spirit,
usually brandy is added.
Depending on the type of wine, the must may be
handled in different ways to intensify the flavor before
and during fermentation.
Most fortified wines have an addition of alcohol
(brandy) to stop fermentation and increase the alcohol
Fortified wine maybe aged in oak barrels before
28. Pinot Noir
One of the easiest and most food friendly wines
out there is Pinot Noir.
It is a red wine grape variety of the species Vitis
The think skins and low levels of phenolic
compounds leads Pinot to producing mostly
lightly covered, medium boiled and low tannin
wines that can often go through phases of uneven
and unpredictable aging
Its flavor characteristics are that of dark, ripe
CONTAMINATION OF WINE
OXIDATIVE YEASTS: Genera Hansaenula, Pichia,
Candida have a predominant oxidative metabolism, but
some species can survive quite high level of alcohol.
Unwanted by-products such as acetic acid, ethyl-acetate
and acetaldeyde are produced.
APICULATA YEASTS: Refers to lemon shaped
appearance of Kloeckera apiculata which is predominant
in grape juice. Considered as the main reason for the
depletion of assimilable nitrogen, vitamins and other
micronutrients in the must.
30. FERMENTATION YEASTS: Some strains of Saccharomyces cerevisiae
can produce excessive amounts of acetic acid, sulphur compounds, SO2,
urea and volatile substances which might be detrimental to wine quality.
ACETIC BACTERIA: Gluconobacter and Acetobacter are the main
genera of aenological significance which degrades sugars into acetic acid
while other uses ethanol as a substrate and metabolizes it to acetic acid
LACTIC ACID BACTERIA: Malolactic bacteria such as Oenococcus
oenii, lactobacillus, Pediococcus. They are widely released into the juice
from damaged grape berries. Without any control over these bacteria, they
grow very fast and consume sugars producing a large amount of lactic and
acetic acid as by-products
31. Is wine good for you?
Studies have been done to show that wine drinkers are
less prone to heart disease, cancer and other diseases.
This could be a result of the antioxidant resveratrol
which may reduce cholesterol and the risk of
However this antioxidant can also be found in other
foods, avoiding the harmful effects of alcohol.
A little alcoholic drink, and specially red wine appears to
boost levels of omega-3- fatty acids in plasma and RBC.
Resveratol may protect the brain from stroke damage,
according to many researchers.