CHEMISTRY OF TASTE AND AROMA COMPOUNDS IN TEA AND COFFEE

1. CHEMISTRY OF TASTE AND AROMA
COMPOUNDS IN TEA AND COFFEE
KUSH VERMA (15/PFT/001)
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2. Growing Conditions
• A hot, moist Climate
• Temperature ranging from 10 – 30 degrees centigrade
• Average yearly rain fall, around 200mm
• Ground level of between 200-600m above sea level

3. Types of Tea
• Black Tea
• Green Tea
• White Tea
• Oolong Tea

4. Health & Benefits of Tea
• Higher antioxidant capacity than fruits & vegetables.
• Help to relax on human
• Assist in natural immune
• Response to infection
• Reduce risk of heart diseases, cancers, cholesterol
level, higher blood pressure.
• Reduce eye fatigue.

5. Product Life Cycle
• Now they are in Maturity Stage in their
product life Cycle.

6. Tea Processing Cycle

7. Plucking

8.  It is a process of harvesting and collecting tea leaves.
 Before the tea plucking we have to maintain foliage
& tipping.
 There are mainly 3 types of Plucking Systems,
– Scale leaf plucking
– Fish leaf plucking
– Mother leaf plucking

9. Mechanical Plucking
Reasons
 Shortage of manual labors
 .
 Low efficiency in manual plucking.
 High labor wages.
 Additional man power equipments.
 During peak flush period necessitate
mechanical .
Limitation
 Decline in leaves Quality.
 Difficulty in using high sloppy
land.
 Difficulty to repair .
•Mechanical Plucking System can use when there is a scarcity of pluckers
during July to September.

10. Withering

11. • The primary aims of withering are, to reduce the
moisture content of the leaf and to soften it.
• the tea leaves are spread out on a large tray of wire
mesh, and hot air blowers are used to heat the leaf
and drive the moisture out.
• Withering duration is dependent on temperature and
humidity and could range from 18 to 24 hours.
• At this point, the leaf has become limp and turned
into a darker shade of green.

12. Rolling

13. • It is a process where rollers are used to rupture the
cell walls of the withered leaves for oxidation of the
polyphenols in the presence of oxygen from air.
• There are two methods used by manufacturers,
– Orthodox
– CTC

14. Fermentation

15. • It is the process of oxidation of leaves.
• The mechanical aspect involves spreading out of the
leaves macerated by rolling a layer 5-8 cm thick, for 45
minutes to 3 hours, depending on the quality of the
leaves.
• In here pay more attention to humidity & Temperature.

16. TEA
• Tea is an aromatic beverage commonly prepared
by pouring hot or boiling water over cured leaves
of the Camellia sinensis,
an evergreen shrub native to Asia. After water, it
is the most widely consumed drink in the world.
There are many different types of tea; some teas,
like Darjeeling and Chinese greens, have a
cooling, slightly bitter, and astringent flavour,
while others have vastly different profiles that
include sweet, nutty, floral or grassy notes.

17. CHEMICAL CONSTITUENTS OF TEA
• The chemical composition of tea leaves has
been thoroughly studied. The main
constituents of tea leaves belong to the
polyphenol group accounting for 25 to 35% on
a dry weight basis (Balentine, 1997; Hara et
al., 1995d). The polyphenols (Mukhtar et al.,
2000) in tea mainly include the following six
groups of compounds: flavonol's, hydroxyl-4-
flavanols, anthocyanins, flavones, flavonol's
and phenolic acids

18. AROMA COMPOUNDS OF TEA
• Aroma is one of the critical aspects of tea quality
which can determine acceptance or rejection of a
tea before it is tasted. All the data reported so far
shows that more than 630 compounds have been
reported responsible in tea aroma.
• Carotenoids include β-carotene, lutein,
zeaxanthin, neoxanthin, xanthophyll, and
lycopene, and more have been identified as
precursors for many tea flavors. Many of them
play key roles in deciding the quality of tea.

19. TASTE COMPOUNDS OF TEA
• Taste of food is mainly composed of five basic
sensations; that is, sweetness, astringency, sourness,
bitterness and umami).
• polyphenols was necessary for the expression of
reasonable amounts of tangy astringency.
• The gallated tea flavonols are related to astringency
and also to the bitterness taste; the non-gallated tea
flavonols are related to bitterness, however, are not
related to or only slightly related to the astringent taste
of black tea infusion. Among theoflavins (TFs),
theoflavin is less astringent. The contribution of TF-
digallate and mono-gallate to astringency is 6.4 and 2.2
times to that of the aflavin.

20. COFFEE
• Coffee is a brewed drink prepared from
roasted coffee beans, which are the seeds
of berries from the Coffea plant.
• Coffee is slightly acidic and can have
a stimulating effect on humans because of
its caffeine content. Coffee is one of the most
popular drinks in the world.

21. CHEMICAL CONSTITUENTS OF COFFEE
• The nonvolatile fraction of green coffee is
composed primarily of water, carbohydrates and
fiber, proteins and free amino acids, lipids,
minerals, organic acids, chlorogenic acids,
trigonelline, and caffeine . Of these compounds
found in green coffee, chlorogenic acids, caffeine,
trigonelline, soluble fiber, and diterpenes from
the lipid fraction are most. likely to be bioactive,
and they may also be important contributors to
the beverage flavor after roasting

22. AROMA COMPOUNDS OF COFFEE
• Coffee aroma is perceived by two different mechanisms. It can either be
sensed nasally via smelling the coffee through the nose or retronasally.
Retronasal perception occurs when the coffee is either present in the
mouth or has been swallowed and aromatic volatile compounds drift
upward into the nasal passage.
• The number of aromatic compounds found in coffee increases every year.
Today the number is well over 800, and as our analytical methods become
more precise, more will be uncovered. Yet, the perception of coffee aroma
is dependent upon both the concentration of the compound and its odour
threshold. With that said, understanding coffee aroma is not as difficult as
understanding how over 800 coffee elements interact with the olfactory
epithelium. It is probable that a relatively small group of compounds that
share both a high concentration and a low odor threshold make up the
fragrance we know as coffee aroma. This article will discuss the recent
research that has narrowed in on these aroma impact compounds.

23. CONTINUE….
• Illy listed the following chemical processses that affect the
development of volatile compounds in coffee:
1) Maillard or non-enzymatic browning reaction between nitrogen
containing substances, amino acids, proteins, as well as trigonelline,
serotonine, and carbohydrates, hydroxy-acids and phenols on the
other.
2) Strecker degradation.
3) Degradation of individual amino acids, particularly, sulfur amino
acids, hydroxy amino acids, and proline.
4) Degradation of trigonelline.
5) Degradation of sugar.
6) Degradation of phenolic acids, particularly the quinic acid moiety.
7) Minor lipid degradation.
8) Interaction between intermediate decomposition products.

24. TASTE COMPOUNDS OF COFFEE
• Coffees taste is perceived mostly on the tongue by the taste
buds.
• SWEET- The first sensation humans develop, In coffee, a
number of sugars (usually called polysaccharides or
carbohydrates) exist and are perceived as
sweetness. Sweetness in coffee is directly related to the
ripeness of the coffee when picked.
• SOUR- We perceive acid on the tongue as the flavor sour. The
term sour in coffee is related to an excess of acetic acid or
tartaric acid due to an over fermentation or unripe coffee.
However, our sour receptors also perceive desirable acidity
characteristics of fine coffees.
• SALTY- Frequently in coffee tasting a saltiness can appear
which is unrelated to mineral content. Salty flavor is a taste
defect in coffee and is usually related to mineral
contamination during processing, especially drying coffee on
the ground.

25. • BITTER- A common alkaloid in coffee is caffeine.
Bitterness is essential to coffee's flavor.
• SAVORY- In the early 1900s, a Japanese Scientist
established the taste sensation of umami (literally:
deliciousness). Glutamic acid is the most common amino
acid in food protein. Savoriness in coffee has developed
due to yeast activity during fermentation phase of
processing.

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