71
24. 3 Catechin C
trt N
Subset 1
2 3
4 3, 200C
2 1.2450
3, 180C 2
1.3200 1.3200
3, 220C 2
1.3400 1.3400
6, 180C 2
1.3950 1.3950
6, 200C 2
1.4250 1.4250
1.4250 6, 220C
2 1.4800
1.4800 1.4800
9, 200C 2
1.5900 1.5900
9, 180C 2
1.5900 1.5900
9, 220C 2
1.6400 Sig.
.059 .086
.075 .083
Means for groups in homogeneous subsets are displayed. Based on observed means.
The error term is Mean SquareError = ,006.
24. 4 Epicatechin EC
trt N
Subset 1
2 3, 200C
2 1.6550
6, 220C 2
1.7300 6, 180C
2 1.7400
6, 200C 2
1.7500 3, 180C
2 1.7650
3, 220C 2
1.8250 1.8250
9, 200C 2
1.8700 1.8700
9, 180C 2
1.9900 1.9900
9, 220C 2
2.3750 Sig.
.229 .060
Means for groups in homogeneous subsets are displayed.
Based on observed means. The error term is Mean SquareError = ,057.
72
24. 5 Epigallocatechin gallate EGCG
trt N
Subset 1
2 3
6, 200C 2
4.6150 6, 220C
2 5.4250
5.4250 6, 180C
2 5.6150
5.6150 9, 220C
2 5.7100
5.7100 9, 180C
2 5.8900
5.8900 3, 180C
2 6.4900
6.4900 3, 200C
2 6.5200
6.5200 3, 220C
2 7.0150
9, 200C 2
7.0550 Sig.
.069 .075
.059 Means for groups in homogeneous subsets are displayed.
Based on observed means. The error term is Mean SquareError = ,247.
24. 6 Gallocatechin gallate
trt N
Subset 1
9, 220C 2
1.4100 6, 200C
2 1.4500
9, 180C 2
1.4600 3, 200C
2 1.5300
9, 200C 2
1.5750 6, 180C
2 1.6000
3, 180C 2
1.6050 6, 220C
2 1.6100
3, 220C 2
1.6350 Sig.
.126 Means for groups in homogeneous
subsets are displayed. Based on observed means.
The error term is Mean SquareError = ,015.
73
24. 7 Epicatechin gallate
trt N
Subset 1
2 6, 200C
2 .7350
6, 180C 2
.8550 .8550
9, 180C 2
.9100 .9100
6, 220C 2
.9250 .9250
3, 200C 2
.9850 .9850
3, 180C 2
1.0150 1.0150
9, 220C 2
1.0500 3, 220C
2 1.0600
9, 200C 2
1.1000 Sig.
.058 .090
Means for groups in homogeneous subsets are displayed.
Based on observed means. The error term is Mean SquareError = ,014.
1
I. INTRODUCTION
A. BACKGROUND
Tea is globally one of the most popular and lowest cost beverages, next only to water. Tea is consumed by a wide range of age groups in all levels of society. The tea plant Camellia
sinensis has been widely used for over 5000 years for its specific aroma, taste, and putative positive physiological functions. According to statistics from the Food and Agricultural
Organization FAO of United Nations 2008, production and consumption of tea are steadily increasing. The worldwide production of tea in 2006 reached up to 3.60 million ton and the
worldwide consumption reached up to 3.64 million ton. Over past decade, world tea consumption has increased by 2.7 annually. The main tea-producing countries are China,
India, Sri Lanka, Kenya, Turkey, Indonesia, and Vietnam, which accounted for 28.73, 25.93, 8.60, 8.59, 5.49, 5.15, and 3.65, respectively, of the 2006 output of total global tea production
Hicks, 2008.
Freshly harvested tea leaves are processed differently to produce specific types of tea such as green, oolong, and black tea. Of all the tea consumed in the world, 78 is black tea, 20
is green tea, and 2 is oolong tea. The green tea consumption in Indonesia was 3.13 thousand tons in 2005, while black tea consumption was more than green tea consumption, 67.9 thousand
tons in 2005. FAO projected that world green tea production would grow at a faster rate than black tea by 2.0 annually, to reach 1097.7 thousand tons by 2016 Ho et al, 2005. Green tea is
heated and dried to avoid enzymatic oxidation. Green tea contains polyphenols, and most of the green tea polyphenols GTPs are flavonols, commonly known as catechins. Tea polyphenols
have been known for their antioxidant activity and antimutagenic and anticarcinogenic properties Yang et al 2007.
Traditionally, tea is prepared from its dried young leaves and leaf buds, made into a beverage by steeping the leaves in boiling water. But today, tea powder is being developed
because it has many advantages such as more practical, simple transport economics, and simply to prolong product’s shelf-life. Tea powder could be applied as functional food and as non food
product, like handbody, shampoo, and toothpaste. Food products being developed are tea-rice, tea-noodles, tea-cake, tea-biscuits, tea-wine, tea-candy, tea-ice cream Hicks 1998. There are
several method for produce tea powder, one of them is spray drying method.
Spray drying is one-step continuous processing operation that can transform feed from a fluid state into a dried form by spraying the feed into a hot drying medium Okos et al, 2007. A
short processing time, usually between three and thirty seconds and controlled operational conditions make the spray drying as an effective and unique method for various products,
especially heat sensitive products and its retaining the high quality properties such as color, flavor, and nutrients.
The quality of a food powder is judged by the amount of physical and chemical degradation occuring during the dehydration process. There are many researchs were did by
researchers to know the effect of spray drying on powder characteristic. At this research, different of feed concentrations and spray dryer inlet air temperatures were used to evaluate its
effects on physicochemical properties of the spray-dried green tea extract. This information
2 however is necessary to establish processing conditions to produce value-added powder green
tea as there is an increasing demand for herbal tea products in the market.
B. OBJECTIVES
The objectives of this research were to investigate the effect of total solid concentration in feed and inlet air temperatures on physical and chemical properties of green tea powder which
was produced by spray dryer.
3
II. LITERATURE REVIEW
A. TEA
Tea, one of the most popular beverages consumed worldwide, is a processed product from the leaves of tea plant Camellia sinensis. The taxonomy of tea is shown in Table 1 and the
figure of tea plant shown in Figure 1. Table 1. The classify the taxonomy of tea
Common name: Tea
Kingdom: Plantae
Division: Spermatophyta
Subdivision: Angiospermae
Class: Dicolyledone
Ordo: Guttiferales
Family: Theaceae
Genus: Camellia
Species: Camellia sinensis
The worldwide production of tea in 2006 reached up to 3.60 million ton and the worldwide consumption reached up to 3.64 million ton. Over past decade, world tea consumption has
increased by 2.7 annually. Tea Production of Indonesia in 2006 reached up to 187.9 thousand of tonnes. Hicks, 2008. Indonesia, a country with more than 222 million people, produces more
than 150,000 tons of tea per year, exporting 80 of it, with the balance consumed by domestic people. The large population provides a ready workforce, as well as a promising market for tea
consumption.
Tea products are usually classified as white tea, green tea, oolong tea, and black tea, categorized by manufacturing process as shown in Figure 2.
Figure 1. Tea plant Camellia sinensis
4 Tea is consumed in different parts of the world as white, green, black, or oolong tea. White
and green tea are known as unfermented tea. The polyphenol oxidase enzyme of green tea is inactivated by steaming. Oolong tea is produced by withering and half fermenting the leaves.
Thus oolong tea is called “semi-fermented tea”. Black tea is known as fermented tea because the leaves are fermented, allowing enzymic oxidation of the polyphenols. Processing tea differently
results in variation of chemical component in tea Hara, 2000. The chemical component of tea are presented in Table 2.
Table 2. Composition of green tea, black tea, infusion Compound
Green Tea Black Tea
Infusion Protein
15 15
Trace Amino Acids
4 4
3.5 Fiber
26 26
Other carbohydrates 7
7 4
Lipids 7
7 Trace
Pigments 2
2 Trace
Mineral 5
5 4.5
Phenolic compounds 30
5 4.5
Oxidixed phenolic compounds 25
4.5 Data refer to dry weight of tea leaves Chako et al, 2010
Fresh leaves Withering
Dr
ying A
B
Fermenting Rolling by tea
roller, rotor vane or CTC
Fresh leaves Withering
Drying Fresh leaves
Solar withering
Pan firing Indoor withering
and rolling
Rolling Mass breaking
Drying Fresh leaves
Rolling Primary drying-
rolling Steaming
Secondary drying-rolling
Final drying- rolling
Drying C
D
Figure 2. The manufacturing process of tea: A white tea, B green tea, C oolong tea, and D black tea Hara, 2000
5 In process of green tea production, tea leaves are steamed immediately after harvesting and
the enzymes are inactivated at the initial stage. Therefore, the composition of green tea is simple and similar to that in the fresh tea leaves. Green tea contains polyphenols, which include
flavanols, flavandiols, flavonoids, and phenolic acids; these compounds may account for up to 30 of the dry weight. Most of the green tea polyphenols GTPs are flavonols, commonly
known as catechins accounting for up to 30 of the dry weight of the leaves,. which are composed of eight kinds of catechins and their derivatives slightly deviates depending on the
species of tea plant and the season of harvesting.
There are eight major catechins in green tea: +-catechin C, --epicatechin EC, -- gallocatechin GC, --epigallocatechin EGC, --catechin gallate CG, --gallocatechin
gallate GCG, --epicatechin gallate ECG, and --epigallocatechin gallate EGCG. The major Epigallocatechin gallate EGCG is the major component of the polyphenolic fraction of green
tea, it makes up about 10-50 of total green tea catechins. EGCG is also most potent antioxidant of polyphenol type of tea, is at least 100 times more effective than vitamin C and 25 times more
effective than vitamin E. The antioxidant activity increase in the following order: ECECGEGCEGCG Meterc et al, 2007. The percentage of major polyphenols in tea are
shown in Table 3.
Table 3. The percentage of major polyphenols in tea Compound
Green Tea Oolong Tea
Black Tea EC
0.74 – 1.00
0.21 – 0.33
– ECG
1.67 – 2.47
0.99 – 1.66
0.29 – 0.42
EGC 2.60
– 3.36 0.92
– 1.08 –
EGCG 7.00
– 7.53 2.93
– 3.75 0.39
– 0.60 Yamanishi, 1995
Caffeine 1,3,7-trimetylxantine, C8H10N4O2 is a plant alkaloid, one of the few plant products which the general public is readily familiar because of its occurence in beverages such
as coffee and tea, as well as various soft drinks. Caffeine extract from tea is added to some pain- relief medicines. Caffeine compound is well known for its stimulant effect and is present at 2-4
of dried tea leaf weight, depending on the types and quality of teas Yoshida et al, 1999.
Studies using animal models show that green tea catechins provide some protection against degenerative diseases. Green tea catechins could also act as antitumorigenic agents Roomi et al,
2007 and as immune modulators in immunodysfunction caused by transplanted tumors or by carcinogen treatment. Green tea consumption has also been linked to the prevention of many
types of cancer, including lung colon, esophagus, mouth, stomach, small intestine, kidney, pancreas, and mammary glands Koo, 2004. This beneficial effect has been attributed to the
presence of high amounts of polyphenols, which are potent antioxidants. In particular, green tea may lower blood pressure and thus reduce the risk of stroke and coronary heart disease. Some
animal’s studies suggested that green tea might protect against the development of coronary heart disease by reducing blood glucose levels and body weight Tsuneki et al, 2004.
6 Figure 3. Structures of the major catechin and caffeine in tea Zuo et al, 2002
The stability of a functional ingredient is fundamental to elaborate a nutraceutical product ecause changes in the ingredient may affect its nutritional value e.g. antioxidant capacity,
composition, and bioavailability. The stability of the grape seed extract GSE was evaluated based on changes in their main individual phenolic compounds, as well as changes in their
antioxidant activity and browning. pH affects the stability of polyphenolic compounds and that a between 4 and 5 confers more stability to catechins and their isomers and polymers than more
alkaline or acidic valuesTabart, 2009.
The concentration of catechins was more stable than the concentration of the rest of compounds. According Pardo et al 2011, the catechins and
antioxidant activity in grape seed extract generally showed decreases after the thermal. The -- Epicatechin gallate ECG
-- Epigallocatechin EGC
-- Epigallocatechin gallate EGCG -- Catechin gallate CG
-- Catechin C -- Epicatechin EC
Caffeine CAF
7 decrease in ECG and EGCG may have affected the antioxidant activity of the extracts because
these phenolic compounds are known to have more scavenging power than the flavan-3-ols that clearly increased: gallic acid, gallocatequin, and catechin, due to their stearic conformation and
the presence of the gallate group joined to the C ring treatments,but they were not always significant p0.05.
B. FOOD POWDER
A major reason for production in powder form is simply to prolong shelf-life of the ingredient by reducing water content; otherwise the ingredient would be degraded in its natural
biological environment. Another important reason is simple transport economics, because reducing water content reduces mass and costs of the ingredient to be transported Gustavo et al,
2010.
Food ingredient powders must possess a number of functionalities which can be broadly classified as: powder handling capability; reconstitution recombination ability and ingredient
functionality in the food product to be consumed. Poor handling during manufacture, storage and transport causes many problems which are quite common, such as no or irregular flow out of
hoppers and silos and problems associated with stickiness and caking of powders. Production and processing will determine the properties of particles and powder, such as particle size
distribution, shape, surface properties and moisture content. They will also influence ingredient functionality, for example, higher temperatures may cause denaturation of proteins and coating
may prevent the ingredient functionality from being destroyed by oxidation Aguilera et al, 2008.
It is well known that ingredient functionality in powder form may degrade over time between manufacture and final application. This depends on the sensitivity of the individual
ingredient and its exposure over time to temperature, moisture and oxygen in the air. Some ingredients are encapsulated and some powders are coated in an effort to prevent its degradation
and protect its functionality outlinedsome of the functional properties of food powders and particulates Lillford, 2002.
Powders are important ingredients in a large variety of food formulations and they are responsible for the development important product characteristics such as texture, flavour, colour
and nutritional value. Most of the powders will be used in some sort of wet formulation and therefore their functionality will depend on their interaction with water. Because the influence of
drying parameters is not the same for all materials, optimal drying conditions vary depending on the final objective: volatile retention, preservation of enzymatic activity and avoidance of protein
denaturation, fat oxidation or crystallisation. Usually, the resulting powder is made of dry particles with an average size of 30 microns and mean water activity around 0.2. The powder
outlet temperature is typically less than 100°C and the residence time is of seconds Huntington, 2004.
All these characteristics will have some effect on handling properties of powders such as: bulk and tapped densities, particle density, mixing with other powders, storage; wettability and
solubility, porosity, specific area rehydration, instantisation; flowability size, surface asperities, friability and creationexistence of dust, stability in specific atmosphere and medium
oxidation, humidification, active component release Huntington, 2004.
Study on quality evaluation instant green tea powder showed that the important quality attributes for a green tea sample was rated as taste flavor color strength. Among the quality
8 attributes, taste was the strongest attribute for both instant tea and green tea granules produced,
and strength was the weakest attribute. Sinija, 2011.
C. FREEZE CONCENTRATION
Concentration of fluid foods by freezing involves lowering the temperature of the product in a sufficiently controlled manner to partially freeze the product, resulting in a slurry of ice
crystals in a fluid concentrate. If formed under the appropriate conditions, these ice crystals will be very pure. That is, very little product will be incorporated within the ice crystals. The ice
crystals are then removed in some way with a minimum of liquid carryover, resulting in a concentrated product. The basic components of a freeze concentration system, as shown in
Figure 4.
Freeze concentration is appliable to many food concentration, such as citrus fruit juices, vinegar, coffee, tea, sugar syrups, dairy product, and aroma extract. The major advantage of
using a freeze concentration process as opposed to evaporation or reverse osmosis are related to the low temperature operation suitable for sensitive food products without the loss of product
quality. In addition, the solid-liquid separation in freeze concentration results in no losses of the more volatile flavors and aromas, as occur in evaporation. The disadvantages of freeze
concentration compared to evaporation and reverse osmosis have include higher capital cost, higher operating costs, and excessive loss of product during the ice separation Hartel, 1992.
D. SPRAY DRYING
Spray drying is one-step continuous processing operation that can transform feed from a fluid state into a dried form by spraying the feed into a hot drying medium. The product can be a
single particle or agglomerates. The feed can be a solution, paste, or a suspension. This process has become one of the most important methods for drying liquid foods to powder form. The
principal of spray drying as shown in Figure 5. Feed
Crystal Nucleation Crystal Growth
Separation Crystal Slurry
Concentrate Ice
Figure 4. Schematic of a basic freeze-concentration process Hartel, 1992
9 The main advantages of spray drying are the following:
• Product properties and quality are more effectively controlled • Heat-sensitive foods, biologic products, and pharmaceuticals can be dried at atmospheric
pressure and low temperatures. Sometimes inert atmosphere is employed. • Spray drying permits high tonnage production in continuous operation and relatively simple
equipment • The product comes into contact with the equipment surfaces in an anhydrous condition, thus
simplifying corrosion problems and selection of material of construction • Spray drying produces relatively uniform, spherical particles with nearly the same proportion
of nonvolatile compounds as in the liqiud feed. The principal disadvantages of spray drying are as follows:
• Spray drying generally fails if a high bulk density product is required • In general it is not flexible. A unit designed for fine atomization may not be able to produce a
coarse product, and vice versa. • For given capacity, evaporation rates larger than other types of dryers are generally required
due to high liquid content requirement. The feed must be pumpable. Pumping power requirement is high
• There is a high initial investment compared to other types of continuous dryers. • Product recovery and dust collection increases the cost of drying Xin and Mujumdar, 2010
Spray drying consist of four process stages: 1. Atomization of feed into a spray
The formation of spray and the contacting of the spray with air, are the characteristic features of spray drying. The selection and operation of the atomizer is of supreme importance in achieving
economic production of top quality products. The selection of the atomizer type depend upon the nature of the feed and desire characteristics of the dried product. In all atomizer types, increased
amounts of energy available for liquid atomization result in sprays having samLler droplet sizes. If, the available atomization energy is held constant but the feed rate is increased, sprays having
Figure 5. Spray Dryer. 1, feed reservoir; 2, feed pump; 3, product feed pipeline; 4, atomizer; 5, drying chamber; 6, air fan; 7, air heater; 8, hot air duct; 9, a mixture of dried product and air-
carrying duct; 10, cyclone separator; 11, heavy powder falling down; 12, product tank; 13,exhaust air Sharma et al, 2000.
10 larger droplet sizes will result. Rotary atomizers are used to produce a fine to medium coarse
product mean size 30-130 µm, while nozzle atomizers are used to produce a coarse product mean size 120-250 µm.
2. Spray-air contact mixing and flow Product and air pass through the dryer in co-current flow, they pass through the dryer in the
same direction. This arrangement is widely used, especially if heat-sensitive products are involved. Spray evaporation is rapid, the drying air cools accordingly, and evaporation times are short. The
product is not subject to heat degradation.
3. Drying of spray moisture volatiles evaporation As soon as droplet of the spray come into contact with the drying air, evaporation takes place
from saturated vapour film which is quickly established at the droplet surface. The temperature at the droplet surface approximate to the wet-bulb temperature of the drying air. A substantial part of
the droplet evaporation takes place when the droplet surfaces are saturated and cool. Drying chamber design and air flow rate provide a droplet residence time in the chamber, so that the
desired droplet moisture removal is completed and product removed from dryer before product temperatures can rise to the outlet drying air temperature of the chamber. Hence, there is little
likehood of heat damage to the product.
4. Separation of dried product from the air Total recovery of dried product takes place in the separation equipment. This system places
great importance on the separation efficiency of the equipment. Separation of dried product from the air influences powder properties by virtue of mechanical handling involved during the
separation stage. Axcessive mechanical handling can produce powders having a high percentage of fines. Master, 1991
There are many variables in spray dryer that give an effect on powder product, such as inlet temperature, feed solid content, drying temperature difference, and feed temperature. Increase of
inlet temperature can decrease the heat requirement of the dryer for producing a given product rate because product dried quickly. Increase in feed solids for a given production rate from 50 to
60 reduces the heat load by nearly 50. Spray drying is an expensive method of evaporating volatiles and thus to obtain optimum heat utilization condition the spray dryer should always fed
with the maximum solids feedstock possible. The higher the temperature difference ie. Inlet drying air temperature minus outlet drying air temperature, the lower the heat requirement to
produce a unit weight of product of constant residual moisture content from a constant solid feedstock. Feed temperature, particularly in existing plants, can also be optimized. Increasing feed
temperature reduces the heat required to produce a unit weight of dried product. Preheating of feed is normally carried out to reduce feed viscosities, thereby improving atomization performance and
to present feed crystallization that can cause atomizer blokage Master, 1991.
11
III. RESEARCH METHODOLOGY
A. MATERIALS AND INSTRUMENTS
1. Materials
Dried green tea var. Oolong No 12 was supplied by Boonrod Tea Factory Thailand. Chemical reagents with analytical grade such as folin-ciocalteu 10 vv and
gallic acid were supplied by Fluka Buchs, Switzerland, anhydrous sodium carbonate and potassium hexacyanoferrate [K3FeCN6] were purchased from Merck Darmstadt,
Germany, standard HPLC of caffeine and catechins were purchased from Sigma-Aldrich St. Louis, Missouri, USA, acetonitrile, trifluoroacetic acid TFA and methanol HPLC-grade
were purchased from Fluka Buchs, Switzerland, trolox ±-6-Hydroxy-2,5,7,8- tetramethylchromane-2-carboxylic acid and DPPH 2,2-diphenyl-1-picryhydrazyl were
purchased from Aldrich Steinheim, Germany. monosodium phosphate monohydrate, Disodium phosphate heptahydrate and trichloroacetic acid TFA were purchased from Fluka
Buchs, Switzerland, citric acid food grade, potassium mitrute salt food grade. Then, distilled water, filter paper No 1 and No 4.
2. Instruments