8
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 cathecinsare purchased from Sigma-Aldrich St. Louis, Missouri, USA, acetonitrile,
trifluoroacetic acid TFA, Monosodium phosphate monohydrate, disodium phosphate heptahydrate, and methanol HPLC grade were purchased from
FlukaBuchs, Switzerland. Other materials were citric acid food grade, ammonium sulphate, dichloromethane, distilled water, and Whatman filter paper
No 1.
2. Instruments
The main instruments are JMC-miniLAB spray dryer Euro Best Technology, ltd, Thailand, freeze concentrating machine March Cool Industry
Co.ltd, Thailand, centrifuge, hydrolic press Owner Food Machinery Co.ltd, Thailand, hand refractometer 1-32
o
Brix ATAGO Model N-2E, Japan, a spectrophotometer UV Vis. BiochromLibra S22, England, oven, disc mill,
analytical balance, pHmeter, vacuum pump, SPME holder, SPME fiber 5030 µm DVBCARPDMS StableFlexSS, round bottom flask, vial 250 mL, and HP model
6890 gas chromatograph equipped with an HP-5MS 5 phenyl- polymethylsiloxane capillary column 30 m, 0.25 mm i.d., film thickness 0.25
µm; Agilent Technologies, USA interfaced to an HP model 5973 mass-selective detector.
B. EXPERIMENTAL DESIGN
This research is divided into two parts. The preliminary research is investigation of the chemical and volatile compounds of raw material dried green
tea leaf. Experiment I is production of concentrated green tea made from green tea extract and increase its concentration using freeze concentration machine, and
then analysis of volatile compounds. Experiment II is production of green tea powder made from concentrated green tea using spray dryer, and then analysis of
instant green tea powder characteristics.
1. Production of concentrated green tea extract
Dried green tea leaf was milled with hammer mill resulted in milled green tea leaf. Then, milled green tea was extracted by dissolved in hot water 90
o
C with regarding green tea: water 1:20 w v. The time of extraction was 60 minutes
9
and pH value was 5.0 pH value was adjusted using citric acid. After that, extracted tea was filtered using clothes sheet and the residu was pressed by
pressing machine to obtain extract of green tea. Total Dissolved Solid TDS of green tea extract was analyzed by refractometer and oven method. Then, green tea
extract was concentrated using freeze concentration method, which was done by ice maker machine.
2. Production of green tea powder
Green tea powder was produced from concentrated green tea extract using spray dryer. The operational conditions of the spray drying process were as follow:
inlet air temperatures are 180, 200, and 220
o
C, outlet air temperature was controlled about 80
o
C, and blower speed was adjusted in 2500 rpm. The air pressure and feed rate need to be increased or decreased in order to control outlet
temperature at 80
o
C. The air pressure and feed rate are affected by inlet air temperature. As the inlet air temperature increases, the air pressure and feed rate
increase. Then, the final product was analyzed to determine volatile compounds, chemical compounds,and physical properties of dried green tea powder.
Extraction
Filtering
Green tea extract Freeze concentrating
Concentrated green tea extract Milling
Dried green tea leaf
Figure 3. 1.Production of concentrated green tea extract
10
C. METHOD OF ANALYSIS
Kategori