Judul: Characterization of The Chemical Constituents and Antioxidant Capacity of Green and Oolong Teas (Camellia sinensis) Manufactured in Thailand
Abstrak: Tea in Thailand most manufactured in northern area, especially Chiang Rai, Chiang Mai, Nan, and Mai Hang Son province. The aim of this study was to determine and compare the chemical compositions and antioxidant capacity of 4 important Thai tea products. A total of 13 of green teas of 2 major cultivars, assamicaand cv. oolong no.12 (chin hsuan oolong) and 26 of oolong tea of 2 major varieties, cv. oolong no. 12 and cv. oolong no. 17 (chin shin oolong) were collected from 18 factories in Chiang Rai province in 2011. The total polyphenol content was determined according to International Organization for Standardization (ISO 14502-1). For antioxidant capacity, DPPH radical scavenging activitiy assay and ferric reducing antioxidant power assay were determined. The catechins content and caffeine content were determined using HPLC by ISO method (ISO-14502-2). Results showed that about 95% of the 39 tea samples manufactured in Thailand had moisture content below 7%, 5% of tea samples being above 7%. The total polyphenol content in green tea was found to vary from 11.86 to 21.19%GAE, while in oolong tea was found in a range of10.22 to 17.57%GAE. The caffeine content in green tea samples were in a range of 1.69 to 3.7%, while in oolong tea samples were in a range of 1.61 to 3.26%. The catechin content in green tea samples were in a range of 8.31-14.08%, while in oolong tea samples were in a range of 6.81-12.46%. The antioxidant capacity in green tea samples was 164.01 mmole TE/100 g dry basis, while in oolong tea samples was about 132.73mmole TE/100 g dry basis. This study provided useful information for the tea industry in Thailand and other countries in processing and selecting a good-quality tea.
Keyword: Antioxidant capacity, Camellia sinensis, Green tea, Oolong tea, Thailand

Judul: Effect of Spray Drying Conditions on Physical and Chemical Properties of Dried Green Tea Extract (Camellia sinensis var. Oolong No 12).
Abstrak: The effect of spray drying conditions on physical and chemical dried green tea (Camellia sinensis var. Oolong No 12) extract were observed. Tea extract was prepared from milled dried tea, dissolved in hot water at temperature 90°C and ratio of dried tea to water 1: 20 (w / v). The time of extraction used was 60 minutes, and pH value was 5.0. Then, tea extract was concentrated with ice maker machine until reached 3, 6 and 9% of total solid, and dried with spray drier with condition inlet air temperatures were 180, 200, 220°C, outlet air temperatures was controlled 75°C, blower speed was adjusted in 2500 rpm. The physical analysis, such as bulk density, color, solubility, hygroscopicity, and the chemical analysis, such as moisture content, total polyphenols content, antioxidant activity (DPPH assay), catechins, and caffeine content were determined. Results showed that different solid concentration of 3, 6, 9% in feed and inlet air temperatures of 180, 200, and 220˚C affected the variation of physical and chemical properties of green tea powder. An increase inlet air temperature, resulted in a significant decrease (p<0.05) in bulk density, hygroscopicity, total polyphenols and antioxidant activity. An increase of solid concentration in feed gave an increase in tea powder solubility, L, a, b value, and antioxidant activity. However, the total polyphenols contents were not affected by the increase. The condition of feed concentrated to 3% and inlet temperature at 220˚C was evaluated with the highest of physical, chemical results and the highest of kg water removal/hour by spray dryer.
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Judul: Rancang Bangun Mekanisme Penggetar Untuk Bajak Subsoil Getar Dengan Dua Bilah Bajak
Abstrak: Bajak subsoil merupakan alat pengolahan tanah pertama yang sering digunakan sebelum pembajakan dengan bajak singkal atau bajak piring untuk memecah lapisan keras di lapisan bawah. Alat ini biasanya digunakan pada tanah yang telah mengalamli pemadatan akibat lalu lintas traktor. Alat ini memiliki tahanan tarik yang tinggi dan biasa ditarik traktor empat roda
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