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All Journal agriTECH Jurnal Perlindungan Tanaman Indonesia Indonesian Food and Nutrition Progress
Rachmad Gunadi
Department Of Soil Science, Faculty Of Agriculture, Universitas Gadjah Mada, Jl. Flora, Bulaksumur, Yogyakarta 55281
Agriculture, Biological Sciences & Forestry

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Pengaruh Iklim terhadap Perkembangan Penyakit Layu Fusarium pada Cabai di Beberapa Topoklimat di Yogyakarta Rachmad Gunadi
Jurnal Perlindungan Tanaman Indonesia Vol 3, No 2 (1997)
Publisher : Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (8930.713 KB) | DOI: 10.22146/jpti.12964

Abstract

The widespread of chilli cultivation and its serious damage caused by Fusarium wilt was observed to study the weather characters of 3 topoclimates in Yogyakarta and their support on the disease development. The result of the study shows that the altitude gradient gives specific effect to weather conditions and this condition shows the specific effect on disease development. The macro elements of weather tends to be more significantly different between topoclimates than the micro ones. The optimal altitude for disease development is around 400 m. Relative humidity and rainfall show the dominant effect on disease development beside of air and soil temperatures. The range of weather condition needed by F. oxysporum for survival tends to be much wider than the range needed for disease development.
Improvement of Antioxidant Activity and Sensory Quality of Pagilaran’s Tea Clones Treated by Tannase Tri Wahyuni Apriyani; Supriyadi Supriyadi; Rachmad Gunadi
agriTECH Vol 42, No 3 (2022)
Publisher : Faculty of Agricultural Technology, Universitas Gadjah Mada, Yogyakarta, Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (203.264 KB) | DOI: 10.22146/agritech.57006

Abstract

PT. Pagilaran developed five new clones named PGL 9, PGL 10, PGL 11, PGL 12, and PGL 15 for black tea. These clones can be potentially made into ready-to-drink (RTD) instant tea beverages with low antioxidant activity. Tannase is an industrial enzyme with great potential for application in the food industry used to hydrolyze gallated ester catechin in green tea. There were no findings on the effects of this enzyme treatment on the chemical composition of PT Pagilaran’s tea clones. Therefore, this study is aimed to observe the effects of tannase treatment on five clones of black tea extracts to the antioxidant activity, profile of phenolic compounds, the tea brew color, consumer acceptance, and volatile compounds. The leaves of the plucking medium were traditionally processed into black tea. Furthermore, the tea brew was added at a 100 mg/100 mL concentration and then incubated for 1 hour at 37 °C. Additional tannase increased their antioxidant activities, the gallic acid, EC, and EGC concentrations due to hydrolysis of ECG, EGCG, or their derivatives. The color of the tea brew was brighter and yellower than the untreated, but the level of consumer acceptance was still good. The profile aroma and volatile compounds showed no significant changes after enzymatic treatment.
Antioxidant Capacity of Black Tea Obtained Using Tyrosinase and Tannase Treatment Fiyan Maulana Rajendra; Rachmad Gunadi; Supriyadi Supriyadi
Indonesian Food and Nutrition Progress Vol 20, No 1 (2023)
Publisher : Indonesian Association of Food Technologists

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/ifnp.64516

Abstract

Black tea has a lower antioxidant capacity than other teas, such as green tea, white tea, and oolong tea. Tannase and tyrosinase can be used as a treatment to improve the quality of black tea infusion. Tannase has been reported to be an effective way to enhance antioxidant activity in black tea infusion. Meanwhile, tyrosinase could produce higher theaflavin content than thearubigin. Research about Ready-to-Drink (RTD) black tea preparation with the addition of tannase and tyrosinase to fresh tea leaves before pasteurization has not been reported. This study aimed to find a good combination of tannase (1 mg/ml) and tyrosinase (111; 446; 1785 U/ml) to produce high antioxidant activity of RTD black tea. The results showed that higher tyrosinase concentration decreased the antioxidant activity (DPPH and reducing power), epicatechin (EC), epigallocatechin (EGC), and epigallocatechin gallate (EGCG) content yet increased the theaflavin content and theaflavin (TF)/thearubigin (TR) ratio in the tannase-tyrosinase treated black tea. Still, the highest concentration of tyrosinase (1785 U/ml) in tannase-tyrosinase black tea produces higher antioxidant activities, gallic acid, EC, and EGC content than commercial black tea and tyrosinase without tannase-treated black tea. Thus, the combination of tannase (1 mg/ml) and tyrosinase (1785 U/ml) could be the best treatment to produce high-antioxidant black tea. 
Co-Authors Fiyan Maulana Rajendra Supriyadi Supriyadi Supriyadi Supriyadi Tri Wahyuni Apriyani