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Tyas Utami
Gadjah Mada University
Agriculture, Biological Sciences & Forestry

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Kinetics and Substrate Partitioning in the Polyphenol Oxidase-Catalysed Oxidation of Catechol in a Two-Phase System Tyas Utami; D.L Pyle
Indonesian Food and Nutrition Progress Vol 5, No 1 (1998)
Publisher : Indonesian Association of Food Technologists

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (165.263 KB) | DOI: 10.22146/jifnp.56

Abstract

The kinetics of catechol oxidation catalysed by polyphenol oxidase in two-phase systems with mixtures of lauryl alcohol and hexane as the solvent phase is investigated, with particular reference to the effect of partitioning of catechol on the enzyme kinetics. Theory is developed to derive a relationship between the apparent K. and the intrinsic or 'true' Kn. The theory predicts that substrate partitioning should not change %Cue but that the relationship between the apparent and intrinsic K,, values should depend on the phase volume ratio and the partition coefficient. The theory shows good agreement with the results and gives a consistent K. value.
Production of Alkaline Lipase from Kluyvera KB4 Retno Indrati; V.S. Pertiwi Rumiyati; Tyas Utami
Indonesian Food and Nutrition Progress Vol 5, No 1 (1998)
Publisher : Indonesian Association of Food Technologists

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/jifnp.59

Abstract

Kluyvera KB4 produced alkaline lipase in a medium containing oil as inducer. Optimum conditions for lipase production were determined in terms of composition of medium, pH, temperature and time of incubation. The highest lipase productivity was obtained from a medium with corn oil as carbon source and peptone as nitrogen source. Oils seem to be. an essential carbon source, since in a medium containing sorbitol without addition of oil the lipase production was very low, approximately only 14%. However, higher concentration of oil (2%) suppressed the lipase production. Production of lipase was greatly influenced by pH of the medium and incubation temperature. It was optimally active at pH 7.5 and 37 °C in medium containing peptone and corn oil 1 %, respectively. Under optimum condition (pH 7.5, at 37 °C), the highest lipase activity was obtained after 36 h of incubation.
Immobilized Lipase - Catalyzed Fish Oil Hydrolysis in Organic Solvent Tyas Utami; Erryana Martati; Pudji Hastuti; Eni Harmayani
Indonesian Food and Nutrition Progress Vol 6, No 1 (1999)
Publisher : Indonesian Association of Food Technologists

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/jifnp.70

Abstract

Immobilized lipase from Mucor miehei catalyzed the hydrolysis of cod liver oil in the presence of hexane was studied. The research was conducted to observe the effect of hexane on degree of hydrolysis, glyceride profile and EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) contents. Enzymatic hydrolyses were carried out in a waterbath shaker at 50°C for 48 hours. Reaction mixtures contained of 1 g cod liver oil, hexane, Tris HCl buffer pH 7.5, and 10% (w/w oil) immobilized enzyme. Addition of various amount of hexane decreased the degree of hydrolysis and changed glyceride profile. Hexane to buffer ratio of 1:9 and 9:1 yielded 77% and 64% hydrolyses respectively. The results showed that degree of hydrolysis was affected by the oil concentration in the solvent system, not by the oil concentration in the overall system. It was observed that after hydrolysis, EPA dan DHA contents in the forms of glycreride and free fatty acid were higher in the addition of hexane than that of in the absence of hexane
Co-Authors D.L Pyle Eni Harmayani Erryana Martati Pudji Hastuti Retno Indrati V.S. Pertiwi Rumiyati