Dyah Hesti Wardhani

Inhibition kinetics of lipid oxidation of model foods by using antioxidant extract of fermented soybeans

Fermentation by using Aspergillus oryzae has been reported to increase antioxidant activity of soybeans significantly. The effectiveness of the extract from fermented soybeans was studied in 3 model foods with different complexities, i.e., linoleic acid emulsion, sunflower oil emulsions and bulk sunflower oil. For the emulsion systems, oxidation at two different pH values (4.5 and 7) was also compared. A reparameterised logistic equation was used to describe and to predict the experimental data. In general, a good agreement between experimental trends and simulated data from the model was found. A crude antioxidant extract (5 mg/g) showed a comparable antioxidant activity to 0.26 mg/g of butylated hydroxytoluene (BHT) in the linoleic acid emulsions. The extract exhibited a better capability to retard primary products in the linoleic acid systems than the secondary products. The opposite effect was observed in the bulk sunflower oil and its emulsion systems.

Effect of deacetylation on functional properties of glucomannan

Glucomannan is one of the highest viscosity polysaccharides with high water absorbing capacity. This property limits glucomannan applications; hence, it requires modifications. Glucomannan has 5-10% acetyl group which confers its functional properties. Replacing the acetyl with alkali transforms the functional characteristic of modified glucomannan. The aim of this study was to determine the effect of deacetylation conditions on the functional properties of glucomannan of A. oncophyllus. Effects of concentration of Na2CO3 (0.1-0.5 M), reaction time (1-5 h) and temperature deacetylation (40-80°C) were studied on glucomannan solubility, viscosity and water binding capacity (WBC). Deacetylation conditions affected solubility, viscosity and WBC of deacetylated glucomannan differently. Concentration of Na2CO3 showed negative impact on solubility, viscosity and WBC of deacetylated glucomannan. Solubility increased with increasing temperature and extending duration of deacetylation. Meanwhile, temperature and re...

Physicochemical Properties of Glucomannan-Alginate as Vitamin C Excipient

Physicochemical Properties of GlucomannanAlginate as Vitamin C Excipient Wardhani, Dyah Hesti Chemical Engineering Department, Faculty of Engineering, Diponegoro University Hapsari, Farida D. Chemical Engineering Department, Faculty of Engineering, Diponegoro University Suryana, Kazenina M. Chemical Engineering Department, Faculty of Engineering, Diponegoro University Aryanti, Nita Chemical Engineering Department, Faculty of Engineering, Diponegoro University 他