Physical and chemical properties of wami tilapia skin gelatin

Gelatin was extracted from the skin of tilapia (Oreochromis urolepis hornorum) and characterized according to its physical and chemical properties. It had pH 4.66, which is slightly higher than the values reported for gelatins processed by acid solubilization. In general, the ionic content was low, and the average yield of the process was 5.10 g/100 g. The proximal composition of the gelatin was similar to that of the commercial gelatins, with slightly higher moisture content. The tilapia skin gelatin had whitish-yellow color and average turbidity of 67 NTU.

Study of thermodynamic water properties and moisture sorption hysteresis of mango skin

The equilibrium moisture content for adsorption and desorption isotherms of mango skin was determined using the static gravimetric method at temperatures of 20, 26, 33, 38 and 44 oC in the 0.056 to 0.873 water activity range. Both sorption curves show a decrease in equilibrium moisture content as the temperature increasing. The hysteresis effect was observed at constant water activity. The Guggenheim, Anderson, and de Boer (GAB) model presented the best fitting accuracy among a group of models and was used to determine the thermodynamic properties of water sorption. Integral enthalpy and integral entropy areas showed inverted values for the adsorption and desorption isotherms over the wide range of water activity studied. These values confirm, in energetic terms, the difference between adsorption and desorption isotherms observed in the hysteresis phenomenon. Finally, the Gibbs free energy revealed that the sorption process was spontaneous for both sorption isotherms.

Alterations in the lipid and soluble sugar content of melanoxylon brauna seeds during natural and accelerated ageing

The decay of seeds is irreversible and at best can only be delayed by applying techniques that reduce the velocity of the metabolic reactions involved. There is little information on the biochemistry of tropical forest tree seeds related to their storability. It was investigated the influence of the composition of lipids and soluble sugars of two storage compartments, the cotyledons and the embryonic axis, of Melanoxylon brauna Schot. (Leguminosae- Caesalpinioideae), a hardwood known as black brauna, seeds stored at 20 ºC for 0, 3, 6, 9 and 12 months (natural ageing) and for 0, 24, 48, 72 and 96 hours at 40 ºC (accelerated ageing). The levels of fatty acids and monosaccharides varied differentially in each of the embryo storage compartments. Changes in oligosaccharide levels were similar for both types of ageing, diminishing in both compartments. Ageing can be attributed to the significant decrease of oligosaccharides and the increase of glucose in both types of ageing and both embryo compartments.