Effect of drying temperature on gelatin characteristics of nila fish (Oreochromis niloticus) skin

Abstract

This research aimed to asses the influence of gelatin extract from nila fish (Oreochromis niloticus) skin in drying temperature on the quality characteristics. Production of gelatin by using 0.05M acetic acid with processing step was degreasing, demineralization, washing, extraction and drying. Degreasing was by immersing skin in the water at a temperature of ±60 ° C for ± 10 seconds, then draining it. Demineralization was carried out by immersing skin in a solution of 0.05 M for 2 hours and washing process until reached neutral pH, and extracted with distilled water (1: 3 / w: w) at 80 °C for 3 hours. Filtration was using a filter cloth and drying at room temperature (20 - 25 °C) and the oven on 55 °C until dry. Observations on gelatin for yield, proximate composition, gel strength, color, and IR spectra of the gelatin molecule groups. Gelatin obtained from drying and oven on 55 °C has a lower moisture content than drying temperature (20-25°C) but has higher protein content, and for ash and fat content was not significantly different. Gelatin obtained from drying oven 55°C has a yield of 17% and a gel strength of 226 g, drying temperature (20-25°C) has a 23% yield and 240 g gel strength. The gelatin color was measured based on the values of L, a *, b * which gelatin obtained from drying oven at 55°C was greater than drying room temperature (20-25 °C). IR spectra of the gelatin molecular groups from the two drying temperatures did not differ, which have spectra at between 1336 cm−1 and 1744 cm−1. It means both of this gelatin has a double helix structure molecule obtained from the hydrolysis process of triple helix structure molecule of collagen during the extraction process.