Optimization of Production of Food Grade Gelatin from Bovine Hide Wastes

Abstract

The optimum conditions for the production of food grade gelatin from the tannerybovine hide wastes are established. The process involves cutting the hide wastes intosmall pieces (1-2 cm2), and washing them with water to remove the dirt. The washedpieces are placed in the liming tank containing 10% of lime in water with stirring forfive weeks. After washing with water to remove the lime, the collagen is neutralizedto pH 7 with hydrochloric acid. The extraction is carried out in four stages using hotwater. The gelatin extracts are filtered, subjected to deionization and concentratedwith vacuum evaporator up to 20-35 wt%. The gelatin is then dried by two types ofdryers (tray dryer and spray dryer).Box-Wilson method is adopted to obtain a relationship between the three variables(temperature, time and pH) and gelatin yield in the first stage of extraction and twovariables (temperature and time) and the gelatin yield in the other third stages ofextraction process. The experimental data were fitted to second order polynomialmodels for all stages.The most favorable operating conditions for the extraction of gelatin are: -The First Stage: Temperature = 64 oC , Time = 5 hr , pH = 7The Second Stage: Temperature = 74 oC , Time = 3.72 hr , pH = 7The third Stage: Temperature = 84 oC , Time = 3.69 hr , pH = 7The fourth Stage: Temperature = 98 oC , Time = 3.83 hr , pH = 7The overall yield of gelatin is 55%, under the previous condition. The quality ofgelatin was checked against food grade specification at the Nutrition ResearchInstitute of the Ministry of Health. The results are acceptable within the boundaries ofthe desired properties.