Authors
Abstract
The optimum conditions for the production of food grade gelatin from the tannery
bovine hide wastes are established. The process involves cutting the hide wastes into
small pieces (1-2 cm2), and washing them with water to remove the dirt. The washed
pieces are placed in the liming tank containing 10% of lime in water with stirring for
five weeks. After washing with water to remove the lime, the collagen is neutralized
to pH 7 with hydrochloric acid. The extraction is carried out in four stages using hot
water. The gelatin extracts are filtered, subjected to deionization and concentrated
with vacuum evaporator up to 20-35 wt%. The gelatin is then dried by two types of
dryers (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 two
variables (temperature and time) and the gelatin yield in the other third stages of
extraction process. The experimental data were fitted to second order polynomial
models for all stages.
The most favorable operating conditions for the extraction of gelatin are: -
The First Stage: Temperature = 64 oC , Time = 5 hr , pH = 7
The Second Stage: Temperature = 74 oC , Time = 3.72 hr , pH = 7
The third Stage: Temperature = 84 oC , Time = 3.69 hr , pH = 7
The fourth Stage: Temperature = 98 oC , Time = 3.83 hr , pH = 7
The overall yield of gelatin is 55%, under the previous condition. The quality of
gelatin was checked against food grade specification at the Nutrition Research
Institute of the Ministry of Health. The results are acceptable within the boundaries of
the desired properties.
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