Abstract:
This work is divided into two parts: crude extraction of proteolytic enzyme from papaya latex, and the use of crude extracted proteolytic enzyme to produce gelatin via the hydrolysis of raw hide. From the results of solvent extraction of proteolytic enzyme using water and phosphate buffer pH6, the yield of extracted enzyme did not change by extraction time but it was dependent on the solvent and the ratio of latex to solvent. The yield of extracted enzyme from water extraction was higher than those from phosphate buffer extraction. Following the solvent extraction, the extracted enzyme was precipitated in 45% saturated ammonium sulfate solution. The yield and activity of precipitated enzymes were considerably decreased. Therefore, crude extracted enzyme from water extraction at ratio of 1:1 was selected to be used in gelatin production comparing to the use of commercial papain. For the gelatin production, the effects of conditions which were temperature, pH, hydrolysis time and enzyme to raw hide ratio, on the yield of gelatin recovery and properties of gelatin were investigated. At the beginning of hydrolysis reaction, the yield of gelatin recovery was greatly increased, and then slightly increased. The optimum conditions of crude extracted enzyme and commercial papain hydrolysis for the highest gelatin recovery are 75 degrees celsius and pH 7. The percentage of gelatin recovery is around 60-70wt%. The results showed that the gel strength and viscosity of gelatin obatined from both types of enzymatic hydrolysis are low. However, gelatin recovery and properties of gelatin could be manipulated by temperature, pH, and ratio of enzyme to raw hide. For example, at the optimum condition for enzyme activity (75 degrees celsius, pH7), the high gelatin recovery could be achieved but the low gel strength gelatin (55.8-58.4 g Bloom) was obtained. On the other hand, at the condition for relatively low enzyme activity (85 degrees celsius, pH7), the lower gelatin recovery was reached and gelatin with relatively higher gel strength (166.4-187.6 g Bloom) was received. The gelatin recovery and properties of gelatin obtained from crude extracted enzyme and commercial papain hydrolysis were similar. But the used amount and the cost of crude extracted enzyme from papaya latex were much less than those of commercial papain.
