HIMANTURA GERRODI اثر تيمارهاي مختلف با اسيدهاي كلريدريك و استيك بر كيفيت و راندمان استخراج ژلاتين از پوست سپر ماهي گزنده

Effects of acetic and hydrochloric acids on the yield and qualtiy of gelatin extracted from skin of sting ray (Himantura gerrardi)

Fish gelatin is a valuable product with different utilization and characteristic from that of land animal. In this research attemps was made to compare and improve the yield and quality of gelatin extracted from skin of sting ray (Himantura gerrardi), dominant species of rays in Persian gulf and Oman Sea. Thirteen different treatments with Acetic (AA) and Hydrochloric acids (HC1) were compared. The results of qualitative indentification of gelatin extracted with all treatments were positive and according to standards concluded that the extracted products were gelatin. Minimum concentration for gel formation varied between 2 to 3%. Treatment with HC10.4% for 90 minutes at 70°showed better results compared with other treatments. The extraction yield of this treatment was 15.6% and showed significantly difference with most treatments (p<0.05). Total nitrogen, humidity, ash and pH of gelatin extracted with this treatment were 15.7%, 6.9%, 1.5% and 5.9, respectively. Melting temperature of this gelatin ranged between 22-25° and was higher than gelatins extracted with all other treatments. It seems that HC1 shows better effects on the yield and quality of gelatin extracted from skin of sting ray compared with AA (an organic acid).