شرایط بهینه استخراج ژلاتین خوراکی از استخوان گاو به روش اسیدی با استفاده از رگرسیون سطوح پاسخ RSREG

This research was carried out to determine the optimum conditions for acidic extraction of gelatine from cattle bones. The effects of different treatments such as pH (1.8 to 2.6), temperature (60 to 80°C) and time (40 to 120minutes) on yield of extraction, gel strength, viscosity and absorption (420 nm) was measured. Coefficients of central composite rotatable design (CCRD) and regression surface response.... (RSREG) were used. The coefficients for yield, gel strength, viscosity and absorption were 0.990, 0.991, 0.998, 0.928, respectively. According to variance analysis of the data, there were significant differences between the effects of three variables (pH, temperature and time) on yield of extraction and viscosity, but no significant difference was observed between the effects of temperature and pH on gel strength and absorption, respectively. Comparisons of the averages of functional characteristics of acidic and commercial gelatin showed that viscosity and strength of acidic gelatin were higher than those of commercial one. The optimum conditions were found to be: pH=1.88, temp. 80°C and 118 min., to reach the highest yield and pH=1.88, temp. 60°C and 48 min. to get maximum strength, and pH=2.56, temp. 69°C and 118 min. to obtain the maximum viscosity and finally, pH=2.6, temp. 62°C and 48 min. for minimum absorption. Also, the results revealed that there were significant differences between trace elements content (Fe, Ca and Pb) of commercial and acidic gelatins. Although, acidic gelatin contained higher amount of the elements, but these amounts were still less than maximum values which are allowed to exist in gelatin. Amino acid compositions of both gelatins were almost identical.