Poultry Processing Waste as an Alternative Source for Mammalian Gelatin: Extraction and Characterization of Gelatin from Chicken Feet Using Food Grade Acids

The present study was focused on extraction of gelatin from chicken feet using different food grade acids (acetic-, citric- and lactic-acid) at different concentrations. The gelatin thus obtained was evaluated for its physico-chemical properties. Gelatin yields in various acid treatments ranged between 6.18 and 14.47% on wet weight basis. The protein content of chicken feet gelatin (CFG) obtained with different acid treatments was in the range of 80.53-90.20%; while, the pH was in the range of 3.43-5.23. Among all, CFG extracted with 1.5% (v/v) acetic acid showed the highest bloom strength (204.3 g) which was similar to commercial porcine gelatin. The CFG prepared using 4.5% (v/v) citric acid had a bloom value of 165.8 g. The bloom strength of CFG prepared in our study was relatively higher than fish gelatin and slightly lower than porcine gelatin. Hydroxyproline content (g/100 g) of CFG prepared using different acids was in the range of 4.58-9.5. The CFG contained glycine (similar to 30%), imino acids (proline + hydroxyl proline; similar to 25%) and alanine (similar to 9%) as the major amino acids. CFG, irrespective of the acids used for preparation, exhibited moderate to strong emulsifying and foaming capacities. The results clearly indicate the potential of CFG to be an effective alternative to mammalian gelatin.