Physicochemical Properties of Duck Feet Gelatin Powder Extracted with Acetic Acid

Abstract

Physiochemical properties such as colour, amino acid composition, melting temperature and hydroxyproline content determines the quality of gelatin. In this study, 4% of acetic acid was used to produce gelatin powder from Pekin, Muscovy and Khaki Campbell duck feet. The duck feet gelatin powders were analysed for their physiochemical properties and compared with commercial bovine gelatin. For colour analysis, Pekin duck feet gelatin (PDFG) had the highest L* value (21.41), followed by Khaki Campbell duck feet gelatin (KCDFG, 20.57) and Muscovy duck feet gelatin (MDFG, 17.85). KCDFG and PDFG had the same a* values (redness) which was -0.05, while the a* value of MDFG was -1.49. Lastly, the b* values of duck feet gelatin powder were 6.17, 8.47 and 9.47 for PDFG, MDFG and KCDFG, respectively. Duck feet gelatin powder had a melting temperature value of 61.91°C, 48.62°C and 44.81°C for KCDFG, MDFG and PDFG, accordingly. PDFG had the highest hydroxyproline content, which was followed by KCDEG and MDFG with the values of 9.15, 8.00 and 7.63 g/100g, respectively. The main amino acids present in the duck feet gelatin powder were glycine (21.73%, 13.62%, 13.46% and 15.33%), proline (13.08%, 8.71%, 8.39% and 9.34%), hydroxyproline (12.57%, 8.05%, 7.84% and 9.39%) and alanine (8.79%, 5.77%, 6.03%, 6.65%) for CBG, KCDFG, MDFG and PDFG, respectively. Furthermore, the lowest amino acids observed were tyrosine, histidine, methionine and isoleucine. No trace of cysteine was observed. Pekin duck feet produced the best quality gelatin compared to Khaki Campbell and Muscovy duck feet.