Physicochemical properties of duck feet collagen with different soaking time and its application in surimi

Abstract

Duck feet are considered as waste products because people normally do not consume duck feet. It is highly available in Malaysia and thus has the high potential to be the alternative source to produce collagen other than fish, bovine or porcine. The main objective of this study is to evaluate the physicochemical properties of different treated duck feet collagen and its effect on the quality of sardine surimi. Duck feet was stirred and soaked in 5% lactic acid solution for different time (12, 24, 36 and 48 h) at 4°C. Another treatment for the duck feet is demineralization. Duck feet collagen was demineralized by 0.5M EDTA solution for 24 h prior soaking in lactic acid solution for 24 h. Soaking time 24, 36 and 48 h has successfully decreased fat content of duck feet collagen significantly compared to 12 h. However, no differences in yield were observed for the samples. Prolong soaking time produced duck feet collagen with higher content of imino acid (hydroxyproline + proline). The intensity of lightness (L*) for the demineralized duck feet collagen is lower compared to duck feet collagen which was not treated by EDTA. Duck feet collagen has the ability to improve the quality of sardine surimi gel by enhancing its lightness, water holding capacity, gel strength and texture with low cooking loss and expressible moisture. The folding test score of sardine surimi gel has been increased from 3.00 to 5.00 by the addition of duck feet collagen. The gel strength for sardine surimi gel with the addition of duck feet collagen is in the range of 2625.90 g.mm to 2681.58 g.mm, which is approximately 9 times higher than the gel strength of sardine surimi without collagen (280.43 g.mm).