| Summary: | 碩士 === 國立中興大學 === 畜產學系 === 89 === Abstract
Chicken feet were major edible poultry by-product in Asia. Annual chicken feet production approximate 31,954 tons, and faced the problem of production excess or being dumped as waste in Taiwan now. Thus, this study was conducted to evaluate the effect of 5% different acid solutions and different soaking times on collagen extraction of chicken feet, further, different lactic acid extracted collagens (L12, L24, L36 and L48) were to extract gelatin with different heating temperatures and times; then the properties of gelatins from chicken feet were compared with other animal species commercial gelatins.
Chicken feet collagen treated with 5% different acid solutions (acetic acid, citric acid, hydrochloric acid and lactic acid) and different times (12, 24, 36 and 48 hours), the results showed that the pH value of all acid treatments was not significantly different among extraction time. The swelling percentage of citric acid treatment was significantly increased by extraction time, but the others were not changed. The collagen yield from acetic acid and lactic acid treatments was significantly（p<0.05） higher than that of the other treatments. The collagen/total crude protein ratio of collagen from lactic acid treatment was significantly（p<0.05） higher than that of the others.
Different lactic acid extracted collagens (L12, L24, L36 and L48) were to extract gelatin with different heating temperatures(50, 60, 70 and 80℃) and times（1, 2, 3, 4 and 5 hours）. The yield, pH, color, gel clearness (O.D. 550nm） SDS-PAGE and rheological properties of gelatin from chicken feet were also determined. The result showed that yield of gelatin from L12 at 50℃ was significantly（p<0.05） lower than the other treatments. The pH value of gelatin from all treatments reduced with heating time. The gel clearness of gelatin for L48 treatment had the highest value among all treatments. The electrophoretogram showed that high molecular polymer of gelatin reduced with increase of heating temperature and times. The gel strength and break strength of L12 and L24 treatments obtained higher value than those of L36 and L48 treatments, however, the gelatin from L24 extracted at 60℃ for 4hrs had the highest gel strength and break strength.
The properties of chicken feet gelatin were compared with other animal species commercial gelatins. The results showed that gelatin color, clearness and rheological properties were different due to different animal tissues, extracted treatmant and drying methods. Gel aaparance of chicken feet gelatin and porcine A were turider than other gelatins, L value of bovine gelatin B was significantly（p<0.05） lower than other gelatins, b value of bovine gelatin A and porcine gelatin A were significantly（p<0.05） higher than other gelatins. Clearness and pH value of porcine gelatin A was significantly（p<0.05）higher than other gelatins. In sum up, there were obviouly differences in the sensory properties of 4 commercial gelatin, but the chicken feet gelatin was significantly（p<0.05） lower than that of the others. The melting point of chicken feet gelatin was significantly（p<0.05） higher than that of the others. The gel strength and break strength of chicken feet gelatin were significantly（p<0.05） lower than that of Bovine gelatin A, Bovine gelatin B and Porcine gelatin B but, significantly（p<0.05） higher than that of Porcine gelatin A. As well as gel softness of chicken feet gelatin was significantly（p<0.05） lower than that the other gelatins. The chicken feet gelatin was suitable for using in softer food (cakes and biscuit) or need increase concentration as other the usage.
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