| Summary: | 碩士 === 國立高雄海洋科技大學 === 水產食品科學研究所 === 97 === Milkfish (Chanos chanos) is one of the most important cultured fishes in Indonesia as well as in Taiwan. Indonesian government also considered promoting the use of milkfish in "boneless" style. During boneless milkfish manufacturing, by-products such as bone, scale and viscera are generated in large quantity. These solid wastes constitute 20~30% and especially bone accounts for 15~20% of the original raw material.
Milkfish bone was provided for the production of collagen and its gelatin hydrolysate. The first part of this study was aimed to extract collagen and gelatin hydrolysate from milkfish bone, and to analyze their yield, biochemical and qualitative characteristics. The SDS-PAGE pattern and amino acid analysis of milkfish bone collagen were examined. Amino acid composition of bone collagen isolated from milkfish was rich in glycine (34.5%). The amount of imino acid was 202 residues per 1,000 residues.
In the other hand, milkfish bone was extracted with an autoclave at 121°C for 15~120 min (Retorted bone gelatin hydrolysate, grouped in RBGH-15, -30, -60, -90, and -120, respectively), and one of these RBGHs was subjected further to enzyme hydrolysis. RBGHs and enzymatic digested RBGH (ED-RBGH) were prepared for the following investigations: the molecular size profiles, antioxidant activities including scavenging activity of DPPH radical, reducing power, ferrous ion chelating activity and inhibition ability of lipid oxidation in the linoleic acid model system.
Main distribution of molecular range of RBGH-15 and -30 were at the ranges between 30,000~70,000 Da, while those of RBGH-60, -90, and -120 were less than 50,000 Da. Degree of hydrolysis (DH) of RBGH reached about 63.70%, 67.88%, 69.26%, 70.58% and 72.10% for RBGH-15, -30, -60, -90, and -120, respectively. RBGH-60 in 12 mg/mL assay concentration showed good functional activities including scavenging activity of DPPH radical, reducing power, ferrous ions chelating activity, and inhibition ability of lipid oxidation, were 84.88±0.73%, 0.661±0.036 (OD700nm), 54.75±0.57%, and 71.90±0.48%, respectively. Moreover, no obvious alteration of function activity was found when extraction time increased.
Then, RBGH-60 was digested with alcalase and collagenase for 30~90 min. The hydrolysis of alcalase and collagenase was almost accomplished within 90 minute (ED-RBGH A-90 and ED-RBGH C-90), and the efficacy of hydrolysis with collagenase was found higher than alcalase. DH of ED-RBGH A-90 and C-90 was 78.77% and 82.68%, respectively. Percentage of molecular weight distribution fraction 189~686 Da of ED-RBGH C-90 (35.68%) was higher than of ED-RBGH A-90 (17.46%). The functional activities of ED-RBGH C-90 in 12 mg/mL assay concentration showed the higher effect of reducing power and inhibition ability of lipid oxidation than A-90. On the contrary, RBGH A-90 showed higher scavenging activity of DPPH radical and ferrous ions chelating activity than C-90.
This study revealed that using high temperature extraction could get hydrolysate with strong antioxidative activities from milkfish bone. Furthermore, bone gelatin hydrolysate with alcalase or collagenase revealed that the peptides with low molecular weight possessed a high in vitro antioxidant activity, especially ferrous ions chelating activity. It is a valuable method in the industry in future.
|
|---|
