Structural characteristics of collagen from cuttlefish skin waste extracted at optimized conditions

Aquatic by-products during fish processing cause environmental pollution and increase disposal costs. Cuttlefish skin is one of the major by-products of cuttlefish (Sepia pharaonis) processing and is generally thrown as a by-product. It can cause severe environmental problems and odor. It has been discovered that cuttlefish skin can be an excellent resource for producing attractive amounts of collagen. This study optimized collagen extraction conditions using response surface methodology (RSM). In addition, SDS-PAGE, specific charge, and scanning electron microscopy (SEM) characteristics of extracted collagen were evaluated. The results showed that the optimal extraction conditions for cuttlefish skin collagen are pH 1.5, 20 mg/L (solid-liquid ratio), 15 U/mg (Pepsin), and the average extraction rate can be obtained as 8.79%. The results of LC/MS/MS analysis of the collagen samples extracted in this study showed that the main m/z signal of proline produced by mass spectrometry was between 2000–4000. Collagen extracted from the cuttlefish skin is type I collagen, which consists of 2 α chains and 1 β chain (α2, α1, β). SEM analysis of collagen confirmed the presence of collagen fibrils in the cuttlefish skin similar to previous reports. Using the response surface methodology, optimal collagen extraction conditions pH 1.5, 20 mg/L (solid-liquid ratio), and 15 U/mg (Pepsin) can be obtained to recycle and utilize by-products.</p

Scatter and regression plots of BF%_DXA according to FFM_BIA8 and FFM_DXA differences.

<p><b>(a) total subjects (<i>n</i> = 711), (b) male subjects (<i>n</i> = 412), and (c) female subjects (<i>n</i> = 299).</b> The bold line represents the regression line.</p

Bland-Altman plot of the difference between BF%_BIA8 and BF%_DXA in mean difference expressed as bias, 95% confidence interval expressed as bias ± 2 SD.

<p>(a) Total subjects (<i>n</i> = 711); bias ± SD: -3.72 ± 4.09%, bias– 2SD: -11.90%, bias + 2 SD: 4.46%, regression equation y = - 0.170 x + 0.430 (<i>r</i> = 0.42, <i>P</i> < 0.01); (b) Male (<i>n</i> = 412); bias ± SD: -3.66 ± 4.24%, bias– 2SD: -12.14%, bias + 2 SD: 4.83%, regression equation y = - 0.340 x + 2.830(<i>r</i> = 0.61, <i>P</i> < 0.01); (c) Female (<i>n</i> = 299); bias ± SD: -3.81 ± 3.87%, bias– 2SD: -11.56%, bias + 2 SD: 3.94%, regression equation y = - 0.187 x +2.134 (<i>r</i> = 0.41, <i>P</i> < 0.01).</p

Physical characteristics of the subjects¹.

<p>Physical characteristics of the subjects<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0160105#t001fn001" target="_blank">¹</a>.</p

Body fat percentage outcome of analyses by ordinary least products regression.

<p>Body fat percentage outcome of analyses by ordinary least products regression.</p