http://orcid.org/0000-0002-0553-5712
ABSTRACT
A research article published in this journal by Sotelo et al. (2016) reported on characterization of collagen from different discarded fish species obtained from the Iberian Peninsula located in the southwest corner of Europe. While the original research contributed new information to the literature, the authors did not provide sufficient details to reproduce the study and adequately interpret the results. This research note provides additional information that may help the reader to understand an important part of the published research study.
A research study published in this journal by Sotelo et al. (Citation2016) presented an overview of the characterization of collagen from different discarded fish species of the West coast of the Iberian Peninusula. While the research contributed new information to the literature, the authors did not provide sufficient information to reproduce the study and interpret their results. This research note provides technical comments and additional information that may help the reader to understand an important part of the published research study.
Fish skins from different discarded fish species were used for collagen extraction, but the report did not adequately describe the fish skins used or the extraction of acid-soluble skin collagen. More information on the fish skin size (pieces), stirrer speed, and dialysis conditions (molecular weight cutoff of dialysis tube/bag) is needed in order to reproduce the study. The complete extraction process of fish skin/scale collagens is well-reported by several research groups (Matmaroh et al., Citation2011; Liu et al., Citation2012; Pal et al., Citation2015) and should be cited.
Protein content of fish skins reported in the study was lower than the extracted collagen content. For example, the fish skin of Leucoraja naevus contained 28.25% proteins, while the extracted collagen content was reported at 29.10%. Fish skin of Chimaera monstrosa, Etmopterus spp., Galeus spp., and Scyliorhinus canicula contains 30.21%, 23.27%, 32.02%, and 30.73% proteins, respectively, and the collagen content calculated on the basis of hydroxyproline is 31.03%, 27.76%, 37.1%, and 31.31%, respectively. The authors state that peptide bands below 100 kDa were observed. However, after extraction, the collagen was not purified/partial purified; therefore, the presence of small peptides may be due to the extraction of noncollagen proteins. In addition, the authors reported the denaturation temperature of collagen in the range of 28–35°C but did not clearly mention the denaturation temperature in the text.
Despite the concerns, the article by Sotelo et al. (Citation2016) gave a good overview of the characterization of collagen from discarded fish species, and we hope the additional information provided will help the readers to understand an important part of the published research study.
References
- Liu, D., Liang, L., Regenstein, J. M., and Zhou, P. 2012. Extraction and characterisation of pepsin-solubilised collagen from fins, scales, skins, bones and swim bladders of bighead carp (Hypophthalmichthys nobilis). Food Chem. 133: 1441–1448.
- Matmaroh, K., Benjakul, S., Prodpran, T., Encarnacion, A. B., and Kishimura, H. 2011. Characteristics of acid soluble collagen and pepsin soluble collagen from scale of spotted golden goatfish (Parupeneus heptacanthus). Food Chem. 129: 1179–1186.
- Pal, G. K., Nidheesh, T., and Suresh, P. V. 2015. Comparative study on characteristics and in vitro fibril formation ability of acid and pepsin soluble collagen from the skin of catla (Catla catla) and rohu (Labeo rohita). Food Res. Int. 76: 804–812.
- Sotelo, C. G., Blanco Comesaña, M., Ramos Ariza, P., and Pérez-Martín, R. I. 2016. Characterization of collagen from different discarded fish species of the West coast of the Iberian Peninsula. J Aquat Food Prod T. 25: 388–399.