In this study, possibility of using Skipjack Tuna (Katsuwonus pelamis) fish skins as a new and alternative raw material source for leather industry was investigated. The structural and chemical properties of fish skins have a high impact on the preparation of special production recipes and the manufacturing of high performance valuable fish leathers. For this purpose, characteristic properties of Skipjack Tuna fish skins were evaluated by histological, histochemical and chemical methods. The chemical characteristics of fish skins were determined by analyzing fat content (%), total Kjeldahl nitrogen (%), hide substance (%), volatile matter (%), total ash (%) and fatty acid methyl esters and total amino acid content through instrumental analysis. Histological and histochemical analyses were carried out by Hematoxylin-Eosin and Van Gieson staining techniques. As a result of histological and histochemical investigations, fish skins were found thin and tough due to their surface characteristics, had less collagen content compared to other raw materials commonly used in leather industry and the fibers were orientated in parallel but opposite to striated muscles differently from the other skins. Besides, the fat content, Kjeldahl nitrogen, hide substance, volatile matter and total ash of Katsuwonus pelamis fish skins were found 24.47±1.76%, 10.20±0.28%, 57.32±1.55%, 37.33±4.01% and 1.23±0.0002% respectively. The results of the study revealed that Katsuwonus pelamis fish skins could be an alternative raw material to be used in the production of high value added luxury leathers.

Enhancing fastness properties of thermochromic dyes and pigments provide unique and assertive design opportunities and an innovative approach for leather industry. For this purpose, the ageing behavior of thermochromic pigments (cold and touch activated) used in leather finishing process by the addition of UV absorbent and cross-linker was investigated. The color changing effect of thermochromic leathers was determined spectrophotometrically prior and subsequent to accelerated ageing tests performed under two different conditions (only heat and heat associated with relative humidity). No significant effect of ageing was found on thermochromic leathers. However, a partial decrease was determined for the cold activated leathers and it was prevented by the use of UV absorbent and cross-linker.