Characterization of Blue Whiting Skin Gelatines Extracted after Pretreatment with Different Organic Acids

Gelatines were extracted from blue whiting (Micromesistius poutassou) skins after pretreatment with different organic acids (acetic, citric, lactic, malic, and tartaric acids). The effect of the pretreatment on the chemical composition and the rheological properties of extracted gelatines were analyzed. It was observed that acetic acid pretreatment resulted in significantly (p < 0.05) higher extraction yield compared to the rest of the gelatines. All gelatines, regardless of the organic acid used in the pretreatment, had similar chemical composition (p > 0.05). The amino acid analysis showed that acetic acid pretreated skins resulted in gelatines with higher imino acid levels with respect to the other pretreatments. Acetic and tartaric acid derived gelatine gels showed highly interconnected protein networks and better viscoelastic properties, in terms of storage modulus, compared to the other pretreatments.