The effect of processing conditions on the properties of gelatin from skate (Raja Kenojei) skins
ABSTRACT Effects of several conditions (liming concentrations, extraction solution pH, extraction temperature and extraction time) to extract gelatin from skate skin on the yield and quality properties were investigated. The optimum conditions for gelatin extraction are as follows; place skin in a lime solution of 1.5% (w/v) calcium hydroxide, extract with three volumes of water (pH 6.0) for 4 h at 50%, filter gelatin through activated carbon (250–350 mesh, 3%) and freeze-dry the colloidal suspension. The functional properties of skate skin gelatin produced by optimum extraction conditions were: gelling point 16.12 °C; melting point 19.30 °C; isoelectric point 6.45; and turbidity 6.98.
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ABSTRACT: Trypsin from the viscera of sierra (Scomberomorus sierra) was purified by affinity chromatography on Sepharose-4B coupled to soybean trypsin inhibitor and characterized with respect to its purity, sensitivity to temperature, pH and inhibition. Trypsin was purified from sierra viscera with 11.9-fold and 29.7% yield. The enzyme had a molecular weight of 25.4 kDa estimated by SDS-PAGE and two possible trypsin isoforms were observed in activity gels. Trypsin activity was strongly inhibited by soybean trypsin inhibitor and porcine trypsin inhibitor, showing a partial inhibition by a serine protease inhibitor. The optimal activity of the enzyme was observed at pH 9 and 60C with n-α-benzoyl-dl-arginine-p-nitroanilide as a substrate. The enzyme maintained more than 50% of its activity in temperatures up to 50C and within the pH range of 8–10 for a period of up to 2 h. Practical Applications The potential applications of purified trypsin from tropical sierra fish viscera are those that are already in use for trypsin, such as an aid for hydrolysis of food proteins, as an aid in reducing viscosity of stickwater from fish processing plants, and in obtaining bioactive fractions from protein hydrolisates. Specific uses of this particular trypsin from tropical sierra could be those that comply with the optimum conditions at 60C and pH 9–10 or stability described in the results.Journal of Food Biochemistry 12/2013; 37(6). · 0.76 Impact Factor
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ABSTRACT: Gelatin was extracted from alkali-pretreated skin of zebra blenny (Salaria basilisca) using commercial pepsin with a yield of 18 g/100 g of skin sample. The polypeptides pattern, gel strength, viscosity, textural parameters and functional properties of the zebra blenny skin gelatin (ZBSG) were investigated. Amino acid analysis revealed that ZBSG contained almost all essential amino acids, with glycine being the most predominant one. ZBSG was identified as a type I gelatin, containing α1 and α2-chains as the major constituents. Its gel strength and viscosity were 170.2 g and 5.95 cP, respectively. Fourier transformed infrared spectroscopy (FT-IR) spectra showed helical arrangements in its structure. Its solubility and functional properties were concentration-dependent. While foam expansion (FE) and foam stability (FS) increased with the increase of concentration, emulsifying activity index (EAI) and emulsion stability index (ESI) were noted to decrease. ZBSG also showed strong clarification ability particularly for apple juice, without affecting nutritional value.LWT - Food Science and Technology. 01/2014; 58(2):602–608.
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ABSTRACT: Optimum conditions for collagen extraction from skate (Raja kenojei) skins with various liming concentrations, extraction solution pH, extraction temperature and time, and functional properties were investigated. The optimum conditions for collagen extraction are as combination of place the skins in a lime solution of 0.15 N of NaOH, extract with 5 volumes water (pH 4.0) for 4 hr at 40°C, filter, centrifuge, and lyophilize to obtain collagen powder. The characteristics of skate skin collagen obtained under optimum extraction conditions were: solubility 82.7%, turbidity 0.28, and Hunter color L, a, and b values were 88.4, 0.92, and 11.2, respectively. On the other hand, the acidic pH values (3.0 and 5.0) of collagen were more resistant to precipitation upon extended heating. Keywordscollagen–skate (Raja kenojei) skin–optimum condition–extraction–functional propertyFood science and biotechnology 01/2011; 20(1):99-106. · 0.70 Impact Factor