The effect of processing conditions on the properties of gelatin from skate (Raja kenojei) skins. Food Hydrocoll

Department of Animal Science, Chonnam National University, 300 Yongbong-dong Buk-gu, Gwangju 500-757, South Korea
Food Hydrocolloids (Impact Factor: 4.09). 08/2006; 20(6):810-816. DOI: 10.1016/j.foodhyd.2005.08.002


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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Available from: Koo Bok Chin, Jul 28, 2015
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    • "Hence, during our final step of collagen conversion to gelatin, the extraction temperature was kept at 40‒45°C in order to achieve a controlled partial hydrolysis of cross-links and peptide bonds in the original collagen structure. Furthermore, yields at 50°C of extraction have been reported to be better than those at 40°C, even though the quality is lower at 50°C of extraction (Cho et al., 2006). "
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    ABSTRACT: The aims of this study are to report on the extraction and characterization of Asian swamp eel (Monopterus albus) skin gelatin. The characterization conducted were includes chemical composition, pH, gel strength, viscosity, thermal property, color and structure determination of extracted eel skin gelatin. Eel skin contains 70.28% moisture, 11.07% protein, 4.21% fat, and 5.01% ash. The chemical composition of eel skin gelatin (yield of 12.75%) was 18.8% moisture, 67.64% protein, 0.34% fat and 1.08% ash, with a pH of 4.62 and gel strength of 215.96 g (± 9.62 g). Although viscosity (2.8 cPa/min) profile of eel skin gelatin showed lower than that of bovine gelatin, the higher melting temperature (35 °C) of eel skin gelatin indicating its higher stability than bovine gelatin with FTIR spectrum similar to that of typical bovine gelatin. Eel skin gelatin has a 71.4 (± 1.14), a +3.2 (± 0.29), and a +7.52 (± 0.29) for L*, a* and b* value respectively, indicate a darker and less yellow colour. These findings show promising potential for the application of eel skin gelatin as an alternative to commercial gelatin.
    Full-text · Article · Jan 2015 · International Food Research Journal
    • "These results have also been confirmed by Zhou and Regenstein (2005). Another study done byCho et al. (2006)showed that alkali concentration up to 1.5% increased gelatin yield significantly. Zhou andRegenstein (2004)confirmed that the concentrations of acid or alkali have a significant effect on gelatin yield, gel strength, and viscosity. Acid treatment is also important for the sensory aspects of gelatin, appearance and smell, as the acid treatment effectively removes odors and color that originate from the raw material (Boran and Regenstein, 2009;Zhang et al., 2007). "
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    ABSTRACT: Gelatin is a multifunctional ingredient used in foods, pharmaceuticals, cosmetics, and photographic films as a gelling agent, stabilizer, thickener, emulsifier, and film former. As a thermoreversible hydrocolloid with a narrower gap between its melting and gelling temperatures, both of which are below human body temperature, gelatin provides unique advantages over carbohydrate-based gelling agents. Gelatin is mostly produced from pig skin, and cattle hides and bones. Some alternative raw materials have recently gained attention from both researchers and the industry not just because they overcome religious concerns shared by Jews and Muslims but also because they provide, in some cases, technological advantages over mammalian gelatins. Fish skins from a number of fish species are among the other sources that have been comprehensively studied as sources for gelatin production. Fish skins have a significant potential for the production of high-quality gelatin with different melting and gelling temperatures over a much wider range than mammalian gelatins, yet still have a sufficiently high gel strength and viscosity. Gelatin quality is industrially determined by gel strength, viscosity, melting or gelling temperatures, the water content, and microbiological safety. For gelatin manufacturers, yield from a particular raw material is also important. Recent experimental studies have shown that these quality parameters vary greatly depending on the biochemical characteristics of the raw materials, the manufacturing processes applied, and the experimental settings used for quality control tests. In this review, the gelatin quality achieved from different fish species is reviewed along with the experimental procedures used to determine gelatin quality. In addition, the chemical structure of collagen and gelatin, the collagen-gelatin conversion, the gelation process, and the gelatin market are discussed.
    No preview · Chapter · Dec 2010
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    • "Processing techniques used for skin gelatin production have been reported, such as thermal treatment, acid-alkaline extraction, enzymatic aided, and also other emerging technologies (high-pressure treatment, ultrasonic , and microwave heating). Gelatins have been produced from various fish species such as Nile perch skin and bone (Muyonga et al. 2004a), skate skin (Cho et al. 2006), bigeye snapper and brownstripe red snapper skin (Jongjareonrak et al. 2006), and giant catfish skin (Jongjareonrak et al. 2010). Gelatin extracted with enzymes from skins of different fish species such as sin croaker and shortfin scad (Cheow et al. 2007); bigeye snapper and brownstripe red snapper (Jongjareonrak et al. 2006; Benjakul et al. 2009; Nalinanon et al. 2007, 2008) have all been investigated. "
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    ABSTRACT: This study was aimed to investigate the re-extraction process for gelatin recovery from the skin of farmed giant catfish. The first extraction was done by incubating the acid-treated fish skin at 45°C for 12h. The remnant was re-extracted at temperatures of 60–90°C for 1–12h. The gelatin yield of the first extraction was 10.14%, while the re-extraction at high temperature provided higher recovery (19.5%). Low band intensity of α1 and α2 chains of gelatin was observed when it was re-extracted at high temperature for a longer time. The absorption bands of amide I and II from both extracted gelatins were similar. Low-transition temperature with high transition enthalpy of gelatin extracted at 90°C was observed. The obtained results suggested that the re-extraction process could be applied as a supplemental step for other sources to obtain high recovery with the desired properties. KeywordsFish skin–Gelatin–Giant catfish–Re-extraction–Recovery
    Full-text · Article · May 2010 · Food and Bioprocess Technology
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