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Title:A surimi-like material made from beef and pork and a novel protease in bovine and porcine skeletal muscle
Author(s):Park, Seonghee Choi
Doctoral Committee Chair(s):Novakofski, Jan
Department / Program:Animal Sciences
Discipline:Animal Sciences
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Agriculture, Food Science and Technology
Chemistry, Biochemistry
Abstract:A surimi-like material made from beef or pork by a series of chopping, screening and repeated water-washing was characterized in terms of nutrient composition and functional properties. Percent salt-soluble protein of water-washed beef or pork was higher than that of commercial fish surimi. Total nitrogen contents of water-washed beef and pork were higher than those of respective muscle. When heated at a constant rate of 0.5$\sp\circ$C per minute, washed beef or pork formed gels with greater hardness than commercial fish surimi at temperatures above 55$\sp\circ$C. Gel forming ability and water-holding capacity of surimi-like pork were significantly enhanced by the addition of NaCl up to 3%. Gel formation was not affected by freeze-thawing, and the addition of known cryoprotectants did not show any effect on the gel forming ability.
The effects of preheating temperature on physical gel strength and on myofibrillar protein degradation were investigated in surimi-like pork. A significant weaker gel formation was found in surimi-like pork preheated at 50$\sp\circ$C compared to that preheated at lower or higher temperatures. The unique weaker gel formation of surimi-like pork preheated at 50$\sp\circ$C corresponded to proteolysis of myofibrillar protein. Heating at 50$\sp\circ$C resulted in a decrease in myosin heavy chain and production of new peptide fragments. The proteolysis was salt dependent and occurred at pH 6.8-7.5.
The myosin-degrading protease in the surimi-like pork or beef was partially purified from swine skeletal muscle by using water-washing, low-salt extraction and two column chromatographic procedures: Phenyl-Sepharose CL-4B; Sephacryl S-200. The protease required Ca$\sp{++}$ and a reducing agent for its activity. The enzyme was inhibited by ethylenediaminetetraacetic acid, ethylene glycol bis($\beta$-aminoethyl ether) tetraacetate, iodoacetate, iodoacetamide, phenylmethylsulfonylfluoride, chymostatin, adenosine triphosphate and ethanol but was unaffected by antipain, aprotinin, bestatin, phosphoramidon, leupeptin, calpastatin, dimethyl sulfoxide and methanol. The enzyme did not show any proteolytic activity on actin, troponin, tropomyosin, light chain, myoglobin and casein. The semipurified enzyme showed good stability with little loss of its activity when kept at 4$\sp\circ$C or $-$20$\sp\circ$C and when subjected to repeated freeze-thawing. Results indicate that the myosin-degrading enzyme has not previously been reported.
Issue Date:1991
Rights Information:Copyright 1991 Park, Seonghee Choi
Date Available in IDEALS:2011-05-07
Identifier in Online Catalog:AAI9136694
OCLC Identifier:(UMI)AAI9136694

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