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Probing the location of casein fractions in the casein micelle using enzymes and enzyme–dextran conjugates. J DAIRY RES 2009. [DOI: 10.1017/s0022029900022779] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
SUMMARYThe rates of milk clotting and of formation of para-κ-casein in milk, colloidal phosphate-free milk and isolated κ-casein by pepsin and by its soluble size-fractionated conjugates with dextran were determined. Milk clotting with all the enzyme derivatives was dependent on the rate of the enzymic phase and required essentially complete κ-casein hydrolysis at 30 °C and throughout the range of pH 5·6–6·7. κ-Casein hydrolysis by pepsin at pH 6·6 was fastest in milk and slowest in isolated κ-casein, but the rate decreased as the enzyme size increased, especially with milk. When corrected for the changes in pepsin activity, the rates of κ-casein hydrolysis in all substrates were identical at 30 and 5 °C, but increased with decrease in pH, especially with the larger enzyme conjugates. Hydrolysis of the C-terminal bonds of β-and κ-casein in native and disrupted casein micelles by carboxypeptidase A and soluble conjugates of it were also investigated. κ-Casein was hydrolysed much faster, and β-casein slightly faster, in native than in disrupted micelles by the native enzyme. Increase in the size of carboxypeptidase A increased the rate of hydrolysis of κ-casein in disrupted micelles and also induced lag periods before hydrolysis commenced, especially with disrupted micelles. The results are compatible with a model for the casein micelle in which the κcasein is on the outside and the casein components are in a more ordered arrangement than in the casein complexes formed on micelle disruption. They also indicate that immobilized coagulants would be unable to clot milk.
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KAMATA Y, SATO A, SAITO N, SUZUKI A. Stability of Enzyme Activity Immobilized on Glycosylated Egg White Beads and Some General Carriers in a Flow System. FOOD SCIENCE AND TECHNOLOGY RESEARCH 2000. [DOI: 10.3136/fstr.6.24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Kamata Y. Enzymatic modification of food proteins to improve the functional properties. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1997; 415:47-65. [PMID: 9131182 DOI: 10.1007/978-1-4899-1792-8_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Y Kamata
- Miyagi University of Education, Sendai, Japan
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Garg SK, Johri BN. Immobilization of milk-clotting proteases. World J Microbiol Biotechnol 1993; 9:139-44. [DOI: 10.1007/bf00327823] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 08/04/1992] [Accepted: 08/12/1992] [Indexed: 10/26/2022]
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YUN SEEOK, OHMIYA KUNIO, KOBAYASHI TAKESHI, SHIMIZU SHOICHI. Increase in Curd Tension of Milk Coagulum Prepared with Immobilized Proteases. J Food Sci 1981. [DOI: 10.1111/j.1365-2621.1981.tb15330.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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