Modified sodium caseinate films as releasing carriers of lysozyme

• Published in: Food hydrocolloids Vol. 24; no. 4; pp. 300 - 306
• Main Authors: Mendes de Souza, Poliana, Fernández, Avelina, López-Carballo, Gracia, Gavara, Rafael, Hernández-Muñoz, Pilar
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.06.2010; [New York, NY]: Elsevier Science; Elsevier
• Subjects: Active packaging; antibacterial properties; antimicrobial agents; Biological and medical sciences; caseinates; chemical structure; Controlled release; Crosslinking; drug delivery systems; Edible coatings; edible films; enzyme activity; Enzymes; films (materials); Food additives; Food industries; food packaging; food pathogens; Foods; Fundamental and applied biological sciences. Psychology; General aspects; glyoxal; Gram-positive bacteria; Handling, storage, packaging, transport; kinetics; Lysozyme; Matrix modification; Micrococcus luteus; Networks; packaging materials; protein-glutamine gamma-glutamyltransferase; Releasing; Sodium; Sodium caseinate; solubility; Staphylococcus aureus; Matrix modification; Sodium caseinate; Edible coatings; Crosslinking; Active packaging; Lysozyme; Controlled release; Caseinate; Modification; Enzyme; Film; Controlled release form; Glycosylases; Edible coating; Glycosidases; Hydrolases; Conditioning
• ISSN: 0268-005X; 1873-7137
• DOI: 10.1016/j.foodhyd.2009.10.005

Films made of sodium caseinate containing lysozyme where modified by chemical or biochemical crosslinkers to achieve a controlled release of the antimicrobial lysozyme. Kinetic studies in buffered solutions at pH 3.02–5.80 were undertaken. Both the pH and the use of crosslinkers had a strong effect on the protein network, and consequently, a significant influence on the releasing of lysozyme activity. Sodium caseinate (NaCas) films became insoluble networks at pHs close to the isoelectric point of caseinate (pH 4.6), therefore decelerating remarkably the diffusion of lysozyme without the addition of crosslinkers. Additionally a slow release of lysozyme was achieved after mixing with glyoxal, achieving a modulation in the antimicrobial activity against Micrococcus lysodeikticus and Staphylococcus aureus. Other crosslinkers, as calcium chloride or transglutaminase, almost blocked enzyme release and were not found adequate to achieve enough antimicrobial activity. Results showed that active caseinate films modified by pH and glyoxal efficiently retarded the release of lysozyme, being a promising way to extend antimicrobial effects during food storage and to enhance food safety. t (min) NaCas + lysozyme, pH 4.6 NaCas + lysozyme + glyoxal, pH 4.6 log reduction ( S. aureus) U lys min −1 log reduction ( S. aureus) U lys min −1 5 min 1.02 922.3 ± 49.6 0.21 140.1 ± 8.8 15 min 1.23 1565.7 ± 209.8 0.28 167.9 ± 5.9 1440 min 1.29 1808.8 ± 286.3 0.97 840.9 ± 74.7 2880 min 1.30 1870.9 ± 320.4 1.03 1041.6 ± 129.8