Physicochemical properties and bioactivity of nisin-containing cross-linked hydroxypropylmethylcellulose films.
Cross-linked hydroxypropylmethylcellulose (HPMC) cast films with citric acid as polycarboxylic cross-linker were elaborated to study the effect of cross-linking level on various properties. Increased amounts of cross-linking agent were not connected to statistically different tensile strength and Young's modulus. Whatever the cross-linking level of the film was, the ultimate elongation parameter decreased by approximately 60% compared to the HMPC control film. Moisture sorption isotherms and water contact angle meter showed that the effect of cross-linking degree tends to reduce the hygroscopic and hydrophilic characteristics of films. In addition, to control bacteria growth on food surfaces, the antimicrobial activity of both 98% cross-linked HPMC-nisin and control HPMC-nisin films was tested on Micrococcus luteus. Despite the incorporation of a significant content of nisin, cross-linked HPMC-nisin films were completely inactive on the microbial strain compared to the HPMC-nisin control films. Cross-linking conditions likely either denatured the nisin or irreversibly bound nisin to the cross-linked HPMC. However, nisin adsorbed into films made from previously cross-linked HPMC maintained its activity.
Sebti
Issam
I
Laboratoire de Chimie des Substances Végétales, Centre de Recherche en Chimie Moléculaire, Université Bordeaux 1, 351 cours de la Libération, 33405 Talence, France.
Delves-Broughton
John
J
Coma
Véronique
V
D000900:Anti-Bacterial Agents; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D019343:Citric Acid / Q000737:chemistry; D003432:Cross-Linking Reagents; D005516:Food Microbiology; D018857:Food Packaging / Q000295:instrumentation; D065347:Hypromellose Derivatives; D008747:Methylcellulose / Q000031:analogs & derivatives / Q000737:chemistry*; D009561:Nisin / Q000032:analysis* / Q000737:chemistry; D013718:Tensile Strength; D014867:Water / Q000737:chemistry
D000900:Anti-Bacterial Agents; D003432:Cross-Linking Reagents; D014867:Water; D009561:Nisin; D019343:Citric Acid; D065347:Hypromellose Derivatives; D008747:Methylcellulose