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Pediocin shows stability in film application.

Bacteriocins attack bacteria, such as L. monocytogenes or the Clostridium responsible for botulism. The vast majority of these natural, nontoxic food preservatives functioned in obscurity until about a decade ago. Now, scientists are trying to use these biopreservatives in prepared foods or incorporate them into packaging systems.

Edible films offer protection against deteriorative processes. You can incorporate additives and antimicrobial agents into a film's structure. A bacteriocin produced by P. parvulus is heat-stable and has a wide inhibitory spectrum. It has potential use as preservative for meat products.

Whey protein isolate (WPI) can be used to produce transparent and flexible edible films with excellent oxygen and aroma barrier properties. However, the process used to prepare WPI films requires the use of high temperatures, high homogenization rates and lipids in order to achieve water vapor permeability.

Mexican scientists wanted to study the stability of pediocin under the conditions used for forming WPI films. They sought to determine the antimicrobial activity of WPI films to which pediocin was added. Freeze-dried pediocin extract was dissolved in a phosphate buffer and subjected to heat treatment at 90 C for up to 30 minutes. It was then homogenized at 13,000 rpm for 30, 60, 90, 120, 150, 180 and 240 seconds. The scientists added stearic acid at levels of up to 15%.

The activity of pediocin was analyzed by the diffusion method using L. innocua as an indicator. Then the scientists fabricated WPI films and incorporated into them various pediocin concentrations. Bacteriocin activity was analyzed by placing the films on petri dishes inoculated with an indicator strain.

Bacteriocin activity was not affected by heating the films at 90 C, although the activity was reduced 10% when the material was homogenized for 5 minutes. Adding stearic acid decreased pediocin activity. Conversely, the antimicrobial activity of WPI films progressively increased with increasing concentrations of pediocin. The stability of pediocin at 90 C and during homogenization suggested that it can be added to WPI as an antimicrobial compound. Further information. B. Quintero-Salazar, Department of Biotechnology, Universidad Autonoma Metropolitana, Avenue San Rafael, Atlixco No.186, Col. Vicentina, Apartado postal 55-535, Mexico DF, 09340 Mexico; URL: www.uam.mx.
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Publication:Microbial Update International
Date:Feb 1, 2005
Words:360
Previous Article:Additional thermal processing can reduce, eliminate surface pathogens.
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