89D-29

H. MINOR-PÉREZ¹, S. Trenado-Gutiérrez¹, E. Vargas-Rodríguez¹, G. Agustín-Xantomila¹, and I. Guerrero-Legarreta². (1) Laboratorio de Alimentos, Tecnológico de Estudios Superiores de Ecatepec, Av. Tecnológico s/n Esq. Carlos Hank Gónzalez, Col. Valle de Anáhuac, Ecatepec, Estado de México, 55210, Mexico, (2) Departamento de Biotecnología, Universidad Autónoma Metropolitana, Iztapalapa, Apartado Postal 55-535, Mexico D.F., 09340, Mexico

Increasing acidity is an efficient way to preserve many food materials. Bacteriocins, potential food preservatives, have high activity at low pH. However, during in situ production, producing cells may adsorb the bacteriocins. Knowing the pH range where bacteriocins are adsorbed is necessary to optimize their diffusion in a given food material, improving pathogen and spoilage microorganism inhibition in the system. The objective of this work was to study the adsorption pH range of a bacteriocin produced by Lactobacillus paracasei. A bacteriocin was produced by Lactobacillus paracasei in MRS broth and concentrated by precipitation with ammonium sulfate. Cell producing bacteriocins were also grown in MRS broth, centrifuged and the cells resuspended in sodium phosphate buffer, pH 2, 4, 6, and 8. The concentrated bacteriocin solution and the cell suspension were then mixed. Percentage of adsorbed bacteriocin was analyzed by the agar diffusion method. The control was cell-free phosphate buffer. The highest bacteriocin activity was obtained in 60 and 80% ammonium sulfate, no significant difference (p>0.2) was observed between these concentrations. The highest adsorption was found within pH range between 6.0 and 6.5. A steady adsorption increase was observed from pH 3.0 to 6.0, decreasing at pH 7.0 and higher. Although high acidity inhibits pathogen and spoilage microorganism growth in food materials, inhibition can be increased if bacteriocins are added. Knowing the pH range where a specific bacteriocin is adsorbed by the producing cells will help to efficiently apply these compounds to low acidity foods, increasing their safety

Session 89D, Food Microbiology: Antimicrobial effects on foodborne microorganisms
2:00 PM - 5:30 PM, Tuesday PM Room Hall I-2

2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana