INVESTIGADORES
CASTRO Marcela Paola
congresos y reuniones científicas
Título:
Effect of Tween®20 on the antimicrobial activity of sorbates in emulsified systems resembling salad dressings
Autor/es:
CASTRO M., GARRO O., CAMPOS C., GERSCHENSON L.
Lugar:
Anaheim, CA, USA
Reunión:
Otro; Institute of Food Technologists Annual Meeting; 2002
Institución organizadora:
Institute of Food Technologists
Resumen:
Non ionic surfactants, such as polysorbates, are used to protect the droplets from coalescence over shelflife in salad dressings. The presence of dissolved surfactants in the aqueous phase of these food emulsions could affect the activity of preservatives due to the effect of the polysorbates on the preservative partitioning. The aim of this research was to determine in which extent the presence of different concentrations of Tween 20 affects the antimicrobial activity of potassium sorbate in salad dressings. The model systems were formulated in order to resemble salad dressings composition and they contained: vinegar, oil, sodium chloride, EDTA, Tween 20, preservative, xanthan and Sabouraud broth. The concentrations of the surfactant used were: 1, 2 and 4 % w/w while the preservative concentration was 0.025 % w/w. For comparison purposes, systems free of surfactant and/or preservative were also prepared. The pH of the systems was adjusted to 3.5 with citric acid. The microorganism tested was Zygosaccharomyces bailii NRRL 7256; its survival in the model systems was monitored by surface plate count method. Samples were analyzed throughout storage at 33°C for 8 days. The results showed that in those systems without the preservative the presence of increasing concentrations of Tween 20 enhances the growth of the microorganism leading to higher viable cell counts. When surfactant was not present, the preservative showed an inhibitory effect on yeast growth. However, in those systems containing both additives a clear antagonist effect of the surfactant on the antimicrobial activity of the preservative can be observed. This effect increased with the concentration of Tween 20. This study stresses the importance of considering the interaction between additives.
