Recovery of Salmonella spp. from Raw Produce Surfaces Using Ultrasonication

Abstract

Fresh fruits and vegetables have been increasingly associated with outbreaks of foodborne illness. Microorganisms on the surface of raw produce may be difficult to remove for decontamination or microbial sampling due to entrapped or attached cells and porous surfaces. The objective of this study was to determine if ultrasonic treatment using 40 kHz with varying temperatures and agitation times can enhance removal and recovery of Salmonella spp. from raw produce surfaces. Strawberry, apple, and cantaloupe surfaces were spot inoculated with a fivestrain cocktail of nalidixic acid-resistant Salmonella spp. Produce were immersed in 0.1% buffered peptone water in either a Whirl-Pak bag for manual shaking (60 sec) or a sterile beaker for ultrasonic treatment (60 or 120 sec). Diluent temperatures of either 25 degrees C or 40 degrees C were used with these sampling protocols. Diluents were spiral plated onto tryptic soy agar supplemented with 50 ppm of nalidixic acid. No significant differences were observed between each Salmonella recovery method for each produce type. In this study, ultrasonic treatment using 40 kHz did not enhance recovery of Salmonella spp. from produce surfaces. The ultrasonic frequency, temperatures, and times used in this study did not enhance or diminish bacterial recovery. Additional research is still needed to determine the efficacy of other ultrasonic frequencies, diluents, and diluent temperatures for enhancing the recovery and enumeration of Salmonella spp. and other microorganisms from raw produce surfaces.

Comparación de la recuperación de células de Salmonella adheridas al tomate Roma con el uso de ultrasonido y vortex

“…Sin embargo, el uso del ultrasonido por 10 min permitió una recuperación significativamente mayor (p < 0.05) de Salmonella en comparación con 1 min. Un efecto similar fue reportado por Sanglay et al (2004), en el que la exposición al ultrasonido a 40 kHz por 1 y 2 min no mostró diferencia significativa en la recuperación de Salmonella de la superficie de fresa, manzana y melón cantaloupe.…”

“…8 (2023) 100-106 El estudio del comportamiento de células adheridas Salmonella sobre la superficie de alimentos requiere contar con métodos capaces de recuperarlas. Son escasos las investigaciones enfocadas en la validación de métodos de homogenización para cuantificar la población de CFA en frutas y hortalizas frescas (Sanglay et al, 2004). En nuestro estudio, la exposición de las muestras de tomate al vortex permitió obtener recuentos mayores de CFA del patógeno en un menor tiempo de homogenización, comparado con el uso del ultrasonido.…”