High-Intensity Light Pulses To Inactivate Salmonella Typhimurium on Mexican Chia (Salvia hispanica L.) Seeds

Recent developments in applications of physical fields for microbial decontamination and enhancing nutritional properties of germinated edible seeds and sprouts: a review

Germinated edible seeds and sprouts have attracted consumers because of their nutritional values and health benefits. To ensure the microbial safety of the seed and sprout, emerging processing methods involving physical fields (PFs), having the characteristics of high efficiency and environmental safety, are increasingly proposed as effective decontamination processing technologies. This review summarizes recent progress on the application of PFs to germinating edible seeds, including their impact on microbial decontamination and nutritional quality and the associated influencing mechanisms in germination. The effectiveness, application scope, and limitation of the various physical techniques, including ultrasound, microwave, radio frequency, infrared heating, irradiation, pulsed light, plasma, and high-pressure processing, are symmetrically reviewed. Good application potential for improving seed germination and sprout growth is also described for promoting the accumulation of bioactive compounds in sprouts, and subsequently enhancing the antioxidant capacity under favorable PFs processing conditions. Moreover, the challenges and future directions of PFs in the application to germinated edible seeds are finally proposed. This review also attempts to provide an in-depth understanding of the effects of PFs on microbial safety and changes in nutritional properties of germinating edible seeds and a theoretical reference for the future development of PFs in processing safe sprouted seeds.

Salmonella spp. in low water activity food: Occurrence, survival mechanisms, and thermoresistance

The occurrence of disease outbreaks involving low-water-activity (a_w ) foods has gained increased prominence due in part to the fact that reducing free water in these foods is normally a measure that controls the growth and multiplication of pathogenic microorganisms. Salmonella, one of the main bacteria involved in these outbreaks, represents a major public health problem worldwide and in Brazil, which highlights the importance of good manufacturing and handling practices for food quality. The virulence of this pathogen, associated with its high ability to persist in the environment, makes Salmonella one of the main challenges for the food industry. The objectives of this article are to present the general characteristics, virulence, thermoresistance, control, and relevance of Salmonella in foodborne diseases, and describe the so-called low-water-activity foods and the salmonellosis outbreaks involving them.

Pulsed-Light Treatment of Dried Parsley: Reduction of Artificially Inoculated Salmonella and Impact in Given Quality Parameters

ABSTRACT

Dried parsley is regularly contaminated with foodborne pathogens, especially Salmonella. Application of contaminated ingredients in ready-to-eat dishes without further thermal treatment represents a considerable health risk. This study examined the suitability of pulsed light as a novel decontamination method of Salmonella in dried parsley, along with the impact on selected quality parameters (chlorophyll content, phenolic compounds, color, and odor) and product characters (temperature and water activity value). Samples were inoculated with one of three Salmonella isolates (Salmonella Cerro or one of two isolates of Salmonella Agona) at two contamination levels of 103 or 107 CFU/g and treated under various experimental factors, including distance to the light source and exposure time, resulting in fluences in the range of 1.8 to 19.9 J/cm2. At selected parameter settings (9.8 and 13.3 J/cm2), the effect of prolonged storage time (48 h) of inoculated samples before treatment on the reduction of Salmonella Cerro was examined. Samples treated at the same fluences were also stored for 35 days at 22 to 25°C. The three Salmonella isolates were significantly reduced by pulsed light (P < 0.05). Reduction factors ranged between 0.3 and 5.2 log CFU with varying sensitivities of the isolates. In general, increasing fluences (depending on exposure time and distance to the light source) resulted in increasing reductions of Salmonella. However, on closer examination, exposure time and distance to the light source had a varying influence on the reduction of the different Salmonella isolates. Decreasing reduction factors were observed by increasing the contamination level and prolonging the storage time of inoculated samples before treatment. No undesirable changes in quality parameters and sensory analysis were detectable at fluences of 9.8 and 13.3 J/cm2, indicating that pulsed light may be a suitable alternative for the decontamination of dried parsley.

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Thermal Inactivation Kinetics of Salmonella and Enterococcus faecium NRRL-B2354 on Whole Chia Seeds (Salvia hispanica L.)

ABSTRACT

Intervention technologies for inactivating Salmonella on whole chia seeds are currently limited. Determination of the thermal inactivation kinetics of Salmonella on chia seeds and selection of an appropriate nonpathogenic surrogate will provide a foundation for selecting and optimizing thermal pasteurization processes for chia seeds. In this study, chia seed samples from three separate production lots were inoculated with a five-strain Salmonella cocktail or Enterococcus faecium NRRL-B2354 and equilibrated to a water activity of 0.53 at room temperature (25°C). After equilibration for at least 3 days, the inoculated seeds were subjected to isothermal treatments at 80, 85, or 90°C. Samples were removed at six time points, and surviving bacteria were enumerated. Whole chia seeds were diluted in a filter bag at 1:30 because bacterial recovery with this method was similar to that obtained from ground seeds. Survivor data were fitted to consolidated models: one primary model (log linear or Weibull) and one secondary model (Bigelow). E. faecium had higher thermal resistance than did Salmonella, suggesting that E. faecium may be a suitable conservative nonpathogenic surrogate for Salmonella. The Weibull model was a better fit for the survivor data than was the log-linear model for both bacteria based on the lower root mean square error and corrected Akaike's information criterion values. Lipid oxidation measurements and fatty acid concentrations were significantly different from those of the control samples, but the overall magnitude of the differences was relatively small. The thermal inactivation kinetics of Salmonella and E. faecium on chia seeds may be used as a basis for developing thermal pasteurization processes for chia seeds.

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