The antimicrobial effects of mist spraying and immersion on beef samples with plasma-activated water

Microbial life abounds on surfaces in both natural and industrial environments, one of which is the food industry. A solid substrate, water and some nutrients are sufficient to allow the construction of a microbial fortress, a so-called biofilm. Survival strategies developed by these surface-associated ecosystems are beginning to be deciphered in the context of rudimentary laboratory biofilms. Gelatinous organic matrices consisting of complex mixtures of self-produced biopolymers ensure the cohesion of these biological structures and contribute to their resistance and persistence. Moreover, far from being just simple three-dimensional assemblies of identical cells, biofilms are composed of heterogeneous sub-populations with distinctive behaviours that contribute to their global ecological success. In the clinical field, biofilm-associated infections (BAI) are known to trigger chronic infections that require dedicated therapies. A similar belief emerging in the food industry, where biofilm tolerance to environmental stresses, including cleaning and disinfection/sanitation, can result in the persistence of bacterial pathogens and the recurrent cross-contamination of food products. The present review focuses on the principal mechanisms involved in the formation of biofilms of food-borne pathogens, where biofilm behaviour is driven by its three-dimensional heterogeneity and by species interactions within these biostructures, and we look at some emergent control strategies. Copyright © 2014 Elsevier Ltd. All rights reserved.

Attachment of potential spoilage and pathogenic bacteria to food contact surfaces and the subsequent biofilm formation represent serious challenges to the meat industry, since these may lead to cross-contamination of the products, resulting in lowered-shelf life and transmission of diseases. In meat processing environments, microorganisms are sometimes associated to surfaces in complex multispecies communities, while bacterial interactions have been shown to play a key role in cell attachment and detachment from biofilms, as well as in the resistance of biofilm community members against antimicrobial treatments. Disinfection of food contact surfaces in such environments is a challenging task, aggravated by the great antimicrobial resistance of biofilm associated bacteria. In recent years, several alternative novel methods, such as essential oils and bacteriophages, have been successfully tested as an alternative means for the disinfection of microbial-contaminated food contact surfaces. In this review, all these aspects of biofilm formation in meat processing environments are discussed from a microbial meat-quality and safety perspective. Copyright © 2013 Elsevier Ltd. All rights reserved.

Non-thermal plasma is a new approach to improving microbiological safety while maintaining the sensory attributes of the treated foods. Recent research has reported that plasma activated water (PAW) can also efficiently inactivate a wide variety of microorganisms. This study invested the effects of plasma-activated water soaking on the postharvest preservation of button mushrooms (Agaricus bisporus) over seven days of storage at 20°C. Plasma activated water reduced the microbial counts by 1.5 log and 0.5 log for bacteria and fungi during storage, respectively. Furthermore, the corresponding physicochemical and biological properties were assessed between plasma activated water soaking groups and control groups. The results for firmness, respiration rate and relative electrical conductivity suggested that plasma activated water soaking can delay mushroom softening. Meanwhile, no significant change was observed in the color, pH, or antioxidant properties of A. bisporus treated with plasma activated water. Thus, plasma activated water soaking is a promising method for postharvest fresh-keeping of A. bisporus.