Cold atmospheric gas plasma disinfection of chicken meat and chicken skin contaminated with Listeria innocua

Gas plasmas generated at atmospheric pressure and ambient temperatures offer a possible decontamination method for poultry products. The efficacy of cold atmospheric gas plasmas for decontaminating chicken skin and muscle inoculated with Listeria innocua was examined. Optimization of operating conditions for maximal bacterial inactivation was first achieved using membrane filters on which L. innocua had been deposited. Higher values of AC voltage, excitation frequency and the presence of oxygen in the carrier gas resulted in the greatest inactivation efficiency, and this was confirmed with further studies on chicken muscle and skin. Under optimal conditions, a 10 s treatment gave > 3 log reductions of L. innocua on membrane filters, an 8 min treatment gave 1 log reduction on skin, and a 4 min treatment gave > 3 log reductions on muscle. These results show that the efficacy of gas plasma treatment is greatly affected by surface topography. Scanning electron microscopy (SEM) images of chicken muscle and skin revealed surface features wherein bacteria could effectively be protected from the chemical species generated within the gas plasma. The developments in gas plasma technology necessary for its commercial application to foods are discussed

Cocoa Bean Shell as Promising Feedstock for the Production of Poly(3-hydroxybutyrate) (PHB)

Cocoa bean shell (CBS), a by-product of the chocolate industry, has been employed as a substrate to obtain poly(3-hydroxybutyrate) (PHB) by fermentation with Bacillus firmus. With this aim, acid-thermal hydrolysis of CBS (20% w/v) was conducted at 135 °C for 10 min so that broths rich in fermentable sugars were obtained. These broths, both non-centrifuged and centrifuged, were employed as fermentation media. Significant polymer production was obtained from the broth with solids (non-centrifuged) with a yield of 107 mg of PHB/g dry matter. These results indicated that the presence of CBS solids played an important role in microorganism metabolism, with them being fundamental to the production of PHB. Experimental data were fitted by a model based on irreversible first-order reactions, and kinetic constants were obtained for solubilisation, hydrolysis, and sugar consumption. Although, several studies on obtaining PHB from other agri-food residues have been published, this is the first work on PHB production from CBS, with the study obtaining promising results with PHB concentrations similar or even higher than the others previously reported

Microplastics in Wastewater and Drinking Water Treatment Plants: Occurrence and Removal of Microfibres

Microplastics (MPs), and specifically microfibres (MPFs), are ubiquitous in water bodies, including wastewater and drinking water. In this work, a thorough literature review on the occurrence and removal of MPs, and specifically MPFs in WWTPs and DWTPs, has been carried out. When the water is treated, an average microfiber removal efficiency over 70% is achieved in WWTPs and DWTPs. These high percentages are still inefficient for avoiding the presence of a large number of microfibres in treated wastewater and also in tap water. RSF, DAF, oxidation ditch and CAS processes have been described as the most efficient treatments for eliminating MPFs from wastewater treatment. It is remarkable the wide range of the data reported on this topic; for example, treated wastewater contains between not detected and 347 MPFs/L, whereas tap water contains between not detected and 168 MPFs/L. Microfibres constitute more than half of the MPs found in treated wastewater and sewage sludge, whereas in DWTP effluents the percentage of MPFs is around 32%. Nevertheless, the relative amount of MPFs reported in tap water is notably higher (71%). Microfibres from WWTPs are discharged to the environment, being a source of MP pollution. Additionally, MPs released by DWTPs directly enter the drinking water lines, which constitute a direct route for MP human consumption, so that it has been estimated that an adult may ingest an average value of 7500 MPFs per year only via tap water. Thus, this review provides an update on the performance of WWTPs and DWTPs in removing MPs from water, which is an issue of great interest