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Nylon-6 nanofibrous membranes (NFM) prepared by electrospinning have been used as solid state support for the immobilization of the yeast Saccharomyces cerevisiae and then applied for the fermentation of grape juice. The membranes were characterized by scanning electron microscopy. The resulting metabolic activity was characterized by microcalorimetry. Sugar and ethanol changes during fermentation were monitored by HPLC. The results showed that the fermentation performance of immobilized yeasts on NFM is equal or even superior to the traditional fermentation process with yeasts freely dispersed in the medium. From calorimetry, free and immobilized yeasts showed the same enthalpy value in model solution, regardless to the amount of yeast loaded (52.2 ± 5.9 kJ mol−1 of glucose). Instead, immobilization of yeasts resulted in shorter lag time. Moreover, the maximum growth rate of immobilized yeasts was the same as with free yeasts in model solutions. However, the growth rate of immobilized yeasts was even higher, when performed in grape juice. In addition, the immobilization of yeasts on NFM exhibits the evident possibility of multiple reuse. Three consecutive fermentations were performed without significant loss of the overall performance. These findings support the development of nanostructured solid support for biocatalytic processes like fermentation of alcoholic beverages.

Isothermal microcalorimetry is often used to monitor microbiological activity and growth in various types of biological samples. Usually, it is useful to convert the isothermal microcalorimetry data into biologically meaningful data such as growth rate, lag phase or maximum growth. In this work, isothermal calorimetry was applied for monitoring of grape juice fermentation by Saccharomyces cerevisiae immobilized in nylon-6 nanofibrous membranes (NFM) prepared by electrospinning in comparison with freely dispersed yeasts. The resulting heat flow can be fitted using various approaches applying graphical, exponential, Gompertz, modified logistic and Michaelis–Menten models. Advantages and drawbacks of each approach for monitoring of the immobilized yeasts have been discussed in relation to the S. cerevisiae yeasts. Analysis of the fitting parameters showed that immobilized yeasts had the highest growth rate and maximum growth in comparison with freely dispersed yeasts. Parallel measurements of sugar and oxygen consumption rates for immobilized and free yeasts cells confirmed the calorimetric data. The results of this work demonstrate practical approach to analysis and modeling of calorimetric data in food analysis and advantages of application of NFM as solid support for yeast immobilization.

The Venice Lagoon is an interesting example of an ecosystem suffering for a considerable anthropogenic impact, resulting in high concentrations of persistent organic pollutants (POPs) in lagoon sediments and seafood. In this context, biomonitoring is a crucially important task. The present study aimed at evaluating the validity of a multiple biomarker approach in a benthic fish species. A total of 567 Zosterisessor ophiocephalus (Gobiidae) fish were collected in spring and autumn from three areas of Venice Lagoon (Porto Marghera, Val di Brenta, and Ca Roman) showing high, intermediate and low amounts of POPs, respectively. Aryl hydrocarbon receptor (AHR) and cytochrome P450 1A (CYP1A) mRNA levels, CYP1A protein amount and ethoxyresorufin O-deethylase activity (EROD) were measured in pooled liver and gills (mRNA levels only). Such biological data were then compared with polychlorinated biphenyls (PCBs) residues, measured in grass goby muscle by gas chromatography. Aryl hydrocarbon receptor and CYP1A mRNAs, protein and EROD were upregulated in accordance with PCB amounts measured in Z. ophiocephalus muscles. In fact, the highest AHR and CYP1A induction was observed in fish sampled in close proximity of the industrial area of Porto Marghera. Overall, the present study confirm the grass goby as a reliable sentinel species for Venice Lagoon, and AHR/CYP1A/EROD as a sensitive set of biomarkers of exposure for AHR ligands.

The use of herbicide such as glyphosate is a common practice in viticulture to limit nutrients and water competition between vine/weed plants. However, the impact of such herbicide on the resulting grapes juice quality and, later, on wine fermentation has not yet been proven. In this work, grapes of Vitis vinifera L. cv Gewurztraminer harvested from plants subjected to the weed control with glyphosate were analysed for their fermenting capacity by isothermal microcalorimetry after inoculation with Saccharomyces cerevisae. The resulting heat flow traces were fitted by two additive Gompertz functions and used to describe the yeast growth rate. The comparison of the fitting parameters showed that glyphosate decreased the heat generated by yeast growth. This effect was consistent with a change in the amino acids and sugars contents in grapes. However, the results also show that the impact of the herbicide on yeast fermentation can be partly overcome with an additional N fertilization (i.e. urea) in the vine. Microcalorimetry has revealed for the first time these effects on the fermenting process of grapes.

Over the past few years, the demand for the introduction of fish products in public canteens (schools, hospitals and nursing-homes) has grown due to their good nutritional proprieties. The particular health conditions and sensitivity of some groups of consumers exposes them to greater risks of food poisoning. It is therefore important to monitor the raw materials that end up in mass catering implementing strategies of mass catering control, both with self-monitoring strategies and with regular controls performed by the competent health authorities. The purpose of this study is to assess the overall quality of seafood dealt out from public catering services located in Northeast Italy. In this paper we illustrate the results of microbiological analysis performed on 135 fish samples (58% of samples were raw fishes, 27% cooked fishes, 6% raw fish products, 9% cooked fish products) and species identification performed on 102 fish samples. Additionally, 135 environmental swabs were collected to determine the effectiveness of cleaning and sanitation of food contact (cutting boards, cooking equipment and food processing surfaces) and non-contact (refrigerator wall and handle, tap lever) surfaces. Of raw seafood samples 24% had total aerobic mesophilic bacteria count >105 CFU/g and for Enterobacteriaceae the faecal contamination was excluded since no Salmonella spp. and Escherichia coli were isolated. Just 3.8% of raw seafood samples resulted positive for Listeria monocytogenes. The results of swab samples of cooking utensils and surfaces showed that sanitation practices should be improved. Molecular analysis for fish species identification revealed a mislabelling for 25% of sampled fishes. The results of this survey can provide valuable information for monitoring and surveillance programmes for the control of quality of fish and fish products.