Johler S.,Institute for Food Safety and Hygiene |
Giannini P.,Cantonal Laboratory |
Jermini M.,Cantonal Laboratory |
Hummerjohann J.,Institute for Food science |
And 2 more authors.
Toxins | Year: 2015
Staphylococcal food poisoning represents the most prevalent foodborne intoxication worldwide. It is caused by oral intake of enterotoxins preformed by Staphylococcus aureus in food. The relevance of newly described enterotoxins in outbreaks of staphylococcal food poisoning is controversially discussed. Although the staphylococcal enterotoxins SEG, SEI, SEM, SEN, and SEO elicit emesis in a monkey feeding assay, there has been no conclusive proof of their emetic activity in humans. In this study, we provide further evidence suggesting that one of these enterotoxins or a combination of SEG, SEI, SEM, SEN, and SEO cause staphylococcal food poisoning. We investigated two outbreaks registered with the Swiss Federal Office of Public Health, in which only Staphylococcus aureus strains harboring the egc cluster, including seg, sei, sem, sen, and seo linked to typical signs of staphylococcal food poisoning were isolated. The outbreaks were caused by consumption of raw goat cheese and semi-hard goat cheese, and were linked to strains assigned to CC45 (agr type I) and CC9 (agr type II), respectively. These outbreaks provide further evidence that newly-described staphylococcal enterotoxins are likely to cause staphylococcal food poisoning in humans. © 2015 by the authors; licensee MDPI, Basel, Switzerland.
Verdenal T.,Institute for Plant Production science |
Spangenberg J.E.,University of Lausanne |
Zufferey V.,Institute for Plant Production science |
Lorenzini F.,Institute for Food science |
And 2 more authors.
Australian Journal of Grape and Wine Research | Year: 2015
Yeast assimilable nitrogen (YAN) in grape must is an important determinant of wine composition. The effect of foliar nitrogen fertilisation on YAN concentration in must of Vitis vinifera L. cv. Chasselas was studied. Nitrogen assimilation and translocation were investigated by applying 15N-labelled urea at flowering and at veraison. Methods and Results: Foliar urea was applied on field-grown Chasselas grapevines using labelled (10 atom% 15N) and unlabelled urea. The vines were excavated at harvest, and plant parts were separated and analysed. Thus, the distribution of dry organic matter and of total organic carbon and total organic nitrogen in the plant at harvest was determined. Bunches were the strongest N sink among all of the organs during both fertilisation periods. The highest YAN in the must, however, was obtained when the urea was applied during veraison. Conclusions: Isotope labelling was used to describe N partitioning throughout the vine in response to foliar nitrogen fertilisation with urea at flowering and at veraison. Differences between organs in carbon and nitrogen isotope discrimination at natural abundance were established. Fertilisation with urea during veraison increased the YAN concentration in Chasselas grape must. Significance of the Study: Results show that it is more effective to correct YAN deficiency in the vineyard with application of foliar urea during veraison than during flowering. © 2015 Australian Society of Viticulture and Oenology Inc.
Gabioud Rebeaud S.,Institute for Food science |
Gasser Agroscope F.,Institute For Lebensmittelwissenschaften Ilm
European Journal of Horticultural Science | Year: 2015
Two new tools for better preservation of fruit quality have been developed in recent years, the treatment of apples with 1-MCP and dynamic controlled atmosphere storage (DCA). The effect of 1-MCP treatment and DCA on ethylene production and quality of ‘Golden Delicious’ apples harvested at two different ripening stages was evaluated in our study over two consecutive years. 1-MCP treatment delayed the climacteric increase of ethylene production and led to better retention of quality during RA- and ULO-storage and subsequent shelf life compared to non-treated apples. In order to achieve the optimum effect of 1-MCP, the treatment must be carried out within 7 days after harvest, as recommended by the supplier of 1-MCP. In most cases, DCA improved quality retention during storage in terms of fruit firmness and acidity compared to ULO-storage. The use of the two methods depends on the cul-tivars stored and conditions such as the infrastructure of the storage facility and type of handling and marketing of the apples. © ISHS 2015.
Egger L.,Institute for Food science |
Nicolas M.,National Reference Laboratory for Milk and Milk Products EURL |
Pellegrino L.,University of Milan
LWT - Food Science and Technology | Year: 2016
Alkaline phosphatase (ALP) activity is used throughout the world as a marker for the proper pasteurization of milk, to guarantee its hygienic safety. The Standard ISO 11816-2/IDF 155-2 describes the analysis of ALP in cheese. However, the method has been questioned in the past because there have sometimes been ambiguous results. The critical operations of the analytical procedure are more precisely defined and a zonal cheese sampling adopted. ALP inactivation is firstly evaluated in the relevant steps of controlled cheese makings of hard (Emmental), semi-hard (Raschera) and soft (Chaource) cheeses. Application of the improved procedure in over 700 samples of typical cheeses from France, Italy and Switzerland proved the applicability of the method. Based on this large study, a limit for ALP activity in cheese from pasteurized milk is proposed at 10 mU/g. © 2015 The Authors.
Weissbrodt D.G.,Ecole Polytechnique Federale de Lausanne |
Weissbrodt D.G.,Urban Water Engineering |
Weissbrodt D.G.,Eawag - Swiss Federal Institute of Aquatic Science and Technology |
Shani N.,Ecole Polytechnique Federale de Lausanne |
And 2 more authors.
FEMS Microbiology Ecology | Year: 2014
Intensive nutrient removal from wastewater in anaerobic-aerobic systems using granular sludge should rely on optimal balances at biofilm and microbial ecology levels. This study targets the impacts of reactor characteristics and fluctuations in operation conditions on nutrient removal and bacterial community structures by means of microbial and numerical ecology methods. The dynamics of both predominant and accompanying populations were investigated with high resolution on temporal and phylogenetic scales in two reactors operated during 5 months with synthetic wastewater. Multivariate analyses highlighted significant correlations from process to microbial scales in the first reactor, whereas nitrification and phosphorus removal might have been affected by oxygen mass transfer limitations with no impact at population level in the second system. The bacterial community continuum of the first reactor was composed of two major antagonistic Accumulibacter-Nitrosomonas-Nitrospira and Competibacter-Cytophaga-Intrasporangiaceae clusters that prevailed under conditions leading to efficient P- (> 95%) and N-removal (> 65%) and altered P- (< 90%) and N-removal (< 60%), respectively. A third cluster independent of performances was dominated by Xanthomonadaceae affiliates that were on average more abundant at 25 °C (31 ± 5%) than at 20 °C (22 ± 4%). Starting from the physiological traits of the numerous phylotypes identified, a conceptual model is proposed as a base for functional analysis in the granular sludge microbiome and for future investigations with complex real wastewater. © 2014 Federation of European Microbiological Societies.