Food-borne listeriosis, caused by Listeria monocytogenes (Lm), is relatively rare but the relatively high rate of fatality (20–30%) compared to other food-borne microbial pathogens such as Salmonella makes it a serious disease. The foodstuff is recognised as the primary route of transmission for human exposure. A wide variety of food or raw material may become contaminated with Lm but the majority of listeriosis cases are related to ready-to-eat (RTE) food. The important factor related to food-borne listeriosis is that Lm can grow under low (refrigerated) temperatures when given sufficient time. Therefore, RTE products with long shelf life are under risk with respect to growth of Lm to critical concentrations. A stochastic model for the growth of Lm with the inhibiting effect of lactic acid bacteria (LAB) in cold smoked salmon (CSS) was developed. An existing deterministic model for the growth of Lm was adapted by adding the Winner stochastic process in order to simulate the growth of Lm. The Poisson distribution is used to represent the initial count (occurrence) of Lm. A deterministic model for growth of LAB is used and the inhibiting effects of Lm and LAB on each other are taken into account. The Beta-Poisson model is used for estimating the dose response. The model has been tested during field trials with CSS performed in August 2010. The salmon was slaughtered in Norway and transported to France where it was processed. The model, implemented within the QMRA module, indicated that growth of Lm would occur in the CSS samples investigated.
Flokkur: Greinar
The aim of this work was to develop an approach for chromosomal engineering of the thermophile Rhodothermus marinus. A selection strategy for R. marinus had previously been developed; this strategy was based on complementing a restriction-negative trpB strain with the R. marinustrpB gene. The current work identified an additional selective marker, purA, which encodes adenylosuccinate synthase and confers adenine prototrophy. In a two-step procedure, the available Trp+ selection was used during the deletion of purA from the R. marinus chromosome. The alternative Ade+ selection was in turn used while deleting the endogenous trpB gene. Since both deletions are unmarked, the purA and trpB markers may be reused. Through the double deletant SB-62 (ΔtrpB ΔpurA), the difficulties that are associated with spontaneous revertants and unintended chromosomal integration of marker-containing molecules are circumvented. The selection efficiency in R. marinus strain SB-62 (ΔtrpB ΔpurA) was demonstrated by targeting putative carotenoid biosynthesis genes, crtBI, using a linear molecule containing a marked deletion with 717 and 810 bp of 5′ and 3′ homologous sequences, respectively. The resulting Trp+ transformants were colorless rather than orange-red. The correct replacement of an internal crtBI fragment with the trpB marker was confirmed by Southern hybridization analysis of the transformants. Thus, it appears that target genes in the R. marinus chromosome can be readily replaced with linear molecules in a single step by double-crossover recombination.
Low field Nuclear Magnetic Resonance (LF-NMR) relaxation time measurements were used to evaluate the effect of different pre-salting methods (brine injection of salt and/or phosphates followed by brining, solely brining, pickling and kench salting) on the protein denaturation and change in muscle properties during the production steps of dry salted cod fillets followed by rehydration. The NMR relaxation curves were affected by the salting method and represented well the structural differences between the salting methods at each processing step. Significant correlations were observed between the NMR relaxation parameters and all physicochemical quality properties measured, except the cooking yield, when samples from all processing stages were analyzed together. The longitudinal relaxation time T1, and the faster relaxing transverse relaxation time T21 were shown to be especially sensitive to protein denaturation in the fillets. The water distribution indicated that the salting and rehydration processes changed the cells irreversibly. The study indicated that pre-brining by brine injection followed by brining, with low salt concentrations, led to the least protein denaturation during the dry salting and rehydration process.
The oxidative stability of mahi mahi red muscle dipped in tilapia protein hydrolysates was evaluated. Alkali solubilised tilapia protein isolate was hydrolysed using Flavourzyme to 13% degree of hydrolysis. Whole tilapia protein hydrolysate and ultrafiltered fraction <10 kDa were used as dip solutions. Mahi mahi red muscle was dip treated either for 2 or 4 min and stored at 4 °C. Lipid hydroperoxides (PV), thiobarbituric acid reactive substances (TBARS) and a∗ value were measured at regular intervals. Results showed that dip treatments significantly decreased (p < 0.05) the formation of PV and TBARS over 90 h storage time. There was no significant (p > 0.05) difference between WH and <10 kDa fractions, and between 2 and 4 min treatments. Red colour of treated samples measured as a∗ value decreased with storage time, but was not significantly different from the control. It could be concluded that dip treatment for 2 min in whole tilapia protein hydrolysate may be used as a potential antioxidant treatment for improving oxidative stability of fish fillets.
Epidemics often result in organizational, policy and technical changes within a country. In 1999, an epidemic of campylobacteriosis was reported in Iceland. The recent availability of fresh poultry products in the marketplace was suggested as the source of infection. This paper reports on the context of the epidemic, reviews interventions implemented to prevent campylobacteriosis, and discusses lessons learned. A retrospective study of interventions implemented in Iceland from June 1995 to December 2007 was conducted by interviewing key informants and reviewing Iceland’s literature. Cumulative incidence rates of domestic campylobacteriosis by year and average incidence rates per epidemic period were calculated. Interventions included on-farm surveillance of Campylobacter, producer education, enhanced biosecurity measures, changes in poultry processing, a leak-proof packaging policy, a freezing policy for products from Campylobacter-positive poultry flocks, consumer education, and the creation of a legislated inter-organizational response committee. These interventions appear to have collectively contributed to a decrease in campylobacteriosis’ incidence rate near pre-epidemic baseline levels. Expert consultations revealed that the implementation of a Campylobacter surveillance program in poultry and the freezing policy were critical to controlling the disease in the Icelandic population. It was also recognized that new multidisciplinary collaborations among public health, veterinary, and food safety authorities and a sustained co-operation from the poultry industry were integral factors to the mitigation of the epidemic. Iceland’s response to the campylobacteriosis epidemic is a lesson learned of inter-disciplinary and inter-organizational precautionary public health action in the face of a complex public health issue.
The spawning stock of Atlantic cod Gadus morhua in West Greenland waters was characterized by a drastic decline in the late 1960s and has since exhibited considerable variation. It has been suggested that the cod stock in West Greenland waters is composed of several stock components that include (1) a number of distinct local inshore populations spawning in separate fjord systems, (2) an offshore spawning component located on the fishing banks, and (3) a periodic Icelandic–East Greenland cod influx that mixes with the offshore and inshore West Greenland stock components. In an attempt to clarify the status of Atlantic cod in Greenland waters, we investigated the genetic structure at different inshore and offshore feeding grounds east and west of Greenland. A total of 1,581 genetic samples were collected within North Atlantic Fisheries Organization areas at inshore and offshore locations as well as within the International Council for the Exploration of the Sea area XIVb. Those samples were genotyped for 18 microsatellite loci and the pantophysin (Pan I) locus. Both types of genetic markers gave congruent results and suggest the presence of two distinct genetic components with limited connectivity in Greenland waters, namely, an inshore component and an offshore component.
The aim of this study was to update the Icelandic Food Composition Database with respect to minerals (Ca, K, Mg, Na, and P) and trace elements (Cu, Fe, Hg, Se, and Zn) in frequently consumed agricultural products and to study the seasonal and geographical variation for these elements. Five food products typical for the Icelandic food basket were analysed: whole milk, fresh cheese (skyr), firm cheese (Gouda), lamb meat and minced beef together with skimmed milk, cream and whey. Concentrations of minerals and trace elements were determined by an inductively coupled plasma mass spectrometer (ICP-MS). Seasonal and geographical variation in whole milk was found only for selenium. Concentration of selenium in meat was variable and especially low for beef (1.4–9.6 μg/100 g fresh weight). Mercury was below the detection limit of 0.3 μg/100 g except for one sample of cheese. Skyr was rich in protein, calcium and phosphorus and retains almost all selenium in the skimmed milk used for its production. Skyr whey contains more calcium, magnesium, phosphorus and zinc than cheese whey. Skyr whey is a nutritious product, almost as rich in calcium, potassium and zinc as whole milk and could be used more by the Icelandic food industry.
High mortality rates commonly observed during the early life stages of intensively reared Atlantic halibut have among other things been related to high bacterial numbers and an unfavourable bacterial community. The study describes the effects of two different methods for environmental shading on larval survival and numbers of cultivable bacteria in the culture water and the gastrointestinal tract of first feeding larvae at Fiskey Ltd. Larval survival was not affected by the method used for environmental shading. Lower bacterial numbers were observed in the tank water with environmental shading provided by inorganic clay as compared with marine algae, primarily during the first days of exogenous feeding. Gram negative, fermentative bacteria dominated the cultivable community in the gastrointestinal tract of larvae during the first weeks in feeding. The use of inorganic clay has clear economic advantages as compared to the use of marine microalgae, and the commercial producer has used the product exclusively for environmental shading during first feeding of halibut larvae since 2003.
The production of good quality larvae is a challenge in marine fish hatcheries. In this study, the proteome profile of Atlantic cod (Gadus morhua) was analyzed using 2-DE, MALDI TOF MS and LC-MS/MS in order to determine its protein composition. Out of 109 abundant spots analyzed with MS 77 proteins were identified. The identified proteins were classified into 5 groups: structural proteins (56%), cytosolic proteins (29%), mitochondrial proteins (7%), secreted and extracellular proteins (7%) and nuclear proteins (1%). This study is the first step in a future construction of an Atlantic cod protein database that will be a valuable resource for molecular analysis of marine fish larval development.
BACKGROUND: Shrimp wastes contain high-quality protein that is underutilized, and particularly peptides derived from shrimp wastes (normally used as animal feed) have not been utilized for bioactive properties. Hence the objective was to utilize shrimp waste proteins in generating peptides and to investigate these for cancer antiproliferative activities. The objectives involved hydrolyzing shrimp proteins (intact in shell) using a food-grade Cryotin enzyme, obtaining gastrointestinal resistant peptides, fractionation to generate < 10, 10–30 and > 30 kDa fractions, and evaluating for colon and liver cancer cell growth inhibitory effects. Three shrimp shells—whole langostino lobster shells from El Salvador (South America), shrimp shells from St Petersburg, FL (USA), and shrimp shell whites from the Gulf of Mexico, LA (USA)—were evaluated for the study.
RESULTS: Peptide fractions (<10 and 10–30 kDa) obtained from shrimp shell whites (Gulf of Mexico) as well as from langostino shells (El Salvador) significantly inhibited the growth of both colon and liver cancer cells by 60%, while < 10 kDa fraction from shrimp shells (FL) inhibited growth of liver cancer cells alone by 55%, compared to controls.
CONCLUSION: The promising anticancer peptide fractions from shrimp waste proteins has the potential for novel nutraceutical ingredient applications.