| 1. |
- Gudbjornsdottir, B., et al.
(författare)
-
The incidence of Listeria monocytogenes in meat, poultry and seafood plants in the Nordic countries
- 2004
-
Ingår i: Food microbiology (Print). - 0740-0020 .- 1095-9998. ; 21:2, s. 217-225
-
Tidskriftsartikel (refereegranskat)abstract
- During 1998/1999 a total of 36 surveys were carried out in six meat, five seafood and two poultry processing plants. A total of 2522 samples, including processing lines and environment, personnel, raw materials and products (raw or ready-to-eat, RTE), were analysed for the presence of Listeria monocytogenes. The environmental and personnel samples were taken after cleaning and after the process had been running for 2 h. Samples of food products were taken after every important step during processing and samples of poultry carcasses were taken immediately after production and after storage for 21 days. The overall incidence of L. monocytogenes in meat processing plants varied from 0% to 15.1%, in poultry plants from 20.6% to 24.1% and in seafood plants from 5.9% to 22.1%. In raw products the average incidence was 15.6% for meat, 22.2% for poultry and 39.0% for seafood products. The heating steps during the production of RTE products eliminated Listeria. On average, 2.3% of RTE meat and 4.8% of RTE seafood products were recontaminated with L. monocytogenes. In the seafood sector almost all Listeria positive samples also included L. monocytogenes (91.1% of the positive samples), whereas in the meat and poultry sectors other Listeria species (mainly L. innocua) dominated. In most plants, the implemented cleaning procedures were insufficient to eliminate Listeria. The results clearly indicated the problematic sites, which in most plants were conveyer belts and other transporting equipment, floors and drains, but also raw material in the meat industry, cutting boards in the poultry industry and cooking equipment in the seafood industry. In order to solve the problems observed in this study, there is a need for close co-operation between the suppliers of equipment and cleaning agents, the staff of cleaning companies and hygiene specialists from the food industry. © 2003 Elsevier Ltd. All rights reserved.
|
|
| 2. |
|
|
| 3. |
- Tham, Wilhelm, 1951-, et al.
(författare)
-
A comparison of six media for isolating Staphylococcus aureus from foods
- 1987
-
Ingår i: Food microbiology (Print). - : Elsevier. - 0740-0020 .- 1095-9998. ; 4:2, s. 133-146
-
Tidskriftsartikel (refereegranskat)abstract
- Six culture media were compared with blood agar regarding colony counts and colony diameters of 53 Staphylococcus aureus strains. There were no statistically significant differences between the media. The forced differentiation of the results via cluster analysis, however, gave some indications that differences existed. In terms of colony counts, LSM, BP Oxoid and BP Oxoid + pp gave results similar to those given by blood agar. Colony diameter seemed to be a doubtful measure of the media's suitability and none of the six media showed similar diameter values to those of blood agar. As regards the appearance of the S. aureus strains on the six media, BP BBL and LSM corresponded the most closely to the inventors descriptions. The selectivities of the media were tested by cultivating 102 food samples from various sources. The most favourable retardation against micro-organisms other than S. aureus was shown by BP BBL, KRANEP and LSM. In terms of all tests performed, BP BBL was the most satisfactory medium for isolating S. aureus. PCVJ was the poorest of all media used in this study.
|
|
| 4. |
- Bergentall, Martina, et al.
(författare)
-
Malolactic fermentation in lingonberry juice and its use as a preservative
- 2024
-
Ingår i: Food microbiology (Print). - 0740-0020 .- 1095-9998. ; 121
-
Tidskriftsartikel (refereegranskat)abstract
- Lingonberry is a common wild berry that is often sold as jams and beverages. It naturally contains high amounts of the weak acid preservative benzoic acid making it an interesting ingredient for shelf-life extension. Despite this, their use as a raw ingredient is limited by the inherently intense sour taste. This study aimed to improve the taste of lingonberry juice by subjecting it to malolactic fermentation in order to reduce the sourness, and to investigate the benzoic acid in lingonberries as a natural preservative in juice blends by determining the microbial stability. After initial screening of lactic acid bacteria, a Lactiplantibacillus plantarum strain was used as the starter for subsequent investigations. Upon raising the pH, all malic acid was completely converted to lactic acid after seven days. The fermented juice was mixed with blackcurrant juice in different proportions. Challenge tests of the blends showed Listeria monocytogenes could not grow in any juice samples, while Candida albicans only grew in the pure blackcurrant juice. Aspergillus brasiliensis growth was delayed in all samples containing benzoic acid in a concentration-dependent manner. The sourness and astringency were substantially reduced in the juice with added L. plantarum compared to the unfermented juice. © 2024 The Authors
|
|
| 5. |
- Bergkvist, Sharon W, 1973, et al.
(författare)
-
Improved iron solubility in carrot juice fermented by homo- and hetero-fermentative lactic acid bacteria
- 2005
-
Ingår i: Food Microbiology. - : Elsevier BV. - 0740-0020 .- 1095-9998. ; 22:1, s. 53-61
-
Tidskriftsartikel (refereegranskat)abstract
- To evaluate lactic acid fermentation as a means to increase the availability of iron in carrot juice, two strains (Lactobacillus pentosus FSC1 and Leuconostoc mesenteroides FSC2), two types of carrot juice and two modes of fermentation were compared. Fermentation improved iron solubility up to 30 fold. The total mineral content and the yield of soluble iron differed between the two types of juice. Addition of pectolytic enzyme and cellulase further improved iron solubility in fermented juice by about 10%. L. pentosus FSC1 yielded the largest improvement in soluble iron, which was not simply a result of a decrease in pH. The concentration of soluble iron in Ln. mesenteroides FSC2 fermentation was linearly related to the major acids produced. Besides, the mineral inhibitor phytate was completely degraded in all the fermentations. Lactic acid fermentation strongly improves iron solubility in carrot juice. The level of improvement was strain specific and related to the produced acids rather than a simple pH effect. Composition of carrot juice and addition of viscosity-reducing enzymes also contributed to this improvement. Our study suggests that carrot juice with high mineral availability may be achieved by fermentation using selected starter cultures, substrate and process.
|
|
| 6. |
- Feng, X. M., et al.
(författare)
-
Rhizopus oligosporus and yeast co-cultivation during barley tempeh fermentation-Nutritional impact and real-time PCR quantification of fungal growth dynamics
- 2007
-
Ingår i: Food microbiology (Print). - London, United Kingdom : Elsevier BV. - 0740-0020 .- 1095-9998. ; 24:4, s. 393-402
-
Tidskriftsartikel (refereegranskat)abstract
- Barley tempeh was produced by fermenting barley kernels with Rhizopus oligosporus. The potential of the yeasts Saccharomyces cerevisiae (three strains), S. boulardii (one strain), Pichia anomala (one strain) and Kluyveromyces lactis (one strain) to grow together with R. oligosporus during barley tempeh fermentation was evaluated. All yeast strains grew during the fermentation and even during cold storage of tempeh (P < 0.01). The growth of yeasts slightly increased the ergosterol contents, but did not influence amino acid contents and compositions, and did not reduce phytate contents. Slight increases of vitamins B6 and niacinamide, and slight decreases of B1 and biotin were observed. Quantification of fungal growth is difficult during mixed species fermentations because ergosterol is found in all fungal species, and colony-forming-unit (cfu) estimations are not reliable for R. oligosporus and other sporulating fungi. Therefore, we developed a quantitative real-time PCR method for individually quantifying S. cerevisiae and R. oligosporus growth in barley tempeh. The PCR results were highly correlated with the ergosterol content of R. oligosporus and with the number of cfu of S. cerevisiae. Thus, real-time PCR is a rapid and selective method to quantify yeasts and R. oligosporus during mixed species fermentation of inhomogenous substrate such as barley tempeh. © 2006 Elsevier Ltd. All rights reserved.
|
|
| 7. |
- Galafassi, Silvia, et al.
(författare)
-
Osmotic stress response in the wine yeast Dekkera bruxellensis
- 2013
-
Ingår i: Food Microbiology. - : Elsevier BV. - 1095-9998 .- 0740-0020. ; 36:2, s. 316-319
-
Tidskriftsartikel (refereegranskat)abstract
- Dekkera bruxellensis is mainly associated with Iambic beer fermentation and wine production and may contribute in a positive or negative manner to the flavor development. This yeast is able to produce phenolic compounds, such as 4-ethylguaiacol and 4-ethylphenol which could spoil the wine, depending on their concentration. In this work we have investigated how this yeast responds when exposed to conditions causing osmotic stress, as high sorbitol or salt concentrations. We observed that osmotic stress determined the production and accumulation of intracellular glycerol, and the expression of NADH-dependent glycerol-3-phosphate dehydrogenase (GPO) activity was elevated. The involvement of the HOG MAPK pathway in response to this stress condition was also investigated. We show that in D. bruxellensis Hog1 protein is activated by phosphorylation under hyperosmotic conditions, highlighting the conserved role of HOG MAP kinase signaling pathway in the osmotic stress response. Gene Accession numbers in GenBank: DbHOG1: JX65361, DbSTL1: JX965362. (C) 2013 Elsevier Ltd. All rights reserved.
|
|
| 8. |
- Holt, Sylvester, et al.
(författare)
-
Bioflavoring by non-conventional yeasts in sequential beer fermentations
- 2018
-
Ingår i: Food Microbiology. - : Elsevier BV. - 0740-0020 .- 1095-9998. ; 72, s. 55-66
-
Tidskriftsartikel (refereegranskat)abstract
- Non-conventional yeast species have great capacity for producing diverse flavor profiles in production of alcoholic beverages, but their potential for beer brewing, in particular in consecutive fermentations with Saccharomyces cerevisiae, has only poorly been explored. We have screened 17 non-conventional yeast species for production of an appealing profile of flavor esters and phenolics in the first phase of alcoholic fermentation, followed by inoculation with S. cerevisiae to complete the fermentation. For measurement of phenolic compoundsand their precursors we developed an improved and highly sensitive methodology. The results show that non-conventional yeast species possess promising potential for enhancement of desirable flavors in beer production. Notable examples are increasing isoamyl acetate (fruity, banana flavor) by application of P. kluyverii, augmenting ethyl phenolic compounds (spicy notes) with Brettanomycesspecies and enhancing 4-vinyl guaiacol (clove-like aroma) with T. delbrueckii. All Pichia strains also produced high levels of ethyl acetate (solvent-like flavor). This might be selectively counteracted by selection of an appropriate S. cerevisiae strain for the second fermentation phase, which lowers total ester profile. Hence, optimization of the process conditions and/or proper strain selection in sequentially inoculated fermentations are required to unlock the full potential for aroma improvement by the non-conventional yeast species.
|
|
| 9. |
- Krovacek, Karel
(författare)
-
Occurrence of toxigenic Clostridium difficile in edible bivalve molluscs
- 2012
-
Ingår i: Food Microbiology. - : Elsevier BV. - 0740-0020 .- 1095-9998. ; 31, s. 309-312
-
Tidskriftsartikel (refereegranskat)abstract
- Clostridium difficile is an anaerobic bacterium commonly considered to be responsible for antibiotic-associated gastrointestinal diseases, ranging from diarrhea of varying severity to pseudomembranous colitis. The aim of this study was to assess the occurrence of C. difficile in marine edible bivalve molluscs, which, as filter feeding organisms, are able to accumulate particles suspended in water, including microorganisms. Samples of Mytilus galloprovincialis, Tapes philippinarum, and Venus verrucosa were collected from mussel farms and fishmongers in the province of Naples (Southern Italy). C. difficile was found in 49% of the 53 samples investigated. Sixteen isolates were grouped in 12 known different PCR ribotypes (001, 002, 003, 010, 012, 014/020, 018, 045, 070, 078, 106, and 126), whereas 10 additional isolates were grouped in 8 new PCR riboprofiles. Two toxinotypes (0 and V) were found. Fifty eight percent of the isolates were toxigenic. These findings indicate that toxigenic C. difficile strains can be isolated in bivalve molluscs. Marine filter feeding organisms, therefore, may be considered as reservoir of toxigenic strains of C. difficile. The ingestion of raw or poorly cooked contaminated seafood and the high temperature resistance of the spore-forming C. difficile could represent an important source of exposure and pose human health concern. (C) 2012 Elsevier Ltd. All rights reserved.
|
|
| 10. |
|
|
