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- Glantz, Maria, et al.
(author)
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Impact of protease and lipase activities on quality of Swedish raw milk
- 2020
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In: International Dairy Journal. - : Elsevier BV. - 0958-6946. ; 107
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Journal article (peer-reviewed)abstract
- An increasing demand for dairy products with long shelf-life is foreseen. A limiting factor for maintaining high quality of these products is the activity of spoilage enzymes during storage. Lipase and protease activities in Swedish raw milk at farm and dairy level were investigated, analysing milk samples from three geographical regions and two seasons. Lipase activity in milk at farm level was affected by regional and seasonal variations, whereas at dairy level only season had an effect. Lipase activity was positively correlated with ionic calcium. For protease activity, no effect of either region or season was seen. Degradation products, e.g., free fatty acids, peptides and plasmin proteolysis products, varied differently between season and geographical origin at both farm and dairy level. The results indicate that lipase and protease activities are important for raw milk quality, while ionic calcium might be a future indicator for milk fat stability.
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| 4. |
- Waak, Elisabet, et al.
(author)
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Comparison of the ISO and IDF methods for detection of Listeria monocytogenes in blue veined cheese
- 1999
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In: International Dairy Journal. - Oxon, United Kingdom : Elsevier. - 0958-6946 .- 1879-0143. ; 9, s. 149-155
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Journal article (peer-reviewed)abstract
- The International Dairy Federation Revised Provisional IDF Standard 143:1990 (1990) is compared with the ISO Draft International Standard ISO/DIS 11290-1 (1995) for detection of Listeria monocytogenes in inoculated samples of the blue veined cheeses Gorgonzola and AG delost (Swedish blue mould cheese) and in non-inoculated market cheeses of mostly soft mould cheese. The ISO method detected L. monocytogenes signi"cantly more frequently than the IDF method when inoculated Gorgonzola samples were analysed. For inoculated AG delost, and non-inoculated market cheeses the methods were equally good. The selective isolation media PALCAM and Oxford Listeria selective agar, were compared for recovery of Listeria spp. Less growth of non-Listeria colonies was obtained on PALCAM agar compared to Oxford Listeria selective agar especially after the primary enrichment step of the ISO method. Consequently, it was easier to identify and isolate growth of Listeria species from the cheeses on the PALCAM agar.
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| 9. |
- Waak, Elisabet, et al.
(author)
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Fingerprinting of Listeria monocytogenes isolated in silos for raw whole milk of a dairy plant
- 2000
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In: Nordic PFGE meeting. January 27–28, 2000. Collection of Abstracts, Department of Food Hygiene, Faculty of Veterinary Medicine, SLU, Uppsala. - Uppsala : Dep of Food Hygiene, Faculty of Veterinary Medicine, SLU. ; , s. 28-28
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Conference paper (peer-reviewed)
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| 10. |
- Waak, Elisabet, et al.
(author)
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Prevalence and fingerprinting of Listeria monocytogenes strains isolated from raw whole milk in farm bulk tanks and in dairy plant receiving tanks
- 2002
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In: Applied and Environmental Microbiology. - 0099-2240 .- 1098-5336. ; 68:7, s. 3366-3370
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Journal article (peer-reviewed)abstract
- The incidence of Listeria species in raw whole milk from farm bulk tanks and from raw milk in storage at a Swedish dairy plant was studied. Listeria monocytogenes was found in 1.0% and Listeria innocua was found in 2.3% of the 294 farm bulk tank (farm tank) milk specimens. One farm tank specimen contained 60 CFU of L. monocytogenes ml-1. L. monocytogenes was detected in 19.6% and L. innocua was detected in 8.5% of the milk specimens from the silo receiving tanks at the dairy (dairy silos). More dairy silo specimens were positive for both Listeria species during winter than during summer. Restriction enzyme analysis and pulsed-field gel electrophoresis were applied to 65 isolates of L. monocytogenes, resulting in 16 different clonal types. Two clonal types were shared by the farm tank milk and the dairy silo milk. All except one clonal type belonged to serovar 1/2a. In the dairy silo milk five clonal types were found more frequently and for a longer period than the others. No Listeria species were found in any other samples from the plant.
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