| 1. |
- Antonsson, Martin, et al.
(författare)
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A comparison between the microflora of Herrgård cheese from three different dairies
- 2001
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Ingår i: International Dairy Journal. - 0958-6946. ; 11:4-7, s. 285-291
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Tidskriftsartikel (refereegranskat)abstract
- The microflora of Herrgård cheese produced at three dairies was grouped by phenotypical key tests and typed by randomly amplified polymorphic DNA (RAPD). Ten cheeses from the same vat at each dairy were analysed, five after 3 and another five after 6 months of ripening. All cheeses were organoleptically graded as Herrgård after uniform national standards, and only small but characteristic differences were found between cheeses from different dairies. Cheese from two dairies were dominated by a spontaneous secondary microflora of Lactobacillus from 3 months of ripening, while strains from the starter culture still dominated in cheese from the third dairy after 6 months. The Lactobacillus flora from the different dairies were mainly of diverse RAPD types, but of the 24 different RAPD types found, three were isolated from cheese made at two different dairies and two other RAPD types were isolated from cheese from all three dairies. A succession of different RAPD types was shown at one dairy.
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| 2. |
- Chen, Jun, et al.
(författare)
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Antioxidant capacity of bovine milk as assayed by spectrophotometric and amperometric methods
- 2003
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Ingår i: International Dairy Journal. - 0958-6946. ; 13:12, s. 927-935
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Tidskriftsartikel (refereegranskat)abstract
- The total antioxidant capacity (TAC) of bovine milk, whey, and low-molecular-weight (LMW) fractions of whey was investigated using spectrophotometric methods including an ABTS-based method (reduction of the cation radical of 2,2′-azinobis(3-ethylenebenzothiazoline-6-sulfonic acid)) and a FRAP method (reduction of Fe3+). Significant antioxidant capacity in milk and whey was demonstrated by the ABTS method (TAC(ABTS)), and it apparently increased with increasing pH. TAC (ABTS) was several-fold higher in milk than in whey, which had a slightly higher TAC than a LMW fraction prepared from it. Also the FRAP method could be used to demonstrate TAC in whey, although the low pH necessary for this method led to some protein precipitation. Most of the ferric-reducing activity of whey was found in the LMW fraction. The TAC values obtained using these methods were also compared to those obtained using a newly developed flow-injection amperometric (FIAmp) procedure for LMW fractions. High correlations were found for the TAC values of LMW samples obtained by the ABTS, FRAP and FIAmp methods (R2>0.8, P<0.001). Furthermore, to identify the major antioxidants in the LMW fraction, it was treated by uricase. Since most of the TAC (using ABTS, FRAP and FIAmp methods) was removed by uricase treatment, it could be concluded that urate is the major antioxidant in the LMW fraction. Also the effect of heat treatment on TAC in milk and whey was monitored. After heating of whey at 63°C for 1 h, TAC(ABTS) tended to increase by at least 20%, while TAC(FRAP) was not significantly changed. In milk, TAC(ABTS) remained constant during the same heat treatment. It is concluded that the methods tested gave the most reliable results for the LMW fraction of whey and that the use of several methods is necessary to characterise the antioxidant capacity of milk.
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| 3. |
- Elfstrand, Lidia, et al.
(författare)
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Immunoglobulins, growth factors and growth hormone in bovine colostrum and the effects of processing
- 2002
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Ingår i: International Dairy Journal. - 0958-6946. ; 12:11, s. 879-887
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Tidskriftsartikel (refereegranskat)abstract
- In colostrum collected 0-80 h postpartum the contents of immunoglobulins (Igs), transforming growth factor beta-2 (TGF-beta2), insulin-like growth factor-1 (IGF-1) and growth hormone (GH) were analysed. Colostrum initially contained 90 mg mL(-1) IgG1, 2.8 mg mL(-1) IgG2, 1.6 mg mL(-1) IgA, 4.5 mg mL(-1) IgM, and these concentrations declined by 92%, 87%, 93% and 84%, respectively, in the samples collected later. Of the growth factors, colostrum initially contained 289-310 ng mL(-1) TGF-beta2 and the concentration diminished to 66 ng mL(-1). The content of IGF-1 and GH postpartum decreased from 870 to 150 ng mL(-1), and from 0.17 to < 0.03 ng mL(-1), respectively. Heat treatment and freeze-drying of colostral whey decreased the content of Igs to 75%, while the contents of IGF-1 and TGF-beta2 were unaffected. A similar processing, including filtration steps reduced also the IGF-1 and TGF-beta2 by 25%. IgM seems to be the most sensitive of the Igs to processing. (C) 2002 Elsevier Science Ltd. All rights reserved.
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| 4. |
- Elofsson, Ulla, et al.
(författare)
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Heat induced aggregation of b-lactoglobulin studied by dynamic light scattering
- 1996
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Ingår i: International Dairy Journal. - : Elsevier BV. - 0958-6946 .- 1879-0143. ; 6:4, s. 343-357
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Tidskriftsartikel (refereegranskat)abstract
- The in situ heat-induced aggregation of commercial β-lactoglobulin as such, or after further purification, was followed to a z-average hydrodynamic diameter of 15–20 nm at 59–63 °C by dynamic light scattering. In this temperature range, measurable increase of hydrodynamic diameter occurred after an apparent lag period, which was strongly dependent on heating temperature, pH and initial protein concentration. The changes in time scale of the aggregation process agreed with changes in amount of unfolded β-lactoglobulin, assuming a two-state model of the denaturation. The pH dependence reflected the midpoint unfolding temperature and not the sulphydryl group reactivity, suggesting that this reactivity was not rate limiting in the aggregation. The aggregation process was modelled numerically with FuchsSmoluchowski kinetics.
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| 5. |
- Karlsson, Camilla A-C, et al.
(författare)
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Some surface-related aspects of the cleaning of new and reused stainless-steel surfaces fouled by protein
- 1998
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Ingår i: International Dairy Journal. - 0958-6946. ; 8:10, s. 925-933
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Tidskriftsartikel (refereegranskat)abstract
- The adsorption of β-lactoglobulin to stainless steel and its subsequent alkali-induced removal were followed using ellipsometry. New steel samples differing in bulk composition, surface finish or chemical pretreatment were used. All surfaces were precleaned in strongly alkaline solution, and some were subsequently passivated in nitric acid. Furthermore, on surfaces differing in pretreatment measurements were performed during repeated fouling and cleaning cycles. No correlation was found between the bulk composition or the surface finish and the fouling tendency or the cleanability. However, striking differences in cleanability between stainless-steel surfaces subjected to different chemical pretreatments were evident, particularly at low temperature. Still, only minor effects on the fouling tendency were observed. When subjecting surfaces to repeated fouling and cleaning without renewed pretreatment, the differences in cleaning performance decreased but were still significant. While the cleanability of non-passivated surfaces appeared to decrease somewhat when reused, changes seemed smaller for passivated surfaces.
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| 6. |
- Lodaite, Kristina, et al.
(författare)
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Fusion of skim milk cheese curd grains: Development of a method to measure the fracture stress of the bonds between fused curd grains
- 2002
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Ingår i: International Dairy Journal. - 0958-6946. ; 12:5, s. 455-461
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Tidskriftsartikel (refereegranskat)abstract
- An experimental technique with which to measure the fracture stress of fused curd grains, submerged in ultrafiltered milk permeate, has been developed and applied to curd grains of rennet-induced skim milk at pH 6.40 during the first 25 min of fusion. Effects of applied compressive stress within the range of 25-50 Pa, syneresis time, fusion time and tension loading rate were investigated. Fracture stress increased with applied compressive stress and fusion time. For the system investigated it was found that very small changes in applied compressive stress dramatically increased the degree of fusion. The degree of syneresis prior to fusion was found to have a large impact on the fusion rate, The rate of fusion was greater for 30 min of syneresis compared to 6 min of syneresis. A longer syneresis time, up to 60 min, did not further improve the fusion rate.
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| 7. |
- Arkbåge, Karin, et al.
(författare)
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Retention of vitamin B-12 during manufacture of six fermented dairy products using a validated radio protein-binding assay
- 2003
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Ingår i: International Dairy Journal. - 0958-6946 .- 1879-0143. ; 13:2-3, s. 101-109
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this work was to study vitamin B-12 retention during manufacture of six fermented dairy products. Careful validation of a commercial radio protein-binding kit showed this assay to be suitable after optimisation of sample pre-treatment and control of the kit for possible matrix effects. In fermented milks, vitamin B-12 concentrations decreased by 40-60%, compared with the starting milk, during storage of the final product at 4degreesC for 14 days, most likely attributed to consumption by starter cultures. In cottage cheese, hard cheeses and blue cheese, 18-56% of the vitamin B-12 originally present in the milk was retained. Removal of the whey fraction was the dominant factor reducing vitamin B-12 retention in cheeses, while the fermentation by starter cultures hardly affected vitamin B-12 concentrations.
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| 8. |
- Berlin, Johanna
(författare)
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Environmental life cycle assessment (LCA) of Swedish semi-hard cheese
- 2002
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Ingår i: International Dairy Journal. - 0958-6946 .- 1879-0143. ; 12:11, s. 939-953
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Tidskriftsartikel (refereegranskat)abstract
- An environmental life cycle assessment was performed to investigate the environmental consequences of the life cycle of Hushållsost, a semi-hard cheese. The assessment identified those activities that contribute most to the cheese's environmental impact throughout its life cycle from extraction of ingredients to waste management. Milk production at the farm was identified as having the greatest environmental impact, followed by cheesemaking at the dairy, retailing, and the production of plastic wrapping. The environmental impact could be reduced by minimising wastage of milk and cheese throughout the life cycle, without any effect on the quality of the product. Increasing the yield of cheese would also bring about substantial improvements as less milk would have to be produced on farms. © 2002 Elsevier Science Ltd. All rights reserved.
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| 9. |
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| 10. |
- Waak, Elisabet, et al.
(författare)
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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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Ingår i: International Dairy Journal. - Oxon, United Kingdom : Elsevier. - 0958-6946 .- 1879-0143. ; 9, s. 149-155
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Tidskriftsartikel (refereegranskat)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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