| 1. |
- 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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| 2. |
- 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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| 3. |
- 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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| 4. |
- 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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| 5. |
- Andersson, I. M., et al.
(författare)
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Impact of surface properties on morphology of spray-dried milk serum protein/lactose systems
- 2018
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Ingår i: International Dairy Journal. - : Elsevier BV. - 0958-6946 .- 1879-0143. ; 85, s. 86-95
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Tidskriftsartikel (refereegranskat)abstract
- This study investigated milk serum protein concentrate/lactose systems with varying ratios and how the morphology of the spray-dried particles of these systems could be described by the surface properties of the feed as well as the protein surface coverage of the particles. An extrapolation of the surface pressure of the feed to 0.3 s, the approximate time for molecular diffusion in an atomised droplet in the spray-dryer, showed a relationship with the particle morphology. At low protein concentrations (<1%), the particles were almost totally smooth. At higher protein concentrations (≥1%), the particles became dented and ridged, and these tended to become deeper and thicker as the protein concentration increased. It is suggested that the surface pressure of the feed at low protein concentrations is the most prominent surface property, whereas the modulus of elasticity seems to be the most prominent surface property for particle surface deformation at higher protein concentrations.
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| 6. |
- Andersson, I. M., et al.
(författare)
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Particle morphology and rehydration properties of spray-dried microgels and fractal aggregates with varying fractions of native milk serum proteins
- 2021
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Ingår i: International Dairy Journal. - : Elsevier Ltd. - 0958-6946 .- 1879-0143. ; 112
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Tidskriftsartikel (refereegranskat)abstract
- To keep their functional properties, it is crucial that protein aggregates maintain their structure after spray drying and that the powders can be fully rehydrated. In this study, microgels and fractal aggregates were prepared by heating a mixture of milk serum protein concentrate and lactose (40/60; %, w/w) at 85 °C for 15 min by varying the pH. Various fractions of native proteins were added to the systems prior to spray drying. This study showed that microgels and fractal aggregates kept their structure after spray drying and reconstitution. The particle morphology could be correlated to the stiffness of the interface of the feed droplet. The forced imbibition rate showed a negative correlation with increasing amount of aggregated proteins in the powders that seems to be a result of denatured/aggregated proteins present at the surface. These findings are of importance for the formulation of spray-dried powders with improved rehydration characteristics. © 2020 The Author(s)
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| 7. |
- Berta, Marco, et al.
(författare)
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Rheology of natural and imitation mozzarella cheese at conditions relevant to pizza baking
- 2016
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Ingår i: International Dairy Journal. - : Elsevier. - 0958-6946 .- 1879-0143. ; 57, s. 34-38
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Tidskriftsartikel (refereegranskat)abstract
- The rheology of mozzarella and imitation cheese was studied at 60 °C, with small amplitude oscillatory shear (SAOS), shear and extensional flow measurement at low strain rates in the range 0.01-1 s-1. These conditions were chosen to replicate those experienced by the cheese during pizza baking and consumption. The extensional viscosity measurements were carried out by means of hyperbolic contraction flow, an alternative method to traditional extensional measurements. The extensional viscosity measured by hyperbolic contraction flow was related to the cheese elasticity and consequently to its stretchability, a major quality characteristic when this is consumed on pizza pies. The rheology of the two cheese materials could be explained by the structural observations made by confocal laser scanning microscopy (CLSM).
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| 8. |
- Gustavsson, Frida, et al.
(författare)
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Factors influencing chymosin-induced gelation of milk from individual dairy cows: Major effects of casein micelle size and calcium
- 2014
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Ingår i: International Dairy Journal. - : Elsevier BV. - 0958-6946 .- 1879-0143. ; 39:1, s. 201-208
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Tidskriftsartikel (refereegranskat)abstract
- Optimisation of cheese yield is crucial for cheese production; a previous study showed large variations in chymosin-induced coagulation in milk from the second most common Swedish dairy breed, Swedish Red. In the present study, the effect of gross composition, protein composition, total and ionic calcium content, phosphorous content and casein micelle size on chymosin-induced gelation was determined in milk from 98 Swedish Red cows. The study showed that protein content and total calcium content, ionic calcium concentration and casein micelle size were the most important factors explaining the variation of gelation properties in this sample set. Non-coagulating milk was suggested to have lower ionic and total calcium content as well as lower relative concentrations of beta-lactoglobulin than coagulating milk. The lower total calcium content in non-coagulating milk poses a problem as the difference was, theoretically, four times larger than the amount of calcium that is normally added in cheese processing. (C) 2014 Elsevier Ltd. All rights reserved.
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| 9. |
- Gustavsson, Frida, et al.
(författare)
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Impact of genetic variants of milk proteins on chymosin-induced gelation properties of milk from individual cows of Swedish Red dairy cattle
- 2014
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Ingår i: International Dairy Journal. - : Elsevier BV. - 0958-6946 .- 1879-0143. ; 39:1, s. 102-107
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Tidskriftsartikel (refereegranskat)abstract
- Chymosin-induced gelation properties of the milk of around 400 Swedish Red dairy cows was investigated with the aim of identifying genetic protein variants that influence chymosin-induced gelation for optimisation of cheese milk through breeding practices. The variation in chymosin-induced gelation properties was shown to be large in the milk of Swedish Red and there was a high frequency of cows producing non-coagulating milk, 18%. The present study showed that the common composite beta-kappa-casein genotypes A(1)A(2)/AE and A(2)A(2)/AA were associated with both poor gelation properties and non-coagulation in the milk of Swedish Red. The present study suggests that if the frequencies of composite genotypes A(1)A(2)/AE and A(2)A(2)/AA were decreased in the Swedish Red population in favour for A(1)A(1)/AA and A(1)A(1)/AE, this could have a positive effect on the rennetability of the milk. (C) 2014 Elsevier Ltd. All rights reserved.
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| 10. |
- Hallén, Elin, et al.
(författare)
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Effect of genetic polymorphism of milk proteins on rheology of acid-induced milk gels
- 2009
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Ingår i: International Dairy Journal. - : Elsevier BV. - 0958-6946 .- 1879-0143. ; 19, s. 399-404
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Tidskriftsartikel (refereegranskat)abstract
- Individual milk samples from 80 cows in mid-lactation of the Swedish Red and Swedish Holstein breeds with known protein genotypes of beta- and kappa-casein and beta-lactoglobulin were analysed for acid Coagulation properties. Glucono-delta-lactone (1.5%) was added to defatted, heated (90-95 degrees C) samples and theological properties of the gels were measured using a Bohlin VOR Rheometer. Coagulation time (CT) and curd firmness after 4, 8 and 10 h (G'(4), G'(8), and G'(10) were registered for each sample. Milk protein composition was analysed by reversed phase HPLC. Concentration of beta-lactoglobulin in milk was found to be an important factor for the variation in CT and G'. The A allele of beta-lactoglobulin was associated with higher concentrations of beta-lactoglobulin in milk compared with B. When no adjustment for beta-lactoglobulin concentration was made, there was a significant overall effect of beta-lactoglobulin genotype on acid coagulation, where the AA and AB genotypes were associated with better curd firmness compared with BB, whereas at equal beta-lactoglobulin concentrations a tendency in the opposite direction was found with a significant and positive effect of BB compared with AB. Lactose concentration of milk had a positive effect on acid coagulation and was shown to improve G' in milk with low beta-lactoglobulin concentrations. (C) 2009 Elsevier Ltd. All rights reserved.
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