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- Priyashantha, Hasitha, et al.
(författare)
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A matter of concentration
- 2019
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Ingår i: Dairy Industries International. - 0308-8197. ; 84, s. 33-34
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 4. |
- Priyashantha, Hasitha, et al.
(författare)
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Interactive effects of casein micelle size and calcium and citrate content on rennet-induced coagulation in bovine milk
- 2019
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Ingår i: Journal of Texture Studies. - : Wiley. - 0022-4901 .- 1745-4603. ; 50, s. 508-519
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Tidskriftsartikel (refereegranskat)abstract
- Interactive effects of casein micelle size and milk calcium and citrate content on rennet-induced coagulation were investigated. Milk samples containing small (SM) and large (LM) micelles, obtained from individual Holstein cows, were modified by addition of calcium and/or citrate and milk coagulation properties were evaluated in a full factorial design. The results showed that LM milk had a higher relative proportion of casein, coagulated faster, and resulted in a stronger gel than SM milk. Addition of calcium slightly decreased casein micelle size, while addition of citrate slightly increased micelle size. Calcium addition resulted in a shorter coagulation time and the strongest gels, while citrate addition increased the coagulation time and resulted in the weakest gels. Addition of calcium and citrate in combination resulted in intermediate coagulation properties. The interactive effect of micelle size and citrate was significant for gel strength. Microstructural differences between the milk gels were consistent with the rheological properties, for example, the micrographs revealed that a more homogeneous network was formed when calcium was added, resulting in a stronger gel. A more inhomogeneous network structure was formed when citrate was added, resulting in a weaker gel. Thus, variations in casein micelle size and in calcium and citrate content influence rennet-induced coagulation in bovine milk. The calcium and citrate contents in Swedish milk have changed over time, whereby calcium content has increased and citrate content has decreased. In practical cheese making, calcium is added to cheese milk, most likely altering the role of inherent citrate and possibly influencing casein micelle size. The observed interaction effect between casein micelle size and citrate in this study, suggests that larger micelles with moderate citrate level will result in firmer gels, whereas a higher citrate content reduced gel strength more in case of large than SM. Since firmer gels are likely to retain more protein and fat than less firmer gels, this interaction effect could have implications in practical cheese production.
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| 5. |
- Priyashantha, Hasitha
(författare)
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Kanelen ger mer än smak
- 2019
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Ingår i: Livsmedel i fokus. - 1652-912X. ; , s. 58-59
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Det finns många varianter av kanel men de mest vanliga kommersiella sorterna är Cassia (kinesisk kanel) och Ceylonkanel (också känd som äkta kanel). Egenskaperna för olika kanelsorter är dock väldigt olika. I den här artikeln har vi främst studerat fördelarna med Ceylonkanel.
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| 8. |
- Sun, Li, et al.
(författare)
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Distribution of bacteria between different milk fractions, investigated using culture-dependent methods and molecular-based and fluorescent microscopy approaches
- 2019
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Ingår i: Journal of Applied Microbiology. - : Oxford University Press (OUP). - 1364-5072 .- 1365-2672. ; 127, s. 1028-1037
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Tidskriftsartikel (refereegranskat)abstract
- Aims To develop a protocol for DNA extraction using whole milk and further, to investigate how the use of whole instead of skimmed milk during DNA extraction affected the resulting microbial composition. Methods and Results In a model study, three selected bacterial species (Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 11775 and Lactobacillus reuteri PTA 4659) were added to raw milk and their distribution between different milk fractions was examined by cultivation on selective agar plates. Quantitative real-time PCR (qPCR) assays and Illumina amplicon sequencing were conducted after DNA extraction of whole milk and skimmed milk. In addition, fluorescent microscopy was used to visualize the distribution of Lactobacillus reuteri R2LC mCherry in milk samples with different fat contents. Depending on spike-in bacterial species, recovery rates of 7 center dot 4-26 center dot 5% of added bacteria were obtained in the fat fraction in culture-based enumeration. qPCR showed a 7-9 fold increase in recovery of spike-in bacteria when the milk fat fraction was combined with the pellet during the DNA extraction step. In the Illumina 16S amplicon approach, relative abundance of six of the top 11 operational taxonomic units identified differed significantly when comparing skimmed milk and whole milk as starting material. Fluorescent microscopy images demonstrated that L. reuteri R2LC mCherry was associated with fat globules in whole milk samples. Conclusions This study demonstrates that milk fat harbours bacterial species that might be underestimated when skimmed milk, rather than whole milk, is used for DNA extraction. Significance and Impact of the Study This study emphasizes the importance of using whole instead of skimmed milk for DNA extraction. A protocol for extracting DNA from whole milk is suggested.
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