| 1. |
- Poulsen, Nina A, et al.
(author)
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Comparison of milk protein composition and rennet coagulation properties in native Swedish dairy cow breeds and high-yielding Swedish Red cows
- 2017
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In: Journal of Dairy Science. - : American Dairy Science Association. - 0022-0302. ; 100:11, s. 8722-8734
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Journal article (peer-reviewed)abstract
- Recent studies have reported a very high frequency of noncoagulating milk in Swedish Red cows. The underlying factors are not fully understood. In this study, we explored rennet-induced coagulation properties and relative protein profiles in milk from native Swedish Mountain and Swedish Red Polled cows and compared them with a subset of noncoagulating (NC) and well-coagulating (WC) milk samples from modern Swedish Red cows. The native breeds displayed a very low prevalence of NC milk and superior milk coagulation properties compared with Swedish Red cows. The predominant variants in both native breeds were αS1-casein (αS1-CN) B, β-CN A2 and β-lactoglobulin (β-LG) B. For κ-CN, the B variant was predominant in the Swedish Mountain cows, whereas the A variant was the most frequent in the Swedish Red Polled. The native breeds displayed similar protein composition, but varied in content of αS1-CN with 9 phosphorylated serines (9P) form. Within the Swedish Mountain cows, we observed a strong inverse correlation between the relative concentration of κ-CN and micelle size and a positive correlation between ionic calcium and gel firmness. For comparison, we investigated a subset of 29 NC and 28 WC milk samples, representing the extremes with regard to coagulation properties based on an initial screening of 395 Swedish Red cows. In Swedish Red, NC milk properties were found to be related to higher frequencies of β-CN A2, κ-CN E and A variants, as well as β-LG B, and the predominant composite genotype of β- and κ-CN in the NC group was A2A2/AA. Generally, the A2A2/AA composite genotype was related to lower relative concentrations of κ-CN isoforms and higher relative concentrations of αS1-, αS2-, and β-CN. Compared with the group of WC milk samples, NC milk contained a higher fraction of αS2-CN and α-lactalbumin (α-LA) but a lower fraction of αS1-CN 9P. In conclusion, milk from native Swedish breeds has good characteristics for cheese milk, which could be exploited in niche dairy products. In milk from Swedish Mountain cows, levels of ionic calcium seemed to be more important for rennet-induced gel firmness than variation in the relative protein profile. In Swedish Red, lower protein content as well as higher fraction of αS2-CN and lower fraction of αS1-CN 9P were related to NC milk. Further, a decrease in the frequency of the composite β-κ-CN genotype A2A2/AA through selective breeding could have a positive effect on milk coagulation properties.
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| 2. |
- Roswall, Nina, et al.
(author)
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Long-term exposure to traffic noise and risk of incident colon cancer : A pooled study of eleven Nordic cohorts
- 2023
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In: Environmental Research. - : Elsevier BV. - 0013-9351 .- 1096-0953. ; 224
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Journal article (peer-reviewed)abstract
- BackgroundColon cancer incidence is rising globally, and factors pertaining to urbanization have been proposed involved in this development. Traffic noise may increase colon cancer risk by causing sleep disturbance and stress, thereby inducing known colon cancer risk-factors, e.g. obesity, diabetes, physical inactivity, and alcohol consumption, but few studies have examined this.ObjectivesThe objective of this study was to investigate the association between traffic noise and colon cancer (all, proximal, distal) in a pooled population of 11 Nordic cohorts, totaling 155,203 persons.MethodsWe identified residential address history and estimated road, railway, and aircraft noise, as well as air pollution, for all addresses, using similar exposure models across cohorts. Colon cancer cases were identified through national registries. We analyzed data using Cox Proportional Hazards Models, adjusting main models for harmonized sociodemographic and lifestyle data.ResultsDuring follow-up (median 18.8 years), 2757 colon cancer cases developed. We found a hazard ratio (HR) of 1.05 (95% confidence interval (CI): 0.99–1.10) per 10-dB higher 5-year mean time-weighted road traffic noise. In sub-type analyses, the association seemed confined to distal colon cancer: HR 1.06 (95% CI: 0.98–1.14). Railway and aircraft noise was not associated with colon cancer, albeit there was some indication in sub-type analyses that railway noise may also be associated with distal colon cancer. In interaction-analyses, the association between road traffic noise and colon cancer was strongest among obese persons and those with high NO2-exposure.DiscussionA prominent study strength is the large population with harmonized data across eleven cohorts, and the complete address-history during follow-up. However, each cohort estimated noise independently, and only at the most exposed façade, which may introduce exposure misclassification. Despite this, the results of this pooled study suggest that traffic noise may be a risk factor for colon cancer, especially of distal origin.
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| 3. |
- Sheng, Bulei, et al.
(author)
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Effects of genetic variants and sialylation on in vitro digestibility of purified κ-casein
- 2022
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In: Journal of Dairy Science. - : American Dairy Science Association. - 0022-0302. ; 105:4, s. 2803-2814
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Journal article (peer-reviewed)abstract
- Milk with different κ-casein (CN) phenotypes has previously been found to influence its gastric digestion rate. Therefore, the aim of the present study is to disentangle contributions of genetic variation and its related sialylation on the in vitro digestion process of κ-CN. Accordingly, κ-CN was purified from milk representing homozygous cows with κ-CN phenotypes AA, BB, or EE and used as substrate molecules in model studies using the INFOGEST 2.0 in vitro static digestion model. Furthermore, the effect of removal of the terminal sialic acids present on the O-linked oligosaccharides of the purified κ-CN A, B, and E protein variants were studied by desialylation enzymatic assays. The κ-CN proteins were purified by reducing anion exchange chromatography with purities of variants A, B, and E of 93.0, 97.1, and 90.0%, respectively. Protein degradations of native and desialylated κ-CN isolates in gastric and intestinal phases were investigated by sodium dodecyl sulfate-PAGE, degree of hydrolysis (DH), and liquid chromatography electrospray ionization mass spectrometry. It was shown that after purification, the κ-CN molecules reassembled into multimer states, which then constituted the basis for the digestion studies. As assessed by DH, purified variants A and E were found to exhibit faster in vitro digestion rates in both gastric and intestinal phases compared with variant B. Desialylation increased both gastric and intestinal digestion rates for all variants, as measured by DH. In the gastric phase, desialylation promoted digestion of variant B at a rate comparable with native variants A and E, whereas in the intestinal phase, desialylation of variant B promoted better digestion than native A or E. Taken together, the results confirm that low glycosylation degree of purified κ-CN promotes faster in vitro digestion rates, and that desialylation of the O-linked oligosaccharides further promotes digestion. This finding could be applied to produce dairy products with enhanced digestibility.
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| 4. |
- Sheng, Bulei, et al.
(author)
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Influence of genetic variants and sialylation of purified κ-casein on peptide release during in vitro digestion
- 2023
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In: Food Chemistry Advances. - 2772-753X. ; 3
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Journal article (peer-reviewed)abstract
- In the present study, digestion pattern of purified bovine κ-casein (κ-CN) variants A, B, E as well as desialylated variant B, using INFOGEST 2.0 in vitro gastrointestinal digestion were investigated using peptidomics. Peptide profiles of the digests were identified and quantified using ion abundancies by liquid chromatography electrospray quadropole time of flight mass spectrometry (LC-ESI/Q-TOF MS/MS). Results showed that the κ-CN variants A and E had comparable digestion patterns at most digestion time points. In the in vitro gastric and in the initial intestinal phases fewer peptides and with lower total abundances were identified for variant B compared to variants A and E, indicating a slower digestion rate for κ-CN B. By desialylation, the digestion rate of desialylated variant B in both gastric and initial intestinal phases increased compared to the natural sialylated counterpart. Bioinformatics search revealed nine potential bioactive peptides released from all three variants A, B and E by the in vitro intestinal digestion, with four additional potential bioactive peptides being released after desialylation of κ-CN B.
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| 5. |
- Sheng, Bulei, et al.
(author)
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Phosphorylation and glycosylation isoforms of bovine κ-casein variant E in homozygous Swedish Red cow milk by liquid chromatography-electrospray ionization mass spectrometry
- 2022
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In: Journal of Dairy Science. - : American Dairy Science Association. - 0022-0302. ; 105:3, s. 1959-1965
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Journal article (peer-reviewed)abstract
- Variations in the phosphorylation and glycosylation patterns of the common κ-casein (CN) variants A and B have been explored, whereas studies on variant E heterogeneity are scarce. This study reports for the first time the detailed phosphorylation and glycosylation pattern of the κ-CN variant E in comparison with variants A and B. Individual cow milk samples representing κ-CN genotype EE (n = 12) were obtained from Swedish Red cows, and the natural posttranslational modifications of its κ-CN were identified and quantified by liquid chromatography-electrospray mass spectrometry. In total, 12 unique isoform masses of κ-CN variant E were identified. In comparison, AA and BB milk consisted of 14 and 17 unique isoform masses, respectively. The most abundant κ-CN E isoform detected in the EE milk was the monophosphorylated, unglycosylated [1P 0G, ∼70%; where P indicates phosphorylation from single to triple phosphorylation (1–3P), and G indicates glycosylation from single to triple glycosylation (1–3G)] form, followed by diphosphorylated, unglycosylated (2P 0G, ∼12%) form, resembling known patterns from variants A and B. However, a clear distinction was the presence of the rare triphosphorylated, nonglycosylated (3P 0G, ∼0.05%) κ-CN isoform in the EE milk. All isoforms detected in variant E were phosphorylated, giving a phosphorylation degree of 100%. This is comparable with the phosphorylation degree of variants A and B, being also almost 100%, though with very small amounts of nonphosphorylated, glycosylated isoforms detected. The glycosylation degree of variant E was found to be around 17%, a bit higher than observed for variant B (around 14%), and higher than variant A (around 7%). Among glycosylation, the glycan e was the most common type identified for all 3 variants, followed by c/d (straight and branched chain trisaccharides, respectively), and b. In contrast to κ-CN variants A and B, no glycan of type a was found in variant E. Taken together, this study shows that the posttranslational modification pattern of variant E resembles that of known variants to a large extent, but with subtle differences.
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| 6. |
- Sundekilde, Ulrik K, et al.
(author)
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Association between the bovine milk metabolome and rennet-induced coagulation properties of milk.
- 2014
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In: Journal of Dairy Science. - : American Dairy Science Association. - 1525-3198 .- 0022-0302. ; 97:10, s. 6076-6084
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Journal article (peer-reviewed)abstract
- The milk metabolomes of 407 individual Swedish Red dairy cows were analyzed by nuclear magnetic resonance spectroscopy as part of the Danish-Swedish Milk Genomics Initiative. By relating these metabolite profiles to total milk protein concentration and rheological measurements of rennet-induced milk coagulation together using multivariate data analysis techniques, we were able to identify several different associations of the milk metabolome to technological properties of milk. Several novel correlations of milk metabolites to protein content and rennet-induced coagulation properties were demonstrated. Metabolites associated with the prediction of total protein content included choline, N-acetyl hexosamines, creatinine, glycerophosphocholine, glutamate, glucose 1-phosphate, galactose 1-phosphate, and orotate. In addition, levels of lactate, acetate, glutamate, creatinine, choline, carnitine, galactose 1-phosphate, and glycerophosphocholine were significantly different when comparing noncoagulating and well-coagulating milks. These findings suggest that the mentioned metabolites are associated with milk protein content and rennet-induced coagulation properties and may act as quality markers for cheese milk.
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