Tove Gulbrandsen Devold

Somatic cell count is used as an indicator of milk quality and udder health in dairy goats, although its interpretation is complicated by noninfectious causes, including seasonality, farm-specific practices, and physiological factors. This study analyzed 868 milk samples from 9 Norwegian dairy goat farms to investigate the interplay between SCC, individual bacterial count (IBC), and milk composition. Samples were collected on 3 occasions during the lactation period (early, mid, and late lactation). The results showed that SCC peaked in the pasture period and then decreased but remained elevated in late lactation. Individual bacterial count showed a positive correlation with higher SCC levels, although this correlation varied significantly across different farms and time periods. The presence of intramammary infections only partially explained the varying correlation between SCC and bacterial counts. This indicates that the relationship between SCC and IBC is influenced not only by infections, but also by management practices, environmental conditions, and other farm-level factors. The study revealed a covariation between SCC and other milk components according to the lactation stage and season. Furthermore, the investigation of factors influencing the interplay between SCC and IBC provides a deeper understanding of SCC as a milk quality indicator in dairy goats.

Kombucha, a fermented tea beverage, is gaining popularity due to its rich content of bioactive compounds and associated health benefits. Kombucha fermentation involves a complex microbial consortium, including acetic acid bacteria, lactic acid bacteria, and yeasts, that works synergistically to enhance its nutritional and functional properties. Key compounds produced during fermentation provide antioxidant, anti-inflammatory, and antimicrobial benefits. Despite its well-documented health-promoting properties, limited research exists on how human digestion influences the stability and functionality of kombucha bioactive components. This study investigated how digestion impacts kombucha made from green and black teas, focusing on free amino acid content, antioxidant activity, antimicrobial potential, and microbiota viability. Results showed that digestion significantly increased free amino acids, as fermentation released peptides suitable for gastrointestinal digestion. However, L-theanine, a beneficial tea compound, was no longer detectable after fermentation and digestion, suggesting limited bioaccessibility. Digested kombucha exhibited higher antioxidant activity and stronger antimicrobial effects compared to undigested tea. Moreover, culture-dependent and PMA-based sequencing confirmed the survival of viable microbial strains through simulated gastrointestinal conditions, suggesting the potential of kombucha as a source of live, functional microbes. These findings support the role of kombucha as a natural functional beverage whose health benefits not only persist but may be enhanced after digestion.

Somatic cell count is used by the dairy industry as an indicator of milk quality and udder health. However, in goats, its reliability is significantly masked by noninfectious variables such as the milk secretion process and physiological lactation changes. Additionally, notable individual variability between goats might exist. This study aimed to investigate fluctuations in SCC in individual goats during an entire lactation and to examine the relationship between SCC and milk parameters such as bacterial count and chemical composition. Individual milk samples from 40 Norwegian dairy goats from the university herd were collected monthly across an entire lactation including the pasture period. The goats were categorized based on SCC levels to analyze patterns in chemical components within these groups. Notably, goats exhibited increased SCC and decreased bacterial counts when moved to summer grazing pastures. At that stage, milk samples from goats with the highest SCC (>2,000 × 10³ cells/mL) showed a distinct decrease in individual bacterial counts. The SCC level affected several milk components (especially lactose, protein, and various minerals), as well as pH. These effects were further amplified when considering the interaction with the lactation stage, influencing a broader range of variables. The results presented in this study provide new insights into the effect of SCC on milk composition and its critical role. These insights underscore the necessity for establishing lactation-specific thresholds for interpretation, as well as for making adjustments in quality payments.

Several factors influence the composition of milk. Among these, genetic variation within and between cattle breeds influences milk protein composition, protein heterogeneity, and their posttranslational modifications. Such variations may further influence technological properties, which are of importance for the utilization of milk into dairy products. Furthermore, these potential variations may also facilitate the production of differentiated products (e.g., related to specific breeds or specific genetic variants). The objective of this study was to investigate the genetic variation and relative protein composition of the major proteins in milk from 6 native Norwegian dairy breeds representing heterogeneity in geographical origin, using the modern Norwegian breed, Norwegian Red, as reference. In total, milk samples from 144 individual cows were collected and subjected to liquid chromatography-electrospray ionization/mass spectrometry-based proteomics for identification of genetic and posttranslational modification isoforms of the 4 caseins (α_S1-CN, α_S2-CN, β-CN, κ-CN) and the 2 most abundant whey proteins (α-lactalbumin and β-lactoglobulin). Relative quantification of these proteins and their major isoforms, including phosphorylations of α_S1-CN and glycosylation of κ-CN, were determined based on UV absorbance. The presence and frequency of genetic variants of the breeds were found to be very diverse and it was possible to identify rare variants of the CN, which, to our knowledge, have not been identified in these breeds before. Thus, α_S1-CN variant D was identified in low frequency in 3 of the 6 native Norwegian breeds. In general, α_S1-CN was found to be quite diverse between the native breeds, and the even less frequent A and C variants were furthermore detected in 1 and 5 of the native breeds, respectively. The α_S1-CN variant C was also identified in samples from the Norwegian Red cattle. The variant E of κ-CN was identified in 2 of the native Norwegian breeds. Another interesting finding was the identification of α_S2-CN variant D, which was found in relatively high frequencies in the native breeds. Diversity in more common protein genetic variants were furthermore observed in the protein profiles of the native breeds compared with milk from the high-yielding Norwegian Reds, probably reflecting the more diverse genetic background between the native breeds.

Little is known about the extent of variation and activity of naturally occurring milk glycosidases and their potential to degrade milk glycans. A multi-omics approach was used to investigate the relationship between glycosidases and important bioactive compounds such as free oligosaccharides and O-linked glycans in bovine milk. Using 4-methylumbelliferone (4-MU) assays activities of eight indigenous glycosidases were determined, and by mass spectrometry and ¹H NMR spectroscopy various substrates and metabolite products were quantified in a subset of milk samples from eight native North European cattle breeds. The results showed a clear variation in glycosidase activities among the native breeds. Interestingly, negative correlations between some glycosidases including β-galactosidase, N-acetyl-β-d-glucosaminidase, certain oligosaccharide isomers as well as O-linked glycans of κ-casein were revealed. Further, a positive correlation was found for free fucose content and α-fucosidase activity (r = 0.37, p-value < 0.001) indicating cleavage of fucosylated glycans in milk at room temperature. The results obtained suggest that milk glycosidases might partially degrade valuable glycans, which would result in lower recovery of glycans and thus represent a loss for the dairy ingredients industry if these activities are pronounced.

This study aimed to investigate the production of acid-coagulated fresh cheese by using slightly acid diafiltered (DF) microfiltered (MF) casein concentrates (8% protein). Three different acidifying agents were tested during DF: carbon dioxide, lactic acid, and citric acid. Fresh cheese was manufactured using acid-DF casein concentrates, or casein concentrates DF with just water, and compared with cheese manufactured using MF casein concentrates without DF. The fresh cheeses were characterized for composition, rheological, and sensorial properties. Acid-DF casein concentrates improved acidification kinetics during cheesemaking and reduced casein leakage to cheese whey, compared with cheese from regular MF casein concentrate. Among the rheological properties investigated in this study, the storage modulus of the fresh cheese was higher when DF of the casein concentrate was performed with nonacidified DF water or when DF water was acidified with citric acid. However, fresh cheese made from casein concentrate diafiltered with DF water acidified by citric acid was most liked in a sensory ranking test.

Cheese made from microfiltration (MF) retentate may suffer from textural defects due to a high Ca concentra-tion. The reduction of colloidal minerals by the acidifi-cation of milk before MF at pH below 6.0 has been well documented in the literature. This process, however, creates less valuable side streams to the MF process and induces changes in the casein micelles that negatively affect their coagulation properties. The objective of this study was to determine whether a minor reduction in pH by using different acidifiers in the diafiltration (DF) water could induce changes in composition and rennet-ing properties of the MF retentate. A 2-stage filtration process was used, with the first designed to increase the casein concentration to 8% and the second to slightly reduce the casein concentrate by 0.1 pH unit by DF, without influencing the total protein concentration. Four acidifying agents were tested during DF: lactic acid, hydrochloric acid, citric acid, and carbon dioxide. Diafiltration with water was used as a reference. At the start of DF, the retentates of acid DF had a slightly reduced pH, with an average of 0.09, whereas the pH of the reference retentate increased by an average of 0.07 unit. The reference retentate regained its starting pH by the end of DF. The carbonated retentate gradu-ally increased in pH during processing, whereas the pH of the lactic, hydrochloric, and citric acid retentates remained constant. The permeate from the lactic acid and carbonated treatments had a reduced whey protein content compared with the reference. The total P and inorganic phosphate were lowered in the retentate by using carbonation. The total amount of Mg and Na were lowered in the retentate by using citric acid. The ionic Ca content in the retentate increased with use of lactic or hydrochloric acid. The type of acidifier used reduced the rennet clotting time. Combined acidified diafiltration with a slight reduction affects the permeate composition and improves the retentate clotting time despite the minimal mineral modification.

Celiac disease (CeD) is an autoimmune enteropathy triggered by immunogenic gluten peptides released during the gastrointestinal digestion of wheat. Our aim was to identify T cell epitope-containing peptides after ex vivo digestion of ancestral (einkorn, spelt and emmer) and common (hexaploid) wheat (Fram, Bastian, Børsum and Mirakel) using human gastrointestinal juices. Wheat porridge was digested using a static ex vivo model. Peptides released after 240 min of digestion were analyzed by liquid chromatography coupled to high-resolution mass spectrometry (HPLC-ESI MS/MS). Ex vivo digestion released fewer T cell epitope-containing peptides from the ancestral wheat varieties (einkorn (n = 38), spelt (n = 45) and emmer (n = 68)) compared to the common wheat varieties (Fram (n = 72), Børsum (n = 99), Bastian (n = 155) and Mirakel (n = 144)). Neither the immunodominant 33mer and 25mer α-gliadin peptides, nor the 26mer γ-gliadin peptide, were found in any of the digested wheat types. In conclusion, human digestive juice was able to digest the 33mer and 25mer α-gliadin, and the 26mer γ-gliadin derived peptides, while their fragments still contained naive T cell reactive epitopes. Although ancestral wheat released fewer immunogenic peptides after human digestion ex vivo, they are still highly toxic to celiac patients. More general use of these ancient wheat variants may, nevertheless, reduce CeD incidence.