Comparison of bovine milk oligosaccharides in native North European cattle breeds.

Milk oligosaccharides are of high interest due to their bioactive properties. This study is the first to characterise milk oligosaccharides from native North European cattle breeds, as represented by 80 milk samples collected from eight native breeds originated from Norway (Norwegian Doela cattle and Norwegian Telemark cattle), Sweden (Swedish Mountain cattle), Denmark (Danish Red anno 1970), Iceland (Icelandic cattle), Lithuania (native Lithuanian Black and White) and Finland (Western Finncattle and Eastern Finncattle). Using high-performance liquid-chromatography chip/quadrupole time-of-flight mass-spectrometry, 18 unique monosaccharide compositions and a multitude of isomers were identified. No N-glycolylneuraminic acid was identified among these breeds. Western Finncattle milk was most abundant in neutral, acidic and fucosylated oligosaccharides. Further, Eastern Finncattle milk was significantly higher in acidic oligosaccharides and Icelandic cattle milk significantly higher in fucosylated oligosaccharides, compared to the mean. This study highlights specific native breeds of particular interest for future exploitation of milk oligosaccharides and breeding strategies.

Effect of sprouting on the proteome of chickpea flour and on its digestibility by ex vivo gastro-duodenal digestion complemented with jejunal brush border membrane enzymes.

The demand for sustainably produced proteins is increasing with the world population and is prompting a dietary shift toward plant sourced proteins. Vegetable proteins have lower digestibility and biological value compared to animal derived counterparts. We explored sprouting of chickpea seeds as a strategy for improving digestibility. Protein evolution associated with by the sprouting process was assessed by proteomics. The sprouting induced breakdown of seed storage proteins and doubled the release of free alpha-amino nitrogen in sprouted chickpea flour. During sprouting, several enzymes involved in plant development were newly expressed. An ex vivo model of gastroduodenal and jejunal digestion was applied to assess the bioaccessibility of the protein digests. Proteins from chickpea sprouts showed a greater susceptibility to digestion with a 10% increase in alpha amino nitrogen. Peptides with potential immunoreactivity or bioactivity were catalogued in both digested chickpea sprouts and seeds using an in-silico approach. Peptides belonging to the non-specific transfer proteins, which are allergens in pulses, and peptides belonging to an IgE-binding hemagglutinin protein could only be identified in the digested chickpea sprouts. The observation collected paved the way to immune-based evaluations to assess the effect of germination on the allergenic potential.

Different digestion of caprine whey proteins by human and porcine gastrointestinal enzymes.

The objective of the present study was twofold: first to compare the degradation patterns of caprine whey proteins digested with either human digestive juices (gastric or duodenal) or commercial porcine enzymes (pepsin or pancreatic enzymes) and second to observe the effect of gastric pH on digestion. An in vitro two-step assay was performed at 37 degrees C to simulate digestion in the stomach (pH 2, 4 or 6) and the duodenum (pH 8). The whey proteins were degraded more efficiently by porcine pepsin than by human gastric juice at all pH values. Irrespective of the enzyme source, gastric digestion at pH 2 followed by duodenal digestion resulted in the most efficient degradation. Lactoferrin, serum albumin and the Ig heavy chains were highly degraded with less than 6 % remaining after digestion. About 15, 56 and 50 % Ig light chains, beta-lactoglobulin (beta-LG) and alpha-lactalbumin remained intact, respectively, when digested with porcine enzymes compared with 25, 74 and 81 % with human digestive juices. For comparison, purified bovine beta-LG was digested and the peptide profiles obtained were compared with those of the caprine beta-LG in the digested whey. The bovine beta-LG seemed to be more extensively cleaved than the caprine beta-LG in the whey. Commercial enzymes appear to digest whey proteins more efficiently compared with human digestive juices when used at similar enzyme activities. This could lead to conflicting results when comparing human in vivo protein digestion with digestion using purified enzymes of non-human species. Consequently the use of human digestive juices might be preferred.

Impact of Interfacial Composition on Emulsion Digestion Using In Vitro and In Vivo Models.

This study explored the influence of different emulsification layers as mono- and bilayers on lipid digestion by using in vitro and in vivo digestion methods. The monolayer emulsion of rapeseed oil contained whey proteins and the bilayer emulsion, whey proteins and carboxymethyl cellulose. The in vitro digestion using human gastrointestinal enzymes showed that the lipid digestion as free fatty acids was slowed down in the bilayer emulsion compared with the monolayer. Droplet size was still low in the gastric phase and pseudoplasticity was well preserved (even though viscosity decreased) during in vitro gastrointestinal digestion. The in vivo studies confirmed a lower fat bioavailability from bilayer emulsions by a reduction in the triglyceride level in the blood of rats, fed by the bilayer emulsion. The results clearly showed that lipid digestion was slower in the bilayer emulsion than in the monolayer. These results provide bio-relevant information about the behavior of emulsions upon digestion. PRACTICAL APPLICATION: The layer-by-layer production approach that was presented here allows the preparation of emulsions with slower fat bioavailability. Such behavior of the bilayer emulsion made it interesting for the formulation of food products with low fat bioavailability.

Effect of human and simulated gastric juices on the digestion of whey proteins and carboxymethylcellulose-stabilised O/W emulsions.

In this study, we analysed the impact of carboxymethylcellulose (CMC) on lipid digestion and physicochemical properties of whey proteins (WP)-stabilised emulsions during in vitro digestion with either artificial or human gastrointestinal juices. The emulsions were made by adsorbing WP on the fat droplets and subsequently adding CMC, which does not interact with the adsorbed proteins. The limited hydrolysis of lipids and their higher physical stability was recorded for WP-stabilised emulsions in the presence of CMC under simulated gastrointestinal conditions. The possible mechanism by which CMC lowers the digestion of WP-stabilised emulsions is related to the limited interaction of fat droplets with gastrointestinal fluids due to the extended thickening network formed by CMC in the continuous phase. The digestion of WP- and CMC-stabilised emulsions in the in vitro model with human gastric fluids led to greater lipid hydrolysis, although the enzymatic activity in both in vitro models was observed at the same level.

Bovine lactoferrin digested with human gastrointestinal enzymes inhibits replication of human echovirus 5 in cell culture.

Many infant formulas are enriched with lactoferrin (Lf) because of its claimed beneficial effects on health. Native bovine Lf (bLf) is known to inhibit in vitro replication of human enteroviruses, a group of pathogenic viruses that replicate in the gut as their primary infection site. On the basis of a model digestion and human gastrointestinal enzymes, we hypothesized that bLf could retain its antiviral properties against enterovirus in the gastrointestinal tract, either as an intact protein or through bioactive peptide fragments released by digestive enzymes. To test our hypothesis, bLf was digested with human gastric juice and duodenal juice in a 2-step in vitro digestion model. Two gastric pH levels and reduction conditions were used to simulate physiological conditions in adults and infants. The antiviral activity of native bLf and of the digested fractions was studied on echovirus 5 in vitro, using various assay conditions, addressing several mechanisms for replication inhibition. Both native and digested bLf fractions revealed a significant inhibitory effect, when added before or simultaneously with the virus onto the cells. Furthermore, a significant stronger sustained antiviral effect was observed when bLf was fully digested in the gastric phase with fast pH reduction to 2.5, compared with native bLf, suggesting the release of antiviral peptides from bLf during the human digestion process. In conclusion, this study demonstrates that bLf may have a role in the prevention of human gastrointestinal virus infection under physiological conditions and that food containing bLf may protect against infection in vivo.