Grazing season and forage type influence goat milk composition and rennet coagulation properties

Two different types of pasture (cultivated and rangeland) and 2 different hay qualities (high and low quality) were examined for their effects on goat milk composition and rennet coagulation properties. Furthermore, the effect of dietary treatments in both the early and late grazing season was studied. As lactation stage is known to influence milk composition, the goats in the early and late grazing season were in the same lactation stage at the start of the experiment. The milk composition was influenced both by dietary treatment and season. Milk from goats on pasture was superior to those on hay by containing a higher content of protein and casein, and the goats on cultivated pasture had the highest milk yield. Casein composition was significantly influenced by forage treatment. Goats grazing on cultivated pasture had higher contents of αs1-casein and also of κ-casein compared with the other treatments, whereas goats grazing on rangeland had the highest content of β-casein. Factors such as milk yield, casein micelle size, αs2-casein, and calcium content were reduced in late compared with early season. More favorable rennet coagulation properties were achieved in milk from the early grazing season, with shorter firming time and higher curd firmness compared with milk from the late grazing season, but the firming time and curd firmness were not prominently influenced by forage treatment. The content of αs2-casein and calcium in the milk affected the firming time and the curd firmness positively. The influence of season and forage treatment on especially milk yield, casein content, and rennet coagulation properties is of economic importance for both the dairy industry and goat milk farmers

Structural rheological properties of model nutritional beverage emulsions stabilized by bovine lactoferrin: Influence of pH and oil type

The objective of this study was to demonstrate the microstructure and rheological properties of model beverage emulsions containing 1% (w/w) canola oil (CO) or rice bran oil (RBO) stabilized by bovine lactoferrin (bLF) 1% (w/w) subjected to highly acidic and neutral pH conditions. The o/w emulsions were characterized using phase contrast microscopy, confocal scanning laser microscopy and image analysis and rheology. Both CO and RBO emulsions exhibited pseudo-plastic behaviour with the flow behaviour index values being less than 1. Irrespective of pH, a difference between CO and RBO emulsions with respect to median droplet size was observed (p<0.05), which might be attributed to the differences in density and viscosity of the respective dispersed phases. The differences in surface hydrophobicity and electrostatic charge of bLF between pH 2 and 7 influenced the emulsion properties. The results might have implications in formulating highly acidic/neutral nutritional beverages containing n-3 and n-6 fatty acids and lactoferrin

Comparison of the digestion of caseins and whey proteins in equine, bovine, caprine and human milks by human gastrointestinal enzymes

The aim of this study was to compare the digestion of milk proteins from different species using an in vitro gastrointestinal model. Raw and heated milks from bovine, caprine, human and equine species were digested by human digestive enzymes. Digestion was performed in two 30-min sequential steps by digestive juices from the stomach (pH 2.5/37 °C) and from the duodenum (pH 8.0/37 °C). The degradation patterns of the milk proteins were visualized by SDS-PAGE and quantified using the ImageQuant program. Caseins in the equine milk were rapidly digested by the gastric juice in contrast to the caseins from the other species. During the subsequent digestion by the duodenal juice most of the caseins from all species were degraded within 5 min, and within 30 min only traces of caseins were detected. The mean casein micellar size varied between species in the range of 146.0–311.5 nm (equine > caprine > bovine > human). The α-lactalbumin from all species appeared to be very resistant to both gastric and duodenal digestions. A similar trend was shown for β-lactoglobulin from bovine and caprine milks, of which ~ 60% intact protein remained, while only 25% remained intact in equine milk after total digestion. Equine milk contained a high amount of lysozyme, of which 60% remained intact in the present study. In heated milks from all species, only α-lactalbumin degradation increased approximately 12–20% in comparison to the raw milk. This study shows that equine milk with fast digestible proteins could be considered as a replacement for bovine milk in the diet of people with special needs, such as infants and the elderly

Quantification of undersea gas leaks from carbon capture and storage facilities, from pipelines and from methane seeps, by their acoustic emissions

In recent years, because of the importance of leak detection from carbon capture and storage facilities and the need to monitor methane seeps and undersea gas pipelines, there has been an increased requirement for methods of detecting bubbles released from the seabed into the water column. If undetected and uncorrected, such leaks can generate huge financial and environmental losses. This paper describes a theory by which the passive acoustic signals detected by a hydrophone array can be used to quantify gas leakage, providing a practical (as opposed to research), passive and remote detection system which can monitor over a period of years using simple instrumentation. The sensitivity in detecting and quantifying the flux of gas is shown to exceed by more than two orders of magnitude the sensitivity of the current model-based techniques used commercially for gas leaks from large, long pipelines