Mariza Gomes Reis

Direct analysis of fatty acid profile from milk by thermochemolysis–gas chromatography–mass spectrometry

The fatty acid composition of milk is of considerable interest due to their nutritional and functional properties. Although rapid milk fat separation and transesterification procedures have been developed, the overall procedure remains time consuming, specially, for the analysis of a large number of samples. In this work, a fast and simple method for direct profiling of fatty acids from milk using thermochemolysis has been developed. This method has the capability of directly analyse fatty acids from one drop of milk without fat extraction or cleanup. Our approach for thermochemolysis is based on thermal desorption integrated with a cold trap inlet. The optimized method does not present isomerisation/degradation of polyunsaturated fatty acid and shows milk fatty acid profiles comparable to the conventional method based on fat extraction and alkaline transesterification. Overall, this method has demonstrated significant potential for high throughput analysis of fatty acids in milk.

Impact of dietary dairy polar lipids on lipid metabolism of mice fed a high-fat diet

The effect of milk polar lipids on lipid metabolism of liver, adipose tissue, and brain and on composition of intestinal microbiota was investigated. C57BL/6J mice were fed a high-fat diet (HFD) for 5 weeks, followed by 5 weeks with HFD without (control) or supplemented with total polar lipids (TPL), phospholipids (PL), or sphingolipids (SPL). Animals fed SPL showed a tendency for lower triglyceride synthesis (P = 0.058) in the liver, but not in adipose tissue. PL and TPL reduced de novo hepatic fatty acid biosynthesis. The ratio of palmitoleic to palmitic acid in the liver was lower for animals fed SPL or TPL compared to control. There was little effect of the supplementation on the cecal microbiota composition. In the brain, DHA (C22:6) content correlated negatively with tetracosanoic acid (C24:0) after TPL supplementation (-0.71, P = 0.02) but not in control (0.26, P = 0.44). Arachidonic acid (C20:4) was negatively correlated with C24:0 in both groups (TPL, -0.77, P = 0.008; control, -0.81, P = 0.003).

Characterization of volatile metabolites associated with confinement odour during the shelf-life of vacuum packed lamb meat under different storage conditions.

Confinement odour was investigated. Volatiles were extracted directly from the pack, using solid phase microextraction and analysed by gas chromatography-mass spectrometry. Sensory evaluation and microbiological analysis of the meat surface were also performed. Commercial samples of vacuum packed lamb legs (n=85), from two meat processing plants, were kept for 7weeks at -1.5°C then at different regimes of temperature (-1.5 to +4°C) until 11, 12 or 13weeks. Persistent odour was observed in 66% of samples, confinement odour in 24% and no odour in 11%. Volatiles associated with confinement odour (3-methyl-butanal, 3-hydroxy-2-butanone and sulphur dioxide) corresponded with end/sub products of glucose fermentation and catabolism of amino acids by bacteria (all bacteria naturally found in meat and do not represent a risk to health). Confinement odour could indicate a stage at which the environment for bacteria growth is becoming favourable for the production of volatiles with strong odours that are noticed by the consumer.

Effect of Dietary Complex Lipids on the Biosynthesis of Piglet Brain Gangliosides

Gangliosides, found in mammalian milk, are known for their roles in brain development of the newborn. However, the mechanism involved in the impact of dietary gangliosides on brain metabolism is not fully understood. The impact of diets containing complex lipids rich in milk-derived ganglioside GD3 on the biosynthesis of gangliosides (assessed from the incorporation of deuterium) in the frontal lobe of a piglet model is reported. Higher levels of incorporation of deuterium was observed in the GM1 and GD1a containing stearic acid in samples from piglets fed milk containing 18.2 μg/mL of GD3 compared to that in those fed milk containing 25 μg/mL of GD3. This could suggest that the gangliosides from the diet may be used as a precursor for de novo biosynthesis of brain gangliosides or lead to the reduction of de novo biosynthesis of these gangliosides. This effect was more pronounced in the left compared to that in the right brain hemisphere.

Aplicação do modelo Tucker-3 para a análise da biodegradação de diesel

Tucker-3 model offers several advantages for analysis of environmental data but its interpretation is still challenging. A Tucker-3 model was applied to a biodegradation experiment involving a large number of overlapped chromatographic peaks and a temporal variation. The Tucker-3 model allowed the data to be decomposed in two processes: evaporation and biodegradation. The results suggest that linear hydrocarbons were those biodegraded first and demonstrate that the data analysis can be simplified by interpreting the elements of the core array. The approach discussed in this work can be applied in similar problems involving multi-way data in other areas of chemistry.

Distribution of fatty acids and phospholipids in different table cuts and co-products from New Zealand pasture-fed Wagyu-dairy cross beef cattle

Wagyu beef products are marketed as luxury goods to discerning consumers and the lipid content and composition are important drivers of wagyu product value. Wagyu beef is an extensively marbled meat product, well characterised for its tenderness and flavour. In New Zealand, pasture-fed Wagyu-dairy beef production is increasing to meet demand for ultra-premium meat products. Important for these characteristics is the composition of lipid species and their distribution across the carcass. The aim of this study was to analyse the distribution of fatty acids and phospholipids in 26 table cuts, nine co-products and three fat deposits of carcasses from New Zealand pasture-fed Wagyu-dairy cross beef carcasses (n = 5). Phospholipid and fatty acid levels varied across different cuts of the carcass, but typically cuts with high levels of phospholipids also had high levels of omega-3 fatty acids and low levels of saturated fatty acids. This work will be used in the future to examine the potential health aspects of pasture-fed Wagyu beef.

Effect of animal age on the nutritional and physicochemical qualities of ovine bresaola

Bresaola made from New Zealand mutton and lamb, were compared in quality attributes. Mutton bresaola had slightly lower protein and higher moisture contents, and similar amount of intramuscular fat and instrumental colour compared to that of the lamb. 36 and 80 unique endogenous peptides were observed in mutton and lamb, respectively. Proteolysis during dry-curing was affected by the age of the animal and has resulted in softer and easier to chew textural properties to the mutton bresaola. Significantly higher amounts of total free amino acids and higher proportion of essential amino acids were detected in the mutton bresaola from digestion simulation compared to that from lamb. Expedited proteolysis measured in the form of the release of free amino acids was positively related to the animal age. Overall, bresaola from mutton had more favourable characteristics compared to that of the lamb.

Effects of season and industrial processes on volatile 4-alkyl-branched chain fatty acids in sheep milk

4-alkyl-branched-chain fatty acids (vBCFAs) are responsible for the goaty-sheepy flavour of sheep and goat milk. The levels of vBCFAs were investigated in sheep, goat and cow milk powders. The effect of season and industrial processes on the levels of vBCFAs in sheep milk was also evaluated. Sheep milk powders contained lower amounts of 4-Me-8:0 and 4-Et-8:0 (143-176 and 1.2-10.7 µg/g milk fat) than goat milk powders (335-481 and 73.1-105 µg/g milk fat), while 4-Me-9:0 was low in both sheep and goat milk powders (<8 µg/g milk fat). Odour activity values (OAVs) of sheep milk powders (17-393) were 6-fold lower than the values of goat milk powders (882-1323). Higher levels of vBCFAs were found in sheep milk produced in spring than in summer. Thermisation had little impact on vBCFAs; however, spray drying led to dramatic increases in free vBCFAs, particularly towards late lactation, which resulted in higher OAVs in sheep milk powder compared to raw milk.

Isotopic labeling of milk disialogangliosides (GD3).

The most abundant ganglioside group in both human milk and bovine milk during the first postnatal week is ganglioside GD3. This group of disialogangliosides forms up to 80% of the total ganglioside content of colostrum. Although dietary gangliosides have shown biological activity such as improvement of cognitive development, gastrointestinal health, and immune function, there is still a gap in our understanding of the molecular mechanisms governing its uptake and the metabolic processes affecting its bioavailability. The use of isotopically labeled ganglioside to track the bioavailability, absorption, distribution, and metabolism of gangliosides may provide key information to bridge this gap. However, isotope labeled GD3 is not commercially available and its preparation has not been described. We report for the first time the preparation of labeled GD3 with stable isotopes. Using alkaline hydrolysis, we were able to selectively remove both acetyl groups from the tetrasaccharide portion of GD3 without promoting significant hydrolysis of the ceramide portion of the molecule to generate N-deacetyl-GD3 (Neu5α2-8Neu5-GD3). The N-deacetyl-GD3 was then chemoselectively re-acetylated in aqueous medium using deuterated acetic anhydride in the presence of Triton X 100 to produce 2H6-GD3 {GD3[(Neu5Ac-11-2H3)-(Neu5Ac-11-2H3)]}. This method provided 2H6-GD3 with approximately 60% yield. This compound was characterized by proton nuclear magnetic resonance (1H NMR) and liquid chromatography mass spectrometry (LC-MS). The oral absorption of the 2H6-GD3 was demonstrated using a Sprague-Dawley weaning rats. Our results indicate that some ingested labeled milk gangliosides are absorbed and transported into the bloodstream without modification.