Acute Stress-Induced Changes in the Lipid Composition of Cow's Milk in Healthy and Pathological Animals.

Producers of milk and dairy products have been faced with the challenge of responding to European society's demand for guaranteed animal welfare production. In recent years, measures have been taken to improve animal welfare conditions on farms and evaluation systems have been developed to certify them, such as the Welfare Quality® protocol. Among the markers used for this purpose, acute phase proteins stand out, with haptoglobin being one of the most relevant. However, the diagnostic power of these tools is limited and more sensitive and specific technologies are required to monitor animal health status. Different factors such as diet, stress, and diseases modify the metabolism of the animals, altering the composition of the milk in terms of oligosaccharides, proteins, and lipids. Thus, in order to study oxidative-stress-associated lipids, a collection of well-characterized milk samples, both by veterinary diagnosis and by content of the acute stress biomarker haptoglobin, was analyzed by mass spectrometry and artificial intelligence. Two lipid species (sphingomyelin and phosphatidylcholine) were identified as potential biomarkers of health status in dairy cows. Both lipids allow for the discrimination of milk from sick animals and also milk from those with stress. Moreover, lipidomics revealed specific lipid profiles depending on the origin of the samples and the degree of freedom of the animals on the farm. These data provide evidence for specific lipid changes in stressed animals and open up the possibility that haptoglobin could also affect lipid metabolism in cow's milk.

Modelling microbial growth in modified-atmosphere-packed hake (Merluccius merluccius) fillets stored at different temperatures.

Market globalization and changes in purchasing habits pose a challenge to the fishery industry because of the short shelf life of fish products. In view of this scenario, it would be very helpful if tools capable of predicting the shelf-life of fish could be developed. Thus, the objective of this study was to employ a modelling approach capable of predicting the evolution of the microbiota of hake fillets packaged under a modified atmosphere (MAP) rich in CO2 (50% CO2 / 50% N2) when stored at temperatures ranging between 1 and 10 °C. Growth curves of ten microbial groups were obtained at four different temperatures and fitted with the Baranyi model. Photobacterium showed high growth rates in hake fillets (0.99 days-1 at 4 °C), similar to those of Shewanella, lactic acid bacteria, and non-specific microbial groups investigated, and significantly higher than those of Pseudomonas. Furthermore, no lag phase was observed for Photobacterium regardless of the temperature investigated. On the other hand, Enterobacteriaceae and moulds and yeasts displayed low growth fitness, and their counts increased by <1.5-2 Log10 cycles along the incubation period regardless of storage temperature. The influence of storage temperature on growth parameters (λ, µmax and Yend) was subsequently studied, and secondary models were developed for the eight most relevant microbial groups. All of the final equations developed in this study showed R2 values ≥0.90, and RMSE values ≤0.50. In addition, results obtained in this investigation strongly suggest that Photobacterium would be the main responsible microorganism for the spoilage of hake fillets stored under MAP conditions (50% CO2/50% N2) along the entire range of temperatures investigated (1-10 °C).

Characterization of the Spoilage Microbiota of Hake Fillets Packaged Under a Modified Atmosphere (MAP) Rich in CO2 (50% CO2/50% N2) and Stored at Different Temperatures.

The aim of this study was to characterize the spoilage microbiota of hake fillets stored under modified atmospheres (MAP) (50% CO2/50% N2) at different temperatures using high-throughput 16S rRNA gene sequencing and to compare the results with those obtained using traditional microbiology techniques. The results obtained indicate that, as expected, higher storage temperatures lead to shorter shelf-lives (the time of sensory rejection by panelists). Thus, the shelf-life decreased from six days to two days for Batch A when the storage temperature increased from 1 to 7 °C, and from five to two days-when the same increase in storage temperature was compared-for Batch B. In all cases, the trimethylamine (TMA) levels measured at the time of sensory rejection of hake fillets exceeded the recommended threshold of 5 mg/100 g. Photobacterium and Psychrobacter were the most abundant genera at the time of spoilage in all but one of the samples analyzed: Thus, Photobacterium represented between 19% and 46%, and Psychrobacter between 27% and 38% of the total microbiota. They were followed by Moritella, Carnobacterium, Shewanella, and Vibrio, whose relative order varied depending on the sample/batch analyzed. These results highlight the relevance of Photobacterium as a spoiler of hake stored in atmospheres rich in CO2. Further research will be required to elucidate if other microorganisms, such as Psychrobacter, Moritella, or Carnobacterium, also contribute to spoilage of hake when stored under MAP.

Dataset on the use of the Ratkowsky model for describing the influence of storage temperature on microbial growth in hake fillets (Merluccius merluccius) stored under MAP.

This article presents the results obtained after applying the Ratkowsky model for developing secondary models describing the influence of storage temperature on microbial growth in hake fillets packaged under a modified atmosphere (MAP) rich in CO2 (50% CO2/50% N2). For this purpose the growth parameters (λ, µmax) already calculated in the related article "Modelling microbial growth in Modified-Atmosphere-Packed hake (Merluccius merluccius) fillets stored at different temperatures" [1] were used. The data include the fit and goodness of the fit parameters calculated as well as the comparison between fitted and observed data.

Solid state and solution studies of lithium tris(n-butyl)magnesiates stabilised by Lewis donors.

Several Lewis base adducts of the synthetically important lithium tris(n-butyl)magnesiate LiMg((n)Bu)3 have been prepared and structurally characterised. The complexes were prepared by a co-complexation approach i.e., by combining the monometallic (n)BuLi and (n)Bu2Mg reagents in hydrocarbon solution before adding a molar equivalent of a donor molecule (a bidentate amine, tridentate amine or cyclic ether). The lithium magnesiates all adopt variants of the "Weiss motif" structure, i.e., contacted ion pair dimers with a linear arrangement and metals connected by butyl anions, where tetrahedral magnesium ions are in the central positions and the lithiums occupy the outer region, solvated by a neutral Lewis donor [(donor)Li(µ-(n)Bu)2Mg(µ-(n)Bu)2Mg(µ-(n)Bu)2Li(donor)]. When TMPDA, PMDETA or (R,R)-TMCDA [TMPDA = N,N,N'N'-tetramethylpropanediamine; PMDETA = N,N,N',N'',N''-pentamethyldiethylenetriamine; and (R,R)-TMCDA = (R,R)-N,N,N',N'-tetramethylcyclohexane-1,2-diamine], are employed, dimeric tetranuclear lithium magnesiates are produced. Due to the tridentate nature of the ligand, the PMDETA-containing structure (2) has an unusual 'open'-motif. When TMEDA (TMEDA = N,N,N',N'-tetramethylethylenediamine) is employed, a n-butoxide-containing complex [(TMEDA)Li(µ-(n)Bu)(µ-O(n)Bu)Mg2((n)Bu)2(µ-(n)Bu)(µ-O(n)Bu)Li(donor)] has been serendipitously prepared and adopts a ladder conformation which is commonly observed in lithium amide chemistry. This complex has also been prepared using a rational methodology. When 1,4-dioxane is employed, the donor stitches together a polymeric array of tetranuclear dimeric units (6). The hydrocarbon solution structures of the compounds have been characterised by (1)H, (7)Li, (13)C NMR spectroscopy; 2 has been studied by variable temperature and DOSY NMR.

Optimisation of a lithium magnesiate for use in the non-cryogenic asymmetric deprotonation of prochiral ketones.

A study has been conducted to determine whether lithium magnesiates are feasible candidates for the enantioselective deprotonation of 4-alkylcyclohexanones. The commercially available chiral amine (+)-bis[(R)-1-phenylethyl]amine (2-H) was utilised to induce enantioselection. When transformed to its lithium salt and combined with (n)Bu2Mg, improved enantioselective deprotonation of 4-tert-butylcyclohexanone (with respect to the monometallic lithium amide) at 20 °C was observed. In an attempt to optimise the reaction further, different additives were added to the lithium amide. The best performing deprotonations at 0 °C were those in which (Me3SiCH2)2Mg (er pro-S 74 : 26) and (Me3SiCH2)2Mn (er pro-S 72 : 28) were added, hence the lithium magnesiate "LiMg(2)(CH2SiMe3)2" was used in the remainder of the study. The optimum solvent for the reaction was found to be THF. NMR spectroscopic studies of a D8-THF solution of "LiMg(2)(CH2SiMe3)2" appear to show that this mono-amide bis-alkyl species is in equilibrium with a bis-amide mono-alkyl compound (and a tris-alkyl lithium magnesiate). When a genuine bis-amide lithium magnesiate solution is used, the deprotonation results were essentially identical to those obtained for "LiMg(2)(CH2SiMe3)2". By adding LiCl to "LiMg(2)(CH2SiMe3)2" the er at 0 °C improved to 81 : 19. At -78 °C good yields and an er of 93 : 7 were obtained. This LiCl-containing base was used to successfully deprotonate other 4-alkylcyclohexanones.