Effect of dietary carnosic acid on the fatty acid profile and flavour stability of meat from fattening lambs

Thirty-two lambs were fed with barley straw supplemented by a concentrate alone, or a concentrate enriched with either vitamin E (VITE006: 0.6 g kg⁻¹ feed concentrate) or carnosic acid (CARN006: 0.6 g kg⁻¹ feed concentrate; or CARN012: 1.2 g kg⁻¹ feed concentrate). In order to elucidate the influence of the dietary supplementation of carnosic compared with a reference diet antioxidant (vitamin E), the animals were slaughtered and the longissimus thoracis were lyophilised to determine the FAs profile and the phenolic compounds. In addition, longissimus lumborum slices were stored in a modified atmosphere package for 3 days and then grilled to determine volatile compounds. Dietary carnosic acid did not modify the FAs profile, but had a clear effect on the production of volatile compounds, in a dose-dependent manner. These results have implications for the food industry, since dietary carnosic acid seems to extend the shelf life of lamb meat.     

Enzymatic activity of lactic acid bacteria (with antimicrobial properties) isolated from a traditional Spanish cheese

Twenty-four strains of lactic acid bacteria (LAB) isolated from a traditional Spanish cheese (Genestoso cheese) were evaluated for their enzymatic activities (acidifying and proteolytic abilities and carboxypeptidase, aminopeptidase, dipeptidase, caseinolytic and esterase activities), in order to select indigenous strains of technical interest for the manufacture of cheese. These strains were selected on the basis of their antimicrobial activity relative to five reference strains and were identified as Lactococcus lactis subsp. lactis (thirteen strains), Leuconostoc mesenteroides (two strains), Leuconostoc pseudomesenteroides (one strain), Lactobacillus paracasei (two strains), Lactobacillus plantarum (one strain) and Enterococcus faecalis (five strains).     

A poro-thermoelastic problem with dissipative heat conduction

Abstract

In this work, we study from the mathematical and numerical points of view a poro-thermoelastic problem. A long-term memory is assumed on the heat equation. Under some assumptions on the constitutive tensors, the resulting linear system is composed of hyperbolic partial differential equations with a dissipative mechanism in the temperature equation. An existence and uniqueness result is proved using the theory of contractive semigroups. Then, a fully discrete approximation is introduced applying the finite element method to approximate the spatial variable and the implicit Euler scheme to discretize the time derivatives. A discrete stability property is obtained. A priori error estimates are also shown, from which the linear convergence of the approximation is derived under suitable additional regularity conditions. Finally, one- and two-numerical simulations are presented to demonstrate the accuracy of the algorithm and the behavior of the solution.     

Deletion of the N-terminal domain of the yeast vacuolar (Na+,K+)/H+ antiporter Vnx1p improves salt tolerance in yeast and transgenic Arabidopsis

Cation/proton antiporters play a major role in the control of cytosolic ion concentrations in prokaryotes and eukaryotes organisms. In yeast, we previously demonstrated that Vnx1p is a vacuolar monovalent cation/H⁺ exchanger showing Na⁺/H⁺ and K⁺/H⁺ antiporter activity. We have also shown that disruption of VNX1 results in an almost complete abolishment of vacuolar Na⁺/H⁺ exchange, but yeast cells overexpressing the complete protein do not show improved salinity tolerance. In this study, we have identified an autoinhibitory N-terminal domain and have engineered a constitutively activated version of Vnx1p, by removing this domain. Contrary to the wild type protein, the activated protein has a pronounced effect on yeast salt tolerance and vacuolar pH. Expression of this truncated VNX1 gene also improves Arabidopsis salt tolerance and increases Na⁺ and K⁺ accumulation of salt grown plants thus suggesting a biotechnological potential of activated Vnx1p to improve salt tolerance of crop plants.     

Effects of linseed and quercetin added to the diet of fattening lambs on the fatty acid profile and lipid antioxidant status of meat samples

Thirty-two Merino lambs fed barley straw and a concentrate formulated either with palm oil (CTRL group) or with linseed (+ LS group), both alone or supplemented with quercetin (+ QCT group or + LS + QCT group) were used to assess the effects of these dietary supplements on meat quality attributes. After being slaughtered, the longissimus thoracis muscles were used to study the fatty acid (FA) profile in detail, whilst longissimus lumborum slices were stored under refrigerated conditions to determine the lipid stability. Linseed increased the content of highly unsaturated n − 3 long-chain fatty acid (20:5n − 3; 22:5n − 3; 22:6n − 3). Interestingly, a significant increment of rumenic acid content (9c,11t-18:2) was observed when this seed was administered together with dietary quercetin. Moreover, the feeding of quercetin resulted in a reduction in the proportion of saturated FA and a decrease in lipid peroxidation of meat when the lambs were fed linseed. In conclusion, from both a nutritional and a commercial (shelf-life) point of view, it may be useful to include a source of quercetin when lambs are fed linseed diets.     

Derivatization of fatty acids and its application for conjugated linoleic acid studies in ruminant meat lipids

Conjugated linoleic acid (c9, t11 CLA) is a dietary fatty acid produced mainly by ruminant animals and exhibits promising health‐promoting biological effects. For lipid fatty acid composition analyses, including CLA, lipids must be pre‐treated so that the free and esterified fatty acids (triacylglycerols, phospholipids, etc) are available for determination. The most common treatments involve fatty acid methyl ester derivatives from relatively simple chemical reactions, but this becomes complicated when esterification of CLA is involved because of potential changes in its positional and geometrical isomers by reaction with certain reagents. In this review we explain concisely the advantages and disadvantages of the most popular methods (acid‐ and base‐catalysed methods) generally employed for total fatty acid derivatization and their determination on a gas chromatograph. Based on our experiences we put forward the (trimethylsilyl)diazomethane method as an alternative and successful approach for ruminant tissue lipid determinations. Copyright © 2005 Society of Chemical Industry     

Simultaneous and Fast Determination of Malachite Green, Leucomalachite Green, Crystal Violet, and Brilliant Green in Seafood by Ultrahigh Performance Liquid Chromatography–Tandem Mass Spectrometry

A new procedure has been developed for the simultaneous analysis of malachite green (MG), leucomalachite green (LMG), crystal violet (CV), and brilliant green (BG) in seafood using a modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) procedure and subsequent determination by ultrahigh performance liquid chromatography coupled to tandem mass spectrometry in <5.5 min. The developed method was validated at 2, 10, 25, and 100 μg kg^?1, obtaining recoveries in the range of 48–112 %, with repeatability and interday precision values (expressed as relative standard deviation) ≤17 and ≤24 %, respectively. Matrix effect was evaluated for different types of seafood (shrimp, salmon, and trout), indicating that shrimp can be chosen as representative matrix for the determination of the selected dyes, except for LMG. Limits of quantification (LOQs) were <0.5 μg kg^?1, which were always below the minimum required performance limits established by the European Union. The decision limit (CC_α) and detection capability (CC_β) values were also estimated in the three matrices evaluated, and CC_β ranged from 0.46 to 1.22 μg kg^?1. Finally, several types of seafood were analyzed, and some dye residues (MG, CV and BG) were detected in a salmon sample.