Oliva Polvillo

Comparison of four extraction/methylation analytical methods to measure fatty acid composition by gas chromatography in meat

Four different extraction-derivatization methods commonly used for fatty acid analysis in meat (in situ or one-step method, saponification method, classic method and a combination of classic extraction and saponification derivatization) were tested. The in situ method had low recovery and variation. The saponification method showed the best balance between recovery, precision, repeatability and reproducibility. The classic method had high recovery and acceptable variation values, except for the polyunsaturated fatty acids, showing higher variation than the former methods. The combination of extraction and methylation steps had great recovery values, but the precision, repeatability and reproducibility were not acceptable. Therefore the saponification method would be more convenient for polyunsaturated fatty acid analysis, whereas the in situ method would be an alternative for fast analysis. However the classic method would be the method of choice for the determination of the different lipid classes.

Meat and fat quality of unweaned lambs as affected by slaughter weight and breed.

Sixty-four male lambs of two Southern Spanish breeds, a dairy breed (Grazalema Merino) and a meat breed (Churra Lebrijana), were used to study the effects of slaughter weight and breed on meat traits and intramuscular and subcutaneous fat composition. Lambs were reared following a traditional production system without weaning and slaughtered when live weight reached 12kg (suckling) or 20kg (light). Meat from suckling lambs of both breeds had lower fat and myoglobin contents, and was more tender and had higher scores for sustained juiciness in the sensory analysis. Fat from light lambs had lower C12:0 and C14:0 levels than fat from suckling lambs. Grazalema Merino meat had higher fat and ash contents, and its fat had higher conjugated linoleic acid content than Churra Lebrijana meat.

Breed effect on carcass and meat quality of foals slaughtered at 24 months of age.

In some areas, horsemeat may be considered as an alternative to beef. And recent studies have shown that it may be positive from a nutritional point of view. However, little research has been done on the effects that influence horse carcass traits and meat quality. Breed effect has been studied by comparing two Spanish local breeds (Burguete and Hispano-Bretón) reared following the same traditional production system (24months old). Some differences between breeds were observed for carcass quality measurements and colour parameters. Proximate composition was generally not affected by breed. Burguete foals had lower SFA and MUFA and higher PUFA than Hispano-Bretón ones. PUFA/SFA ratio from both breeds was higher than 0.4 and CLA levels were similar to those found in ruminants.

Preferential accumulation of selectively preserved biomacromolecules in the humus fractions from a peat deposit as seen by analytical pyrolysis and spectroscopic techniques

Abstract A series of structural features of the three main humic fractions (humic acid, fulvic acid and humin) from different depths of a peat bog deposit in Mazagon (Huelva, Southern Spain) were isolated and analysed by flash pyrolysis–gas chromatography–mass spectrometry, solid-state 13C-nuclear magnetic resonance and Fourier transformed infrared spectroscopy. Such techniques demonstrate that the various humic fractions were very different not only in terms of molecular weight but also in their composition and structural characteristics, showing well differentiated patterns in the relative distribution of alkyl, O-alkyl and aromatic moieties in each humic fraction. To a large extent, selectively preserved lignin accumulates in the humic acid (HA) fraction, whereas the fulvic acid (FA) consists of a colloidal carbohydrate with a substantial peptidic moiety and the humin includes the noteworthy concentration of insoluble, macromolecular polyalkyl structures. A diagnostic lignin signature in the resolution-enhanced infrared spectra of the HA points to processes of selective preservation of macromolecular substances derived from vascular plants. In general, the humic fractions were not extensive sources of chemotaxonomic descriptors of previously documented biodiversity changes along the period of the peat deposit formation. This is in harmony with a substantial homogenising effect of diagenetic transformations throughout the whole sedimentary record with peat stratigraphy recording mostly the authigenic processes of bog formation and development. Anthropogenic perturbations may be also responsible for the loss of information in the humic proxy resulting in the lack of an apparent relationship between any particular input and the composition of the humic fractions from the peat bog.

Near Infrared Spectroscopy (NIRS) for the determination of the milk fat fatty acid profile of goats

Milk fatty acid (FA) composition is important for the goat dairy industry because of its influence on cheese properties and human health. The aim of the present work was to evaluate the feasibility of NIRS reflectance (oven-dried milk using the DESIR method) and transflectance (liquid milk) analysis to predict milk FA profile and groups of fats in milk samples from individual goats. NIRS analysis of milk samples allowed to estimate FA contents and their ratios and indexes in fat with high precision and accuracy. In general, transflectance analysis gave better or similar results than reflectance mode. Interestingly, NIRS analysis allowed direct prediction of the Atherogenicity and Thrombogenicity indexes, which are useful for the interpretation of the nutritional value of goat milk. Therefore, the calibrations obtained in the present work confirm the viability of NIRS as a fast, reliable and effective analytical method to provide nutritional information of milk samples.

Associations between DGAT1, FABP4, LEP, RORC, and SCD1 gene polymorphisms and fat deposition in Spanish commercial beef

The objective of the present study was to assess the frequency distribution of markers in the diacylglycerol acyltransferase (DGAT1), fatty acid binding protein 4 (FABP4), leptin (LEP), retinoic acid receptor-related orphan receptor C (RORC), and stearoyl-CoA desaturase (SCD1) genes in a Spanish commercial crossbred population (n = 286) produced in southwest Spain. We have also evaluated the association of these 5 major SNP with backfat thickness (BFT) and intramuscular fat (IMF) to use them routinely in the industry (if the associations are confirmed) due to their ease of use. The KK genotype of the DGAT1 gene was associated (P = 0.046) with the greatest BFT value. Bulls presenting the GG genotype for SNP in the FABP4 gene showed greater values for the percentage of IMF (P = 0.030), which means an increase of 0.155% IMF per copy of the G allele of this marker (P = 0.009). A significant association was found between the RORC: g.3290T > G marker and the percentage of IMF. The GG genotype of the RORC: g.3290T > G marker showed the lowest IMF percentage (P = 0.025). The specific associations found in this study not only provide information about the involvement of these genes in the fat deposition at different levels in the southwestern Spain cattle population, but can also serve as a tool to improve certain meat quality attributes through Marker Assisted Selection. However, sensory studies are needed to explore further the usefulness of these genes in meat quality and the impact on the actual palatability of the beef.

Meat quality of tenderloin from Iberian pigs as affected by breed strain and crossbreeding

In 2007, a new National Quality Standard was published in Spain to regulate the products derived from the Iberian pig carcass, including for the first time fresh meat. In the same way, four different Iberian strains were recognized as official (Lampiño, Entrepelado, Retinto and Torbiscal). A batch (n=10) of each pig strain was selected using neutral DNA markers, and another batch of the most common crossbreeding pigs (Iberian×Duroc) was included into the study as a control. The main meat quality parameters of tenderloin, the most expensive meat cut for fresh consumption, from those five pig groups were analysed. Retinto and Lampiño strains showed the closest phenotypic distances, followed by Entrepelado strain. Meat from crossed and Torbiscal pigs had lower water holding capacity, L∗ and a∗, and higher SFA than meat from the other three strains. Crossbred pigs had the lowest protein, intramuscular fat and PUFA contents.

Pleiotropic effects of the goat prolactin receptor genotype on milk fatty acid composition.

In the lactating mammary gland, prolactin (PRL) stimulates the synthesis of lactose as well as fatty acid uptake, lipogenesis, and triacylglycerol synthesis. Associations between bovine PRL receptor (PRLR) genotype and fat yield have been reported, which illustrates the role of PRL in conveying lipids toward the udder as well as in stimulating their local synthesis during lactation. Conversely, and to the best of our knowledge, the effects of PRLR genotype on milk fatty acid content have not been studied so far in any mammalian species. In this study, we sequenced most of the coding region of the caprine PRLR gene in several individuals from the Malagueña and Murciano-Granadina breeds. This approach allowed us to identify 2 long and short mRNA isoforms, produced by alternative splicing, and 4 single-nucleotide polymorphisms (SNPs), namely, c.177T>C, c.1131G>A, c.1201G>A and c.1355C>T. Two of these SNPs are nonsynonymous and involve G401R (c.1201G>A) and T452I (c.1355C>T) amino acid substitutions in the cytoplasmic domain of PRLR, which plays a fundamental role in signal transduction. Performance of an association analysis with milk composition traits in a Murciano-Granadina goat population revealed highly suggestive effects on palmitoleic acid content, whereas suggestive effects were detected for other fatty acids, such as palmitic and linoleic. These results are consistent with the pleiotropic effects of PRL on mammary gland lipid metabolism and milk composition.

Association Study Between a SNP in Bovine SCD1 Gene with Fatty Acid Composition in a Spanish Commercial Population Fed with Two Different Diets

Stearoyl-CoA desaturase (SCD1 gene) is an enzyme responsible for the endogenous conversion of saturated fatty acid into monounsaturated fatty acids. The objective of this study was to assess the association of a single nucleotide polymorphism (SNP) in the SCD1 gene with the fatty acid composition of beef intramuscular fat of a Spanish commercial bull population (n = 155) finished with two different diets. The results suggested that the marker could be used as a candidate gene to obtain a healthier final product.

Genetic variation at the goat hormone-sensitive lipase ( LIPE) gene and its association with milk yield and composition.

Hormone-sensitive lipase (LIPE) plays a fundamental role in the regulation of energy balance by releasing free fatty acids from adipose triacylglycerol stores. These fatty acids can be subsequently transferred to other body compartments to be oxidized or employed in other biochemical reactions. This enzymic function is particularly important in lactating animals because the synthesis of milk components involves the mobilization of lipid depots to satisfy the large energy demands of the mammary gland. In the current study, we partially sequenced the goat LIPE gene in several individuals. In doing so, we identified two synonymous polymorphisms at exons 2 (c.327C>A>T, triallelic polymorphism) and 3 (c.558C>T). Moreover, we found a mis-sense polymorphism at exon 6 (c.1162G>T) that involves an alanine to serine substitution at position 388. Analysis with Polyphen and Panther softwares revealed that this amino acid replacement is expected to be neutral. Performance of an association analysis with a variety of milk traits revealed that goat LIPE genotype has highly suggestive effects on milk yield (P=0.0032) as well as on C18:3 n-6g (P=0.0051), trans-10 cis-12 CLA (P=0.007) and C12:0 (P=0.0084) milk contents. These associations are concordant with the preference of LIPE to selectively mobilize medium-chain and unsaturated fatty acids.