Elsevier

Meat Science

Volume 76, Issue 4, August 2007, Pages 787-795
Meat Science

Influence of slaughter season and muscle type on fatty acid composition, conjugated linoleic acid isomeric distribution and nutritional quality of intramuscular fat in Arouquesa-PDO veal

https://doi.org/10.1016/j.meatsci.2007.02.023Get rights and content

Abstract

The effects of the slaughter season and muscle type on lipid and conjugated linoleic acid (CLA) contents, fatty acid composition and isomeric profile of CLA in Arouquesa veal, from calves reared according to the specifications of the protected designation of origin (PDO), were assessed. Arouquesa purebred calves (n = 31) were raised in a traditional production system, slaughtered in early autumn (October) or late spring (June), and the longissimus dorsi and semitendinosus muscles were sampled for analysis. Arouquesa-PDO veal only showed seasonal differences in the levels of some minor fatty acids (16:1c9, 17:1c9, 18:1t, 18:3n  3, 20:0 and 22:4n  6) and CLA isomers (t12,t14, t9,t11 and c11,t13). Furthermore, significant interactions between the slaughter season and muscle type were obtained for several fatty acids and CLA isomers, total lipids and CLA, and the PUFA/SFA ratio. In both seasons, veal-PDO depicts values of pasture-fed cattle. From a human nutritional perspective, veal-PDO in both slaughter seasons has relatively high CLA contents and percentages of the c9,t11 CLA isomer, which is favourable, while the n  6/n  3 ratios are within the recommended values for the human diet. In conclusion, the results suggest that intramuscular fat in Arouquesa-PDO veal has high nutritional value throughout the year.

Introduction

In most industrialized countries, a high meat intake contributes to higher than recommended total fat (15–30% of calories) and saturated fatty acids (SFA; <10% of calories) intakes (World Health Organization, 2003), which are associated with an increased risk of obesity, hypercholesterolemia and some cancers (Wood et al., 2004). Meat accounts for 10–20% of the total calories in human diets and ruminant meats are high in SFA (up to 50%) (Chizzolini, Zanardi, Dorigoni, & Ghidini, 1999). In addition, it is well known that the lower polyunsaturated fatty acids to SFA (PUFA/SFA) and higher n  6/n  3 ratios in some meats contribute to the imbalance in the fatty acid intake of today’s consumers (Wood et al., 2004). Furthermore, typical western diets display low ratios of PUFA/SFA, which have been considered as major risk factors for cardiovascular diseases, and high n  6/n  3 ratios (15–17/1), which favour the development of cardiovascular diseases, cancer and inflammatory and autoimmune diseases (Simopoulos, 2002).

Conjugated linoleic acid (CLA) comprises a group of positional (from positions 6,8- to 12,14-) and geometric (trans,trans, trans,cis, cis,trans and cis,cis) isomers of linoleic acid (18:2n  6), containing conjugated double bonds, with a multitude of potential health benefits (Prates and Mateus, 2002, Tricon and Yagoob, 2006, Wahle et al., 2004). Twenty different CLA isomers have been reported as occurring naturally in food, especially in ruminant fat (Sehat et al., 1998). The major CLA isomer, rumenic acid (18:2c9,t11), is produced in the rumen during microbial biohydrogenation of dietary 18:2n  6 and in the tissues through delta9 desaturation of 18:1t11 (Griinari & Bauman, 1999). It is now accepted that the major contribution to 18:2c9,t11 present in ruminant milk (Corl et al., 2002) and meat (Palmquist, St-Pierre, & McClure, 2004) is the endogenous synthesis. Some of CLA isomers exhibit interesting biological activities that include anticancerinogenic, anti-obesity, antidiabetogenic, anti-atherogenic, immunomodulation and modulation of bone growth (Belury, 2002).

Lipid content and composition in veal is mainly influenced by the feeding system, age, slaughter weight and duration of milk consumption (Moreno et al., 2006). Meats with protected designation of origin (PDO) are certified by European Union legislation and are expected to present unique quality and organoleptic characteristics, especially associated with specific properties of its lipid fraction (Council Regulation No. 2081/92 of 14/7, EEC). In Portugal, meat from autochthonous bovine breeds, reared in traditional production systems, has been progressively reintroduced in human diets as a result of its high intrinsic quality (Costa, Roseiro, Cunat, Alves, & Santos, 2003) and of public perception of BSE and chemical residues safety issues (Rodrigues, Andrade, & Rodrigues, 1998). One such example is Arouquesa-PDO veal, obtained from Arouquesa purebred calves, produced in some councils within the Districts of Aveiro, Viseu, Porto and Vila Real (Centre-North of Portugal), based on a traditional production pasture-based system according to the product specifications.

In previous reports we described the lipid composition and nutritional value of three Portuguese traditional meats: Carnalentejana-PDO beef (Alfaia et al., 2006a), Mertolenga-PDO beef (Alfaia et al., 2006b) and Barrosã-PDO veal (Alfaia et al., 2007). In addition, we reported cholesterol, tocopherols and β-carotene contents in Barrosã-PDO veal (Prates, Quaresma, Bessa, Fontes, & Alfaia, 2006). Arouquesa-PDO veal is another important commercial Portuguese meat-PDO (40 carcass tons in 2003; Instituto do Desenvolvimento Rural e Hidráulica, 2003), in increasing demand by consumers. In spite of this, scientific information available to support the claimed quality and reputation, mainly dependent on its lipid composition, is scarce. Moreover, little work has been conducted to assess the effects of slaughter season and muscle type on meat CLA profiles. Therefore, the aim of this work was to characterise the influence of the slaughter season and muscle type on the content, composition and nutritional value of the intramuscular fat in Arouquesa-PDO veal.

Section snippets

Reagents

Analytical grade and liquid chromatographic grade chemicals were purchased from Merck Biosciences (Darmstadt, Germany). Sodium methoxide (0.5 M solution in anhydrous methanol) was obtained from Sigma–Aldrich Ltd. (St. Louis, MO, USA) and the fatty acid methyl ester (FAME) standard mixtures were acquired from Nu-Chek-Prep Inc. (Elysian, MN, USA) and Supelco Inc. (Bellefonte, PA, USA). Commercial standards of individual CLA isomers (18:2c9,t11, 18:2t10,c12, 18:2c9,c11 and 18:2t9,t11) as methyl

Intramuscular fatty acid composition

The influence of slaughter season and muscle type on fatty acid composition (wt%) of intramuscular fat in Arouquesa-PDO veal is presented in Table 1. In both seasons, the predominant fatty acids in intramuscular fat were 16:0 (23–24% of total FAME) and 18:0 (14–17%) as SFA, 18:1c9 (34–35%) as monounsaturated fatty acids (MUFA), and 18:2n  6 (3–5%) as PUFA. Similar results have been found by many other authors in cattle (e.g. Nuernberg et al., 2005, Raes et al., 2003a, Realini et al., 2004). The

Conclusions

Arouquesa-PDO veal only showed seasonal differences in the levels of some minor fatty acids and CLA isomers. In addition, significant interactions between slaughter season and muscle type were observed for several fatty acids and CLA isomers, total lipid and CLA, and the PUFA/SFA ratio. The data indicate that Arouquesa-PDO veal has similar values to pasture-fed cattle, in both slaughter seasons, with regard to the content of several fatty acids, some partial sums of fatty acids, n  6/n  3 ratio,

Acknowledgements

Sampling assistance (Eng. Manuel Cirnes and Dr. Carlos Venâncio, ANCRA – Associação Nacional dos Criadores da Raça Arouquesa, Cinfães), doctorate fellowship (SFRH/BD/2005/22566 to Susana Martins) and financial support (Grants AGRO/2003/512, POCTI/CVT/2002/44750 and CIISA/2002/52) are acknowledged.

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