Factors influencing fatty acids in meat and the role of antioxidants in improving meat quality

Abstract

Meat has been identified, often wrongly, as a food having a high fat content and an undesirable balance of fatty acids. In fact lean meat is very low in fat (20-50g/kg), pork and poultry have a favourable balance between polyunsaturated and saturated fatty acids (P : S) and grazing ruminants produce muscle with a desirable n-6:n-3 polyunsaturated fatty acid ratio. In all species, meat fatty acid composition can be changed via the diet, more easily in single-stomached pigs and poultry where the linoleic, a-linolenic and long-chain polyunsaturated fatty acid content responds quickly to raised dietary concentrations. Recent work in pigs has attempted to manipulate the n-6 :n-3 ratio by feeding higher levels of a-linolenic acid (e.g. in rapeseed) or its products eicosapentaenoic acid (20: 5) and docosahexaenoic acid (22 : 6) present in fish oils. In ruminants the challenge is to increase the P : S ratio whilst retaining values for n-6 : n-3 found in cattle and sheep fed on forage diets. The saturating effect of the rumen can be overcome by feeding polyunsaturated fatty acids which are protected either chemically, by processing, or naturally e.g. within the seed coat. Some protection occurs when grain-based or grass-based diets are fed normally, leading to relatively more n-6 or n-3 fatty acids respectively. These produce different flavours in cooked meat due to the different oxidative changes occurring during storage and cooking. In pigs and poultry, high n-3 fatty acid concentrations in meat are associated with fishy flavours whose development can be prevented with high dietary (supranutritional) levels of the antioxidant vitamin E. In ruminants, supranutritional vitamin E delays the oxidative change of oxymyoglobin to brown metmyoglobin and may also influence the characteristic flavours of beef and lamb. Meat: Fatty acids: AntioxidantsIn recent years awareness of the importance of diet in human health has increased. Many authorities have recommended that the contributions of fat and especially saturated fatty acids to dietary energy intake should be reduced. In the UK recent recommendations are 35 % of energy for fat and 10 % of energy for saturated fatty acids (Department of Health, 1994). Within these general guidelines more particular advice is to reduce the intake of short-and medium-chain saturated fatty acids and the intake of n-6 polyunsaturates relative to n-3 (Gibney, 1993). Although it is the dietary balance of fatty acids in the total diet which is physiologically important, attempts have been made with many individual foods to change them in line with the new dietary guidelines in order to make them more attractive to consumers. The present paper considers the options for meat, a food which has been criticized on the grounds of its fat and fatty acid content. FAT AND FATTY ACID COMPOSITION OF RED MEATSA recent study by Bristol University investigated the fat content and composition of steaks or chops from equivalent parts of the carcass (the loin) in beef, lamb and pork. The results (Table 1) showed t...

The effect of grazing on the fatty acid profile of longissimus thoracis muscle in Galician Blond calves

“…One possible way to achieve an acceptable balance ratio in beef is to supplement animal diets with natural sources of n-3 FA, specially 18:3 n-3, which is the most predominant FA in grass lipids (Wood and Enser, 1997). Our results clearly showed that calves raised on pasture (P) presented healthy lower values (P , 0.001) for n-6:n-3 ratio than calves finishing on either a long or short concentrate-based period (C or PC, respectively).…”

Use of recovered frying oils in chicken and rabbit feeds: effect on the fatty acid and tocol composition and on the oxidation levels of meat, liver and plasma

“…In addition, the oxidative stability and shelf life of meat depend on the balance between certain FA (such as PUFA), pro-oxidants and antioxidants (Wood and Enser, 1997;Bou et al, 2009) and therefore can be also altered by the modification of the FA composition. Antioxidant vitamins, such as a-tocopherol (aT) and other tocols, contribute to decrease meat oxidability.…”

Food restriction and refeeding in lambs influence muscle antioxidant status

“…This finding has not been previously reported in the literature in which effects of diseases or of specific antioxidants such as vitamin E, vitamin C, plant extracts tested on humans and/or animals were related (Liu et al, 1995;Fano et al, 2001;Alia et al, 2003, etc.). In ruminants, the effects of various antioxidants and especially vitamin E, a liposoluble antioxidant, have been tested in animals fed diets enriched in unsaturated lipids (for review, see Liu et al, 1995;Wood and Enser, 1997;Wood et al, 2003;Durand et al, 2005).…”