Meat quality can be defined in several terms according to the purpose. A definition made by Andersen, Oksbjerg, Young & Therkildsen (2005) described meat quality as a complex and multivariate property of meat, which is influenced by multiple interacting factors including the conditions under which the meat is produced. Warriss (2000) divided meat quality in two types of quality; the functional quality referring to the characteristics of the meat and secondly the conformance quality meeting the consumers requirements. In more detail this includes yield and gross composition, appearance and technological characteristics, palatability, wholesomeness and ethical quality. The different quality characteristics may conflict with
21 each other. A solution suggested was to further divide the quality traits into three distinct qualities, the first taking care of the wholesomeness and that the product should be safe to consume, the second meeting the processing demands and the third covering requirements as appearance, convenience and eating quality (Kaufmann et al. 1990 cited by Warriss (2000)).
It is when the consumers recognize a quality trait and appreciate it, that the intended quality trait may be a competitive trait for food producers (Grunert, 2005). The quality has gained focus among the consumers the recent years. To meet the market requirements it is necessary to know the factors affecting quality. There are several ways of changing the intrinsic pork quality; this includes nutrition, genetic breed, sex, age, body weight, hormones, pre-slaughter handling, carcass treatment and processing. This thesis will focus on the sensory attributes colour, odour and flavour, technological quality of meat and fat and finally the nutritional quality.
1.3.1 Sensory quality
When a consumer’s decision to purchase pork is made, the appearance is very important since it is the only way acceptability can be judged. The appearance is mainly dependent on colour, fat and drip loss. Meat colour is determined by to main factors; the state and content of haem myoglobin and secondly the muscle structure. The state of myoglobin can appear as purple red deoxymyoglobin (Mb), bright red oxymyoglobin (MbO2) or the brownish metmyoglobin (MetMb). Available oxygen will affect the colour by reacting with Mb towards MbO2 and make a brighter red colour. This is why blooming is used to standardize the colour measurement in meat.
Fat colour is dependent on the composition of fat tissue and can vary from clear white to light pink. It is suggested that increased unsaturation of fatty acids leads to a greyer appearance of fat tissues (Lebret & Mourot, 1998). Young animals have generally a higher content of unsaturated fatty acids than older animals and the incidence of discoloration towards grey or yellow is more common (Wood, 1984). Warnants, Van Oeckel & Boucque (1996) found a pink backfat colour in thin bakcfat layers. A high content of linoleic acid has shown a yellow fat colour (Maw, Fowler, Hamilton & Petchey, 2003).
Bryhni et al. (2003) found a correlation between the consumers satisfaction and consumption indicating a higher consumption when a higher quality of pork is available. Consumers are influenced by the appearance of pork but the palatability traits texture and flavour are also
22 important sensory traits (Aaslyng et al., 2007). Juiciness and tenderness is according to Risvik (1994) an easy and good way of describing texture. A newly finished marketing study with students in Tromsø discovered that young consumers have a preference towards healthy products that are easy to prepare (Roaldstveit, 2010). This study also emphasises the sensory traits; good odour and flavour, appearance and texture as contributing factors when the consumers make a decision.
1.3.2 Technological quality
The technological quality of fat can best defined by the firmness and the preferred fat is normally firm and white compared to soft, yellow and oily fat. Soft fat may lead to increased fat layer separation in loins. Soft fat can be recognized by a high content of PUFA (Madsen, Jakobsen & Mortensen, 1992). Several quality criteria’s has been proposed concerning fat quality. These are mainly linked to individual fatty acids, ratios of fatty acids or combinations of fatty acids.
Iodine value gives an estimate on the overall unsaturation and is being used as a quality parameter of backfat. Lea, Swaboda & Gatherum (1970) suggested an iodine value below 65 to obtain good quality while a value higher than 70 was considered as soft fat. Later Barton-Gade (1987) concluded that as long as the iodine value was below 70 it would be of acceptable quality.
The fatty acid C18:0 (Wood, Jones, Bayntun & Dransfield, 1985) or the C16:0/C18:2n-6 ratio (Whittington, Prescott, Wood & Enser, 1986) has been proposed as good indicators of firmness. Girard (1988) also claimed that fat should contain at least 12% C18:0 to obtain good fat quality.
A high content of PUFA may reduce the oxidative stability since PUFA are more susceptible to oxidation than saturated fatty acids. Limitations in feed of 50 g PUFA/kg feed have been suggested to reduce problems with oxidation (Bryhni et al., 2002b). In a study with different dietary PUFA levels it was concluded that the maximum threshold of dietary PUFA should be limited to 18 g/kg and a maximum of 22% PUFA in backfat (Warnants, Van Oeckel &
Boucque, 1996)
23 1.3.3 Nutritional quality
The pig has been blamed for a high fat content with a high content of saturated fat. The heritability for lean meat percentage is high across sex with heritabilities between 0.40 and 0.57 (Hallenstvedt & Pedersen, 2004). Norwegian Landrace had in 1933-1944 a backfat thickness of 35.1 mm, this was reduced to 34.1 mm in 1952/53 (Altern, 1955) and nowadays backfat thickness is reported to be around 15 mm (Overland, Kjos, Olsen & Skrede, 2005).
Due to breeding schemes towards leaner breeds most pigs produced are lean with reduced fat content. Lower backfat thickness has shown a higher PUFA content (Wood et al., 2008).
The fatty acids C18:2n-6 and C18:3n-3 are essential fatty acids for humans. C18:3n-3 can be elongated and desaturated into VLC n-3 fatty acids C20:5, C22:5 and C22:6 but this process seems to be limited to produce C20:5n-3 and C22:5n-3 in humans (Brenna, Salem, Sinclair &
Cunnane, 2009). There may be gender effects, men being less capable than woman to produce C22:6n-3 (Burdge, 2006). The positive health effects of VLC n-3 fatty acids in connection with cardiovascular diseases are well established (Baghurst, 2004). Providing dietary n-3 fatty acids the content will be deposited in the pork and increase the nutritional quality. Increased dietary n-3 fatty acids will also reduce the C20:4n-6. This is considered to be positive since C20:4n-6 has been reported to enhance the blood supply to cancer cells (Hyde & Missailidis, 2009).
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