Differences between people
Different people mean different things when they talk of functional quality depending on their cultural background, personal experience and where they stand in the production chain; whether farmer, processor, retailer or consumer. In other words, quality has a number of different components. While certain of these are of interest to everyone, others are only immediately important to some sectors. Meat yield mainly concerns the farmer and wholesaler, technological characteristics mainly the processor and palatability – what the meat is like to eat – the final consumer.
The cultural effect on quality perception is illustrated by the results of an interesting experiment in which the eating quality of meat from lambs produced in Spain and the UK was independently assessed by both Spanish and British taste panels (Sañudo et al., 1998). The two panels were in agreement that odour and flavour were stronger in meat from the British lambs (which were older and heavier) and that juiciness was higher in the Spanish meat. However, when the members of the taste panels were asked which meat they preferred, the British panel best liked that from the British lambs and the Spanish that from the Spanish lambs. This shows how quality preferences can be determined by previous experience and possibly conditioning. In other words, people will often most like what they are used to.
Variation with time
Concepts of quality vary over time. The main purpose of rearing pigs was originally less for their lean meat and more for the lard they produced. Pigs were selected to grow large and fat because this produced most lard. In the early North American meat industry, instead of curing the pork, meat packers would often collect the fat, rather as used to be done with whale’s blubber, by ‘trying’ it – heating the butchered carcasses in large vats or kettles to melt the fat which floated on the surface and could be ladled off. In contrast, modern North American and European pigs are relatively very lean, having been selected over the years to have less and less fat and proportionally larger muscles. At different times the highest quality has therefore been associated with both the fattest and the leanest pigs.
The major components of quality
Some components of meat quality – yield, technological properties and palatability – have already been mentioned. A full list of quality characteristics would include those in Table 6.1.
Yield and composition
The yield of product is important because it determines how much you have to sell. Higher yields mean more product and potentially greater profit. In meat terms this could mean a higher proportion of carcass relative to the weight of the live animal (a higher killing-out percent- age) or a higher yield of saleable lean and fat to non-saleable waste bone. As well as the absolute yield of lean and fat, the relative amount of lean is important. In general, a higher ratio of muscle to fat is preferred since the majority of consumers, at least in Europe and North America, want very little fat for reasons outlined in Chapter 1 and reviewed by Gibney (1993). However, fat is also associated with flavour development and so at least a minimal level is desirable. Above this level, fat will need to be trimmed leading to waste and reduced overall value. The shape of muscles is important, as well as the overall yield of lean, because this affects their attractiveness. Plump, rounded muscles are more attractive than thinner, flatter ones.
Appearance and technological characteristics
Appearance of the lean and its technological characteristics are often related. This is because factors that influence the microstructure of the muscle post mortem affect both aspects of colour and also water- holding capacity (WHC). Colour is a major determinant of appearance and WHC of technological value. Appearance is important because it is practically the only criterion the consumer can use to judge the accept- ability of most meat at purchase. This presupposes that spoilage has not resulted in an unpleasant odour as it can in fish that is not fresh.
Unlike, for example, many fruits, where the firmness or texture of the raw product is a good index of ripeness, the texture of raw meat Table 6.1. The major components of meat quality (from Warriss, 1996c).
Yield and gross composition: Quantity of saleable product Ratio of fat to lean
Muscle size and shape Appearance and technological characteristics: Fat texture and colour
Amount of marbling in lean (intramuscular fat) Colour and WHC of lean Chemical composition of lean
Palatability: Texture and tenderness
Juiciness Flavour
Wholesomeness: Nutritional quality
Chemical safety Microbiological safety
Ethical quality: Acceptable husbandry of animals
usually tells little or nothing about that of the cooked material. The lean has a characteristic colour appropriate for each species and muscle but in general it should be bright in colour, and red or pink rather than brown, purple or grey. Moreover this colour should be stable to give the product a long shelf life.
There are three main reasons why waterholding capacity is important. First, the drip or exudate that results from poor WHC detracts from the appearance of the meat. This is especially so in modern retail packs where drip tends to collect, rather than draining away, and despite the frequent inclusion of absorbent pads in the bottom of trays to soak up the liquid. Second, loss of drip leads to weight loss in fresh meat, and in processed meats poor WHC may reduce water retention and therefore yield of product. Third, WHC is thought to influence the perceived juiciness of fresh meat after cook- ing. Meat with low WHC loses a lot of fluid in cooking and may taste dry and lack succulence. Problems with the colour and WHC of the lean are exemplified by the extreme conditions referred to as PSE (pale, soft, exudative) and DFD (dark, firm, dry) meat and which will be described later. The chemical composition of the lean, in particular its protein content may be important in determining the yield and quality of processed products.
The colour and chemical composition of the fat associated with the lean are important. Generally, the preference is for white or very pale pink fat over yellow pigmentation although the latter is accepted in certain cattle such as the Channel Island breeds, for example the Jersey.
The yellow colour is caused by carotenes derived from green plants. It is therefore commoner in older animals and those that are grass-fed.
The pigments are fat-soluble and the propensity to lay them down in the fat is genetically determined. Normally, firm fat is preferred over softer, oilier unsaturated fat. Soft fat may in fact be a problem in some modern very lean pigs but is beneficial in the Spanish breed of pig used to make Iberian hams. The pigs are fed on acorns from the locally grown cork oak trees and the pigs’ fat is therefore unsaturated and soft.
In the preparation of the hams this is taken advantage of, the sub- cutaneous fat covering being carefully smoothed over the ham surface.
The fat characteristics may also contribute to the desirable distinctive flavour of the product. An important characteristic of fats is their resistance to oxidation. As we have seen in Chapter 3, this is also dependent on the degree of saturation of their component fatty acids.
Palatability
Palatability or eating quality encompasses three main characteristics.
These are texture, juiciness and flavour/odour and, at least in red and poultry meats, their importance is usually in this order. In many developed countries, people prefer their meat to be tender and the
value of different cuts or joints reflects this. Fillet steak is both the most tender and most expensive cut of beef. In some cultures this is not true.
Many Africans prefer their meat ‘chewy’. Good texture of fish flesh generally implies firm flesh, and a ‘flaky’ texture is sometimes perceived as desirable.
The extremes of juiciness are dryness and succulence. Modern meat is occasionally criticized for its lack of succulence and this is attributed to either poor WHC or low levels of intramuscular or marbling fat. Intramuscular fat has tended to be reduced with the selec- tion of animals for overall greater carcass leanness, particularly in pigs.
The human perceptions of tenderness and juiciness appear to be inter- related. Juicy meat may be perceived as more tender than a similar sample which has inherently the same texture (for example, as measured by an instrumental shear test) but is less juicy.
Flavour and odour are closely associated. Flavour is mainly determined by water-soluble constituents, odour by fat-soluble, volatile elements. Odour becomes very important if abnormal odours or taints are present. These override all other perceptions of quality.
This is of obvious selective importance since meat that smells unpleasant often does so because it has spoiled and may therefore be unsafe to eat. Not all abnormal odours are produced by spoilage. An example is the odour associated with meat from some carcasses from entire male pigs (boars). This is referred to as boar taint and is often described as faecal in character or reminiscent of urine (see below).
Women are more sensitive to certain components of boar taint and moreover find them more unpleasant than men appear to.
Wholesomeness
The wholesomeness of meat has two components. First, meat should be safe to eat, both in terms of freedom from parasites that may also infect humans, and microbiological pathogens and hazardous chemicals. People do not want to get food poisoning from eating meat.
Neither do they want to be exposed to high levels of residues from previous veterinary medication of the animal, or from growth- promoting agents (Heitzman, 1996), or from adventitious contaminants such as pesticides.
Second, as well as this, people would prefer that meat was positively beneficial to their health in contributing minerals, vitamins and high value protein, and possibly essential fatty acids, such as eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids (see Chapter 3), to their diet. The value of meat as a concentrated source of protein and energy is illustrated in Table 6.2. Only dried seeds like lentils have comparable protein contents, and only lentils or grains like rice are more concentrated sources of energy (because of their high carbo- hydrate contents). However, it should be remembered that the energy
value of meat will vary somewhat with variation in its fat content.
Much of the older information about the fat content of joints is based on analyses of meat that was much fatter than it is today. It came from fatter animals and was less closely trimmed of subcutaneous and inter- muscular fat during butchery. For example, a boneless pork chop with 15 mm of subcutaneous fat might contain nearly 30% chemical fat.
Trimming to 5 mm could reduce this to about 10% and some very lean pork may contain less than 3% fat. Carefully trimmed beef topside and rump steak may also now contain only 3–4% fat. As mentioned previously, meat is an important source of the B vitamins and various minerals (Table 6.3) including iron, zinc, phosphorus, potassium and magnesium.
Table 6.2. The protein, fat and energy content of some foods (based on data from McCance and Widdowson, 1997).
Percentage Percentage Energy content
protein fat (kJ 100 g!1)
Lean beef 20 5 517
Lean lamb 21 9 679
Lean pork 21 7 615
Skinless chicken 21 4 508
Herring 17 19 970
Potatoes 2 0.2 318
Peas 7 2 344
Carrots 1 0.3 146
Cabbage 2 0.4 109
Rice 7 3 1518
Lentils 24 2 1264
Table 6.3. The concentrations of iron, zinc and five vitaminsain meat and vegetables (based on data from McCance and Widdowson, 1997).
Iron Zinc Thiamine Riboflavin Niacin B6 B12
Lean beef 2.1 4.3 0.07 0.24 5.2 0.32 2
Lean lamb 1.6 4.0 0.14 0.28 6.0 0.25 2
Lean pork 0.9 2.4 0.89 0.25 6.2 0.45 3
Potatoes 0.4 0.3 0.21 0.02 0.6 0.44 0
Peas 2.8 1.1 0.74 0.02 2.5 0.12 0
Carrots 0.3 0.1 0.10 0.01 0.2 0.14 0
Cabbage 0.7 0.3 0.15 0.02 0.5 0.17 0
Rice 1.4 1.8 0.59 0.07 5.3 – 0
Lentils 11.1 3.9 0.41 0.27 2.2 0.93 0
a Iron, zinc, thiamine, riboflavin, niacin and vitamin B6 concentrations in mg 100 g!1; concentration of vitamin B12 in µg 100 g!1.
In some regards, different types of meat may be better or worse in terms of their potential contribution to a healthy diet. This is exemplified by the characteristics of the fat in beef, lamb and pork, particularly the ratios of polyunsaturated to saturated fatty acids (the P:S ratio) they contain and the ratios of the n!6 to n!3 polyunsaturated acids (Wood and Enser, 1997). Values of 0.45 or above for the P:S ratio, and 4.0 or below for the n!6:n!3 ratio in dietary fats have been recommended in the UK. The ratios reported by Wood and Enser (1997) in UK meat are given in Table 6.4, together with their measurements of the proportion of dissectable fat in retail joints. Pork has the best P:S ratio (0.58), well above the recommended value, but the meats from the two ruminant species have the best n!6:n!3 ratios. However, the n!6:n!3 ratio for pork (7.22) is higher than desirable. Therefore, from one point of view pork is the healthiest of the three meats to consume, from another the least healthy.
Ethical quality
The last major component of meat quality, ethical quality, might be disputed by some. However, there is concern amongst many people that meat should come from animals which have been bred, reared, handled and slaughtered in ways that promote their welfare (see Chapter 10) and in systems which are sustainable and environmentally friendly.
Problems of conflicting requirements for different quality characteristics Achieving some quality characteristics may be incompatible with achieving others. Juiciness is associated with higher levels of intra- muscular (marbling) fat, but larger amounts of marbling are often found in meat that also has larger amounts of subcutaneous and inter- muscular fat. As we have seen, consuming large quantities of fat is undesirable from the point of view of health. There is thus a potential dilemma that meat which is healthier for us to consume is likely to be
Table 6.4. The dissectable fat content, P:S and n!6:n!3 ratios of beef steaks, and pork and lamb chops in the UK (based on data in Wood and Enser, 1997).
Percentage dissectable fat P:S ratioa n!6:n!3 ratiob
Beef 15.6 0.11 2.11
Lamb 30.2 0.15 1.32
Pork 21.1 0.58 7.22
aThe ratio of polyunsaturated to saturated fatty acids.
bThe ratio of n!6:n!3 polyunsaturated acids.
less juicy, and therefore have a poorer eating quality, than meat which is fatter and therefore less healthy. Health and palatability are to a degree incompatible, since the requirements for wholesomeness and eating quality are conflicting. It was mentioned that soft fat can be a problem in modern very lean pigs. This is because soft fat does not support the lean as effectively as firm fat and therefore may result in poorer muscle shape and less firm overall texture to the joint. However, softer fat contains a higher proportion of unsaturated fatty acids, which are healthier to eat. Again, one quality characteristic, appearance of the joint, is difficult to maintain while also achieving another, healthiness of the fat. A very effective way of improving carcass quality through reducing fatness is to use entire, rather than castrated, male animals, but the resulting lean meat may have less desirable eating qualities.
The problem of boar taint has been mentioned and there is a suggestion that beef from young bulls may be less tender than that from steers (Morgan et al., 1993).
Nitrite is used in the production of cured meats like ham and bacon (see Chapter 9). It reacts with the myoglobin to give the attrac- tive characteristic pink colour of these products. It also inhibits the growth of pathogenic bacteria like Clostridium, but the consumption of nitrite has been implicated in the potential development of some cancers. Nitrite therefore has both beneficial and potentially undesir- able characteristics as a meat additive.
Rapid carcass cooling inhibits the growth of microorganisms, so reducing potential spoilage, and also reduces weight losses by evapora- tion of water from the surface layers. However, cooling too rapidly may lead to less tender meat, either by reducing the activity of the naturally occurring proteolytic enzymes or by inducing cold shortening (see Chapter 8). There are thus both positive and negative consequences of rapid carcass chilling.