Producing over-fat carcases for processors supplying the major retailers is not a good idea, as they are heavily penalised and have taken a lot of food to produce – fat costs about three times more than lean per kg. Yet processors want some fat, due to its role in eating quality. Fat provides flavour and retains moisture in the meat during cooking. Fat inside muscle, marbling fat, improves all aspects of taste – particularly juiciness and tenderness.
In some countries, marbling fat development in the loin is assessed during grading and contributes positively to price. High prices are paid for well-marbled kobe beef in Japan. Duroc pigs produce high scores in taste panel tests because of more marbling fat. However, although cookery writers and TV chefs extol the virtues of marbling fat, many British shoppers are put off buying meat with streaks of fat running through it, in the belief that it is ‘unhealthy’. In fact, the fat inside muscle only amounts to about 5% of the muscle weight in well-marbled beef or pork.
Adverse publicity against meat on nutritional grounds is often over-done. Saturated fat, of the type which raises blood cholesterol, is about 25% of the total fat and this is balanced by about 35% monounsaturated fat – which is the main constituent of ‘healthy’ olive oil. There are also healthy polyunsaturated fatty acids in meat – especially in pork. Research shows that meat can be enhanced nutritionally by including polyunsaturated fatty acids in the diet – pork of the highest nutritional value can be produced by feeding linseed. Grass-fed beef and lamb have the advantage of containing healthy Omega 3 fatty acids..
Jeff Wood, professor of food animal science, Bristol University