Calf’s liver should be pale and pinkish in colour; beef liver is darker and has a stronger taste and odour. Pork liver has the strongest flavour; chicken liver has the mildest. Liver should have a bright colour with a moist but not slimy surface and a fresh smell. Beef, pork, lamb, and poultry hearts tend to be tough; younger hearts are more tender. Hearts should have a fresh smell and red colour—not brown or grey. Veal or lamb kidneys should be firm, pink or pale red rather than purple, and should not have a uric acid smell. Calves liver should be a deep rose colour, not red or purple. Look for kidneys that are evenly coloured and do not have dry or dull spots. Beef, pork, and lamb brains should be firm, plump, and pinkish-white. Veal, beef, lamb, and pork sweetbreads should be plump, firm, and white. Tripe should be pale white.