ing the smoking and curing of meats, no
appreciable losses of nutrients occur.[51] The smoke acts as a
preservative, and imparts condimental properties. Saltpeter (potassium
nitrate) has been used from earliest times in the preparation of meats;
it preserves color and delays fermentation changes. When used in
moderate amounts it cannot be regarded as a preservative or injurious to
health. Excessive amounts, however, are objectionable. Smoked meats,
prepared with or without saltpeter, give appreciable reactions for
nitrites, compounds formed during combustion of the wood by which the
meat was smoked. Many vegetables contain naturally much larger amounts
of nitrates, taken from the soil as food, than meat that has been
preserved with saltpeter.[52]

137. Poultry.--The refuse and waste from chickens, as purchased on the
market, ranges from 15 to 30 per cent. The fat content is much lower
than in turkeys or ducks, the largest amount being found in geese. The
edible portion of all fowls is rich in protein, particularly the dark
meat, and the food value is about equal to that of meat in general. When
it is desired to secure a large amount of protein with but little fat,
chicken supplies this, perhaps, better than any other animal food. A
difference is observed in the composition of the meat of young and old
fowls similar to that between beef and veal. The physical composition
and, to a slight extent, the solubility of the proteids are altered by
prolonged cold storage, the difference being noticeable mainly in the
appearance of the connective tissue of the muscles. In discussing
poultry as food, Langworthy states:[53]

"A good, fresh bird shows a well-rounded form, with neat, compact
legs, and no sharp, bony angles on the breast, indicating a lack of
tender white meat. The skin should be a clear color (yellow being
preferred in the American market) and free from blotches and pin
feathers; if it looks tight and drawn, the bird has probably been
scalded before being plucked. The flesh should be neither flabby
nor stiff, but should give evenly and gently when pressed by the
finger."

138. Fish.--From 30 to 60 per cent of the weight of fresh fish is
refuse. The edible portion contains from 35 to 50 per cent, and in some
cases more, of water. The dry matter is rich in protein; richer than
many meats. The nutrients in fish range between comparatively wide
limits, the protein in some cases