Only the mollusks are considered in this book, because the crustaceans are not easily digested, and therefore are not suitable for an invalid diet.

Oysters

Oysters are valuable food for invalids and convalescents. Their nutritive value is not high, but they are easily digested and possess a delicate flavor which is acceptable to most palates.

Composition

The five food principles are represented in oysters. Reckoned as "solid," i. e., removed from the shell, oysters contain 88.3 per cent. of water, 6.1 per cent. protein, 1.4 per cent. fat, and 3.3 per cent. carbohydrate. Oysters come nearer to milk than almost any other common food material, both in amount and proportion of nutritive principles.

The carbohydrate is in the form of glycogen, being found in the liver, which constitutes a large proportion of the oyster.

Digestibility

The soft part of the oyster or clam is made up largely of the stomach and liver and is easily digested when cooked in a variety of ways - broiling, roasting, stewing, panning and steaming - but not fried when served to the sick.

The hard part of shellfish is the muscle which fastens the animal to the shell, and is rendered tougher by all forms of cooking; therefore, when whole oysters are to be eaten, they are more easily digested when served raw or broiled slightly in the shell. They can be digested by fever patients and those suffering from many forms of gastric disorders.

It is desirable in acute illness to serve only the soft part of the oyster, but in the later stages of convalescence the whole oyster can be served raw or in stew and soups, which are recommended on account of their liquid form and warmth.

When In Season

Oysters are in season from September to May. During the rest of the year they are insipid and unfit for food.

Principles To Be Carefully Observed In Serving And Cooking Oysters For The Sick

(a) Make every effort to have the oyster alive when used, or as fresh as can be obtained from a reliable dealer. Many serious cases of illness and even death have been caused by eating oysters so long dead that poisonous substances had formed in them. Great care should also be taken that oysters are not procured from beds where the water has been contaminated in any way. "As it is in general impossible to learn their origin the rule of never eating them in the raw state is adopted by many. The practice of fattening or 'floating' oysters in fresh or in brackish water robs them of much of their fine flavor, and since the most accessible supply of such water is at the outlet of streams, and as such streams are frequently polluted by sewage, many persons believe that this practice should be forbidden by law." 1

(b) Oysters contain an albuminous substance which increases in hardness with an increase of temperature, just as the albumin of an egg does. When oysters are cooked with reference to this albuminous substance, they are also cooked in the best possible manner with reference to their other constituents; therefore subject them to a low temperature, for a short time, bearing in mind that 160 to 180 degrees Fahrenheit is the cooking temperature of albumin.

General rule is to remove the oyster from heat as soon as the body grows plump and the edges curl, if cooked beyond this stage they are over-cooked.

Varieties

In New York State the "Blue Points" are considered the finest for serving raw. They come originally from Blue Point, Long Island.

In Massachusetts the "Cove" Oyster is considered the finest for serving raw. They come from a still water cove near Plymouth.