PART III. FISH FOODS. (continued 2)
Reading edition
Drying and Salting Fish.
—The preservation of fish by pickling, salting, drying, and smoking is a great industry and produces some of the most palatable products. Mackerel, herring, and cod are types of fish which upon proper curing make a most delectable dish. Nothing but encouragement should be given to industries of this kind, but in order that they be of their true value they should be conducted properly with due regard to hygienic principles and for the sole purpose of making a wholesome and palatable product.
Adulteration of Fish Products.
—Attention has already been called to the adulteration of salmon by canning an inferior grade or even a different kind of fish under the name of a better species. The same remark may be made respecting all fish, hake, haddock, and cusk being often offered as cod. In the case of sardines a similar practice is in vogue, and the small herring which are captured off the coast of Maine are often sold under the name of sardines. The substitution of one variety of fish for another, however, is injurious only in the way of fraud, the substitute fish presumably being of equal wholesomeness to the other under whose name it is sold. On the contrary, the form of sophistication which permits the introduction of deleterious substances into fish food is highly objectionable from the dietetic point of view. Following the general principles of nutrition, all chemical, non-condimental preservatives are to be rigidly excluded from fish products. This rule excludes boric acid, borax, benzoic acid and benzoates, sulfites, formaldehyde, and all other forms of chemical preservatives.
When fish are packed in oil the character of the oil used should be made known to the consumer. Especially is this true if from the locality where the fish is preserved and the general method of packing the consumer is led to believe that a high-grade oil such as olive oil has been used.
Value of Fish as Food.
—From the statements which have been made in connection with fish in particular and the analyses which have been given it is seen that fish is a food of a peculiarly nitrogenous character. The edible portions, exclusive of water, are at least three-fourths, and probably more composed of protein. The other edible nutritive product is fat or fish oil. The mineral nutrients compose the remaining edible portion of fish after the protein and fat are considered. The mineral portions of fish cannot be regarded as not nutritious since they contain phosphoric acid and lime, which are essential ingredients of food. The flesh of fish, however, as it has been seen, is not a complete ration, but is lacking in carbohydrates, and for this reason fish should be eaten with potatoes, rice, or other highly starchy foods. The value of fish as a food is unquestionable and its more general consumption would doubtless prove beneficial.
Those who live in the interior of large and extensive regions where fresh water fish are not very abundant do not appreciate the value of fish as food as do those who live upon the coasts washed by salt water and near the interior fresh waters where an abundant supply of fish is secured.
SHELLFISH.
Clams.
—Clams are shellfish which, though not so extensively used as the oyster, are valued food products. The clams of commerce are of two kinds. The species known as long or soft clam is abundant on the New England coast, and is of considerable commercial importance both fresh and as a canned product. This is the clam used at clam bakes, for which the New England coast is famous. Its technical name is Mya arenaria.
The other species, the round or hard clam, northward known as quahog, is the most common clam of the markets south of New York. Its scientific name is Venus mercenaria.
A very small round clam is known as the little neck. This has a flavor which is extremely delicate and it takes the place, in the warm months, of the blue point oyster on the menus of the hotels and restaurants. The clam may be considered as a supplemental shellfish to the oyster, being most delicious and most abundant during the closed oyster season. The average weight of the round clam is about 60 grams, of which about one-fourth is flesh, one-fourth liquid, and one-half shell and refuse. There are many specimens very much larger than this but the weight is given for those usually eaten.
Composition of Clams.
—Edible portion:
Water, 78.57 percent
Protein, 14.86 „
Fat, 1.78 „
Ash, 2.49 „
Undetermined, 2.30 „
The liquid which escapes upon the opening of the shell is composed chiefly of water and salt and its composition is as follows:
Water, 96.02 percent
Protein, .65 „
Fat, None
Common salt, 2.81 „
Undetermined, .52 „
The flesh of clams, it is seen, is not very different from that of fish in general. It is composed chiefly of water and of the nutrients the protein is the predominating constituent. The ash content is somewhat higher than is the case with fish.
If the flesh and fluid substance of the clam be considered together the composition of the whole mass is represented by the following data:
Water, 86.11 percent
Protein, 8.71 „
Fat, 1.01 „
Ash, 2.63 „
Undetermined, 1.54 „
Composition of Water-free Substance of the Flesh.—
Protein, 69.37 percent
Fat, 8.32 „
Ash, 11.64 „
Undetermined, 10.67 „
Composition of the Dry Substance of the Liquid Portion.—
Protein, 16.37 percent
Fat, .10 „
Ash, 70.41 „
Undetermined, 13.12 „
Composition of the Dry Substance of the Flesh and Liquid Together.—
Protein, 62.81 percent
Fat, 7.30 „
Ash, 18.92 „
Undetermined, 10.97 „
The Lobster (Homarus americanus).
—The lobster is a crustacean which occurs along the northern Atlantic coast. Formerly it was so very abundant that it was almost a drug on the market. In the last quarter of a century the increase in the consumption of the lobster has been more rapid than the increased growth, so that the price has become higher and higher; and this, to a certain extent, is limiting the consumption. The coast of Maine is especially the fishing grounds for the American lobster, though it is found much further south and also in great abundance further north. The lobster varies greatly in size. The law, at the present time, prevents very young lobsters from being sent into commerce. They are usually from 10.5 to 15 inches in length, though occasionally examples of enormous size are taken. The edible portion of the lobster is the liquid and the flesh of the body, claws, and tail. Only about one-half the weight of the lobster, including the liquid, therefore, is edible. The rest is refuse. In a lobster weighing a thousand grams (2.2 pounds), five hundred grams (1.1 pound) will be the average edible portion, and the other half the refuse and loss. The average lobster of the present day, perhaps, weighs scarcely two pounds, though in former times the weight was very much greater because the younger and smaller lobsters were not sent to the market. The color of the lobster as it comes from the water is dark green, almost black at times. Heat changes the color of the shell, so that after boiling or baking the lobster becomes red. The flesh of the lobster is decidedly sweet, owing to the large quantity of glycogen which it contains. There is only one kind of meat that is eaten which approaches the lobster in its content of glycogen, and that is horse meat.
Composition of the Lobster.
—Edible portion:
Fresh. Dry.
Water, 84.30 percent
Protein, 11.63 „ 74.06 percent
Fat, 1.82 „ 11.62 „
Ash, 1.63 „ 10.38 „
Glycogen, .62 „ 3.94 „
Crabs.
—The crab is a shellfish very highly prized along the whole of the Atlantic coast. Numerous species of crabs are used for food. These are used in two forms—as hard-shelled or soft-shelled crabs. The species most valued is Callinectes hastatus. It is very abundant on the middle and south Atlantic coast. Crabs are quite abundant on the Pacific coast also. About 44 percent of the total weight of the crab is edible and 56 percent shell and refuse. In the edible portion about 77 percent is water and 23 percent solid matter.
Composition of the Water-free Substance of the Crab.—
Protein, 72.56 percent
Fat, 8.55 „
Ash, 13.64 „
The flesh of the crab is, therefore, essentially a nitrogenous food, containing only a small quantity of fat. A considerable portion of the ash is common salt.
Crawfish.
—The crawfish may be regarded as a fresh-water lobster. It is found practically over the whole of the United States in the fresh waters but is not used to any extent for food purposes, except on the Pacific coast. It contains even a less proportion of edible matter than the lobster. The refuse, shell, etc., form about five-sixths of its weight. In the edible portion the water constitutes 81.22 percent, while the solid matters are only 18.78 percent.
Composition of the Water-free Substance of the Crayfish.—
Protein, 85.19 percent
Fat, 2.45 „
Ash, 6.98 „
Canned Lobster, Clams, and Crabs.
—As in the case of oysters, there is a large industry in the United States engaged in the canning of the flesh of lobsters, clams, and crabs. The same precautions should be observed in the eating of these canned products as those mentioned in the case of salmon. Numerous instances of illness and sometimes of death have been recorded as the result of eating these canned products which have been imperfectly sterilized. When the flesh is canned immediately after the capture of the animal, before any incipient decomposition has taken place and when the sterilization is perfect, the canned product can be eaten without fear. Where the health of the people is so seriously involved, the factories where these products are prepared should be carefully inspected either by the municipal, state, or federal authorities. All material used in canning which is not perfectly fresh from the water is to be rejected and the processes employed in the preparation and sterilization must be those which will effectively secure a complete immunity from subsequent fermentation and the development of ptomain products.
Composition of Canned Lobster (Dry Substance).—
Protein, 81.46 percent
Fat, 4.64 „
Ash, 11.23 „
As seen from the above the composition of the dry substance in canned lobster, except content of water, is not perceptibly different from that of the fresh sample.
Composition of the Dry Substance of Canned Crabs.—
Protein, 79.10 percent
Fat, 7.55 „
Ash, 9.68 „
Shrimp (Crangon vulgaris).
—The shrimp is a highly valued article of food, especially when it can be had fresh or properly canned. It has been a practice to ship shrimps in bulk preserved with sulfites or boric acid. This is a most reprehensible form of adulteration.
Canned Shrimps.
—In the total dry edible portion, including solids in the liquid contents of the can, are found:
Protein, 86.89 percent
Fat, 3.44 „
Crude ash, 8.84 „
In edible portion (flesh plus liquids):
Water, 70.80 percent
Water-free substance, 29.20 „
Protein, 25.38 „
Fat, 1.00 „
Crude ash, 2.58 „
Extractives, 0.24 „
Nitrogen, 4.06 „
Total edible portion, 100.00 „
The above data show that the shrimp in the canned state has less water in it than in the fresh state, and contains one-fourth of its weight of protein.
Aquatic Reptiles.
—All forms of turtle may be used for edible purposes, both of the fresh-water and salt-water species. Both the turtle and terrapin are amphibious animals; that is, they can live either in the water or on the land. Among the turtles the marine variety known as the green turtle is most highly prized for food purposes. Its Latin name is Chelonia mydas. It grows sometimes to an enormous size, weighing several hundred pounds, and specimens weighing 50 and 100 pounds are not unusual. It is utilized chiefly for making soup, and green turtle soup is considered of high quality by experts. The flesh is also edible, and in the making of some varieties of green turtlesoup pieces of the flesh are included.
Composition of the Green Turtle.
—The edible portion of the green turtle has the following composition:
Water, 79.78 percent
Protein, 19.83 „
Fat, .53 „
Ash, 1.20 „
The edible portion of the green turtle is not very large in proportion to its weight, as it forms only from 20 to 24 percent of the whole weight of the turtle.
Among the reptiles there are several aquatic species which are used as food. The most noted of these is the diamond-back terrapin, which is found in the salt-water bays, lagoons, and marshes of our Atlantic coast from New Jersey to Texas. Its center of greatest abundance is in Chesapeake Bay. There is no fish or other water animal that has a higher value for edible purposes than the terrapin. The extreme delicacy of its flavor, the richness of its aroma, and its easy digestibility give to it a rank which perhaps no other usual food product possesses. In addition to this the increased scarcity of the terrapin, especially the more famous variety of it, namely, the diamond-back, has gradually increased the cost until at the present time the terrapin is eaten only by the rich. In the United States it exists along the whole Atlantic coast from New York southward and also along the Gulf coast. Formerly it was most abundant on the Maryland coast, but the nearness of this field to the great markets of the country has resulted in such a depletion of the stock as to make the terrapin very scarce. Many attempts have been made at artificial growing of terrapin and these have been more or less successful, but have not met with pronounced success which has been expected. The enclosure in which the terrapin are kept, viz., the “crawl,” is a feature in the artificial cultivation or breeding of these marine vertebrates. It is to be hoped that greater success in the future will attend the artificial breeding of terrapin, since the natural stock seems well on the way to extinction.
Composition of the Terrapin.
—Edible portion:
Fresh. Dry.
Water, 74.47 percent
Protein, 21.23 „ 83.13 percent
Fat, 3.47 „ 13.59 „
Ash, 1.02 „ 3.99 „
The Mussel.
—The mussel may be described as a fresh-water oyster. It occurs in almost all parts of the United States in the fresh waters and in external appearance resembles to some extent the oyster, but the shell is usually smoother. In the mussel is often developed concretions of the carbonate of lime in a particular form known as pearls. In fact the chief value of the mussel is in the supply of pearls which they furnish, since their flesh, although often eaten, is not considered very palatable nor desirable. Pearls may be found in mussels in every locality, but in some regions they are more abundant than in others,—for instance, the mussels of Wisconsin are especially noted for the occurrence of the pearls. Pearls are also frequently found in oysters, but by no means so frequently as in the mussel.
Composition of the Mussel.
—The edible portion of the mussel forms about one-half its weight.
Water, 78.64 percent
Protein, 12.51 „
Fat, 1.67 „
Ash, 1.73 „
Undetermined, 5.45 „
Oysters.
—Oysters belong to a class of animals known as mollusks. They grow in salt or brackish water and are found along almost the whole of the coast of the United States. They exist in the greatest abundance along the coast in the vicinity of Long Island Sound, Norfolk, Virginia, along the coast of the Gulf of Mexico, off the coast of Mississippi, Louisiana, and Texas, and along the Pacific coast from San Francisco to the northern limits of Washington.
Size.
—The size of an oyster depends greatly upon its food and also upon its species. There are some varieties which at a given period of growth are naturally very much larger than others. The larger variety grows near Norfolk and along the Gulf coast. A smaller species is especially abundant on the Pacific coast, though a number of very large specimens of oysters have been found on that coast.
Age.
—An oyster is eaten at any time after two years. Oysters, however, three or four years old are, perhaps, in all respects the best. The age is determined largely by the appearance of the shell, experts being able to practically determine the age of an oyster by an examination of the shell.
The oyster grows within a shell which is composed almost exclusively of carbonate of lime. The periphery of the shell is ovoid in shape, irregular, and the surface, especially of old oysters, is corrugated, rough, and unattractive. The interior of the shell is smooth and generally white, but sometimes has a blue or reddish tinge. The shells of edible oysters vary in size from 2 to 6 inches in length and from 2 to 4 inches in width. The oysters sold in the market are known by various names, usually derived from the location from which they come. A small variety distinguished by a blue color on the inside of the shell is known as blue points. The real blue points come only from Long Island. Another variety named Rockaway is also a Long Island variety, and should come exclusively from Rockaway or vicinity. Shrewsbury is another highly prized variety from the neighborhood of Shrewsbury, New Jersey. Buzzards Bay, James River, Norfolk, Lynnhaven, Rappahannock, Stony Creek, Saddle Rock, etc., are names commonly found in the trade. Unfortunately, the name of the location is not always an indication of the actual source from which the oysters may have come. For instance the term “blue point” is now very commonly given to small oysters not exceeding 2 or 21⁄2 inches in length with a correspondingly diminished breadth. On the contrary “saddle rock” is a name given to very large oysters no matter from what region they may come. It is a common practice to separate the oysters taken from one location into groups of similar size and attach to each group a special name which may or may not be indicative of location.
Cultivation of Oysters.
—The natural beds of oysters are rapidly exhausted by the free fishing which is in some cases allowed, and the supply must be kept up by proper cultivation. Oyster farming has become a great industry along all parts of the coasts where the conditions are well suited to culture. The ideal conditions are inlets where the oysters are protected from the action of ocean waves and where abundant food can be derived from the low marshy grounds in the vicinity. The laws in force in the states protect the oyster farms from poachers and deeds are given for oyster beds which are beyond the low water line. The conditions of culture vary in various states. The public beds are also protected by law in many states and incipient war is sometimes carried on between the authorities of one state and the poachers from other states. Maryland, especially, has laws of a very strict character respecting the taking of oysters, and the state furnishes armed forces for the protection of public beds.
Season for Oysters.
—The best season for oysters on the Atlantic coast of the United States extends from September first to May. These dates may also be applied to oysters of the Gulf and Pacific coasts. It is commonly said that all months which have an “R” in them are suitable for eating oysters. In point of fact oysters are eaten the year round, especially on the Atlantic coast, though to a very limited extent during the spring and summer months. Those who own their own oyster beds are privileged to take oysters at all seasons, and it is not unusual that a restaurant furnishes oysters during the whole year, those in the closed season being derived from private beds.
Life of an Oyster.
—After an oyster is taken from its bed it may be kept alive for a long time at a temperature which does not rise too high nor sink too low. The best temperature for keeping oysters alive is about 40 to 50 degrees Fahrenheit. The oysters should be protected from the sunlight by a proper covering in a cool place and kept moist with sea water or brine which is sprinkled over them in such a way as to come in contact with each oyster in the heap. Oysters kept under these conditions often remain in an excellent state for consumption for a week or ten days or even longer. If such conditions are maintained oysters may be shipped in bulk to all parts of the country in cars kept cool, and this is the best way in which oysters should be distributed for consumption in a fresh state.
The treating of oysters with fresh water in order to swell them and thus make them appear larger and plumper than they really are is a treatment which is reprehensible in every respect. Not only does it deceive the customer in regard to the size of the oyster but it deprives the oyster of its proper taste and flavor. “Soaked” oysters quickly lose their flavor, whereas the oysters kept as above described and sprinkled with brine retain their natural flavor and odor. The objection to the transportation of oysters in this way is that the shell usually weighs many times more than the oyster and the same rate of freight must be paid upon it as upon the oyster itself. Nevertheless, the fact remains that fresh oysters should be eaten directly after removal from the shells. As soon as the shell is removed and the oyster killed by this removal it begins to deteriorate and in a short time its flavor and aroma are impaired. It is a common practice in many cities, even where oysters are delivered fresh daily from their beds, to open large quantities of them and put them in tubs and sell them from these tubs to customers. It thus happens that customers often buy oysters that have been opened 24 hours or more and which are naturally of a very changed flavor. Strict regulations in regard to the use of fresh oysters, favoring their being opened when they are ready for consumption or requiring that they should be kept in the condition of palatability and properly kept cool until ready for consumption, should be observed.
Shipment of Opened Oysters.
—Opened oysters are shipped extensively to all parts of the country. After removal from the shell the oysters are washed to remove the natural water, since this becomes ropy during shipment. They are then packed in wooden tubs of various sizes, a piece of ice added, covered, and delivered to the fast express or freight service. In this way the oysters may be kept free of dangerous deterioration for several days. In such cases care must be exercised to keep the temperature low and to secure a sanitary environment. Thus protected the oysters should arrive at their destination without any further change than the necessary loss of flavor caused by the conditions of preparation and transportation.
Proportion of Shell and Oysters.
—The following illustration (Report of the U. S. Commissioner of Fish and Fisheries for 1888, page 784) shows the relative proportion of the flesh, liquid, and refuse for two or three varieties of oysters:
Name: Oysters (“East Rivers”).
Locality: Cow Bay, Long Island Sound, New York.
Received: April 8, 1881, from E. G. Blackford.
Description: Length, 21⁄2 to 51⁄2 inches; breadth, 13⁄4 to 31⁄2 inches.
Weighings in Preparation for Analysis.
Grms. Lbs. Oz. Percent.
Flesh, 558.0 1 3.6 10.27
Liquid, 543.7 1 3.1 10.01
Refuse (shells, etc.), 4,284.7 9 7.2 78.86
Loss, 47.3 .. 1.7 .86
Total, 51 oysters, 5,433.7 11 15.6 100.00
Name: Oysters (“Sounds”).
Locality: Princess Bay, Staten Island, New York.
Received: November 30, 1881, from Dorlon & Shaffer, New York City.
Description: Thirty oysters in shell.
Weighings in Preparation for Analysis.
Grms. Lbs. Oz. Percent.
Flesh, 384.0 .. 13.5 8.24
Liquid, 436.0 .. 15.4 9.35
Refuse, 3,816.0 8 6.6 81.87
Loss, 25.0 .. 0.9 0.54
Total, 30 oysters, 4,661.0 10 4.4 100.00
The above data show that for 100 pounds of shelled oysters only about 10 pounds of meat are found. There is also about 10 pounds of liquid or juice that escapes when the oyster is opened. There is an average of 80 pounds of shell and other refuse. When it is remembered that, as will be shown in the table given below, in 10 pounds of the meat there is over 80 percent of water it is seen that the actual nourishment contained in 100 pounds of oysters is reduced to a little over 1 pound. There is a general opinion that oysters are a very nutritious food and this is true in so far as the nitrogenous element of food, that is, the protein, is concerned, and in proportion to the quantity present. As a nourishing food the oyster cannot be considered as worthy of any very great esteem. It must be confessed that it will continue to be used as it has been in the past, that is, practically, as a condimental food substance and not to satisfy hunger nor provide the heat and energy of the human activities.
Process of Floating.
—Reference has already been made to the practice of soaking oysters in fresh water for the purpose of making them more plump and increasing their weight. This, in the language of the fisherman, is called “floating,” “drinking,” or “laying out.” By this process the body of the oyster affects a plumpness and largeness which materially increases its selling qualities, as it increases its weight and size and, therefore, the profits of the dealer. The principle of this process depends upon the fact that when a soft substance like an oyster, containing a mineral salt in its composition, is brought in contact with water, a process of diffusion takes place which is known, in chemical physics, as osmosis, whereby water passes through the cell walls and enters the cells of the oyster and the mineral substance thereof is forced out into the external water. Larger volumes of water pass into the cells than accompany the particles of mineral matter to the outside of the cells and the result is a swelling of the oysters and consequent increase in the size and weight by the addition of pure water, but at the expense of the natural salt, mostly chlorid of sodium or common salt, which the oyster contains.
The U. S. Bureau of Fisheries has been experimenting to show the change which takes place with the following results:—
STATISTICS OF WEIGHTS, ETC., OF SPECIMENS OF OYSTERS.
From beds. From floats. From beds. From floats.
Lab. No. 82; 31 oysters. Lab. No. 83; 34 oysters. Lab. No. 85; 35 oysters. Lab. No. 84; 41 oysters.
Shell contents: Grms. Lbs. Oz. Grms. Lbs. Oz. Grms. Lbs. Oz. Grms. Lbs. Oz.
Flesh (body) 312.5 11.0 412.5 14.5 302.5 10.7 415.5 14.7
Liquids (liquor) 181.5 6.4 208.0 7.3 282.0 10.0 264.3 9.3
Total 494.0 1 1.4 620.5 1 5.8 584.5 1 4.7 679.8 1 8.0
Refuse:
Shells 2778.0 6 2.0 2976.0 6 9.1 3017.0 6 10.4 3386.0 7 7.4
Loss[18] 21.0 0.8 17.5 0.6 22.5 0.8 15.2 0.5
Total 2799.0 6 2.8 2993.5 6 9.7 3039.5 6 11.2 3401.2 7 7.9
Total weight of specimen 3293.0 7 4.2 3614.0 7 15.5 3624.0 7 15.9 4081.0 8 15.9
COMPARATIVE PERCENTAGE COMPOSITION OF OYSTERS BEFORE AND AFTER “FLOATING.”
Constituents of Oysters. James River Oysters Transplanted To New Haven. Potomac River Oysters Transplanted To New Haven.
As taken from beds. As taken from floats. As taken from beds. As taken from floats.
No. 82. No. 83. No. 85. No. 84.
In whole specimen: Percent. Percent. Percent. Percent.
Shell contents:
Flesh 9.49 11.41 8.35 10.18
Liquids 5.51 5.76 7.78 6.48
Total shell contents 15.00 17.17 16.13 16.66
Refuse:
Shells 84.36 82.35 83.25 82.97
Loss in preparation for analysis 0.64 0.48 0.62 0.37
Total refuse 85.00 82.83 83.87 83.34
Total constituents, shell contents, and refuse 100.00 100.00 100.00 100.00
In flesh (body):
Water 77.99 82.77 77.90 82.06
Water-free substance 22.01 17.23 22.10 17.94
Total flesh 100.00 100.00 100.00 100.00
In water-free substance:
Nitrogen 1.70 1.40 1.65 1.45
Protein (nitrogen × 6.25) 10.63 8.79 10.31 9.09
Fat (ether extract) 2.61 1.91 2.33 1.93
Ash 2.21 1.55 2.17 1.58
Carbohydrates, etc. (by difference) 6.56 4.98 7.29 5.34
Total water-free substance 22.01 17.23 22.10 17.94
In liquids:
Water 94.74 95.22 94.99 95.69
Water-free substance 5.26 4.78 5.01 4.31
Total liquids 100.00 100.00 100.00 100.00
In water-free substance:
Nitrogen 0.31 0.34 0.29 0.33
Protein (nitrogen × 6.25) 1.95 2.09 1.81 2.05
Fat (ether extract) 0.04 0.13 0.02 0.01
Ash 2.54 1.42 2.47 1.19
Carbohydrates, etc. (by difference) 0.73 1.14 0.71 1.06
Total water-free substance 5.26 4.78 5.01 4.31
In total shell contents, flesh, and liquids:
Water 84.15 86.95 86.14 87.36
Water-free substance 15.85 13.05 13.86 12.64
Total shell contents 100.00 100.00 100.00 100.00
In water-free substance:
Nitrogen 1.19 1.05 0.99 1.02
Protein (nitrogen × 6.25) 7.44 6.54 6.20 6.37
Fat (ether extract) 1.66 1.31 1.21 1.18
Ash 2.32 1.50 2.32 1.43
Carbohydrates, etc. (by difference) 4.43 3.70 4.13 3.66
Total water-free substance 15.85 13.05 13.86 12.64
In whole specimen:
Shell contents:
Water 12.62 14.93 13.89 14.55
Water-free substance 2.38 2.24 2.24 2.11
Total shell contents 15.00 17.17 16.13 16.66
Refuse 85.00 82.83 83.87 83.34
Total shell contents and refuse 100.00 100.00 100.00 100.00
In whole specimen:
Shell contents:
Nitrogen 0.18 0.18 0.16 0.17
Protein (nitrogen × 6.25) 1.12 1.12 1.00 1.06
Fat (ether extract) 0.25 0.22 0.20 0.20
Ash 0.35 0.26 0.37 0.24
Carbohydrates, etc. (by difference) 0.66 0.64 0.67 0.61
Total water-free substance 2.38 2.24 2.24 2.11
Water 12.62 14.93 13.89 14.55
Total shell-contents 15.00 17.17 16.13 16.66
Result of Treatment.
—As shown by the data the first result is one which would naturally be expected, namely, that the total weight of the oyster thus inflated with water is increased relatively to the total weight of the shell since no change takes place in the weight of the shell during floating. The gain of weight in the oyster is due to the absorption of the water, although there is a loss of mineral salt. The average gain of the oyster was, in round numbers, 10 percent. The danger of infecting oysters thus treated with any germs, which may be present in the water or ice used, should also be taken into consideration.
In respect of the composition of the oyster itself when subjected to floating the chief change is in the increase of the water content. As has already been said the process of floating is fatal to the flavor and palatability of the product.
Adulteration.
—The chief adulterations of oysters are the “floating” above described and the treatment of the “shucked” oysters with formaldehyde, boron compounds, and other preservatives to keep them from spoiling. These processes are thoroughly reprehensible and are rapidly disappearing. The consumer who lives near the source of supply should never eat any but freshly shelled oysters and those at a distance confine themselves to the properly prepared and shipped article. The chief delight of the epicure is the freshness, and not the quantity of nourishment of this justly prized bivalve.
Average Composition of Oysters:
[19]—
Water, 60.08 percent
Solids, 39.92 „
Nitrogen, 1.56 „
Phosphoric acid, .42 „
Sulfur, .19 „
Fat, 9.48 „
Ash, 1.77 „
Protein, 9.73 „
ANIMAL OILS.
The same distinction is made between oils and fats for animal products as has been made for the vegetable preparations further on. An animal fat remains solid or semisolid at the ordinary temperature of the living room. An animal oil, on the other hand, is one which at ordinary temperature is a liquid. Animal oils, as a rule, are not used for edible purposes directly, but are used to some extent in cooking, and to a large extent as medicinal food. Inasmuch as these oils are used for medicinal food purposes, those which are most important in this use may be very properly described in this manual. As these oils are derived both from sea and land animals they are often conveniently divided into marine animal oils and terrestrial animal oils. There is also a marked difference as a rule between the oils of marine origin and those of terrestrial origin. The oils of marine origin, as a rule, have a very high iodin number while the animal oils of terrestrial origin have an iodin number not much greater than the fats from which they are derived. This distinction corresponds somewhat closely to those vegetable oils which belong to the drying and non-drying variety. The iodin number represents the percentage of iodin absorbed by a unit weight of substance. If one gram of an oil absorb 0.67 gram of iodin, the iodin number is 67. The marine oils correspond to the dry vegetable oils and the terrestrial oils to the non-drying vegetable oils. While this difference is one which is marked, it does not always exist in each individual case.
Marine Animal Oils.
The marine animal oils may be conveniently divided into fish oils, liver oils, and blubber oils. Of these the liver oils are the most important from an edible point of view or a medicinal edible point of view. The fish oil and blubber oil are used chiefly for illuminating and other technical purposes.
Fish Oils.
—These are obtained by rendering from all parts of a fish where fat exists. The herring, sardine, salmon, and the menhaden are the fish which are chiefly used for getting oil of this kind. The fish oils have very much improved in quality since the steamer has taken the place of the sail boat for gathering the fish. During the days of the sail boat the fish were often kept for ten days after seining before they were brought ashore. The decomposition which took place would naturally affect the oil. At the present day the steamers fishing close to the shores deliver their products much more frequently, often the same day they are caught, and thus a better quality of oil is produced. In this country menhaden is the chief fish used for obtaining oil. The scientific name of menhaden is Brevoortia tyrannus. These fish appear in enormous quantities around the Atlantic coast from May until November. It is estimated that nearly one-half million tons have been taken of these fish during a season. Menhaden oil is rarely if ever used for edible purposes. It is used principally in the leather trade and sometimes in the adulteration of cod liver oil made in Newfoundland.
Sardine Oil.
—Sardine oil is principally prepared in Japan from the Japan sardine (Clupea sardinus). It is not used to any extent for edible purposes. It is also prepared to some extent in the boiling of sardines in France preparatory to packing in oil.
Salmon Oil.
—This oil is obtained in large quantities on the Pacific coast. It is one of the fish oils which has an agreeable odor and taste and, therefore, can be used for edible purposes. It has a specific gravity at 15 degrees of about .926 and its iodin number is about 160.
Cod Liver Oil.
—The most important of all the animal oils for food purposes is the oil which is obtained from the liver of the cod (Gadus callarias). Cod liver oil is valuable for food purposes not on account of its odor and taste, which are usually quite disagreeable, but by reason of the specific effect which it is often said to exercise in cases of emaciation and general disorder of the functional activities of the body. It is a food or medicine, whichever it may be best called, which is highly prized in tuberculosis and similar diseases. The oil is chiefly prepared in the Loffoden Islands. Different classes of oil are prepared which are differentiated chiefly by their color, the lighter the color the higher the quality of the oil. The chemical composition of cod liver oil is extremely complex, many different kinds of substances having been found in it by various authorities. The probability is that many of these supposed substances are only mixtures of others. Yet it cannot be denied that the number of chemical compounds occurring in cod liver oil is very much greater than that which occurs in ordinary oils. Both the medicinal and food values of the oil are often attributed to these bodies which occur in minute quantities.
Properties.
—Cod liver oil at 15 degrees has a specific gravity of .922. Its iodin number varies very greatly but is always high, ranging from 150 to 180. Its refractive index is also very high, namely 1.47.
An important constituent of cod liver oil is cholesterol. Cod liver oil contains naturally a small quantity of iodin and this natural compound of iodin is one of the properties to which much of its medicinal virtue has been attributed. The quantity present is extremely minute, and probably never exceeds .002 of one percent.
Adulteration of Cod Liver Oil.
—Owing to its increasing price cod liver oil has been subjected to many forms of adulteration. The chief adulteration consists in the admixture of fish liver oil of lower quality or the use of blubber oil. Seal and whale oils have been used very extensively in the adulteration of cod liver oil. Japan fish oil and, in fact, all other fish oils which are of a character not to disguise the properties of cod liver oil have been used. It is evident that it is with extreme difficulty that the presence of these adulterants can be detected, especially if they are used in small quantities. The only certain method of guarantee of the purity of a cod liver oil is in the proper inspection and control of the manufacturing works. The livers of many other kinds of fish are employed in the manufacture of cod liver oil, but the other varieties have little value as compared with the cod liver oil itself and they are probably used almost exclusively in the adulteration of the genuine article. The Norwegian cod fish gives a much better character of oil than those coming from the Atlantic coast of America. In fact the latter product is of little medicinal food value and is used chiefly in the leather trade.
Blubber Oil.
—Blubber oil includes the oils made from seals, whales, turtles, etc., and is used exclusively for technical purposes, unless surreptitiously placed in cod liver oil as an adulterant.