CHAPTER II. THE HYGIENE OF HABITATIONS. (Part 7)

in the >'olk of eggs, in raw meat, in fresh fruits, vegetables, etc. CeUvlose. — Cellulose is a constituent of vegetables, fruits, grains, etc. It is contained in a large measure in certain vegetables, like lettuce, celery, spinach, asparagus, cabbage, tomatoes, berries, etc. While cellulose is not strictly a food, it is necessary to give bulk to the foods ingested and to aid in the intestinal peristalsis. Estimates of Food Values. — Foods are necessary for the metabolism of the body. Like all organic sub- stances, foods, when oxidized, burned or metabolized in the body, produce heat. The exact amount of heat produced by a certain food, or a given quantity of a certain food, will differ according to the nature of the food and also according to the amount of water and elements incapable of producing heat which it may contain. Foods when ingested, digested and assimilated, produce the same amount of heat and energy as when burned outside of the body. Hence this amount of heat may be measured, standardized and serve as the criterion of heat and food values. The definite meas- FOODS 93 lire of tlu' lu-at \aliU' of a food is tlir nili>rlr. A raloric is tlu- amount of heat ri'(|iiir('(l to raise one kilogram of watrr one (U-uiht ( 'cnti^radc, or the aiiioiiiit of licat reciuirod to raise one j)oun(l of water four degrees Fahrenlieit. Aeeordinj; to liul)ner. oi\e ^n'ani of protein or carho- hydrate gives l.o calories wliile one j,M*ain of fat j^ives y.o calories. According to Laugworthy, one pound of i)rotein or carbohydrate gives 1860 calories, while one pound of fat will give 4220 calories. We have therefore in these standards a means for finding out tlie calorie value of foods, provided we know what percentage of jjrotein, fat and earhohydrate they contain. Dietetics and Preparation of Food. By diet is under- stood the (piantity, (|uality, and kind of food taken in by the person daily. There are a great many factors determining the vahie of the average j)erson's diet. The main factors are as follows: The person: Age, weight, physical condition, race, condition of rest. The food: Cliemical composition, physical condi- tions as to foi-ni, xdjuine. con>istency. perct'iitage of edible and inedible parts, temperature. »'tc. (icneral conditions: ("limate. tem])erature. It is difhcult to make liard-aiid-fa>t rules for dietetic standards. Human beings adjust tliemseKcs easily to difVerent kinds and forms of food, and during health, as a rule, do not suffer much except when they take either too inuch or too little food, or are fed ex- 94 HYGIENE OF FOODS AND FOOD SUPPLY clusively on one food or on food which lacks some of the necessary nntrient ingredients. A prolonged and constant overuse or underuse of certain food " element is bound to cause pathological conditions and is the cause of certain diseases of digestion and metabolism. The form and consistency of food is of much impor- tance, for food must be in such condition as to be readily digested. Many foods must be mechanically ground by the teeth; some are chemically acted upon in the mouth by the processes of mastication. This not only prepares the food for the stomach by softening and dividing it into small particles, but also aids much in the conversion of starches of vegetables and cereals into sugars. There is still much controversy as to the value of an exclusively vegetarian diet, as well as to the com- parative percentage of the protein and carbohydrate elements needed for persons. For the average healthy person a mixed diet of animal and vegetable food is probably the most appropriate, and the amount of the protein matter must be somewhat limited, much depending upon the physical condition and habits of the person. The cost of food depends also upon very many factors. Often it is not the most costly food that is the most useful or nourishing, as some of the causes of the high cost of food are its rarity, difficulty of obtaining it, the manner of preparation, the place where it is sold, and the matter of taste. For physical subsistence, cereals, vegetables, nuts, fish, and flesh of animals furnish all the necessary nutrient qualities, Fi)(H)S 95 and sonu' among tlit'sc are of comparatiNcly low cost, tlieir nutritive \alno being, however, (piite as great, if not greater, than that of the more costly foods. Raw, Cooked, and Prrparrd Food.s. — Some cereals, a large number of vegetal)les, most of the fruits, a numi)er of nuts, and some forms of animal foods may be taken in their natural state. 'I'lie flesh of animals is seldom used raw, although the fat is often so used and in some climates the flesh is also eaten raw. The process of cooking foods greatly improves the consistency and form of most foods, develops the flavors, increases the digestibility, improves the taste, and generally enhances the value of food for human beings. Much of the increased dige.stibilitx' and \alue of the food dei)cn(ls ujxin the 'arious forms Mud pro- cesses of cooking. The food may be heated (pasteurized at 100^ F. for ten minutes). This process destroys certain patho- genic germs, softens the food, and is valuable for the l)rei)aration of milk, for the cooking of soft-boiled eggs, etc. Boiling, stewing, steaming, baking, roasting, and frying are some of the various nnules of subjecting foods to heat. The ^•alue of each process depends more or less uj)oii the kind of food anrl various other conditions. \n strir'n)(j,\\v UnA is cut into >niall pieces ami put in (•iijij water and heated slowly. This is an economic methoil of j>reparing certain meats and vegetables. lioiUng is a more rapid process in which the food is put into hot water and kept at a boiling temperature. Certain foods, especially fruits and cereals, are more 96 HYGIENE OF FOODS AND FOOD SUPPLY tender and digestible when prepared by means of sieamiiKj. The food is placed in a double pot, the water is boiled in the lower part, and the food in the upper part is subjected to the steam formed by the heat. Baking and roasting are processes by which the food is exposed to the direct radiation of heat in open or enclosed ovens. Frying is a form of roasting in which the food is placed in a pan and fried in fat. Boiling and frying somewhat toughen the fibers of the food and render it less digestible than the other processes. Care, Storage, and Preservation of Food. — All foods when left exposed for some time undergo a process of deterioration and decomposition. This is due to the breaking up of organic tissue into its simple com- ponents, and finally into its primary elements, the decomposition lieing due to the action of microorgan- isms. The majority of the microorganisms which cause the breaking up of the tissue of the foodstuffs are harmless. The deterioration of food is also due to various moulds, yeasts, and other vegetable and animal germs which are found almost everywhere. In order to pre'ent the deterioration of foodstuffs, the action of the destroying germs must be inhibited or stopped. Foods that are overripe or underripe, that have fungi, parasites, or worms in them, or that lack pro- tective coverings, usually undergo more rapid decom- position. Certain foods when in a process of decom- position develop chemical poisons which cause serious rooDs 07 disturhaiurs in tliost- ratiiij; the foods. Tlicx' arc soinctiincs called ptoniaiii poisoiiiiij:. In order to care, store, and i)reserve foods in tlie house, certain conditions are necessary: (1) A sound condition of the footl; (2) dry air; moisture is abso- lutely necessary to decomposition, and its i)resence favors the jirowth and devcloi)inent of low or^Miiic and bacterial life; absence of moisture is a i)reven- tive against decomposition; (3) absence of dies and insects: certain insects injure the food and also bring to it germs which aid in decomposition; all foods must be examined and covered to ])revent the access of these insects. It is best to have all foods covered or wrapped in protective coverings so as to prevent their injury from the outside agents. Teinpemiurc—k low temperature, even below the freezing-point, does not kill bacteria, but it stops and inhibits tlu-ir further growth. At a temperature of 40° to 4.')° V. the growth of germs is greatly retarded, and this is the be.st temperature at which to keep and store foods. Food in houses is stored in separate rooms, pan- tries, cellars, or ice-chests. Wherever it is stored care must be taken to have an equable temperature, below 4o° F., and a- far as possible cadi food should be sejKirated and kept ajiart from other foods. Dri/liig. 'Vhr method (»f drying footls in order to preserve them is cHicient in proportion to the thor- oughness of tin- procc-s. I )rying is adai)table to meats, cereals, seeds, and some fruits. The drying is done either in the sim or on fires, ."^ome foodstuffs may be preserved for a long tiinr. 7 98 HYGIENE OF FOODS AND FOOD SUPPLY Salting and PicJding. — Salting and pickling are partly chemical and partly physical methods of food preservation. Salt prevents decomposition by reason of its antiseptic qualities and by its absorption of moisture. This method is applicable to meats and fish. Fish are also preserved in brine or salt solution. Pickling is the keeping of food, such as fish, certain vegetables, and fruits, in vinegar. These processes harden to some extent the fibers and diminish the digestive qualities of the food. Smoking. — The method of food preservation by smoking is really a combination of several methods, drying, salting, and chemical. It is said that the creosote in the wood smoke to which the food is ex- posed serves as an antiseptic. Certain meats and fish are preserved by smoking. This hardens the fibers and makes them less digestible. High Temperature. — Foods may be preserved by subjecting them to high temperature. This destroys all microorganisms and prevents the decomposition of the food. The heating of the food to 140° F. from ten to fifteen minutes is called pasteurization. Heat- ing to the boiling-point and subjecting the food to this heat for one-half hour or longer is called steriliza- tion. It effectively destroys all microorganisms, even the spore-bearing bacteria. Canning. — Many foods may be preserved for in- definite periods of time by sterilization with heat and by subsequent storage in hermetically closed tin or glass receptacles. Many kinds of meats, fish, fruits, and vegetables are at present preserved by the process of canning. The food is cut in appropriate FOODS 99 forms and [)Iacr(l in tin cans of varions si/.cs. It is then covered witli hot water and Koilcd. The cans ari" co-ered except for a vvvy small opening at their tops, and snhjeeted to a hi<:;h decree of heat in steam boilers for th(> period of an hour or longer. When taken out the opening is sealed with solder, and after the cans have again been subjected to licat, they are taken out, cooled, labelled, and stored. In this condition they may be kept for very long periods. If the food in the cans is not ])roperly sterilized and if decomposition subsequently sets in, the carbonic acid gas developed in the cans causes a bloating or bulging out of the top or bottom of the cans, which indicates that the food has undergone some decom- position. Such cans should be rejected. Adulteration. — By adulteration is meant the "alter- ing" of the normal composition and consistency of the food. Food adulteration is accomplished in vari- ous ways: (1) By mixing with tlv food some foreign substance to reduce, lower, or injure its quality and strength; (2) by the entire or ])artial substitution of an inferior substance; (o) by the entire extraction of a portion of valuable substance from it; (4) by the sale of imitations leading the consumer to i)urchase articles he never intended to buy; (5) by the sale of food, in part or wholly, of a diseased, decayed, or decomposed substance; (6) by colf)ring, coating, pol- ishing, or j)owd('ring the food, thus concealing its ])oor (|ualit.', or nuiking it look better than it is; (7) by introducing into the food a poisonous con.stituent, or any ingredient likely to be harmful to the consumer. Adulteration may be harmful, fraudulent, or acci- 100 HYGIENE OF FOODS AND FOOD SUPPLY dental. Harmful adulteration includes all those which are either directly harmful by the addition of injurious substances, by the decomposed or unwholesome state of a part or the whole of the food, or by the dilution or extraction of some nutrient part of the food, thus rendering it less nutritious. Under fradulent adul- terations are classed all those which do not directly or indirectly harm the consumer, except in deceiving him and making him pay more than he would normally have paid. There is much adulteration of foods in commerce and trade. The Federal Food and Drugs Act makes stringent provisions against adulteration and mis- branding, and much has been done by the Govern- ment to insure the purity of foods and the honesty of their adulteration. ]\Iuch more, however, remains to be done. The methods of adulteration of foods are many and change from time to time. MEAT AND MEAT SUPPLY. Hygiene of Meat Foods. — The hygiene of meat foods may be considered according to the following sub- divisions: Dangers to Health. — Infection by entozoa, bacteria, toxins, and ptomains. Ktiologi/. — Diseases of the animals, conditions of the animals, postmortem changes, postmortem infection, adulteration. Prophylaxis. — Hygiene of the food animals: meat inspection, antemortem and postmortem; hygiene of Mi:.\r AM) Mi:.\r srri'i.y 101 place and persons; picxTNatioii, sanitary Nnpcrxisioii of inaunfacturo. etc. Ihmgcrs in Ilralfh. — The daiifjers to licaltli fioiii the iufjestion of flesh foods are (hie to infection hy entozoa, infections l)y l>acteria, and \n the a(ti<iM (if toxins aii/l ptoniains. Parasitic Diseases Due to Meat.--The?o are rluc to (1) infection l)y tapeworms, (2) infection hy trichina, (3) infection hy echinococci. T(i])nrnrins. — The two ])rin(i]ial species of ta))ewonn found in man whicii are (hic To meat infection arc the TfPiiKi .s'(i(ii)i(tta and the Tan id .soliinii; the former is due to infection hy "measly" heef, the latter by "measly" pork. The CysHcercus ceUuhsop is the larval form of the ToBiud solium. It appears in hoj^s in the shape of minute bladder worms, encased in little cysts which are found in the intestines, mnscniar fil)cis. hrain, liver, and other parts, and especially under the tongue, where it may readily be recognized. The cysticercus is derived from the segment and egg of the Tcetiia .tohiim, which are passed from the human intestine ingested })y the hog, and on reingestion l)y man dcvelo]) again into tenia. The Ct/stircrcii.s Ixiri.s- is the lar\al form of the Taiiid saffinaia of man, and is found in the intermuscular fibers and connective tissue of cattle. Trichnui. — The Trichina spiralis is a parasite found mostly in the muscular hl»er> of ])ork in the form if minute spiral-form worms, which are encaj)- sulated, but may be recognized with the naked eye as white specks. The ingestion of i)ork infected by 102 HYGIENE OF FOODS AND FOOD SUPPLY trichina causes in man the acute disease called "trichi- nosis," which is due to the presence of the trichina in the muscular fibers. Its symptoms resemble those of typhoid fever. The disease is often fatal. EchinoaoiX- us. —Echmococcus sometimes infect sheep andj rarely- cattle. The infected meat causes in man the hydatid diseases. Originally the infection comes from TcBtiia eckinococcvs foimd in dogs. Meat Infection by Bacteria. — Pathogenic bacteria may be found in the flesh of animals, and such in- fected flesh on consumption is capable of producing disease. The pathogenic bacteria may originate in the diseased condition of the live animals suffering from the infectious diseases, or they may gain entrance into the meat of healthy animals through infection by contact, etc., after killing. The diseases of animals infectious to man which are caused by pathogenic bacteria and which, it is claimed, may be transmitted through their meat to man, are the following: Tuberculosis, pleuropneumonia, foot- and-mouth disease, cattle plague, anthrax, glanders, malignant edema, erysipelas, actinomycosis, tjT3hoid fever, cholera, pyemia, septicemia, tetanus, sheep-pox, Texas fever, etc. Toxins and Ptomains.^ — Certain meat causes, on in- gestion, toxic symptoms. These symptoms are due to toxic substances in the meat or to bacterial products of decomposition called "ptomains." The symptoms resemble those of severe gastro-intestinal inflamma- tion, and may be fatal. The Bacillvs botuHnvs has been regarded as the cause of some of the toxic influ- ences of certain meats. mi-:at AM) \ii:.\T srrri.y Kt3 The \inil<'iict' of the iiitn\ic;it ioii 1)\ iiiciit ditlVr-^ according to tlu- coiulitioii ot" meat, tlw iiiamuT (»f ])n'i)aratioii. the (luaiitity ingested, and the individual idiosyiu-rasies of the victim. Intoxication is most frecjuently caused hy tlie eating of "prepared meats," such as ch(»p|)ed meats, sausages, canned, "potted," and "de\iled" meats, etc Causes of the Unfitness of Meat for Food. These niac- in': il) The diseases of animals; (2) the unfit condi- tion of liviim animals; (3) i)ostmortem changes; (4) infection of the meat by persons or by places of manu- facture, sale, etc.; (5) adulteration. Diseases of Food Aiii)iiaJ.s. — Tlie diseases of food animals, which render their meat totally or ])artly imiit for food, have already been enumerated. Condition of Food Aninnds. — The conditions of the food animals, which may render their meat unfit for food, are the following: 1. The death of the animals from agi', disease, or accident. '2. Moribund conditions from injury, drugs, over- work, fright, overdriving, etc. 'A. Immaturity: unborn calves and lanib> and animals in the first few weeks of life, are unfit. 4. Artificial conditions and treatment of the car- casses by bhnving up (blown veal), coloring, etc. Postmortem Changes. — The temperature, moisture, and substances of the slaughtered carcass make a