CHAPTER XII. PRESERVATION OF FOODS IN THE HOME (Part 2)

well as tern- 444 HOUSEHOLD REFRIGERATION perature on the keeping qualities of milk. If the table is read down- ward, we note the effect of temperature and if read across, the effect of time. When milk is first drawn from the cow it usually contains bacteria, even though it is produced under sanitary conditions, and if held at the ordinary temperature of the surrounding air, in a short while the bacteria will grow and increase in numbers so rapidly, that when such milk reaches the consumer it will contain many thousand bacteria per cubic centimeter. TABLE XCIII.— THE EFFECT OF TEMPERATURE ON THE GROWTH OF BACTERIA IN CREAM. Temperature of | Time Cream I Held Number of Bacteria per C C. rp X f I m. Number of Temperature of Time | Bacteria Cream | Held | per C. C. Degrees Fahr. 32 ..._ Hours 10 50 _ 10 60 ioy2 Degrees Fahr Hour's 3,300 70 11 188,000 11,580 80 11 2,631,000 15,120 90 WA 4,426,000 Conn furnishes an example of milk, giving the following results: Bacteria per c. c. Milk drawn at 59° F 153,000 After 1 hour 616,000 " 2 hours 539,000 " 4 hours 680,000 " 7 hours 1,020,000 •• 9 hours 2,040,000 " 24 hours 85,000,000 According to Park, two samples of milk maintained at different temperatures for 24, 48, 96 and 168 hours, respectively, showed the development of bacteria as indicated in Table XCIV. The first sample was obtained under the best possible conditions, while the second sample was obtained in the usual way. When received, the first sample contained 3,000 bacteria, and the second 30,000 per cubic centimeter. In Table XCIV, it will be noted that at 32° F., there is an actual decrease in the number of bacteria in both samples of milk during the 168 hours, while at all other temperatures there is an increase in the numbers of bacteria. Ordinarily, the consumer receives milk when it is from 24 to 48 hours old; hence, it becomes an easy matter to deliver the milk in good condition, providing the milk is produced under sanitary conditions and is properly cooled and held at a temperature of 50° F., or below. An examination of the tables and figures will show how intimately the two influences of time and temperature act and interact in relation to the multiplication of bacteria in milk. PRESERVATION OF FOODS IN THE HOME 445 From the foregoing, it is obvious that proper refrigeration is of the utmost importance in the preservation of milk. In fact, without thorough cooling, it is impracticable to keep milk for any considerable length of time, in a condition that would justify its use for household purposes. It should be cooled at 50° F. or below as quickly as pos- sible after it is drawn from the cow, as such cooling will at once check the increase of bacteria. TABLE XCIV. — EFFECT OF TIME AND TEMPERATURE ON THE GROWTH OF BACTERIA IN MILK. Temperature 24 Hours 48 Hours 96 Hours 168 Hours 32° F. (0 C.) 2,400 2,100 1,850 1,400 30,000 27,000 24,000 19,000 39° F. (4 C.) 2,500 3,600 218,000 4,200,000 38,000 56,000 4,300,000 38,000,000 42° F. (5 C.) 2,600 43,000 3,600 210,000 400,000 5,760,000 46° F. (6 C.) 3,100 42,000 12,000 360,000 1,480,000 12,200,000 50° F. (10 C) 11,600 89,000 540,000 1,940,000 55° F. (13 C.) 18,800 187,000 3,400,000 38,000,000 60° F. (16 C.) 180,000 900,000 28,000,000 168,000,000 68° F. (20 C.) 450,000 4,000,000 25,000,000,000 25,000,000,000 86° F. (30 C.) 1,400,000,000 14,000,000,000 94° F. (35 C.) 25,000,000,000 25,000,000,000 Bacteria in Milk.— Farmers' Bulletin No. 1207 of the United States Department of Agriculture gives the following discussion on the development and growth of bacteria: Besides the chemical compounds, milk also contains large num- bers of minute organisms called bacteria. Few, if any, are normally present in the milk within the udders of clean, healthy cows, but they are so abundant everywhere in the air, especially about the stable and barnyard, and cling in such numbers to the bodies of the cows, that they are almost always found in milk as soon as it leaves the udders or even just inside the teats. Utensils that have not been sterilized are another very common source of bacteria in milk. Bac- teria reproduce very rapidly in a favorable medium, such as warm milk, and the number present 'becomes very large unless measures are taken to hinder their increase. The amount in milk of a given age varies of course with the conditions. 446 HOUSEHOLD REFRIGERATION A oreat many kinds of bacteria have been found in milk, each of which occasions a special set of changes as it develops. Perhaps the most prevalent kinds are those that cause the ordinary sourmg of milk and are the first to produce any noticable change in the taste and odor. In their growth they feed upon the milk sugar and convert it into lactic and volatile acids, which give slightly soured milk its peculiar taste and odor. When enough of this lactic acid has formed it acts upon the casein, causing it to separate into loose, light flakes and to form, upon standing, the ordinary "clabbered" milk. Other 'bacteria developing in sour milk may give it a strong, un- pleasant odor or flavor, and still others, w-hich occur occasionally color It very brightly or give it a slimy or ropy consistency. Some of the products of bacterial action on milk are desirable, however, — for in- stance, those that give to butter and cheese the characteristic flavors and odors. Since there is frequently more or less dirt in freshly drawn milk (most of it fine particles of litter and manure that fall into the pail from the body of the cow), milk should always be strained directly after the milking is over. Of course, the amount of dirt varies with the condition in which the cow and her surroundings are kept. Under ideal dairy conditions only very small quantities are found, while milk from untidy establishments may contain enough in a quart to form a noticeable sediment. Milk with enough dirt to be visible indicates a badly kept dairy and should not be tolerated. Moreover, visible dirt does not tell the whole story; some of the manure that "falls into milk is dissolved and it sometimes carries disease-producing bacteria. Consumers should always insist upon having clean milk, and they should also remember that cleanliness should not stop at the dairy but should be scrupulously maintained at every step of the way to the final consumption of the milk. Ice Chests. — Mrs. Mary Hinman Abel, under the beading "Care of Food in the Home," gives the following considera- tions in reference to ice chests and refrigerators: There are many varieties of ice chest or refrigerator, all built on one of two general plans. In one kind, both ice and food are kept in one large compartment. In the other, the ice is placed in a top compartment, below which are cupboards for the food; the prin- ciple here utilized is that cold air seeks a lower level and that the air cooled by the melting ice w'ill sink to the shelves below. It probably better utilizes a given amount of ice, for the further reason that the ice compartment may remain tightly closed except when being filled. In both cases, the air space between the outside wall and the zinc lining is filled with some non-conducting material as cork or asbestos. PRESERVATION OF FOODS IN THE HOME 447 It is of great convenience to have the ice chest built against the outer wall of kitchen or pantry, so that it may be filled from the outside by means of a small door cut for that purpose. In such a case, it is of course advisable to choose a wall on which there is little or no sunshine. The ice box may also be drained by a pipe leading to the outside and then properly cared for, thus saving much labor in the emptying of pans. It is not considered safe to connect it with the house sewer, because of the danger of sewer gases back- ing into it, even if a good trap is provided. Care of Ice Chests. — Farmers' Bulletin No. 375 of the United States Department of Agriculture gives the following- instructions in reference to care of ice chests : If on a warm summer day you put your hand into an ice box well filled with ice you may think that the temperature is very low, and yet it is in all probability nearer 50° than 40° F. As low a temperature as 40° or 45° is only to be obtained in a very well-con- structed box with a large receptacle for ice, and then only for a short time after it is filled. A box that maintains but 60° is, however, very useful in keeping food from day to day. The ice box, no matter how well cooled, is and must be damp, and dampness is one of the requirements for bacterial growth. It must be remem'bered, also, that some varieties of bacteria grow at low temperatures. Therefore, the interior of an ice chest should be wiped every day with a dry cloth and once a week everything should be removed, so that sides, shelves, and drain may be thoroughly scalded. The water must be actually boiling when it is poured in, and the process repeated several times. It must 'be remembered that refrigerator ice is often dirty, and that it may bring in putrefactive or even typhoid bacilli, for most bacteria are resistant to low temperature and are not destroyed by freezing. On this account, no food should be brought in direct con- tact with it, nor should it 'be put into drinking water, unless its purity is above suspicion. All cooked food should be cooled as soon as possible before being placed in the ice box. Butter may 'be kept from taking up the flavors of other food by keeping it in a tightly covered receptacle. Milk requires more access of air, but in a clean ice box in which no strong- smelling food is kept, milk should remain uninjured in flavor for twelve to twenty-four hours. If vegetables or other foods of pro- nounced odor are kept in glass jars with covers, or in covered earthen- ware receptacles, there will be a fewer odors to "be communicated. Portions of canned food should never 'be put into the ice box in the tin cans. Such food does not of necessity develop a poisonous product, as has sometimes been claimed, but experiments show that 448 HOUSEHOLD REFRIGERATION ptomaines are particularly liable to develop in such cases. Casting out this somewhat remote possi'bility, the "tinny" taste acquired by such keeping is enough to condemn the practice. Foods that are to be eaten raw, such as lettuce and celery, should be carefully cleaned before being placed in the ice box, and may with advantage be wrapped in a clean, damp/rloth. If they e ;e to be kept for some days they should, however, Tie put in without removing the roots, the further precaution being taken to wrap them carefully in clean paper or to put them into grocers' bags. Keeping of Vegetables, Fruits, and Meats. — The Farmers' Bulletin No. 375 of the United States Department of Agricul- ture gives some additional considerations in reference to the keeping of vegetables, fruits, and meats in the home. These are as follows : The following hints regarding the keeping of different kinds of food may be found useful: Potatoes are kept without difficulty in a cool, dry, and dark place. Sprouts should not be allowed to grow in the spring. Such roots as carrots, parsnips, and turnips remain plump and fresh if placed in earth or sand filled boxes on the cellar floor. Sweet potatoes may be kept until January if cleaned, dried, and packed in chaff so that they will not touch each other. Pumpkins and squash must be thoroughly ripe and mature to keep well. They should be dried from time to time with a cloth and kept not on the cellar floor, but on a shelf, and well separated from each other. Cabbages are to be placed in barrels, with the roots uppermost. Celery should be neither trimmed nor washed, but packed, heads up, in long, deep boxes, which should then be filled with dry earth. Tomatoes may be kept until January, if gathered just before frost, wiped dry, and placed on straw-covered racks in the cellar. They should be firm and well-grown speciments, not yet beginning to turn. As they ripen they may be taken out for table use, and any soft or decaying ones must be removed. Apples, for use during the autumn, may be stored in barrels without further precaution than to look them over now and then to remove decaying ones; but if they are to be kept till late winter or spring they must be of a variety known to keep well and they must be hand-picked and without blemish or bruise. They should be wiped dry and placed with little crowding on shelves in the cellar. As a further precaution they may be wrapped separately in soft paper. Pears may be kept for a limited time in the same way, or packed in sawdust or chaff; which absorbs -the moisture which might other- wise favor molding. PRESERVATION OF FOODS IN THE HOME 449 Oranges and lemons are .kept in the same way. Wrapping in soft paper is here essential, as the uncovered skins if bruised oflfer good feeding ground for mold. Oranges may be kept for a long time in good condition if stored where it is very cold, but where freezing is not possible. Lemons and limes are often kept in brine, an old-fash- ioned household method. t Cranberries, after careful looking over to remove soft ones, are placed in a crock or firkin and covered with water. A plate or round board placed on top and weighted serves to keep the berries under water. The water should be changed once a month. In winter, large pieces of fresh meat may be purchased and hung in the cellar. Thin pieces, as mutton chops, are sometimes dipped in mutton suet, which keeps the surface from drying and is easily scraped off before cooking. Turkeys, chickens, and other birds should be carefully drawn as soon as killed and without washing hung in the coolest available place. Smoked ham, tongue, beef, and fish are best put in linen bags and hung in the cellar. Salt pork and corned beef should be kept in brine in suitable jars, kegs, or casks, and should be weighted so as to remain well covered. A plate or board weighted with a clean stone is an old- fashioned and satisfactory device. Eggs may be packed for winter use in limewater or in water- glass solution, methods which are described in an earlier bulletin of this series. Many housekeepers have good success in packing them in bran, in oats, or in dry salt, but according to experiments sum- marized in the aforementioned bulletin, the preference is to be given to the 10 per cent solution of water-glass. Exclusion of the air with its accompanying microorganisms and the prevention of drying out are what is sought in all cases. Packed eggs are not equal to fresh eggs in flavor, but when they are well packed are of fairly good qual- ity and perfectly wholesome. V- Apples.^ — The United States Department of Agriculture, in Farmers' Bulletin No. 1160, gives the following informa- tion in reference to the keeping of apples: Apples will stand a temperature several degrees below freezing (32° F.). The danger point is at about 28° F. The effect of freezing is to cause brown spots which extend to the surface and are easily seen. These spots may appear on any part of the apple, but usually occur at places where the water content is highest. Freezing has about the same effect on either green or ripe fruit. Slightly frozen apples may be thawed out slowly without injury except to the quality. Apples should be packed in barrels, allowing good ventilation when stored for long periods. Some of the common diseases of apples are: Scab, blotch, fruit spot, Jonathan spot, bitter pit, drought spot, stig- 450 HOUSEHOLD REFRIGERATION nonose, water core, bitter, anthracnose, black rot, altervaria rot, blue mold, pink rot, spongy dry rot, brown rot, gray mold, soft scald, and scald. Drinking Water. — The desirable temperature for drinking water is 45° to 50° F. Tests have proven that at this temper- ature it is a mild heart stimulant and slightly reduces the in- ternal temperature of the body. When drinking water colder than 45° F. is used there is danger of cramps. The amount of drinking water required in industrial plants is usually considered to be approximately % gallon per man per working hour. This amount is based on using fountains and includes the waste. The amount of refrigeration required to cool drinking water varies from 0.0003 to 0.0005 tons refrigeration per hour per man. Fig. 217 shows the refrigerating effect due to placing one, two, and three cubes of ice in a glass of drinking water. The weight of the water in the glass was 0.4 lbs. ; the weight of the ice cube was 0.1 lb.; the size of the glass was three inches in diameter at the top, 2.3 inches in diameter at the bottom and five inches high; the room temperature was 7S° , and the glass was placed on a wooden table. Inasmuch as 50" is the desir- able temperature for the water, it will be observed that this temperature is practically obtained by the use of two cubes of ice per glass of water. It is further noted from Fig. 134, that the use of three cubes of ice,