Preservation Of Foods By Frozen Storage

BULLETIN NO. 220 JUNE,1943 Preservation Of Foods By Frozen Storage BY BESSIE E. McCLELLAND EXTENSION NUTRITIONIST Successful storage of food in freezer lockers depends on certain definite factors: 1. Quality and freshness of product. 2. Variety of fruit or vegetable. 3. Method of preparation best suited to the product and the use for which it is intended. 4. Airtight, moisture-vapor proof containers and wrappings. 5. Quick freezing. 6. Storage at even temperature near zero with correct humidity. 7. Proper care, and use of food after it is removed from locker. Containers And Wrappings Glass jars with wide mouth and good lids and rubbers are satisfactory for freezer-locker storage, but sufficient head space must be allowed to prevent breakage. They do not stack well and are less convenient than other containers. Tin containers, either friction top, slip-on top, or sealed as in canning are good and may be used repeatedly if they do not rust. Fruits and berries will discolor, and brined vegetables will rust the cans unless fruit lacquer-lined tins are used. Moisture-vapor proof cartons of heavily waxed paperboard or fiber are available and very practical. Some have straight sides and tight lids, other have special linings. The usual pasteboar~ box and ice cream carton are not satisfactory since they permit an exchange of gas and moisture-vapor. Montana Extension Service in Agriculture and Home Economics..I. C. Taylor, dirf'(:lol'. Montana State College and United States Department of Agriculture cooperating, Distl'ibuterl In furtherance of the Acts of Congress. May 8 and June :~O. 1914. 10M 'I'~.(\ 6 43

2 MONTANA EXTENSION SERVICE BULLETIN NO. 220 Cellophane bags are excellent if sealed with a warm iron or curling iron. Special wrapping paper should be used for meat. Ordinary waxed paper and regular butcher paper are not satisfactory. Tough, moisture-vapor proof papers are made for this purpose. Thirtypound base waxed papers are proving satisfactory. Cellophane is good, but expensive. Headspace in containers is important. Allow from 1 to 11/2 inch headspace in glass jars and from % to 1 inch in other containers for expansion of the product while freezing. Pint and quart can tainers are best for fruit and vegetables, and more than five pound? of such products should not be frozen in one container. Temperatures And Length Of Storage Periods Quick freezing causes less damage to animal and vegetable fiber than slow freezing. Freezing does not sterilize the product, but it slows or temporarily stops the action of spoilage causing organisms. Molds stop growing at temperatures below 15 degrees, but enzymes that ripen meat and cause changes in fruits and vegetables continue to work at temperatures nearer zero. Freezing foods quickly at zero or below and storing them at a temperature of zero seems to give the best results. Where a sub-zero "quickfreezing" compartment is not available, good results can be obtained by holding the temperature in the locker room at 0 degrees F. all of the time. Packages or containers of food should not be stacked together until they are completely frozen. Otherwise, food in the center of the stack may freeze too slowly. The locker temperature should not fluctuate more than 3 or 4 degrees. Variation in temperature causes drying and absorption of odors and flavors.. The locker room should be clean and as free as possible. from odors. A relative humidity of about 85ro has generally been found satisfactory. Length of time products will keep satisfactorilyin the locker will depend on extent to which the contained or wrapper is moisture-vapor proof, on the temperature of the locker room, and on the quality and freshness of the food when frozen. Fruit will keep in sirup for a year and vegetables at least four months 01' longer with the temperature at 10 degrees above zer o. Vegetables will keep much longer if held at 0 degrees F. A higher temperature permits slight changes to occur due to enzymes within the vegetable. Beef, lamb, and poultry should keep well at least six months at 10 degrees above zero if properly wrapped. Pork is liable to become rancid if kept over four months at that temperature. All meats will keep longer at zero. Temperatures used in this bulletin are all Fahrenheit.

PRESERVATION OF FOODS BY FROZEN STORAGE Preparing Vegetables S~l~ct vegeta1;>les in. prime condition for table use and get them mto storage ImmedIately. A few hours delay in hot weather may render the pro~uct unfit for storage. Sort carefully, wash, and prepare as for cookmg, Scald or blanch (See Table I), cool quickly and pack. Freeze promptly, Keep the prepared products cool until they reach the freezer. Blanching or scalding of vegetables helps retain color flavor and firmness, Scald small quantity at a time so that the w~ter wili be boili~g hot each time.. If blanching in hot water, use a large kettle WIth plenty of water. Have water boiling rapidly and put in a quart or less of vegetables at a time. The water should return to boiling V?"ithin a1;>out. one minute af~er each addition of vegetables. Q~uck coolmg ill c?ld water IS essential after scalding. Slow coolmg causes undesirable changes to occur in the finished product. Drain well before packing. Corn on the cob will have a "cob flavor" unless thoroughly scalded. (See Table I) '. Use stainless steel knives and avoid galvanized and iron utensils since they cause some products to discolor. Vegetables may be packed dry or well drained or they may be packed in cold 2% brine. The method may vary according to the product and the use to be made of it. Commercially frozen vegetables are packed dry, but many products can be packed in a cold 2% brine. See Table II for proportions. The b.rine must be cold when added to vegetables. Dry pack is preferred when the locker temperature is kept near zero. If the temperature of the locker room is 8 or 10 degrees above zero, a few packages of green vegetables that are to be kept longest might well be packed in the brine. It seems to protect color and flavor better than dry pack at the higher temperature over a long period of time. Certain varieties of vegetables seem better suited to freezing than other varieties. (See. Table III.) Preparing Fruit And Berries Select firm, ripe fruit in perfect condition for eating. Sort, wash, pack with sirup or dry sugar and freeze quickly..handle carefully to avoid bruising, Remove pits and skins if desired. Peaches should be peeled by scalding but it is usually not necessary to remove the peel from other fruit. Choose the method of packing according to the kind of fruit and the way it is to be used. Use stainless steel knives. Peaches may be sliced and allowed to stand for a few minutes in a weak salt solution (1 teaspoon sale to 1 cup water) or water to which a little lemon juice has been added.. ThIS helps preven discoloration but either solution shoul~ be rmsed off before the fruit is put into sirup or sugar for freezmg. 3

4 MONTANA EXTENSION SERVICE BULLETIN NO. 220 Sirup Pack-Fruits to be eaten as a sauce retain color flavor and texture mare like the fresh product when packed in Sir'up tha~ by other methods. The sugar may be mixed with hot or cold water and stirred until it is dissolved. The sirup need not be cooked and it :must be coo! wh~n added to the fruit. Fifty per cent sirup made with equal parts of sugar and water is of medium sweetness and suitable for most fruits. Dry Sugar Pack-Fruits to be cooked before serving or for use in puddings, ice cream. shortcake, or sauce may be packed with dry sugar instead of sirup. Mix one pound of sugar evenly through three or four pounds of fruit; then pack, and freeze. The sugar draws juice from the fruit to form a sirup. Peaches do not pack well by this method. Apricots may be halved (unpeeled), mixed with dry sugar in the usual proportion, packed and then covered with 60 to 65% sirup to keen out air and prevent discoloration. Sweet whole cherries may be dipped in water and packed without sugar or sirup but must be used as soon as they thaw. Cherry stems give an undesirable flavor in sirup. For most purposes the cherries are better if pitted and packed in sugar,or sirup. Freezing Fruits with Less Sugar During the War Emerg-cncy This year homemakers will have to use less sugar in freezing fruits. White corn sirup or honey may be used in place of part of the sugar as given in table II. Dl'Y Pack-Most fruits are not satisfactory when frozen without either sirup or sugar. Rhubarb and berries for use in pies, marmalade, or other cooked dishes may be packed and frozen plain, but the results are usually less attractive than by other methods. Fruit Juices and Pulps-Fruits that do not discolor easily may be put through H sieve to remove seeds, hard pieces, and skins. Sugar may be added to the pulp in the proportion of 4 Ibs. fruit pulp to 1 lb. sugar and the mixture frozen in small containers. Less su~ar may be lised during sugar shortage or corn sirup or honey substituted as for dry sugar pack. Fruit juice may be frozen with or without sugar. Bottles that taper up to a sman neck should not be used since they sometimes break while freezing. Prcpaloing Meats To be assured of a good quality meat product it is important that only well fleshed animals be slaughtered for processing. Meat from poorly finished animals will deteriorate most rapidly. Pork should be well trimmed before freezing. The meat should be allowed to ripen at a temperature just above freezing, 32 degrees to 36 degrees, before it is frozen. ~eef and lamb should ripen from six to ten days. Pork should be quickly chilled and may be aged two or three days, although many

PRESERVATION OF FOODS BY FROZEN STORAGE 5 operators now believe it has less tendency to becdme rancid if frozen as soon as it is thoroughly chilled. All meat should be cut into pieces suitable for cooking and each piece carefully wrapped. A tough, heavy paper that will not tear easily (thirty-pound base) and that contains sufficient wax to prevent drying and absorptidn of odors and flavors must be used. Several such papers are now on the market. Glazed butcher paper is not satisfactory. Each piece of meat should be well wrapped and the edges of paper folded in such a manner as to make as airtight a seal as possible. Label each package clearly. The length of time such meat will keep well will depend upon the condihon of the fresh product, thorough chilling or aging before freezing, how well it is wrapped, and how near zero the locker is kept. Pork is especially liable to become rancid if kept more than four months unless the locker temperature is held at zero. Steaks, chops, or pieces of chicken will be easier to separate and thaw for cooking if two pieces of wax paper or locker paper are placed between the layers of meat. Cured meat may be wrapped and stored in freezer lockers to keep it sweet and free from mold. It should be wrapped and quick frozen just as any other meat. Poulh'y-Poultry is best if kept from food long enough to empty the crop, then dressed carefully, chilled, wrapped, and frozen. Some operators age the bird 12 to 24 hours at 32 to 36 degrees F., while others freeze as soon as all animal heat is gone and the bird is cold. Ice water' or cold well water may be used for chilling if no other method is available. Poultry frozen for home use should be drawn when it is dressed. Prompt cooling and freezing are essential as bacterial changes can take place rapidly in the moist, warm body cavity. Birds are more satisfactory if dry picked or slack scalded. Poultry frozen whole for roasting may have the giblets wrapped in waxed paper and placed inside and the whole bird wrapped in the special meat paper and frozen. Young chickens may be cut into suitable pieces for frying, chilled, and wrapped in a single package, or the pieces may be packed into an airtight can, jar, or waxed container and frozen. Some prefer to pack the pieces into a container and cover with water or a 2 percent brine solution made by adding 1 teaspoon salt to 1 cup cold water. Chicken may also be glazed before packing. (See directions for glazing fish.) Fish-Fish should be kept cold and should be frozen as soon as possible. If the fish are properly wrapped and a low, even temperature maintained in the locker room, there will be no odor. Clean and dress the fish, removing the heads. Wash, and if they are large, they should be cut into suitable pieces. They may

6 MONTANA EXTENSION SERVICE BULLETIN NO. 220 be wrapped in the special meat paper be: ore freezing, but are more often glazed and then wrapped. To be glazed, the fish are frozen, then each fish is dipped quickly into cold water. The zero temperature of the fish causes a thin coating of ice to form over it immediately that seals and protects it. Wrap and store in the locker. Use Of Frozen Foods Food taken from the locker should be kept frozen until ready for use. It will spoil quickly after it thaws. Vegetables should not be kept longer than 48 hours, even in a good, cold refrigerator. Dry frozen vegetables may be dropped into boiling water while still frozen. Those packed in brine may be allowed to thaw in the brine before they are removed from the container and then be cooked at once. Frozen vegetables cook quickly, usually in about half the time required for fresh ones. Frozen vegetables may be cooked by steaming in a tightly covered steamer or waterless cooker. If such utensils are 110t available, one-fourth to one-half cup of boiling water may be added and the kettle kept covered. Green vegetables will retain their color better if kettle cover is removed (after they start to cook). Roasting ears should be thawed before cooking but must not be kept long after thawing. Fruits frozen in sirup or sugar should be served while still cold, but almost entirely thawed. Peaches and apricots discolor quickly after they thaw. All fruits should be thawed in the container. Dry frozen fruit for pies should be poured into the pastry shell while still partly frozen and the necessary flour, sugar, and seasonings added.. Meat for roasting retains its flavor, texture, and juice best if put on to cook before it is entirely thawed. The cooking time will need to be extended to allow for the slow heating, 10 to 30 minutes per pound, depending upon size of the piece of meat and how nearly thawed it is. Steaks and chops brown more readily if they are completely thawed. Meat may be thawed in the refrigerator or at room temperature. Choice Of Products Some vegetables and fruits are better adapted for freezing than others, and certain varieties of each seem to give best results. Apples, apricots, berries, peaches, an~ prunes have been frozen successfully. Pears and plums are less satisfactory. Asparagus, beets, broccoli, Brussels Sp~outs, cabbage, carrots, cauliflower lima beans, mushrooms, parsmps, peas, peppers, rhubarb, snap'beans, spinach, sw~et corn, Swiss chard, and similar greens are satisfactory for freezmg. Celery, cucumbers, lettuce, and tomatoes have not been frozen successfully.

PRESERVATION OF FOODS BY FROZEN! STORAGE 7 Table III of this bulletin lists varieties best adapted for freezing. To get maximum service from a freezer locker, it should be made a part of a planned food preservation pro'gram for the entire year. First, the food needs of the family for a year can be estimated, then the garden planned as to quantity and variety that will best supply the need. Consideration of the time and cost and quality of finished product involved in canning, curing, freezing, dehydration, or storing in cellars should help determine the method to be used for different products. Keep refilli!l;g the locker to get the utmost service~poultry at culling time, vegetables, berries, and fruit in season, and meat from time to time as butchered. The meat for summer use can be stored after the year's supply of other products has been used and the locker is becoming empty. Food " TABLE I J;'REPARATION OF VEGETABLES AND FRUITS FOR STORAGE IN VEGETABLES Asparagus Beans (snap) Beans (tender shelled) Broccoll* (wash & soajc) Brussels Sprouts' (soak) Cabbage Call1tflower Corn (on cob) Corn (whole cut) Mushrooms Peas Peppers Spinach, Chard, (other greens) FREEZER LOCKER Method of Packing Cool quickly in cold water Preparation for Freezing an=d:...::dr;..:a=in=.. _ Scald 2 to 3 minutes Scald 2 to 4 minutes Scald 1',1, to 2 minutes Scald 3 to 4 minutes Scald 3 to 4 minutes Cut in pieces. scald 3 min. Scald 2',1, to 3% minutes Scald 6 to 9 minutes Scald 2 to 3 minutes Sort, scald 2 to 4 minutes Scald 1 to 1% minutes Wrush, halve or slice, and scald 2 minutes Scalc! 2 minutes For brine pack, use 1 teaspoon salt to 1 cup water. Pack dry or in brine Pack dry or in brine Dry Pack Pack dry or in brine Paclc dry or in brine Pack dry or in brine Pack dry 01' In brine Dry Pack separate ears Dry pack preferred Brine preferred Pack dry or in brine Dry pack or brine Dry pack FRUITS: When sugar is Apricots" Cherries (sour) Cherries (sweet) Peaches" Prunes Grapes Rhubarb plentiful use the following proportions: Cut and pit In sirup of 3% to 4 cups sugar to 4 cups water Stem, wash, pit In sirup of 4 to 6 cups sugar to 4 cups water or 4 pounds cherries to 1 pound sugar (2'A, c.) Stem and wash In sirup of 30/4 to 4 cups sugar to 4, cups water or 3,llolm<ls cherries to 1 pound sugar (2 1 14 c.) As for canning In sirup or 4 cups sugar to 4 cups water As for canning In sirup of 30/4 to 4 cups sugar to 4 cups water Sort and wash In sirup of 2 1/5 to 4 cups sugar to 4 cups water Wash. trim, cut 1 inch In sirup of 3% to 4 cups sugar to 4 cuj}s water

8 MONTANA EXTENSION SERVICE BULLETIN NO. 220 BERUIES Huckleberries Sort, wash, drain 4 pounds berries to 1 pound sugar (2'14 c.) or sirup of 4 to 6 cups Bugar. Raspben'les to 4 cups water Sort, wash, drain 4 pounds berries to 1 pound sugar (2lA. c.) 01' sh'up of 4 c. sugar to 4 Strawberrles (Whole) Sort, wash, drain c. water In sirup of 4 to 6 cups sugar to 4 cups Strawbel'l'ies (silced) Sort, wash, drain water 4 pounds berries (10 c,) to 1 pound Othel' berries sugar (2',4, c.) Sort, wash, drain 4 pounds berries to 1 pound sugar or in sirup of 4 cups sugar to 4 cups water Glass jara, waxed cartons, or tin cans may be used for fruit and vegetables. For nil fruits and berries, asparagus, corn, and all brine'packed vegetables, tin cans, if used, should be lacquer lined. BI'occoll and Brussels Sprouts should be soaked a few minutes 'in weak brine. "Peaches and apricots )'equire absolutely air-tight containers to prevent discoloration.. Fl'uit TABLE II WAn ]<:Jl\mRGI~NCY SUGGESTIONS FOR USING LESS SUGAR Tal<en from War Emergency Circular Prepaid by Experiment Station, Montana State College DRY SUGAR pack FOR FROZEN FRUITS, USING SUGAR AND SUGAR SUBSTITUTES Proportions for Dry Sugar Pack Amount of fruit No. 1 sugar..j.. corn sirup sugar ouly No.3' No, 2' sugar + honey Strawberries 4 lb. 1J,B c. Bugar 1)h c. sugar sliced or (10 c.) 2',4, c. sugar and and chopped 1'h c. corn sirup % c. honey Huckleberries 5 lb. 2'A c. sugar sanje as above. same as above (15 e.) Chel'ries 4 lb. 2% c. sugar sanje as above same as above -red SOlll' pitted Cantaloupe 5 lb. Ph c. sugar uo sugar cut in amah and 1% c. honey p.leces - firm but %, c. corn sirup ripe 'Place washed fruit in a suitable pan, and sprlnlcle the sugar over it. Let sugar llissolve on the fruit for 3 or 4 minutes. Then pour corn sirup or honey over the fruit, turn the mlxtul'e over several Umes with a spoon until each berry or piece is coated. Pack into containers for freezing. Fruit Raspberries or Sweet cherries, pitted SIRUP PACK FOR FROZEN FRUI'l'S. USING SUGAR AND SUGAR SUBSTITUTES Approximate amount of fruit 4 qt. No. l' sugar ouly 3%. e. sugat' '1 c. wate)' Proportlolls for Sirup Pack No. 2* No.3 sugar + corn Sll'Up sugar + honey 1'h e. sugar 2%. c. corn sirup 3'h c. water 1 1 k c. sugar 1 c. h<mey 4 c. water Peaches.sliced... 2'/4 c. sugar 2'14 c. sugar 01' 4 qt. 4'14 c. sugal' 2~ c. corn sirup 1'14 C. honey AprIcots-halved" 4 c. water 3 c. water 4 c. water 'All sirups must be cold when added to fruits. Sirups need not be coolred. '.Sliced peaches and apricot halves should stand at least 10 minutes in salt solution made by adding 4 teaspoons of salt to 1 quart of cold water.

PRESERVATION OF FOODS BY FROZEN STORAGE 9 TABLE III VARIETIES OF VEGETABLES AND FRUITS THAT HAVE BEEN FOUND SATISFACTORY FOR FREEZING The practice of freezing home produced foods is so new in Montana that It Is Impossible to give a complete list of varieties adapted to Montana conditions that are also best suited for freezing. This table gives a partial list. Vegetable Varieties Asparagus Beans Beans (green pod) (dwarf wax pod) Beans (polo type) Broccoli Brussels Sprouts Cabbage (early) Carrots Cauliflower Sweet Corn Peas (wrinkled) Spinach Mary Washington" Stringless Green Pod Giant Stringless Green Pod Asgrow Stringless Green Pod Mosaic Resistant Stringless Green Refugee Round Pod Kidney Wax Round Pod Blaclt Wax Kentucky Wonder Half Dwarf Improved Copenhagen Market Red Core Chantenay Nante.~ Early Snowball Dry Weather or Danish Giant Golden Bantam Golden Cross Bantam Thomas Laxton Asgrow 40 Improved Gradus Peas w:lth green skin and wrinkled seed are best and not all canning types are good. King of Denmark Long Standing Bloomsdale Savoy ApJ'icots Cherries (sweet) Chet'rles (sour) Peaches Huckleberries Raspberries (black cap) Strawberries (standard) Strawberries (everbear) Other Berries FRUIT VARIETIES Tilton Blenheim Moorpack Bing Lambert Large Montmorency English Morello J. H. Hale Slappey Crawford Wild (for pies) Cumberland Plum Farmer Dorsett Blackmore Fairfax Wayzata Boysenberry Youngberry

10 MONTANA EXTENSION SERVICE BULLETIN NO. 220 Part of the information used in this leaflet was taken from the following publications: 1. "Storage of Fruits and Vegetables in Community Freezer Lockers," H. C. Diehl, Senior Chemist, Frozen Pack Laboratory, Bureau of Chemistry and Soils, Seattle, Washington, and Miriam Birdseye, Senior Nutritionist, Division of Cooperative Extension Service, United States, Department of Agriculture. 2. "The Farm Freezing Plant and How to Use It," Extension Bulletin No. 249, Extension Service, State College of Washington, Pullman, Washington. 3. "Refrigerated Food Lockers," by L. B. Mann, Farm Credit Administration, Washington, D. C. 4. "Preservation of Fruits and Vegetables by Freezing in the Pacific Northwest," by H. C. Diehl, Senior Chemist, Frozen Pack Laboratory, Bureau of Chemistry and Soils, Seattle, Washington. 5. "Cold-Storage Lockers for Preserving Farm-Dressed Meat," by K. F. Warner, Extension Meat Specialist, United States Department of Agriculture. 6. "Quality in Frozen Fruits and Vegetables," Agricultural Experiment Station, University o Minnesota. 7. "Some Methods of Fruit Preservation in Wartime," Circular 173, Agricultural Experiment Station, Montana State College.