B-139 1945

SOME IMPORTANT FACTORS CAUSINGSPOILAGE and POOR QUALITYIN HOME CANNED FOODS

*

by

Mrs. Winifred J. LeverenzExtension Specialist in Food Preservation

A. & M. College of Texas

and

O. B. Williams, ProfessorBacteriology DepartmentUniversity of Texas

*Issued by

The Extension ServiceAgricultural and Mechanical College of- Texas andThe United States Department of AgricultureIde P. Trotter. Director, College Station. Texas

Some Important Factors Causing Spoilage and PoorQualit~ in Home Canned Foods

byMrs. Winifred J. Leverenz*

O. B. Williams*"*

Introduction

Fresh food is commonly in a continuous state of ·change.Enzymes and microorganisms, which normally are present inthe product, are responsible for the changes which take place.The texture, flavor, color~ palatability and nutritive value offood are affected by the cpanges. If allowed to continue overa long enough period of time the food spoils. The objective offood preservation is to prevent or control the activities of theenzymes and microorganisms in such a way that the preservedproduct may be safe and retain maximum palatability~ whole-someness and nutritive value.

Canning long has held a prominent place among the meth-ods of preserving food because, when properly done, it is bothsatisfactory and economical. If not properly canned, however,the product is fairly certain to be of poor quality. In additionthere may be a high percentage of spoilage. Poor quality mayresult in a considerable loss because of a lack of appetizingappearance and taste. Spoilage, of course, means total loss.

The purpose of food preservation is obviously to providefood for consumption at some future time. If the preservedfood is not eaten because of low quality or spoilage, nothinghas been gained and much time, labor and money have beenlost.

I t is the purpose of this bulletin to point out some of thecauses of spoilage and poor quality which experience and re-search have shown to be most common, and to suggest methodby which they can be avoided.

*Extension Specialist in. Food Preservation, A. & M. College of Texas.**'Professor of Bacteriology, University of Texas, and formerly Bacteriologi t. ResearchLaboratory, National Canner's Association.

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ENZYMES IN RELATION TO CANNED FOOD

The cells of all plants and animals contain chemical agentsknown as enzymes. These are concerned in the ripening of thefruit or vegetables. Up to peak maturity their action improvesthe quality of the raw product. Beyond the peak of maturitythe changes make the product less and less desirable from aquality standpoint, until it finally becomes unsuitable for useas "fresh" food. The enzymes continue to act in the raw fruitsand vegetables from the time of harvesting until the productis heated to an inactivating temperature, which is at or nearthe boiling point.

Enzymes usually are of minor importance as spoilageagents, because they are easily destroyed by heat. Amongthe most significant or undesirable changes in food broughtabout by enzymatic activity are: a loss of desirable flavors;lowered quality in texture and color; the transformation ofsugar to starch with an increase in toughness; and accelerateddestruction' of ascorbic acid (Vitamin C).

A recognition of the important and easily controlled fac-tors which favor enzymatic changes points the way to methodsof handling the raw food which will result in better quality inthe canned product. Especial attention should be given to thefollowing suggestions:

1. Peak Maturity.Harvest the fruit or vegetable to be canned at thepoint of peak maturity for the product. For some prod-ucts, as for example pears for sweet pickles, or toma-toes for chow-chow, peak maturity does not mean fullripeness. But for most products it does mean that thefruit or vegetable should be fully ripe, but not over-ripe. Corn should be gathered while in the milk stagebefore the sugar is changed to starch. Tomatoes shouldbe allowed to remain on the 'bush until red ripe butstill firm. In extremely hot climates, it may be betterto harvest tomatoes in the deep pink stage and letthem ripen in a cool storage place in order to avoidsun-blisters. Peaches should be fully ripe, still firmand not soft or bruised. Fruit which is overripe, butstill edible may be made into preserves or canned foruse in pies or ice cream. Peas and beans should be can-ned while still tender and succulent. If seeds have al-ready begun to form in beans and the hull :isslightly tough they should not be canned as s.napped

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beans, but canned as shelled beans or allowed to drynaturally on the vine. The most that one can do is tokeep the quality of the canned food as near that of thefresh as possible.

2. Cool of the morning.Harvest the fruit or vegetable in the cool of the morn-ing, and try to finish the canning before the day getshot. Keep the raw product as cool as possible until itis given the heat treatment.

3. Small amounts.Harvest only the amount that can be handled imme-diately. One or two hours between garden and can isideal. Do not attempt too much at one time because itis easy to become careless as one becomes tired.

4. Blanch or heat promp,uy.As soon as the food is prepared blanch it, that is, heatit to stop enmymatic action. If necessary to postponecanning for a short time, the blanched food can becooled in water and held· without loss of quality some-what longer than if not blanched. If the raw packmethod is being used, fill the container and start heat-ing with as little delay as possible.

MICROORGANISMS IN RELATION TO CANNED FOOD

Most important as a cause of spoilage in' canned foodsare the microorganisms which are always present in or on thesurface of the foodstuff, whether fruit, vegetable or meat.Success in canning demands the destruction by heat of thesemicroorganisms which are naturally present or which mayhave been accidentally introduced into the food during prep-aration, as well as the prevention of the entrance of more or-ganisms by hermetic sealing of the filled container.

Some knowledge of the nature and distribution of micro-organisms is necessary in order that effective measures forthe·prevention of spoilage may be carried out. Microorganismsare universally present in water, soil, air, on the surface andwithin the bodies of man and animals. They can grow over awide range of temperature, but most of them grow best at a

4

moderately warm temperature. Food for man is likewise foodfor microorganisms. In many instances their growth in foodmay result in a desirable change, as for example, in the fermen-tation of bread dough by yeast, the bacterial fermentation ofcabbage for kraut, or the ripening of cheese. Their uncon-trolled growth even in these foods quickly results in decom-position to such an extent that the food will be classed asspoiled or inedible. Certain types which may be present in foodare capable of causing serious illness; hence there is a hazardto health associated with their presence.

There are three groups of microorganisms which causespoilage in food-the yeasts, the molds and the bacteria. Theindividual cells of all of these are very small and can beseen only under the microscope. A mass of a large number offilaments of a mold gives the familiar cottony or fuzzy appear-ance of mold growth. Sediment and a cloudy appearance ofliquids are usual indications of yeast and bacterial growth.

Under favorable conditions of temperature and moisturethese organisms can grow very rapidly and may, therefore,produce undesirable changes before canning. The change~

which take place may not be readily apparent, but may besufficient to give an abnormal flavor. This condition is knownas incipient spoilage, and is favored by the changes in the foodduring preparation such as peeling, trimming and blanching.In order to prevent incipient spoilage, it is very important tokeep clean all utensils that the food touches and to can thefood promptly after it is washed and prepared.•

If no microorganisms were present it would not be nec-essary to do more than destroy the enzymes to preserve food.Since it is not possible to have raw food free of microorganisms,the sealed container must be heated at a temperature and for aperiod of time adequate to destroy the most heat resistant typepresent. This time-temperature combination is known as theprocess, and is somewhat greater than that which would beadequate merely to cook the food.

Yeasts, molds and many bacteria are of low resistanceand can be destroyed by heating the food at or near the boilingpoint for a short time. Certain bacteria, however, producestructures known as spores which may be compared to seeds.When spores are present, the bacteria have a much greaterresistance to heat. If the sealed container does not receive anadequate process, spores may survive. Later while in stor-age, they may grow and cause spoilage.

5

HOW THE PROCESS IS DETERMINED

A number of factors must be taken into consideration indetermining the process for a canned food. Among those ofprimary importance there are the following:

1. Heat resistance of the spo~e.

Not all kinds of sporeforming bacteria produce sporesof equal resistance. It is neces~ary to determine theresistance to heat of the spores of a large number ofthose types which may at any time be present in thefood in question, and to assume that types of extremeresistance are always likely to be present.

2. Number of spores present.The larger the number of spores present, the longerthe time required to kill them at any given tempera-ture. It is sometimes easier to wash off most of thebacteria than to kill them by heating. Too much em-phasis, therefore, cannot be placed upon thoroughwashing of the raw food and upon the closest attentionto general cleanliness throughout all of the canningoperations.

3. Acidity of the food.The time of processing is in part determined by theacidity of the food being canned. Technically, it is notcorrect to refer to vegetables and meats as "non-acid"since practically all foods are acid. Instead of "non-acid," meats and vegetables may be called "low-acid"foods. The acidity of foods may be gr'eatly different.

Acidity is expressed in terms of pH. A pHof 7.0 is neutral, that is, neither acid nor alkaline. Anumerical value greater than 7 indicates an alkalinereaction, and a value less than 7 indicates an acid reac-tion. A pH of 6.0 is 10 times as acid as a pH of 7.0. ApH of 5.0 is 10 times as acid as a pH of 6.0 and 100times as acid as a pH of 7.0. Most vegetables andmeats have a pH value between 5.0 and 6.5. Most fruitshave a pH value between 3.0 and 4.5. Bacteria aremost ea~ily killed in foods that are high in acid, thatis, foods which have a low pH value. It is for thisreason that fruits can be preserved by a process inboiling water, while vegetables and meats which arelow acid but high in pH value require a pressureprocess.

6

The botulinum organism, which is the most danger-ous in canned foods, will not grow at a pH value as lowas 4.5. Note in the chart below that figs, pears andtomatoes are near the border line of acidity in whichClostridium botulinum will develop; therefore, it isespecially important to process these foods properly'when a water bath canner is used.

The average pH values of a few of the commonlow acid and acid foods are as follows:Corn 6.3Lima beans _ 6.1Peas _ 6.0Meat ._ 5.8Greens __ 5.5Green snap beans __ 5.2Beets __ __ .__ ..5.0 - 5.4Carrots __ __ __ ..5.1

Figs __ .. __ 5.0Tomatoes .4.3Pears .__ .__ 4.3Peaches __ 3.7Pineapple __ 3.5Kraut .. __ __ __ 3.1 - 3.5Berries 3.0 - 3.4

4. Presence of fat.Bacteria are most easily killed in water or steam. Ifthey are trapped in oil or fat they are protectedagainst contact with the water or steam and are lessreadily destroyed. Consequently, foods containing fatmust be processed for a lpnger time or at a highertemperature than those which do not contain fat.

5. Rate of heat penetration.The transfer of heat from the outside to the center ofa can is either by conduction or convection. In con-duction heating the transfer of heat is from particleto particle without much or any movement of the par-ticles. It can perhaps be compared best to heating a barof metal at one end. Gradually the bar will becomehot throughout its length. With convection heatingthe transfer of heat is by currents within a volumeof gas or liquid. If heat is applied to the side or bottomof a vessel of water the layer of water adjacent to theheat will expand and rise, and in rising will mix withand be replaced by cooler water to which it will impartsome of its own heat. In this way convection currentsare set up so that the liquid throughout the vessel ra-pidly attains a maximum temperature. These sameprinciples apply fo the heating of foods in sealed con-tainers. Thus in a product such as beets in brine the

7

heat will be distributed throughout the container tothe surface of the beets by convection currents in thefree flowing liquid, while the beet will heat moreslowly from the surface to the center by conduction.In solid products, such as meats or cream style corn,the heat transfer will be by conduction alone. Since theparticles of food, and even sugar or salt dissolved inthe liquid, interfere to some extent with the formationof convection currents, it should be obvious that withmost canned foods both types of heat transfer occur.

. In order to determine a safe process for any givenproduct in a particular container size, it is necessaryto measure the rate of heating and to know how longit takes for the coldest part of the container (usuallythe geometrical center) to reach a temperature highenough to kill any organisms which may be there. Aninstrument known as a thermocouple is used for thismeasurement. .

The canning processes recommended by the Bureau of Hu~man Nutrition and Home Economics in Washington, D. C.,the Texas Extension Service, and other reliable agenciesare based upon a knowledge of the factors which in-fluence the destruction of bacteria by heat. They take intoconsideration the amount of heat and length of time necessaryto kill something more than an ordinary number of spores ofordinary resistance in the container of the size in question. Ifthe spores present have an unusually high resistance, the proc-ess recommended may not be adequate and spoilage of the foodis probable. Furthermore, the same product may heat at differ-ent rates depending upon the stage of maturity. Thus youngtender peas with a low starch content will heat rapidly by con-vection. Mature peas or beans with a high starch content willbreak down to some extent and liberate sufficient starch tointerfere with the transfer of heat. In such a case the productwill heat more by conduction and less by convection. Conse-quently, a process adequate for young peas may sometimesnot be adequate for mature peas.

It is important that the home canner use procedures rec-ommended by reliable agencies and follow details of canningsuch as the amount of fill, the headspace, the temperature ofthe product at the time of sealing, the time to process andwhether to process in a water bath or a pressure cooker. Un-der no circumstance should a person without technical train-ing vary recommended canning procedures. If they do so,there is danger of spoilage and danger of food poisoning.

8

KINDS OF SPOILAGE

3.

2.

5.

Mold indicates leakage. In preserves, jelly and jam itmay indicate leakage, understerilization of containers,or underprocessing of food.Other spoilage due to leakage is almost always gas-eous. Spoilage due to underprocessing may be eithergaseous or non-gaseous.With leakage, different containers of the same lotcan vary greatly in the odor and appearance of thespoiled food. Some may be frothy, some slimy; nearlyall have a disagreeable sour odor, but the odor may notbe identical for all spoiled containers. Different con-tainers of the same lot showing spoilage due to under-sterilization are fairly uniform in odor and appearance.

4. Frequently in cases of leakage an obvious containerdefect can be seen, such as a faulty seam or an illfitting lid. No such defect is apparent with spoilagedue to underprocessing.Spoilage due to leakage usually develops soon aftercanning. Spoilage due to underprocessing may be de-delayed for several days, weeks, or even months.

Microorganisms may cause spoilage in canned food afterprocessing under only two conditions. These are leakage andunderprocessing. The following points may help to differ-entiate spoilage due to leakage from that due to underprocess-ing:

1.

LEAKAGESpoilage caused by leakage through a faulty seal of a

can or jar usually develops within 3 to 4 days after processing.The changes which may be observed in the food are quitevaried. There may be a mat of mold on the surface. The foodmay be very slimy, or it may be frothy. It usually has a dis-agreeable sour odor. The spoilage is commonly gaseous 'sothat sealed cans will swell. Frequently the contents will leakout through the defective seam. In glass jars bubbles of gasmay be seen, and the contents may leak out around the lid.

Causes of LeakageOrganisms causing spoilage by leakage may be yeasts,

molds or non-sporeforming bacteria which have a low resistanceto heat. They enter the containe:r;: in air or water sucked induring cooling. Specific causes of leakage are as follows:

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In Jars.1. Nicks or chips on rims of jars;2. Old or damaged rubber or rubber compound in lid;3. Rubbers not adjusted properly;4. Particles of food or grease on sealing surfaces;5. Insufficient heat to seal lid;6. Too rough handling when processing; inverting or

tilting jars while food is still hot;7. Excess fat that deteriorates rubber in storage and

causes leakage;8. Improper storage:

a. Heat and light deteriorate rubbers and spoilagemay follow.

b. Freezing may break seal.

In Tin Cans.1. Not having sealer adjusted for kind of lid and can to

be used. Lids with compound gasket must have atighter seal than those with paper gasket;

2. Paper gasket that gets wet and fall out;3. Can bent badly or placed crooked in sealer;4. Food particles or grease left on the rim of the can;5. In No.3 cans and larger, too high pressure or a sud-

den release- of steam may cause the seam to spread andallow air to enter.

6. Fat of meat may cause deterioration of compoundgasket and cause leakage.

RemarksLeakage is a common type of spoilage in home canned

foods. Food spoiled by leakage should never be tasted or eaten.Too much emphasis cannot be given to proper adjustment

of sealers for cans, and to proper instructions in use of lids onjars. Always follow manufacturer's directions in using ealersand in tightening lids on jars.

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Test for -a good seal on jars: Seals on j aI'S should beinspected carefully 12 to 24 hours after cooling. If there is afaulty seal, the food can then be used or reprocessed to preventwaste. In checking a seal on jars that have self-seal type lids,remove the metal band and tap the metal disk with a spoon orfork. If there is a good seal, there will be a clear ringing sound.If there is a poor seal, there will be a dull thud. A piece of'foodtouching the top may cause a dull note; therefore, shake thejar before removing the band; then tap to test the seal. Whentesting the 3 piece type, remove the metal band. The rubberring should be smooth, and the glass disk securely attachedto the rubber. Leave metal bands off both these types becausethey rust easily. Other types of lids should be firmly attachedto the rubber. When the jar is tilted, there should be no leak-age of liquid.

Test for cans: Tin cans should be checked after sealingand before processing. All directions for using sealers giveways of testing a good ~eal. Just after processing, while cansare hot, if they are. immersed into cold water, usually a poorseal will show up by bubbles rising to the surface of the water.

UNDERPROCESSING

Spoilage due to underprocessing is the result of a failureto heat the sealed container long enough to destroy the bac-teria which are present. Ordinarily, it is due to the survivalof spores. In acid products, however, which usually. are pro-cessed in the water bath, it may be due to the survival ofyeasts or non-sporeforming bacteria. If the product is one withslow heat penetration and is sealed at a low temperature, thenthe boiling water process may not raise. the temperature of thefood in the center of the container to a degree which will killeven the non-sporeforming organisms.

The best safeguard against avoidable spoilage loss isthe use of a process embodying adequate time and temperature.How the process is determined is described on pages 6-8 inthis bulletin. Note particularly the statement "the larger thenumber of spores present the longer the processing period re-quired to kill them". Even though an adequate processing timeis used, if the food or the containers in which it is handled havenot been as clean as they should be, spoilage by underprocessingmay result.

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Specific Causes of Underprocessing

1. Processing for too short a period (not followingreliable processing time tables for either pressurecooker or water bath).

2. Using food which has not been washed thoroughlyor which has already started spoiling.

3. Canning low acid vegetables or meats without a pres-sure cooker.

4. Using a pressure cooker with an inaccurate gauge.

5. Closing the petcock of the cooker before air hasbeen driven out (exhaust cooker seven to ten min-utes before clos.ing petcock).

6. Beginning to count the processing time in a pressurecooker before the gauge registers the necessarypressure if canning vegetables or meats.

7. Counting the time before the water in the water bathhas come to a boil again, after the containers offruit or tomatoes have been put in.

8. Failing to increase the processing ,time if the waterdoes not completely cover the containers; if the wa-ter does not boil constantly; if the kettle is not tight-ly covered; or if the jars have unusually large diam-eters. .

9. Preventing free circulation of water by packing jarstoo closely t.ogether or by not using a rack.

10. Preventing adequate heat penetration by packingcontainers too full or too tightly, especially withshelled beans, corn, greens, mature peas or pumpkin.

11. Using too much fat in meats or adding fat to vege-tables. (Bacteria are less readily killed in fat thanin water; discussed on page 7 in this bulletin.)

12. Sealing food cold and processing it the same lengthof tIme as if it were hot when sealed.

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Di cussion of Bacteria Causing Spoilagein Undel'processed Foods

Spoilage due to the survival of spores is most common infoods of low acidity. Spores do not always start growingpromptly, so that several weeks may pass before spoilagetakes place.

Spoilage of this type is usually considered under two head-ings (1) That caused by thermophilic bacteria, and (2) thatcaused by mesophilic bacteria.

THERMOPHILIC BACTERIA

The term thermophilic is used to designate those bacteriawhich prefer a temperature for growth well above ordinaryroom temperature. Although some types will grow over a widetemperature range, many will not grow below 1000 F. and 'mostof them grow best at about 1300 F. All thermophilic bacteriaproduce spores of very great resistance to heat. Because ofthe high resistance to heat of the' thermophilic bacteria in' thespore stage, it is not always possible to obtain a sterile productby any process which is practical. Since these organismsprefer a fairly high temperature for growth, spoilage of thenon-sterile container can frequently be avoided by promptcooling after processing and storage in a cool place. As longas the storage temperature of the food can be kept below thatnecessary for the growth of any thermophilic spores whichsurvived the process, the food will remain wholesome.

Thermophilic spoilage falls into three main groups basedupon the changes which occur in the food. These are sulfidespoilage, flat sour spoilage, and "swell" spoilage. The last twoare of much greater importance.

Sulfide spoilage:

Sulfide spoilage is of very rare occurrence, and deservesonly brief mention. This type of spoilage has been found inboth peas and corn. The causal organism produces hydrogensulfide which is absorbed so that the container remains flat.The product has a "rotten egg" odor, which makes this spoil-age easily detected.

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Flat Sour Spoilage:

Flat sour spoilage is caused by thermophilic bacteriawhich produce acid without gas. It occurs most frequently incorn and peas, but may occur in other low acid vegetables. Thecontainer shows no evidence of gas and the product showslittle, if any, change in appearance. A faintly disagreeable odorcan sometimes be noted. The only indication of spoilage maybe the very sour taste of the food. The bacteria concernedpossibly enter the can on the food; but are more likely to beintroduced in an ingredient: for example in sugar which hasbeen added to corn, peas or meat.

"Swell" Spoilage:

Spoilage due to the thermophilic anaerobic group ischaracterized by the production of gas as well as acid. The gascontains hydrogen so that if a lighted match is held near theopening at the time a swelled container is punctured a flamewill burn. Frequently the can swells to the point of seam rup-ture.. The food is sour and usually frothy and has an odorsuggestive of rancid butter.

MESOPHILIC BACTERIA

Spoilage due to mesophilic bacteria, which grow readily atordinary room temperature, is most commonly caused by putre-factive anaerobes, although other types may sometimes be con-cerned. The putrefactive anaerobes are· soil organisms. whichgrow only in the absence of free oxygen or air. Many of thesepro<;luce spores of great resistance to heat. Typically, thesebacteria attack the protein of the food and produce a very foulsmelling gas so ·that the container will swell if it is a can, orshow gas bubbles if it is a jar.

This typical picture of spoilage may not always be ob-served with some products. If the acidi~y of the product isnear the acid limit of growth of the organism, as in stringbeans, there may not be sufficient growth to result in a readilyperceptible spoilage. In such an event the food may show onlya slightfy cloudy brine, and have a faintly disagreeable odorwhich will become more pronounced upon heating. The changesmay not be sufficiently apparent to cause the average house-wife to realize that the food is spoiled.

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Clostridium botulinum:

Spoilage due to putrefactive anaerobes would not be ofany more interest and importance than that due to any othergroup of organisms if it were not for the fact that the highlydangerous Clostridium botulinum is a memqer of this groupof bacteria. CI. botulinum is a sporeforming organism of prac-tically universal occurrence in the soil. Any food may be con-taminated with the organism or its spores. The bacteria them-selves are not poisonous, 'but when they grow in food, theyproduce as a: by product of their growth a very powerful toxin,or poison, which can be absorbed from the digestive tract. Thispoison causes the disease known as botulism. The death rateof this disease is about 65 ~ of the cases.

Although the spores of CI. botulinum may be very resist-ant, the poison produced by the organism is fairly readily des-troyed by heat. Since experience has shown that 'a food can betoxic and not be obviously spoiled, and since the poison, if pre-sent, can be destroyed by heating, many authorities recommendas a safety measure that all home canned low acid foods beheated before serving. The length of time which the foodshould be heated must be enough to insure that all particlesare heated through to the boiling point. To be certain of ade-quate heating, the food should be stirred frequently duringthe boiling period. Most authorities recommend heating meatsand vegetables 10 to 20 minutes.

The botulinum organism will not grow in foods which havea pH value as low as 4.5, such as tomatoes, fruits, pickles andkraut. Although the spores do not grow in these foods theymay remain alive for long periods and if the food should bechanged in such a way as to lower the acidity, as through thegrowth of mold or acid tolerant bacteria, then the spores maystart growing and liberate toxin. For this reason spoiled foodor food that is doubtful, no matter whether fruit or vegetables,should not be tasted without first having been boiled. Merelywarming the food is not adequate.

Caution: Food which shows putrefactive spoilage, orwhich is suspected of such spoilage, should be disposed ofin such a way that animals cannot eat it. Add severalspoonfuls of lye to the container. Mix thoroughly andbury both container and food. Under no circumstancesshould the food be eaten by people or domestic animals.

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Other Types of Spoilage by Mesophilic Bacteria:

. Spoilage other than putrefactive which may be caused bymesophilic bacteria includes the so-called flat sour of tomatojuice and, very rarely, black beets. Flat sour in tomato juice ia non-gaseous sDoilage, characterized by a medicinal flavor.Black beets occur only when small amounts of dissolved ironare present. The combination of beet pigment, iron in solutionand causal organism results in a black color which may ex-tend throughout the beet. Food spoiled in this. way is notpoisonous but should not be eaten.

At times various sporeforming bacteria from the soilmay survive the process and cause a souring of the product.Generally these types are not of high resistance and the spoil-age due to underprocessing can be kept at a low level by care-ful attention to the physical cleanliness of all equipment and bythorough washing of the product.

SUMMARY

The contents of this bulletin might easily be summarizedin the following simple rules of canning:

1. Select fresh, good quality products.2. Clean products and utensils thoroughly.3. Work fast. "One hour from garden to can."4. Use good containers and proper equipment.5. Seal food hot, whether precooked or steamed in can.6. Have a good seal whether jar or can.7. Follow reliable processing times.8. Cool properly.9. Store in a clean, cool, dark, dry place.

Cooperative Extension Work in AgriCUlture and Home Economics, Agricultural andMechanical College of Texas and United States Department of Agriculture Cooperating.

Distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914.

5M-4-4516