Home Critical Review of Home Preservation Literature and Current Research
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I. Introduction and Objectives

Preservation of food in the home by canning remains a popular activity with a large percentage of the American population. Even though spoilage occurred frequently, home canning was practiced widely in America from the late Nineteenth Century until the mid-Twentieth Century. Interest declined after World War II until the 1973 energy crisis. Since that time, gardening and canning activities have continued to rise annually.

Seven out of ten households (over 24 million) preserved fruits and vegetables in 1944. Most of the preservation was done by canning — about ten percent did some drying and about 6 percent used freezing. Seventy percent used the open-kettle method of canning for fruit; about 45 percent used this method for vegetables. The majority of households canned 100 to 200 quarts of food; many canned 200 to 500 quarts (Bureau of Ag. Econ., 1945).

In a 1976 study conducted by USDA (Davis and Page, 1979), one out of three households surveyed canned fruits and/or vegetables in 1975. A range of processing methods had been employed for these products, some of which are approved methods and some which were questionable or hazardous. Pressure, boiling-water bath, open-kettle and oven canning were used for all types of fruit and vegetable products. The majority of households canned 100 quarts of food or less; 10 percent canned 200 quarts or more. Ten to 15 percent experienced food spoilage.

More recent surveys indicate an increase in home canning activity. However, unsuitable and potentially hazardous processing methods continue to be used. A survey conducted in North Dakota in 1977 indicated that 65 percent of homemakers in the state did some canning. Approximately 30% of the homemakers surveyed canned more than they did 5 years ago; almost 30 percent planned to can more the next year. Improper methods were cited, and 25 percent had experienced spoilage (Anon., 1977).

The Midwest generally leads in gardening and canning activity. Nevertheless, nearly 40 percent of all American households were expected to do some home canning in 1982 (Jones, 1982). A 1977 survey in Pennsylvania (Kuhn and Hamilton, 1977) indicated home canners were of wide age range, from teen years to retirees. The majority canned 25-100 jars. Unacceptable processing methods were cited for both acid and nonacid foods. Up to 20 percent of canners using unacceptable directions reported spoilage for some food groups.

Another home canning survey conducted in Pennsylvania in 1982 (Kuhn, 1982) indicated that unacceptable processing methods are still being used for a variety of products. In particular, boiling water canning of low acid foods and open-kettle canning of fruits still remain as problems. Canners ranged in age from 18 years to over 55 years. Almost 50 percent of the sample canned 25-100 jars of food; however, 25 percent canned over 100 jars. More than 50 percent of those surveyed were interested in low-salt and low-calorie canning.

These and other surveys (Phillips and Bass, 1976; Anderson and Mendenhall, 1978) also present proof of the wide diversity of other practices being used by home canners. Jar sizes, jar and lid types, sources of instruction, practices of sealing, tightening and removing lids, and storage of canned goods are some of the variables that must be dealt with in encouraging proper home canning techniques. new equipment, concerns about process adequacy and demand for innovative canning directions require an assessment of the knowledge bases related to canning technology.

The USDA Extension Service has traditionally been a recognized authority in the home preservation of food. One of the first publications on the subject was "Canning Vegetables in the Home," Farmers Bulletin 359 (Brazeale, 1909), issued by the USDA Bureau of Chemistry in 1909. In later years, the Office of Home Economics and then the Bureau of Home Economics conducted research and issued consumer-oriented publications. However, the current recommendations are based on research prior to 1957. Many changes have occurred during the last 25 years in terms of canning ingredients, equipment, horticultural varieties and food preferences which have not been accommodated by research developments.

Home canning failures and unsafe home-canned food persist, indicating that this lag in research may be serious. Indications of the extent of spoilage are evident in the aforementioned surveys. Tables 1 and 2 summarize botulism outbreaks caused from eating home canned food for the years 1970-1980 (CDC, 1978; 1979a; 1979b). Since 1973, there has been a rise in the number of outbreaks and cases. The foods involved in these cases indicate a lag between the public's habits or demands for certain products and research developments. The number of outbreaks per year attributed to home processed foods averaged 7.5 for 1899-1949, for a total of 382 outbreaks. From 1950-1977, however, the average was 5.9 outbreaks per year, for a total of 166 outbreaks. Although there has been a small decline overall during the last 28 years, 45 percent of the outbreaks since 1950 occurred from 1970-77 (75 outbreaks). It is possible that the recent increased activity in home canning may have contributed to the 43 percent increase in botulism outbreaks for 1970-77 over the decade of 1960-69.

Table 1
Outbreaks of Botulism from Home Canned and Processed Food*

Year Number of Outbreaks Number of Cases Number of Deaths
1970 5 9 4
1971 6 16 4
1972 3 6 4
1973 7 20 2
1974 17 26 6
1975 11 15 2
1976 10 21 3
1977 16 79 5
1978 10 13 3
1979 7 8 0
1980 14 18 not available
*As reported by Center fof Disease Control, U.S. Dept. Of H.E.W.

Table 2
1970-79 Summary of Botulism1

Home Canned Vegetables Outbreaks     Home Canned Specialites Outbreaks

Home Canned Vegetables
Beans, green
Bean, juice
Beans and pork
Beans, not specified
Beets
Cabbage
Carrots
Corn
Mushrooms
Okra
Olives
Peppers, chili
Peppers, not specified
Potatoes
Vegetables, mixed
Vegetables, not specified

Home Canned Fruits
Applesauce
Blackberries
Figs
Tomato juice

Home Canned Specialities
Bar-B-Q Beef
Beans, pickled
Beverage, non-dairy
Chow chow
Mexican food

.
5
1
1
2
4
1
2
2
2
1
2
2
9
1
2
4

.
1
1
1
3

.
1
1
1
1
1

    Home Canned Specialities
Potatoes and peas
Sauce, chili
Sauce, hot
Sauce, spaghetti
Sausage with vegetables
Soups
Spaghetti

Other Home Canned Food
Fish
Meat

Home Processed Food2
Antipasto
Beaver tail
Beef & mushroom stew
Eel
Fish
Fish soup
Seal meat
Soybeans
Whale meat

.
1
1
1
1
1
1
1

.
1
1

.
1
1
1
1
6
6
3
1
1

 


1As reported by the Center for Disease Control, U.S. Dept of H.E.W.
2Salted, fermented, smoked, refrigerated or frozen.

  Due to the lack of coordinated, concentrated research relevant to home canning process determinations for over two decades, wide areas of concern have arisen. The research which has been conducted in recent years has presented questions concerning the effects of new bacteriological developments, the chemical properties of food systems being preserved in the home, recent design changes in equipment, processing method alternatives and practices used by the home canner. In an attempt to identify needed research programs and educational goals, a thorough search of relevant literature was conducted to determine the current state of the knowledge base related to home canning.

  1. to collate the data base for assessing the process recommendations in the USDA Home and Garden Bulletins No. 8 (USDA, 1977) and No. 106 (USDA, 1966);
  2. to determine critical problem areas of concern in the field of home canning and the topics which need to be researched;
  3. to enable the Cooperative Extension Service to devise a plan to improve the credibility of their recommendations in this field.
Meeting these objectives are considered crucial steps to decreasing the potential dangers associated with home canning practices. Reliable research which is designed to answer high-priority questions in light of all the available related data would serve a crucial role in achieving uniform process recommendations for all state extension services.