E. L. Andress1, E. M. D’Sa2, M. A. Harrison2, W. L. Kerr2, J. A. Harrison1, and B. A. Nummer1. (1) Department of Foods and Nutrition, 208 Hoke Smith Annex, (2) Department of Food Science and Technology, The University of Georgia, Athens, GA 30602.
Paper 46B-2. Presented at the Institute of Food Technologists Annual Meeting, Anaheim, CA, June 17, 2002.
Freezing food is an easy and popular method of home food preservation. Improper practices can lead to poor food quality and satisfaction as well as economic losses. Educational efforts and publications for the home food preserver need to be targeted toward the interests and practices of today's consumer. The objective was to conduct a national survey of households that routinely practice home freezing preservation of foods, to determine the level of activity and types of practices. A series of 42 close- or open-ended questions were answered by 473 adults in a national telephone interview conducted by the Survey Research Center, University of Georgia from October 24, 2000 to January 10, 2001. Questions included respondent's source of freezing instructions, types and quantities of foods frozen, blanching methods, packaging materials used, food spoilage and demographic information. A freezer separate from the refrigerator/freezer is maintained by 53% of respondents, most commonly in a basement. Vegetables are frozen by 43%, seafood by 36% and fresh fruits by 31%. Fresh meat, mainly beef, is repackaged and frozen by 76%. Foods other than meats are repackaged and frozen by 49%. One in four report blanching food before freezing. Plastic bags are the most preferred packaging method, followed by plastic containers. Over 90% reported that the foods they froze did not spoil. Food freezing instructions were obtained from family or friends by 29% of respondents and from cookbooks, magazines or newspapers by 15%. A significant number (25%) obtained instructions from 'other' sources that included 'common sense'/general knowledge. Public awareness of the Extension Service and USDA as a source of home food freezing recommendations could be improved. Significant activity in freezing fresh foods as well as repackaging of purchased foods indicates that consumer information on packaging techniques and other practices for preserving quality is important.
Home preservation of foods, including home freezing, has always been popular, being traditionally used to process and preserve seasonal, surplus or economically available foods for use in off-peak seasons or through the year. Early household refrigeration and freezing methods relied on the use of iceboxes (6), but the introduction of mechanical refrigeration in the late 1800s stimulated the cold-preservation of foods. The earliest commercially available household refrigerators were demonstrated by General Electric in 1911 and electric refrigerators with freezers were available to the public in the 1920s and 1930s, though mass production of refrigerators did not begin until after World War II (7). The 1940s and 1950s witnessed the birth of several innovative commercial frozen foods and techniques and rapid growth in frozen food storage. In the 1950s, USDA began publishing scientific research on methods in home freezing. Later, data from the FDA confirmed that frozen fruit and vegetable products have equivalent or superior nutrient profiles as compared to their fresh counterparts (8).
Appropriate methods yield high quality frozen foods. Home freezing is deemed 'slow-freezing', where the target temperature is achieved in 3-72 h (3). Attention to all steps in the freezing process is essential to maintain the desired appearance, consistency, microbiological and nutritive quality, and shelf life of the frozen food. They include pre-freezing food preparation (blanching or anti-discoloration treatments, choice of freezing materials), achieving a fast rate of freezing, a constant freezer temperature, and suitable thawing procedures. Improper practices can lead to poor food quality and economic losses, as well as food safety concerns.
Surveys conducted earlier on home-freezing practices date back to 1964 and 1976 (1). Knowledge of contemporary consumers' home-freezing practices would be helpful in understanding current family food management practices, the extent to which traditional freezing recommendations are still being adopted, and gaps in consumers' knowledge of recommended practices. An additional aim of this national survey was to identify potential areas of research, in order to update home freezing recommendations based on sound scientific principles.
The National Center for Home Food Preservation (NCHFP), in conjunction with the Survey Research Center (SRC), University of Georgia, Athens, conducted a national telephone survey of adults from randomly selected households across the nation, between October 24, 2000 and January 10, 2001. A 42-item survey instrument which included 16 open-ended questions was developed by the NCHFP and refined with the assistance of the SRC. Structuring and supervision in an interviewer's work is essential in order to gather data in a controlled and standardized fashion (4). Thus, interviewers trained in survey research and telephone-interviewing technology by the SRC were used for the interviewing. Appropriate supervision (one-fifth to one-quarter of all interviews were monitored) during interviews helped maintain quality control. 1244 eligible respondents were contacted; these yielded 473 complete interviews. For several questions, in addition to selecting a 'first-choice' response, respondents were provided with the option of selecting more than one choice as their 'second-choice, third-choice' etc. responses. Probability analyses estimated that the number of interviews conducted were more than sufficient to achieve the target levels of precision and accuracy in drawing conclusions on population responses based on sample estimates (5).
Freezing instructions: Of a total of 501 interviews conducted, 473 respondents (94.4%) reported freezing foods in their household, other than those purchased in the supermarket. The sources of freezing instructions were as follows:
| Source of instructions | % of respondents (n=473) |
|---|---|
| Friends or relatives | 29 |
| Cookbooks | 12 |
| Magazines or newspapers | 3 |
| Pressure canner manufacturer instructions | 2 |
| Jar/lid manufacturer instructions | 2 |
| USDA publications | 1 |
| Extension Service publications | 1 |
| 'Other' (general knowledge, common sense, prior experience, internet, city health department, package inserts, appliance manufacturer instructions) |
26 |
Where is the freezer? 53% respondents possess a freezer that is separate from their refrigerator, located:
The ideal location for a freezer is a well-ventilated room near the kitchen, with ambient temperatures between 50-65°F, away from direct sunlight. Contrary to popular thought, keeping the freezer in a cold place does not increase efficiency. This is particularly significant in areas experiencing several months of below-freezing temperatures where an unheated garage is not an ideal location (2).
What is being frozen and by how many?
| Food Frozen | % of respondents |
|---|---|
| Repackaged meat items (including beef, poultry, pork, seafood, and 'other' meats) | 76 |
| 'Fresh' meat items (including venison, turkey, seafood, rabbit, duck, squirrel, bear, pork) | 14.6 |
| Seafood (including shrimp, salmon, crab, catfish, trout, bass, lobster, tuna, scallops, oysters) | 36 |
| Fresh fruit | 31 |
| Fresh vegetables | 43 |
| Repackaged non-meat items (including bread, bagels, cheese, pastries, cake) | 49 |
| Home-prepared foods (including entrées with and without meat, breads, pastries, casseroles, cookies, pies, desserts, sandwiches) |
49 |
Packaging materials: Fig.1. represents the types of packaging materials used for freezing various food categories.
Plastic bags were also the packaging material of choice for seafood, followed by freezer paper (16%), plastic wrap (13%), plastic containers (11%) and aluminum foil (9%).
How much is being frozen?
| Food Category | % of respondents freezing | |||
|---|---|---|---|---|
| 1-10 lbs | 10-50 lbs | 50-100 lbs | >100 lbs | |
| Repackaged non-meat items (n=233) | 35 | 30 | 5 | 4 |
| Fresh meat items (n=69) | 19 | 26 | 19 | 17 |
| Seafood (n=171) | 53 | 30 | 1 | 1 |
| Fresh fruit (n=148) | 57 | 32 | 1 | 1 |
| Fresh veggies (n=203) | 45 | 37 | 3 | 1 |
Pre-freezing preparation
Blanching is an important pre-freezing step for some foods that ensures the inactivation of enzymes and fixing of green color of vegetables, among other functions. Approximately one in four respondents reported that they blanched mainly vegetables in preparation for freezing, in boiling water (86%), using steam (7%) or in a microwave (6%).
Spoilage of frozen foods
Only 7% (33 respondents) reported spoilage of the food that they froze, the indicators of spoilage being freezer burn (18 respondents), thought that it was left in the freezer too long (8), tasted bad, looked brown, broken seal, packaged improperly, and 'power was out for several days' (one each).
Demographic analyses
This material is based upon work supported by the Cooperative State Research, Education, and Extension Service, U.S. Department of Agriculture, under Agreement No. 00-51110-9762.
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Reprinted with permission of the University of Georgia. Andress, E.L., E.M. D'Sa, M. A. Harrison, W. L. Kerr, J. A. Harrison, and B. A. Nummer. 2002. A survey of practices in freezing foods at home in the U.S. Athens, GA: The University of Georgia, Cooperative Extension Service.
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