Home Canning - Ensuring High Quality Canned Foods
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United States Department Of Agriculture, Extension Service
Begin with good-quality fresh foods suitable for canning. Quality varies among varieties of fruits and vegetables. Many county Extension offices can recommend varieties best suited for canning. Examine food carefully for freshness and wholesomeness. Discard diseased and moldy food. Trim small diseased lesions or spots from food.
Can fruits and vegetables picked from your garden or purchased from nearby producers when the products are at their peak of quality-within 6 to 12 hours after harvest for most vegetables. For best quality, apricots, nectarines, peaches, pears, and plums should be ripened 1 or more days between harvest and canning. If you must delay the canning of other fresh produce, keep it in a shady, cool place.
Fresh home-slaughtered red meats and poultry should be chilled and canned without delay. Do not can meat from sickly or diseased animals. Ice fish and seafoods after harvest, eviscerate immediately and can them within 2 days.
Maintaining Color and Flavor in Canned Food
To maintain good natural color and flavor in stored canned food, you must:
Remove oxygen from food tissues and jars,
Quickly destroy the food enzymes,
Obtain high jar vacuums and airtight jar seals.
Follow these guidelines to ensure that your canned foods retain optimum colors and flavors during processing and storage:
Use only high-quality foods which are at the proper maturity and are free of diseases and bruises.
Use the hot-pack method, especially with acid foods to be processed in boiling water
Don't unnecessarily expose prepared foods to air. Can them as soon as possible.
While preparing a canner load of jars, keep peeled, halved, quartered, sliced, or diced apples, apricots, nectarines, peaches, and pears in a solution of 3 grams (3,000 milligrams) ascorbic acid to 1 gallon of cold water. This procedure is also useful in maintaining the natural color of mushrooms and potatoes, and for preventing stem-end discoloration in cherries and grapes. You can get ascorbic acid in several forms:
Pure powdered form --seasonally available among canners' supplies in supermarkets. One level teaspoon of pure powder weighs about 3 grams. Use 1 teaspoon per gallon of water as a treatment solution.
Vitamin C tablets --economical and available year-round in many stores. Buy 500-milligram tablets; crush and dissolve six tablets per gallon of water as a treatment solution.
Commercially prepared mixes of ascorbic and citric acid --seasonally available among canners' supplies in supermarkets. Sometimes citric acid powder is sold in supermarkets, but it is less effective in controlling discoloration. If you choose to use these products, follow the manufacturer's directions:
Fill hot foods into jars and adjust headspace as specified in recipes.
Tighten screw bands securely, but if you are especially strong, not as tightly as possible.
Process and cool jars.
Store the jars in a relatively cool, dark place, preferably between 50 degrees and 70 degrees F.
Can no more food than you will use within a year.
Advantages of Hot-Packing
Many fresh foods contain from 10 percent to more than 30 percent air. How long canned food retains high quality depends on how much air is removed from food before jars are sealed.
Raw-packing is the practice of filling jars tightly with freshly prepared, but unheated food. Such foods, especially fruit, will float in the jars. The entrapped air in and around the food may cause discoloration within 2 to 3 months of storage. Raw-packing is moresuitable for vegetables processed in a pressure canner.
Hot-packing is the practice of heating freshly prepared food to boiling, simmering it 2 to 5 minutes, and promptly filling jars loosely with the boiled food.
Whether food has been hot-packed or raw-packed, the juice, syrup, or water to be added to the foods should also be heated to boiling before adding it to the jars. This practice helps to remove air from food tissues, shrinks food, helps keep the food from floating in the jars, increases vacuum in sealed jars, and improves shelf life. Preshrinking food permits filling more food into each jar.
Hot-packing is the best way to remove air and is the preferred pack style for foods processed in a boiling-water canner At first, the color of hot-packed foods may appear no better than that of raw-packed foods, but within a short storage period, both color and flavor of hot-packed foods will be superior.
Controlling Headspace
The unfilled space above the food in a jar and below its lid is termed headspace. Directions for canning specify leaving 1/4-inch for jams and jellies, 1/2-inch for fruits and tomatoes to be processed in boiling water and from 1- to 1-1/4-inches in low- acid foods to be processed in a pressure canner This space is needed for expansion of food as jars are processed, and for forming vacuums in cooled jars. The extent of expansion is determined by the air content in the food and by the processing temperature. Air expands greatly when heated to high temperatures; the higher the temperature, the greater the expansion. Foods expand less than air when heated.
Extracted from the "Complete Guide to Home Canning." First published: January, 1993. Revised: 2015.
Courtesy of the USDA and National Institute of Food and Agriculture
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Stephini Candella is a Nutritionist, and attended the University of Texas for a B.S. in Nutrition and Didactics. She was a manager for a small gourmet restaurant, and has spent over 15 years cooking as a hobby for health. She has extensive knowledge of food science, micro-nutrition, history of the classic foods from across cultures, modern commercial and home cooking processes, disease restricted diet meal planning (cardiovascular, GAPS, diabetes), and popular diet trend (Paleo, Keto, Vegan) diets. Stephini most enjoys meal planning that focuses on simplicity and cost-effectiveness, and she strongly believes these are the foundations for delicious and healthy meals—the basis for a happy life. She is addicted to reading food labels, and uncovering the nutritional benefits of traditional cooking techniques of the classical foods across cultures. If you let her, she will talk your ear off over her fascination for how traditional fermentation cultivates the metabolic byproduct of certain bacteria into nutritional gold for human health. Stephini is also a CRLA (Certified Reading and Writing English Tutor) and has professionally tutored college students as well as K-12 students for an accumulated 15 years expanding to private school curriculum development and teaching in STEM and STEAM. She has been a professional researcher for multiple private and non-profit companies and organizations including the University of Texas Food and Housing Division. There, she researched and wrote recommendations for the University’s campus wide composting and food waste reduction initiatives, design and management of campus wide food waste studies, and the procurement of technologies best suited for large scale composting and food waste reduction. As a former Red Cross shelter manager, she has worked with her National Guard, and the US Army and Marines in search and rescue, procuring, and deploying multiple shelters serving thousands of evacuees. She has overseen the management of over 25 shelters in the state emergency operation center, and was held responsible for procurement of meals, medical supplies, and basic necessities. She also assisted in local county natural disaster rescues, providing insurance evaluations and recommendations for approving families affected by natural disasters to receive financial aid, housing, and food assistance. In addition, she volunteered for her local food pantry and domestic violence shelter where she prepared food. These discovered passions for emergency aid volunteer work led her to pursue national and state EMS licensures. She has traveled from Houston to New York to Seattle on a Leadership Scholarship, listening to world renowned scholars on the values of great leadership. Her favorite being the opportunity to sit and connect with the grandsons of Gandhi, listening to their first hand childhood experiences growing up alongside their grandfather organizing and executing his activism. Presently, Stephini conducts research and assistance on customer relationship management campaigns for 30 year veteran executives and business owners as an operations manager for a small, boutique executive assistance CRM firm. She has retired into a quiet, family-centric life, and can be found living between her home and college towns where she is raising her children. There, she is imparting her love for DIY learning and food on to them in the hopes that self-directed creativity and production will bring to them the same sense of holistic wellness that she’s experienced for herself.
