By: Kate Delany

Fall is almost here. It is about that time to start harvesting fruits and vegetables. Preserving the harvest is immensely satisfying work. When done correctly, in season fruits, veggies, and herbs can be made to last for seasons to come through canning, drying, or the creation of herbal oils or vinegars. With each of these techniques, there are some key safety rules to in keep in mind.


 Home canning is a time honored method of food preservation. With proper processing, home canning seals in the freshness of the season for future enjoyment. Safe and effective home canning is done through two methods, the boiling water method or the pressure method.

High acid foods, such as tomatoes, pickles and many fruits, are processed in a boiling water canner. A temperature of 212 degrees Fahrenheit must be maintained at all times during water bath canning in order to destroy any molds, yeasts or bacteria in the food. Low acid foods such as peas, corn and beets should never be processed by the boiling water method because a water bath never reaches a high enough temperature to destroy toxins and bacterial spores in these foods. In order to avoid botulism, low acid foods must be processed via the pressure method. A pressure canner processes food at a temperature of 240 degrees Fahrenheit, killing the toxins that might be present in these low acid foods. Knowing the pH of the food you are processing is therefore critical.

Whether you are canning via the boiling water method or the pressure method, it is essential to stick to established guidelines that stipulate how long a food must be processed and at what temperature. Ball’s Blue Book Guide to Preserving is one such resource. While creativity and experimentation might be beneficial in routine cooking, when canning, you should never deviate from the instructions.

The use of proper sterile equipment is also essential to home canning safety. Glass home canning jars, such as Mason jars, include a two piece vacuum cap comprised of a flat metal lid that seals out contaminants, and a metal screw band that holds the lid in place. Unlike other glass commercial jars, these home canning jars are manufactured to withstand the high temperatures of canning. Regular jars should never be used, as they may not seal correctly, resulting in spoiled or contaminated food. It is also essential that all canning jars be washed and sterilized before use in a water bath or process canner.

Drying or Dehydrating 

 Fresh herbs and ripe produce are ideal candidates for drying or dehydrating. If using an oven or electrical dehydrator to dry fruits, be sure to slice them to a uniform size and to avoid overcrowding drying trays. Plated metal trays should never be used, as they may leach chemicals that could render the food toxic.

Air drying fresh herbs is easy and effective, as it simply involves hanging herb bundles upside down to dry. The herbs should be tied in small bundles and hung in areas protected from direct sunlight. Overlarge bundles of herbs may not dry correctly or uniformly. Overcrowding the herbs decreases air circulation which is need to wick moisture away. As medical herbalist Tammi Hartung notes in her book Growing 101 Herbs that Heal, “If your plants are dried improperly, they may show signs of mold and mildew in the form of a white downy of black slimy coating. The plants will often smell musty or rotten; these plants must be discarded.”

Oils and Vinegars

 Herbal oils and vinegars are a simple way to preserve the flavors of fresh herbs. As with canning, it is vital to work with clean materials. Bottles, jars and lids should be sterilized before use.

To prepare an herbal oil, place thoroughly dried plant material into a clean, dry jar and cover it with food quality vegetable oil. To prepare an herbal vinegar, follow the same procedure using vinegar. The oil or vinegar must completely cover the plant material. If the oil or vinegar is absorbed, add another inch of liquid. Herbal oils and vinegars should be infused for two weeks’ time before being strained through cheesecloth.

With both methods, it is essential that the container and the plant material both be absolutely dry at the start or mold may grow. When preparing an herbal oil, place plastic wrap over the top of the jar before securing the jar lid. Never place a metal lid directly on an herbal vinegar container as the vinegar may corrode the metal and leave sediment in the mixture. Make sure that you label all herbal oils and vinegars just as you would with canning so that you know what herbs you are using or ingesting.

When done safely and correctly, home preserving is richly rewarding. Using these techniques, the bounty of your garden or fresh farmers market finds can be shared and savored. Preserve with care and you will be safely enjoying healthy, natural flavors for seasons to come.

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