Row by Row Episode 256: Food Preservation | Essential Techniques and Tips
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Introduction
Preserving food not only extends its shelf life but also allows us to enjoy seasonal flavors straight form the garden throughout the year. Some of the oldest methods of preservation are drying, refrigeration, and fermentation. More modern techniques include canning, freezing, dehydrating, and freeze drying. The goal is to prevent food spoilage from bacteria, yeast, and mold. We aim to empower you with the knowledge you need to grow your own food and how to preserve your harvest. An important note to remember is that improperly packaged frozen foods lose small amounts of moisture during storage, resulting in surface dehydration (commonly called freezer burn).
Food Preservation
Essential Techniques and Tips: Freezing
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You can freeze "almost" any food, frozen foods remain safe indefinitely. Two of our favorite vegetables to grow are corn and peas. Freezing preserves food for extended periods because it prevents the growth of microorganisms that cause both food spoilage and food-borne illness. Freezing to 0 °F inactivates any microbes — bacteria, yeasts and molds — present in food. Once thawed, however, these microbes can again become active, multiplying under the right conditions to levels that can lead to foodborne illness. Since they will then grow at about the same rate as microorganisms on fresh food, you must handle thawed items as you would any perishable food.
Most vegetables that freeze well are low acid and require brief, partial cooking to prevent deterioration. This is called "blanching." For successful freezing, blanch or partially cook vegetables in boiling water or in a microwave oven. Then rapidly chill the vegetables prior to freezing and storage. Blanching also inactivates enzymes that cause deterioration of foods during frozen storage. Blanching is carried out at temperatures close to 100 °C (212 °F) for two to five minutes in either a water bath or a steam chamber.
Essential Techniques and Tips: Canning
Canning is a food preservation technique that involves sealing food in airtight containers, typically glass jars, to create a sterile environment that prevents the growth of bacteria, yeasts, and molds. Some of our favorites to can are tomatoes, green beans, potatoes, broth, and soups. The process typically involves placing prepared food into jars, sealing them with lids, and subjecting them to heat treatment. This heat treatment, often achieved through boiling or pressure canning, destroys microorganisms and enzymes that could cause spoilage, ensuring the long-term preservation of the food.
Water bath or Pressure Can?
Depends on the acidity of the food. Low-acid foods are not acidic enough to prevent the growth of bacteria. Low acidic foods have pH values above 4.6. Acidic foods have pH of 4.6 or lower. You can acidify by adding lemon juice or citric acid. All low-acid foods should be sterilized at temperatures of 240° to 250°F, attainable with pressure canners. Begin with good-quality fresh foods. Discard any diseased and moldy food. Trim off any bad spots.
Hot packing, raw packing
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. Raw-packing is the practice of filling jars tightly with freshly prepared, but unheated food.
Essential Techniques and Tips: Dehydration
Dehydrating, also known as drying, is a food preservation method that involves removing the moisture from food to inhibit the growth of bacteria, yeast, and molds, thus extending its shelf life. It is accomplished by circulating warm air around the food, either through natural air drying or using specialized dehydrators. During the dehydration process, moisture is evaporated from the food, reducing its water content to a level where microorganisms cannot thrive. This preservation technique is commonly used for fruits, vegetables, herbs, meat, and even dairy products. Dehydrated foods are lightweight, compact, and have a significantly longer shelf life compared to fresh or frozen alternatives.
Dehydrated foods can be rehydrated by soaking them in water or adding them to recipes that involve cooking with liquids. Overall, dehydrating is a versatile and convenient method for preserving food while maintaining its flavor and nutritional value. Dehydrated foods can be healthier alternatives to many snacks, and you can add them to salads, oatmeal, baked goods, and so much more. Try dehydrating figs or herbs!