there’s definitely a right way to go about it. As with all preserving methods, you must always begin with the freshest and highest-quality vegetables to insure good results. Cleanliness and sanitation when handling and preparing the food are also crucial. And, though drying vegetables isn’t difficult to do, it demands plenty of careful attention. The vegetables must be stirred, the temperature checked, and tray positions changed about every half hour. That means you must be at home during the whole time it takes to dry your vegetables.
Speed is of the essence when preparing foods to dry. For best results, vegetables should be blanched, cooled, and blotted dry within a very short time of harvesting. And you must never interrupt the drying process once it’s begun. You can’t cool partly dried food and then start it up again later, because there’s a chance bacteria, molds, and yeasts will find a home in it. Always schedule your home drying for a day when you’re certain your work won’t be interrupted.
Cleaning and cutting
Harvest only as much food as you can dry at one time. Using a kitchen oven, that’s about four to six pounds; an electric dryer or dehydrator can handle up to 14 pounds of fresh produce. Wash and drain the vegetables, then cut and prepare as the recipe directs. Depending on the size of the vegetables and the dryer, that could mean slicing, grating, cutting, or simply breaking the food into pieces so it will dry evenly on all sides. Remember that thin pieces dry faster than thick ones. If you have a choice between French-cutting and crosscutting green beans, remember that the French-cut beans will dry faster.
Blanching
Nearly all vegetables must be blanched before drying. Blanching—a brief heat treatment—stops the action of enzymes, those catalysts for chemical change present in all foods. If certain enzymes aren’t deactivated before vegetables are dried, the flavor and color of the food will be destroyed. The drying process alone isn’t enough to stop enzyme activity.
Although blanching can also help seal in nutrients, some other water-soluble nutrients are leached out into the cooking water. You may want to steam blanch your vegetables; it takes a bit longer, but won’t lead to as great a loss of nutrients.
Always follow the blanching times given in the recipes exactly. Overblanching will result in the loss of vitamins and minerals; underblanching won’t do the job of stopping enzyme action. Either way, you’ll end up with an inferior product.
Boiling water blanching. Heat one gallon of water to boiling in a blancher. Put no more than one pound or four cups of prepared vegetables at a time into the blancher’s insert, colander, or strainer, and carefully lower it into boiling water for the time given in the recipe.Steam blanching. Pour enough water into the blancher to cover the bottom, but not touch the insert. Heat to boiling. Arrange the prepared vegetables in a single layer in the blancher’s insert; put them in the blancher over boiling water, cover tightly, and steam for the time given in the recipe. You can use any large pot or kettle for steam blanching by putting a rack about three inches above the bottom to hold the vegetables in the steam and up out of the boiling water. You may also wish to put the vegetables in a cheesecloth bag to keep the pieces together during blanching.
Chilling
You must always chill blanched vegetables before drying them, to be certain the cooking process has stopped. After removing the vegetables from the blancher, immerse the colander or steamer rack full of vegetables in a sink full of ice water or a dishpan full of ice water. The vegetables should be chilled for the same amount of time the recipe gives for blanching in boiling water. Drain well, then blot with paper towels.
Preparing to dry
Spread the blanched and drained vegetable pieces in a single, even layer on the drying tray. (You can dry more than one vegetable at the same time, but strong-smelling vegetables such as onions, cabbage, and carrots should be dried separately.) Put the trays in the oven or electric dryer, leaving at least one to two inches between the trays for air circulation.
Maintaining proper drying temperature
Vegetables must be dried at low, even temperatures — just enough heat to dry the pieces without cooking them. The proper temperature for drying in a conventional oven is 140°F, 1S0°F for convection ovens. Follow the manufacturer’s directions for microwave ovens and all other appliances. Maintaining the right temperature steadily, with some air circulation, is the trick to successful drying. Electric dryers and dehydrators automatically maintain the right temperature. For oven drying or when using a homemade box dryer, check your oven thermometer every half hour. (To insure even drying, you must also stir the vegetables every 30 minutes or so, shift the trays from top to bottom, and rotate the trays from front to back.)
Although rapid drying is important, too rapid drying in an oven will result in the outer surface of the food hardening before the moisture inside has evaporated (case hardening). You can prevent case hardening by keeping a constant watch on the oven temperature and doing whatever is needed to maintain the heat at 140°F.
Scorching. Each vegetable has its own critical temperature beyond which a scorched taste will develop. Although there’s not much danger of scorching at the start of the drying process, vegetables can scorch easily during the last couple of hours. Even slight scorching will ruin the flavor and affect the nutritive value of dried foods, so be extravigilant about maintaining the proper temperature toward the end of the drying process.
Ventilation. When vegetables are drying, the moisture they contain escapes by evaporating into the surrounding air. If the air around the food is trapped, it will quickly reach a saturation point. Trapped, saturated air won’t be able to hold any additional moisture — and drying won’t take place. For this reason, ventilation in and around your oven is as important as keeping the temperature constant.
Electric dryers or dehydrators automatically provide proper ventilation. With oven drying or when using a homemade box dryer, you’ll need to leave the oven door slightly ajar — and possibly use an electric fan to insure good air circulation.
In addition, the cookie sheets or trays you use for drying should be at least one to two inches smaller all around than the inside of your oven so air can circulate around the front, sides, and back of the trays. There should also be at least three inches of air space at the top of the oven.
Testing for doneness
In most forms of food preserving, processing times are exact. You know just how long it takes before the food is done. However, the times for drying vary considerably — from four hours to more than 12 — depending on the kind of vegetable, how thinly it’s sliced, how much food is on each tray, and how much is being dried in the oven or dryer at one time. The recipes that follow give you the drying time range for each vegetable, but the only way you can be sure the food is sufficiently dry is to test sample pieces.
When you think the vegetables are dry, remove a few pieces from the tray, then return the tray to the oven. Let the sample pieces cool before testing — even food that’s perfectly dry will feel soft and moist while still warm. When the pieces are cool, follow the test for doneness given for the vegetable in each recipe. A rule of thumb is that properly dried vegetables are hard and brittle to the touch. Exceptions to the rule are mushrooms, sweet peppers, and squash, which will feel pliable and leathery when dry. Some food experts recommend the hammer test: if sufficiently dry, the vegetable pieces will shatter when struck with a hammer.
Conditioning
Foods don’t always dry evenly, nor does each piece or slice dry at exactly the same rate as all the others. To be sure all the food in a single batch is evenly dried, you’ll have to condition it. Put the cooled, dried vegetables into a large, deep crock, dishpan, jar, or coffee can; then store it in a warm, dry room for a week to 10 days. Cover the jar or can lightly with cheesecloth to keep out insects, and stir the dried pieces at least once a day so that the moisture from any underdried pieces will be absorbed by the overdried pieces.
After conditioning, give the vegetables one final treatment to get rid of any insects or insect eggs. Either put the dried vegetables in the freezer for a few hours, or heat them on a cookie sheet in a closed oven at 175°F for 15 minutes. Be sure to let the food cool completely again before packaging.
