Putting Food By - Janet Greene [174]
Most gas ovens have only one heating element (at the bottom) for both baking and broiling. If your gas oven has an upper burner, don’t turn it on.
Gas ovens are always vented, but electrics may not be. If your electric oven isn’t vented, during drying time leave the door ajar at its first stop position or prop the oven door open with rolled-up hot pads or a block of wood. If feasible, arrange a fan so that it blows past the oven door, carrying away humidity.
Preheat the oven to 140 F/60 C. If the oven cannot be set this low, you have two choices. You can skip the lowest slide so that the bottom tray is at least 8 inches from the heat source. Or you can set the oven at warm (or whatever its lowest setting) and monitor the temperature with a thermometer. If the temperature goes above 140 F/60 C, turn the oven off briefly to cool it.
Don’t overload the oven: with limited ventilation (even with a fan aimed toward the partly opened door) it can take as much fuel to dry a batch too big as might be used to dry two fairly modest batches.
For drying small amounts of food in your oven, cake racks set on cookie sheets make an acceptable make-do alternative to trays.
Pre-drying Treatments for Produce
Before being dried at home by any method, fruits make a better product if they undergo one or more of the treatments given hereafter, while all vegetables are treated to stop the organic action that allows low-acid foods to spoil.
And, still speaking generally, a pre-drying treatment for fruits is optional, but the pre-drying treatment for vegetables is a must.
The optional treatments for fruit involve (1) temporary anti-oxidants, to hold their color while they’re peeled/pitted/sliced; (2) blanching in steam or in syrup as a longer-range means of helping to save color and nutrients; (3) very quick blanching—either in boiling water or steam (lye is not recommended)—to remove or crack the skins; (4) exposing to the fumes of burning pure sulfur as longest-range protection.
The treatment for vegetables is steam-blanching. The quick dunk in boiling water that’s used in freezing is not adequate to protect them against spoilage in drying; and the much longer boiling time needed here would waterlog the material, in addition to leaching away a number of its nutrients.
The following descriptions are given in the order that the treatments are likely to occur in handling produce for drying: they’re not necessarily in order of importance.
Temporary Anti-Oxidant Treatment
Pure ascorbic acid is our best safe anti-oxidant, and is used a lot in preparing fruits for freezing. Use it here too. But with the difference that the solution will be somewhat stronger, and thus food coated with it can hold its color in transit in the open air for a longer time.
One cup of the solution will treat around 5 quarts of cut fruit, so prepare your amount accordingly. Sprinkle it over the fruit as you proceed with peeling, pitting, coring, slicing, etc., turning the pieces over and over gently to make sure each is coated thoroughly.
For apples: dissolve 3 teaspoons of pure crystalline ascorbic acid in each 1 cup of cold water.
For peaches, apricots, pears, nectarines: dissolve 1½ teaspoons of pure crystalline ascorbic acid in each 1 cup of cold water.
If the variety of fruit you’re working with is likely to become especially rusty-looking when the flesh is exposed to air, it’s OK to increase the concentration of ascorbic acid as needed. The proportions above usually do the job.
The commercial anti-oxidant mixtures containing ascorbic acid don’t work as effectively, volume for volume, as pure Vitamin C does. Follow the directions for cut fruits on the package.
Blanching Fruits in Heavy Syrup
Blanching fruits in heavy syrup is little practiced by average householders, who generally want simplicity.
Treating