Putting Food By - Janet Greene [21]
Pectin, a starch found in large amounts in green apples and the white spongy layer under the thin skin of citrus fruits, swells to form a clear, thick substance when heated with sugar (usually sucrose) and acid. There is more about pectin in Chapter 18, “Jellies, Jams, and Other Sweet Things”; plus a discussion of low-methoxyl pectin, which creates a gel with less-than-standard amounts of sugar, but which requires a calcium compound as an aid to firming.
Thickeners
Modified Cornstarch
Gravies and sauces thickened with all-purpose wheat flour, with potato flour—or even with that old stand-by, cornstarch—are likely to separate or thin out in freezing.
Since PFB discovered a modified cornstarch called ClearJel some years ago, we have advocated its use wholeheartedly. Its maker is National Starch and Chemical Company of Bridgewater, New Jersey. We give it as an ingredient in our fruit-pie fillings in Chapter 12, and we have used it at home as a household staple in gravies, sauces, and casseroles for freezing: we believe it is the best thickener we have ever handled. It is not available in grocery stores but is sold in 8-ounce packages in some bakery-supply stores and by many online retailers. Be sure to use regular ClearJel only—not Instant ClearJel.
If you do get some, handle it like run-of-the-mill cornstarch. Unlike such cornstarch, though, it won’t become runny if it is long-cooked or processed in canning.
Mochiko: “Sweet” Rice Flour for Frozen Sauces
Mochiko (mo’-chi-ko) is a special rice flour that is often termed “waxy,” and is known as “sweet” rice flour by the Japanese (it’s not sweet in itself, but gets its name from being used in cakes and other confections). Its virtue for our purposes is that it “stretches,” and, like ClearJel, makes a smooth sauce. It does not equal the corn product in producing silkiness, however, and it does not perform well in puddings.
Mochiko is relatively easy to get at any Asian food store in fairly large cities, and routinely in supermarkets that serve communities with Indonesian or Japanese heritage.
6
The Canning Methods
Home-canning emerged as an industry with the patenting in 1858 of the mason jar. The usual method was simple. It was called “open-kettle,” whereby hot jars were filled to brimming with hot, fully cooked food, then the lids were clapped on, and a vacuum was expected to form an airtight seal (proof against contamination) as the contents cooled. In its youth, open-kettle was used primarily for the home-canning of fruit and tomatoes (botanically a fruit). Because of this generally observed limitation, the method continued to be sanctioned, but only for strong-acid foods, until World War II. By the mid-forties, though, microbiologists and food scientists had started chipping away at its reputation for safety. Now, open-kettle is held to be inadequate for making a safe product.
Acidity and heat penetration dictate how a food must be processed when it is being canned at home. With these factors in mind we choose the Boiling–Water Bath or Pressure-processing.
Note: the processing times for food in glass mason jars using both Boiling–Water Bath and Pressure Canning given in this edition of PFB are based on recommendations by the USDA’s Complete Guide to Home Canning (2006). The processing times for home canning in metal containers are from bulletins of National Food Processors Association, which is now called Food Products Association.
Before we start on the safe, right ways, though, hear words from two former professors