Canning Concerns Jan Walden, Food and Nutrition Specialist What a wonderful feeling of pride and accomplishment you get, looking at shelves filled with your own home can- ning. Cherries, apricots, peaches, plums, pears, tomatoes glow through the glass with jel-like colors . . . the sunslune flavors ofsummer are captured to brighten winter meals. All the work seems worthwhile - 1F your canning was success- Sometimes, things go wrong, though. Liquid may ooze from the jars, mold can develop, syrup may turn c10udy, foods can go mushy, take on a strange smell or spurt from the container when it‘s opened. These are just some ofthe trouble signs. The main aims in canning are to sterilize food and con- tainers, killing any spoilage-causing microorganisms (bacte- ria, molds or yeasts) that may be present and to drive air out of the container so the food is stored in a germ-free vacuum. To achieve these goals, use only top quality food. Have it and any equipment used, scrupulously clean. Follow up-to-date recipes. Grandmother’s preserving "receipts" may be treasured for nostalgia‘s sake, but please don’t use them, Research has shown that many of the old ways just aren‘t good enough. Look at "open kettle" canning. With this method, fully cooked, boiling hot food is put into freshly sterilizedjars and the lids are quickly put in place. There’s no further processing. Although this is a fairly easy procedure, it’s not really safe! Heating food to the boiling point may not de- stroy microorganisms present. Even if they are killed, as food is being ladled into jars, it can be easily recontamirtated by bacteria in the air. Canned food must be processed AFTER the containers are filled and sealed. Steam canning is another old, unsafe method. A steamer (not to be confused with a pressure canner) is a one or two shelf metal cabinet that sits on a stove element. Water is added to the tank at the bottom and â€" theoretically, as the water boils. steam at 100 C (212 F) swirls around the jars, steriliztng the food. in actual fact â€" this doesn‘t happen. The steam qu1ckly cools so the temperature is too low and uneven. Amazingly, steam canners have reappeared on the market. but they‘re still not safe! 10 Some of the more modern ideas aren’t successful either. Electric dishwashers don‘t reach high enough temperatures to work. Microwave ovens are too uneven in heat, and you Can't Put the meta] rings and lids in them. With the unequal heating and resulting pressure builde, the jars may explode, Canning with aspirin is another dangemus method. It doesn’t increase the acidity of the food enough to replace or reduge the need to sterilize. The methods of processing have been re-examined, tro, Oven canning has several possible pitfalls. Heat in an Oi -n normally fluctuates above and below the set temperature, a steady flow of high heat is necessary for proper processi; g, The thermostat itself may be inaccurate and there’s alws s the danger ofjars exploding when y0u open the oven or r and cooler air from the kitchen hits them. The biggest d1: ._ culty is, dry heat can‘t penetrate as thoroughly as that fit .1 boiling water, Food in the center of the jars may not ‘2 sterilized. The length of processing time depends on the density i the food. That’s why a good canning guide lists differc r times for various fruits and vegetables. Because of this d: r sity factor, squash and pumpkin should be cubed for pp . sure canning, not mashed. The method of processing depends on the amount natural acid in the food. Those low in acid, such as all ve tables except tomatoes, meats, fish, and poultry requ > temperatures higher than boiling. This means a preSSu a canner set at 70 kPa (10 lbs.) MUST be used for safer) 3 sake. Boiling a longer time without pressure won't do ti 3 job. Don‘t use a pressure cooker/saucepan for canning unle s it has an adjustable weight gauge. Pressure canners are qur c expensive. If you won‘t can enough tojustify the cost, co - sider freezing these low acid foods. Remember, too, at ‘ low acid canned food should be boiled rapidly for 10 ml - utes before it‘s even tasted. Fruits and tomatoes contain enough natural acid to 3 safely canned in a boiling water bath. In the last few yea . though, many varieties of lower acid tomatoes have be 1 developed. Since it’s impossible to tell which is which, i a better to be on the safe side. Add citric acid or bottled (n r. fresh) lemonjuice to eachjar. Citric Acid bottled lemonjuice pints 1 mL (‘1: tsp.) 15 mL (1 tbsp.) quarts 2 mL (V2 tsp.) 30 mL (2 tbsp.) Boiling water bath prooessing is straight forward but thr : are a few points to keep in mind. The water must remain the full, rolling boil for the entire processing time. To p= - vent liquid from cooking out ofthe jars, to ensure sterilir - tion, and to help get a good seal, you need 5 cm (2 in) l water OVER TOP of the jar lids. Today, it’s difï¬cult ï¬nd canners deep enough to hold a rack on the bottor . quart jars, 5 cm of extra water, and still have room for ‘31 water to actively boil. If you have an old canner that's tr . enough to do the job, treasure it. Remember to leave least 2.5 cm (i in) between the jars so the water can real i all surfaces. illâ€"m.“ _