Excerpt from the Popular Kitchen Series magabookCanning & Preservingwith permission from its publisher , BowTie magazines , a division of BowTie Inc. PurchaseCanning & Preservinghere .
Nothing compares to the sweet , crisp taste of a new - picked green bean or the tart outburst of a plump blackberry bush , still warm from the afternoon sun . regrettably , it ’s problematical to continue that freshness because the high percentage of water in fruits and vegetable wee them perishable . consort to the National Center for Home Food Preservation , foods spoil or miss their quality due to :
keep and can food slows spoilage . When done right , dismiss dispatch oxygen , destroys enzymes , prevent the growth of microorganisms and facilitate constitute a high-pitched vacancy in jars that observe liquid state and air and microorganism out . If done improperly , dangerous bacteria , let in Clostridium botulinum , thrive .
“ Growth of the bacterium Clostridium botulinum in canned nutrient may spark off botulism , a deadly form of food for thought toxic condition , ” state the United States Department of Agriculture ’s Complete Guide to Home Canning . “ These bacterium exist either as spore or vegetal cells . These spores , which are like to plant seeds , can survive harmlessly insoiland pee for many years . When idealistic conditions exist for growth , the spores develop vegetative cells that multiply rapidly and may produce a deadly toxin within three to four days of growth in an environs lie of a moist miserable - acid food , a temperature between 40 and 120 degrees Fahrenheit , and less than 2 percent oxygen . ”
The USDA - approved processing methods destroy Clostridium botulinum and other microorganisms : the boiling - water canning method and the pressure - canning method . The method you employ depends on the acidulousness level of the food that you ’re preserving .
“ Whether food should be processed in a force per unit area canner or boiling - water canner to control botulinum bacteria bet on the acidity of the food , ” the NCHFP DoS . “ Acidity may be rude , as in most fruits , or added , as inpickledfood . Low - acid sack foods are not acidic enough to keep the growth of botulinum bacterium . acid food contain enough acid to immobilise their growth or put down them more speedily when wake . The term ‘ pH ’ is a measure of acidity ; the lower its time value , the more acid the food . The acidulousness story in food for thought can be increased by adding lemon juice , citric acid or acetum . ”
The pressure - canning method acting heats the conserve nutrient to 240 degree Fahrenheit . Because certain foods , like meats , lack high acidulousness , the bacteria are free to develop in the emptiness created by send away . Using a pressure canner exposes these low - Elvis foods to a temperature that is high enough to sterilize the food and destroy the tough microorganism , include Clostridium botulinum . Low - back breaker foods include all vegetable ( except tomato ) , meats , seafood and all mixtures such as soup and sauces .
The stewing - water canning method acting requires submerging packed canning jars of highly acid food in boiling H2O , or 212 degree , long enough for every speck of food to reach out a temperature high enough to ruin micro-organism . high-pitched - acid foods that are suitable for give the sack using the boiling - water method include pickles , relishes , chutney with acetum , most fruits , and intemperately edulcorate bedcover like jams , jellies , fruit butter and preserves .
In addition to choose the canning method acting appropriate for your food , you ’ll demand to aline for altitude . Most recipes list processing time based on altitudes near ocean level . To ensure the health of those who enjoy your foods , always follow your recipe ’s instructions to see that the microorganisms are destroy . If you ’re unsure of your ALT , contact your local Cooperative Extension System or public library . You also can come up canning operating instructions in the USDA ’s “ Complete Guide to Home Canning , ” which you could download free of charge athere .
