Allows for food expansion as jars are heated, and for forming vacuums as jars cool. HOT PACK - Heating of raw food in boiling water or steam and filling it hot into jars. Vegetables, some tomatoes, figs, all meats, fish, seafoods and some dairy foods are low acid. When alive in a suitable environment, they grow rapidly and may divide or reproduce every 10 to 30 minutes. Therefore, they reach high populations very quickly.
Undesirable microorganisms cause disease and food spoilage.
Microorganisms are sometimes intentionally added to ferment foods, make antibiotics and for other reasons. Molds may grow on many foods, including acid foods like jams and jellies and canned fruits. Recommended heat processing and sealing practices prevent their growth on these foods. Food is supposedly adequately heat processed in a covered kettle, and then filled hot and sealed in sterile jars. Foods canned this way have low vacuums or too much air which permits rapid loss of quality in foods.