Food Preservation: Jars and Cans
PRESERVING IN JARS
Preserving fruit and vegetables in vacuum-sealed jars is a popular method ofseasonal produce for use later in the year. Carrots, peas, beetroot, peppers, olives, gherkins, onions, pears, peaches, cherries and plums are among the wide range of suitable foods. The fruit or vegetables are cooked in boiling water so that any bacteria present are destroyed before being packed carefully (to avoid bruising) into glass jars.
Depending on the type of produce being preserved (and personal taste), the fruit or vegetables are then covered with a liquid which may be water, syrup (water and sugar), brine (salted water) or vinegar (sometimes with spices). The jars are vacuum-sealed to prevent new bacteria entering. Foods preserved in this way have a similar nutritional value to fresh foods, but much of the vitamin C and vitamin B5 is lost during storage. Foods preserved in brine may have a high sodium content, while foods preserved in vinegar can have a high level of acidity.
PRESERVING IN CANS
Canning is a popular method of long-term food preservation. The commercial canning process generally involves placing foods, such as vegetables, fruit or fish, in metal or glass containers and heating them to a temperature that is high enough to destroy any micro-organisms in the food. The contents are then sealed to prevent oxidation and contamination.
Although freezing can prolong the life of some fresh foods, other foods do not react well to this storage method. Salad leaves are damaged by freezing. Raw tomatoes, bananas, single cream and milk may be frozen, but once defrosted they are best used in cooking. Eggs should be separated before freezing. Unwashed food, particularly poultry, should never be frozen.