Vegetables for canning should be perfectly sound, and, if possible, fresh out of the garden. If it is not possible to can the vegetables immediately, do not allow them to wither, but keep them in a cold place so that they may be nice and crisp. Maize (Mealies) and Peas lose their sweetness and flavour soon after they are gathered, and so it is advisable not to leave them over too long. Young vegetables are superior in flavour and texture to the more mature ones.
As seen in the previous Chapter, the germs which attack vegetables form seeds or spores and are most resistant to heat. Therefore much greater care has to be exercised in the canning or sterilisation of vegetables than in the canning or preserving of fruit; and, in addition to thorough sterilisation by the application of a high temperature, it is also very important to use fresh rubbers and a jar which is thoroughly reliable and completely air-tight.
One difficulty in canning vegetables is to make them retain their colour, especially green peas, beans, etc., unless chemicals or colouring matter is used, which, of course, is not to be recommended, as there is no reason why one should object to the colour as long as the flavour is good. Besides, from a health point of view, it is better to have them pure and wholesome than artificially coloured and adulterated. However, there is no objection to the use of bi-carbonate of soda and borax, both of which will to a large extent preserve the green colour. When using these add about an eighth of a teaspoon of bi-carbonate of soda and 1 1/2 teaspoons borax to each pint of water used in filling up the bottles.
In doing peas, mealies, and beans, it is better to omit the salt, especially if they are somewhat hard, as salt has a tendency to harden, and when re-heating them for the table it may then be added.