Sterilising Jars: Jars and lids must be sterilised: Either boil them in plenty of water so they soak in the water while it simmers. Drain out carefully, place them first upside down, then upright on a clean kitchen towel till they dry out completely. Or dry in the sun for a while to ensure complete dryness.
You can even microwave by filling jars 1/3 full of water, keep as many as fit comfortably with in between space. Bring water to a boil on high, simmer for 1 minute. Remove, drain water, dry as above.
Use rustproof and airtight lids which will not allow air to enter.
Filling Jars: While filling bottles and jars, take care that bubbles are not formed inside the bottle. The incorporated air, might be the cause of bacterial growth after closing the bottle.
Dipping the cap and mouth of bottle in a bowl of molten wax for a few seconds is a good way to seal filled jars and bottles.
Equipments And Vessels Used Should Be Dry: Wipe fry all equipment and vessels before using them. Contaminated moisture can be harmful to preserves.
Moisture While Washing Vegs./Fruit: If the fruit is delicate(eg.strawberries), wash, carefully arrange on a soft kitchen towel to absorb excess moisture.Dab dry if required. Other fruit,(eg.apple,mango) may be washed and wiped clean before using.
When Sauce / Preserves Is Done: Consistency: Sauces & preserves should not be underdone, in which case it would stay watery, and may go bad soon. Neither should it be overdone, in which case it will taste a bit gooey, and may solidify into crystals.
It may also get charred. There are a few tests which give an indication that it is done.
- Plate test: Pour a tsp. of the jam on a cold plate.If it spreads a little, not leaving water around it, then the jam is done.
- Spoon test: Take on a tsp, and sway it a bit. If the surface starts wrinkling, the preserve is done.
- Fly test: When droplets of the mixture start flying about in big bubbly outbursts, then the recipe is done.
- Water test: If a blob of jam is dropped into cold water, it should not disintegrate immediately, but start descending in a blob itself. Then the mixture is ready.
Labelling And Dates: Always label the preserves,etc. that you make.Write the name, date on which made and if you need to remember any other detail. This will simplify your work later, as to which batch to finish first.
Quality Of Fruit/Veg: Use best quality fruit. Do not use underripe or overripe fruit, in which case there is chance of the product going bad.
Use Of Artificial Colours And Their Optionality: Colours and essences though not vital to the recipes, go a long way in enhancing the visual effects and aural temptation of the product. Therefore, if using the right quantities, and not overdoing it by using in daily cooking, they are not going to cause any major health hazards. Do not use them in overdose.
Where to Store Preservatives: If storing for a short while (2 weeks or so) then one need not use preservatives, and mere storing the fridge is enough. But for storage for long term, proper food methods and use of preservatives becomes imperative. Always add preservative towards the end of the cooking cycle.
A general approximation is 1/2 tsp.citric acid to 1 kg. sugar used.
1 level tsp. potassium metabisulphite is required to make 1 kg. sherbet. For sour fruit like kokum, mango raw, jambul, etc. 1 kg. sugar requires 3/4 tsp. sodium benzoate and 3/4 tsp. citric acid.
Other preservatives like sodium benzoate are also used.