There are 5 methods available to you when steralising the containers and food for botttling.
- Cold water bath - for bottled fruit only, most reliable, needs a thermometer
- Hot water bath - for bottled fruit only, second best and no thermometer required
- Pressure cooker - only method to be used for vegetables, quickest method for fruit with the risk of overcooking
- Oven, dry pack - for bottled fruit only, the greatest challenge here is getting the temperatures correct, dry pack means adding the boiling liquid after the contents have been in the oven, using the oven has the highest failure rate.
- Oven, wet pack - as above the difference being that you add the liquid before you heat
Of those listed the top 3 are the most successful and least complex, therefore I will cover these only. In all cases what you are doing is heating the containers and their contents then leaving them in that heat long enough for any bacteria present to be killed, which is why the process is called steralising. You will need a false bottom to stand the containers on inside the steralising pan or pressure cooker and cloths to pack around the containers whilst they are being heated, so that they dont knock against each other.
Slow water bath method - for bottled fruit only
The slow water bath method is so called because you take 1 and 1/2 hours to get up to temperature, you need to monitor the temperature regularly throuout the steralising process. The final temperature and steralising time required will depend upon the fruit being heated, see the chart below for guidance. Load the containers using cold syrup, add the lids and loosen buy 1/4 turn, this allows the air to expand inside without causing a problem.
Load the pan with the false base, containers and cloths. Add enogh cold water to cover the conatiners then put a lid on the pan. Slowly heat the water, you are aiming for 55°C after 1 hour, after a further 30 mins you need the temperature required for the fruit being steralised, see chart below. Maintain this temperature for the required cooking time. At exactly the right time remove the bottles from the pan and tighten any screw top lids, leave to cool tightening further if necessary.
Fast water bath method - for bottled fruit only
The fast water bath method is so called because it is fast in relation to the slow water bath method. You bring the water to a simmer in 30 mins . The fruit is steralised for their specified time at simmering point, see the chart below for guidance, so you dont need a thermometer making life a little simpler.
When using this method you need to use hot syrup, this means less opoertunity for preparation in advance and working a production line. So when you are ready, prepare the bottles, add the hot syrup and put the lids on, releasing 1/4 turn to allow for the air to expand inside as above. Load the pan with the false base, containers and cloths. Add enogh hot water to cover the conatiners, then put a lid on the pan. Over 30 mins bring the water to simmering point, then leave to simmer for the required steralisation time. When finished remove the jars, tighten the lids and allow to cool tightening again if necessary.
Pressure cooker method - for bottled fruit and vegetables
Your pressure cooker must be able to maintain a low pressure of 5lbs per sq inch for fruit and 10lbs per sq inch for vegetables and be large enough to hold a false base, the bottles and packing with the lid securely sealed.
For fruit - prepare the fruit in warm bottles with boiling syrup. Add about 2.5cm of boiling water with a little vinegar to the cooker then place the base, bottles and cloths in. Put the lid on the cooker and bring up to low pressure, this should happen between 5 and 10 mins. For soft fruit apples and berries hold the pressure for 1 minutes, for and tightly packed apples, figs and pears hold the pressure for 5 mins. remove the cooker from the heat and leave sealed for 10 mins, at this point release the pressure and remove the containers, tighten the lids and leave to cool
For vegetables - prepare the vegetables in warm bottles with boiling brine. Add about 600ml (1 pint) of boiling water with a little vinegar to the cooker then place the base, bottles and cloths in. Put the lid on the cooker but do not set the valve, heat until a steady stream of steam floews for 10 mins. Set the pressure vale to 10lbs per sq inch and cook for the required time for the vegetables being steralised, see below. After the required cooking time remove the cooker from the heat and leave to cool slowly. When the pressure is zero release the valve and remove the containers, tighten the lids and leave to cool
Steralising times for fruit
|Fruit||Temp||Steralising time mins|
|°C||Slow Method||Quick Method|
|Apples packed solid||82||15||20|
|Apricots whole and halved||82||15||10|
|Cherries whole and stoned||82||15||10|
|Plums halved and stoned||82||15||20|
Pressure cooking time for vegetables
|Potatoes - new||50|