A while back we posted how we tried the technique of preserving olives in brine. Previously we've preserved fruit using a Fowlers Vacola - which cooks the contents of the jars - and also dehydrated fruit and tomatoes using various methods. Preserving olives was our first go at preserving using brine. We followed the recipe outlined in Preserving the Italian Way by Pietro Demaio with some slight modifications such as slitting the olives to speed up the process and not adding any herbs or spices to the brine. The recipe stated that the olives could be eaten after 6 months. As we slitted ours, they would have been ready earlier, but we still left them for about 6 months.
This week we opened one of the jars to have a taste. There was some gas buildup which could be due to the olives fermenting a bit or possibly indicating that the preservation technique hadn't worked properly and that the olives might be contaminated. There is a risk of dangerous contamination and food poisoning with any preservation technique. A quick check on the internet had several sources saying that some gassing with this technique was OK although one source said that the gas indicated we should throw them out. Feeling a bit more confident we went ahead and had a taste. We drained the brine off (by this point in the process it is very bitter) and rinsed the olives under running water before tasting a couple. They tasted great! Being cautious by nature, we waited a week - no trip to the hospital with botulism or other food poisoning observed - before deciding that the process had been a success for that jar at least :)
For the remaining jars, we made up a new brine solution. Our recipe recommended a 6% brine (i.e. 60 grams salt per litre of water). As was the case in the original recipe, the brine was poured hot into the jars and then they were sealed. According to the recipe we followed, these olives should store for a year.
The olives we tasted from the original jar were put into a fresh jar with olive oil. Yum!
We found that preserving olives in brine is a quick, inexpensive preservation method that keeps the shape and colour of the olives. A method we'll definitely be using again.