Lacto-fermentation is a process we can employ to home-preserve food - particularly milk products and vegetables. As well as preserving them, this process makes food more easily digestible, and as a by-product, adds considerably to their nutritional value.
Briefly, lactic-acid-producing bacteria, which are widely present on fresh vegetables, and in raw milk, feed on the starches and sugars present in the food, and generate lactic acid as a by-product. As the acid level increases, other bacteria which would cause the food to go rotten are unable to survive. The food is preserved — in some cases for up to a year, in others for several months.
The two principal species of lactic acid producing bacteria are leuconostoc (chiefly found on vegetables) and lactobacillus (chiefly found in raw milk products.)
Kefir, if you can obtain the living culture and make it for yourself, contains both of these types of bacteria and a number of other bacteria and yeasts besides. Highly probiotic.
Notice that if you leave raw milk to itself for several days, it goes sour, or "clabbers", and separates into curds and whey, both of which can be used in further valuable food products. It does not go rotten — at least initially. Pasteurised milk will go rotten very fast, as its lactobacillus population has been totally destroyed, along with any other organisms that might have been present. Hence, the putrefying bacteria — present everywhere — have a field day.
When pasteurisation of milk was first introduced, a case could be made for it. Dairy farm hygiene and government inspection were nowhere near as advanced as they are today, and bovine tuberculosis, salmonella, and a number of other nasties were thereby effectively removed as possible contaminants. These days, if you are able to source a supply of raw milk, especially from an organic farm, (in many countries it is forbidden to sell it to the public) it is very unlikely that you will place your family at risk — such herds are typically tested regularly and thoroughly — and the benefits available are considerable.
Even if there are no sources of raw milk available, you can get many of the benefits of raw milk by turning pasteurised whole milk into kefir — obviously not for your coffee or tea, but as an ingredient in a number of different dairy-derived foods. Once you have the grains, it is much simpler to make than yoghurt, which, if you are keen, is also an option.
Commercial yoghurts advertised as containing "living cultures" mostly have these added after pasteurisation. Very safe, nice mouth feel, but nowhere near the interest or variety that a live yoghurt provides. A bit like sex through a hole in a blanket.)
In the case of vegetables, to prevent these putrefying bacteria from becoming established in the first few days of fermentation when lactic acid levels are low, a quantity of salt is normally added, which also assists in drawing moisture from the vegetables. Putrefying bacteria are vulnerable to both salt and acid.
Unlike many food acids, for example, vinegar or lemon juice, which can cause problems with digestion, lactic acid is pretty much stomach friendly. (Note that the lacto-fermented pickles are not treated as main courses, but generally more as condiments, digestive aids and taste fresheners.
If you add a little whey to the vegetables, especially kefir whey, you can speed up the fermentation process considerably and thereby use much less salt. As the fermentation proceeds, the salt taste diminishes somewhat.
All you require are several large mouthed glass jars with close-fitting lids. I typically use 750ml to 1500ml jars, to accommodate my normal use rate. With a large and ravenous family you may want to go larger, but in general, just use more of the smaller ones.
1 kg peanut butter jars used to be glass, and were ideal, but alas, these days they are plastic and that is no longer an option. Gherkin or dill pickle jars will do fine. (Have you noticed you can often buy gherkins or pickles in the supermarket for about the same price as they are charging for same size glass jars in the kitchenware department.)
The vegetables are typically grated or sliced, pounded in a stainless steel pot to release their natural juices, innoculated with salt and whey, and packed into the jars leaving an inch or so of space at the top and no air bubbles. (If necessary, add a little more whey or clean water to ensure the vegetables are covered, and not in contact with air.) Typically, cabbage, broccoli, carrot, onion, chillis and capsicums, beetroot and cucumbers are favourite candidates for preserving.
(Pottery crocks can be used, so long as they are stoneware. Earthenware glazes frequently contain either lead or boron or other chemicals which can leach out if the crock is used to store acid foodstuffs. Some stoneware glazes may contain soluble barium salts, but on the whole these are much less common.)
These are left at room temperature for several days with the lids lightly closed, so as to allow air out if necessary. 22 degrees C will normally see a fermentation under weigh in a couple of days. Cooler weather may cause it to take up to 4 or 5 days. You may see a necklace of small bubbles at the top of the jar when fermentation is established. Remove the jars to a cool and dark storage area - about 5-7 degrees C. If you have room, the top shelf of your refrigerator will do.
Lacto-fermentation is essentially a home activity. The process presents many challenges to commercial exploitation, and quite frequently, as with sauerkraut, these are met by using vinegar instead of lactic acid, and by pasteurisation.
Which rather removes the initial reason for eating them. And much of the flavour and nutritional value.
How would you know if the fermentation had failed, and the food spoiled? Answer: I have never had a failure, but consensus on the internet seems to be that if it's off, you won't even want to bring it near your face, let alone eat it. It will smell rotten.
Sally Fallon and Nourishing Traditions. This book is the mother lode for lacto-fermenters, and you should get yourself a copy. That said, it suffers IMBNMHO from a pervasive anti-authority political stance that in my experience with other examples of the sort will tend to filter or ignore contrary evidence sooner than be modified by it. It's also a tad irritating. Use the recipes: they are wonderful, but do check out other claims thoroughly before taking up any "disciple" stance. The book is polarising.
(Hence the larger title for my own website: A Bonnetful of Bees, a constant reminder to myself to be careful.)
Where to from here: The following pages list some of my own experiments with lacto-fermentation:
Glass v Plastic: In theory, food grade plastic should be OK for lacto-fermentation, especially short term, and a number of people on the web report using it. My own hesitation stems from the relatively little that is known about potential reactions between plastic and various kinds of food, especially as the plastic ages, and the often changing nature of what is known.
(I do brew beer in plastic containers, but I bottle in glass for longer storage.)
Under weigh: Why do I spell it like this? Because I can, and because the expression was used originally to refer to a ship that had weighed anchor and was about to set forth on its next journey. It's a lost battle, but I was a school teacher. The spellings "under way" or, worse, "underway", began in blissful ignorance and continued as such, until now they are now regarded as more or less normal. Maybe I could have some fun with "under whey" in this context.