I think the simplest and least energy intensive method of preserving would have to be lactic fermentation. As this method lets bacteria do all the work, it doesn't require any heat or pressure, or the addition of excessive salt or sugar. The lactic acid bacteria naturally increase the acidity of the brine. The lack of temperature or pressure processing also ensures that vitamins and enzymes are retained in the veges. Apart from getting used to the taste, this would have to be the ideal method for preserving veges. I have used it so far for pickles and cabbage.
|Fermented pickling cucumbers|
In the case of drying, food spoilage is prevented by reducing the water content of the veges. This is an energy intensive method, which I wouldn't use for high water content fruit and veges. I think its a good way to preserve herbs and greens with low water content, that don't take too long to dry. So far I've used this method to dry herbs and silverbeet (and other veges). Drying uses low temperatures(60-70 degC), so most of the enzymes and vitamins survive. One day I'd love to build a solar drier as well.
Preserving food by freezing also reduces the water content as the water is not available to bacteria when its solid and the low temperatures reduce bacteria growth rates. You're supposed to blanch veges before freezing to destroy enzymes that cause off-flavours. I freeze beans (sliced into 2 cm pieces), thinly sliced zucchini and squash and whole cherry tomatoes, mini capsicums and chillis. I also make soups and sauces to freeze, including pumpkin and tomato. As we have several freezers for meat anyway, its very easy for me to add a few veges to last through the winter, but this would not be ideal is freezer space was limited.
|Sliced beans for freezing|
|Cherry tomatoes ready for freezing whole (not the green ones!)|
|Roasting pumpkin in the BBQ for pumpkin soup|
PreservingPreserving veges generally involves preventing spoilage by reducing the "water activity", this means the water available to bacteria or moulds for growth. High water activity leads to quicker spoilage. Water activity can be reduced by increasing salt, sugar or acidity, by drying the food or freezing the food. Generally preserving involves heating the produce to boiling point in a sauce containing sufficient salt, sugar or vinegar to prevent microbial growth. This includes jams, vinegar pickles and olives. I don't have any fruit to preserve (yet!), and any veges I'd rather use one of the above methods, as I don't want the heat to destroy the enzymes and vitamins in the vegetables, so I don't do any preserving so far.
How do you preserve your harvest?