Here’s a quick post to answer a question I was asked recently.
“When you’re reading posts and books about preserving, especially drying, you’ll see a mention of lemon juice, even when you’re not drying lemons. Why do you reckon that is”?
It’s because coating foods to be dried with a little lemon juice helps it to retain its original colour and not go brown.
The browning is caused by both contact with the oxygen in the air and some chemical processes associated with the natural decay of fruit or vegetable tissues.
Lemon juice contains Citric Acid which is an antioxidant. Just like antioxidants work in our bodies, the Citric Acid reacts with oxygen before the tissues of the fruit or vegetable react and thus, prevents oxygenation which is the main cause of discolouration . Being acidic and of a pretty low pH, Citric Acid also changes the way that some of the enzymes in the fruit or vegetable tissue react, further reducing discolouration. Citric Acid can also partially reverse small amounts of oxygenation through a chemical process called ‘reduction’.
You can see the difference a little lemon juice made to these banana slices during drying. Those on the left had lemon juice applied before going into the dryer and those on the right didn’t. The difference is pretty clear.
How much lemon juice do you need?
You only need a little. Just a drizzle. I mix 4 teaspoonfuls into a cup of water and dip the fruit or vegetable pieces into that or, if I have a lot, I just add the cupful to a bowl and toss the pieces in that.
You can, of course, use straight lemon juice, that will work just as well.