Like many fresh fruits and vegetables, crisp heads of cabbage tend to brown quickly once they're cut. That's especially unfortunate in the case of cabbages, which are usually too large to conveniently use up in one meal. Whether you're preserving a large cut piece of cabbage, or a quantity of sliced cabbage, the enzymes that cause browning can be thwarted by a few simple and well-proven measures.
A Cut Cabbage
Peel back any wilted or browned outer leaves, and discard them. Cut the portion of cabbage you'll need for immediate use with a sharp, thin-bladed knife, and set it aside.
Cut a slice from the thick portion of a lemon. Rub the lemon slice over the exposed edge where the cabbage was cut, covering it thoroughly with the acidic lemon juice.
Wrap the cut surface of the cabbage tightly with plastic cling film, making an airtight seal. Put the cabbage into the fridge.
Squeeze the juice from a lemon into a small bowl. Remove any pips that are in the juice.
Place your sliced or shredded cabbage into a large bowl, one that provides room to toss the cut greens.
Pour the lemon juice over the cut cabbage, and then toss the vegetable thoroughly with wooden spoons, salad servers, or your own gloved or scrupulously-washed hands.
Cover the bowl tightly using with plastic cling film, once the cabbage is thoroughly coated with lemon juice. Refrigerate the sliced cabbage, and use it within three days for the best results.
Always use a sharp, thin-bladed knife to cut cabbage. Dull and thick-bladed knifes can crush or tear the cabbage's cells, unnecessarily releasing additional enzymes and making the cabbage more prone to browning. A clean, sharp cut causes less damage.
The enzyme-driven reaction that causes browning can be slowed by acidity, by chilling, and by restricting the enzymes' exposure to oxygen. By covering the cut surfaces with lemon, wrapping the cabbage with plastic wrap and refrigerating it, you're covering all three bases.