Preventing Brown Oxidation -- More than Lemons???
I know that a squeeze of lemon juice can prevent brown oxidation on foods like avocado or raw potato. But often I don't have a lemon, and buying them singly has become so darn expensive. So my question is: Will a squeeze of lime juice do the same thing? What about a squeeze of orange juice? How about pineapple? Other ideas?
The process you describe is called acidulation. Hence, any acid may be used but obviously not all juices, vinegars etc. have equal pHs. Orange juice has acid and is often included in ceviche marinades, but its overall effect is sweet, not sour and will certainly impart flavor to whatever you are trying to merely protect. A good bet for artichokes and the like is simpler than you might expect--- cut parsley stems in your water will accomplish the same thing as lemon juice while imparting almost zero flavor.
You can get a product in the canning section of your grocery or hardware store called Fruit Fresh which is mainly vitamin C with dextrose and silicone dioxide added to prevent clumping. You could crush vitamin C tablets to a fine powder and toss the fruit with it, I frequently find Minute Maid pure lemon juice or lime juice which is in the frozen fruit juice section on sale and 2 Tbs. are equal to the juice of 1 lemon. Defrost adn keep in the refrigerator. It lasts a long time and is a quality product with no added sugars etc. Lime juice will work too.
Actually, lemon or lime juice doesn't really help much with avocado. The best way to keep avocado from turning brown is (1) use it shortly after you cut it, and (2) if you must store a cut peice of it, cover the cut end (or the top of the guacamole) directly with plastic wrap pressed right on the flesh/top of the dip.
For potatoes, i.e. if you are keeping peeled potatoes for a while before cooking, keep the peeled potatoes in a bowl of water. Drain and dry well before cooking. I don't often save half a raw potato, so not sure if this technique works for overnight or longer.
For green vegetables that are to be cooked, salt in the water will help with discoloration (i.e. follow a blanching method of cooking the veggies).
*Avocado: I have also heard that leaving the pit in the avocado or guacamole prevents it from browning but I have not tried it myself.
*Potatoes: You can keep them in water overnight. If I'm serving brunch and plan on making sauteed potatoes I will often cut them into cubes the night before and put them in a bowl of cold water (making sure to cover them completely) and then I store them in the fridge until I am ready to use them. As the poster above mentioned you have to drain and dry them really well before cooking.