As each year draws to a close, I think about certain annual chores I must do. Not that I do them, you understand; I think about them. Like filing all the year's tax-related papers where I will be able to find them at tax time. Like exchanging my winter and summer clothes between accessible and out-of-the-way locations. Like catching up on my e-mail.
I can procrastinate for the first two, but I do have newspaper deadlines to meet. If I'm going to use my dwindling number of 2004 columns to answer batches of readers' questions, I'd better get started forthwith:
Among the ingredients on some candy my son received at Halloween was "shellac." Why would shellac ever be found in anything we eat? Is shellac edible?
Not in large quantities, no.
Shellac is a transparent coating made by dissolving lac in alcohol. Lac is a resinous secretion of the lac beetle, an insect that lives in tropical trees, especially in India. Believe it or not, lac is used as a coating or glaze on candies such as Reese's Pieces because it provides a high gloss in thin coatings. It was used briefly to coat the centers of peanut butter M&Ms.
Shellac is approved by the Food and Drug Administration as a food-safe coating when the lac is dissolved in pure ethanol (ethyl alcohol.) Vegans who eschew all animal-derived foods including honey may not be aware that shellac is an animal (insect) product.
When making mashed potatoes for Thanksgiving, I peeled the potatoes, covered them with cold water and set them aside at room temperature for a few hours. Is there any reason this might not have been a good idea?
No problem. Freshly peeled potato surfaces turn brown because of an enzyme (polyphenol oxidase) that's released when the cells are cut open. But the enzyme needs oxygen to work, so the potatoes in water are protected. A few drops of lemon juice in the water would be extra insurance, because acid inhibits the enzyme. There is no other problem that I can think of. Just the browning.
Recently I read that the seeds of certain fruits -- especially apples, apricots and cherries -- are toxic to humans if eaten raw. Supposedly they contain cyanide. Cooking is said to render the cyanide harmless. Is any of this true?
Yes. Reputedly, the Romans used ground-up peach pits to poison one another.
Apple, peach and apricot seeds contain amygdalin, a glycoside that reacts with stomach acids to form hydrogen cyanide. It would be hard to eat enough of the seeds to get a lethal dose, but it's not a good idea to eat them, anyway. Although hydrogen cyanide is a gas, cooking cannot be counted on to remove it completely.
Our friend, an excellent cook, mentioned that she has her husband remove the stems from fresh spinach before cooking. She said that they contain oxalic acid, which is known to be poisonous. Can you confirm this?
Oxalic acid and its salts, called oxalates, are indeed poisonous in large enough doses, but they're harmless in the amounts found in spinach, chard and beet greens. It's the oxalic acid that gives these greens their astringent, puckery effect.
In all these plants, however, there is a higher concentration of oxalate in the leaves than in the stems and stalks. Rhubarb is a case in point. Its leaves contain enough oxalate to be dangerous, but its stalks are routinely eaten. (But not by me; I hate rhubarb.)
