Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: THURSDAY, November 23, 1995 TAG: 9511220013
SECTION: EXTRA PAGE: 4 EDITION: METRO
SOURCE: JOEL ACHENBACH
DATELINE: LENGTH: Medium
A: Every year you look at the autumn colors and see lovely hues of red and yellow and orange. The Why staff sees only the anthocyanin pigments, and the carotenoids, or a mixture of the two.
Here's what happens: During the growing season, the green chlorophyll in a leaf is broken down by day and replaced by night. When the weather gets cold, the chlorophyll no longer is replaced, and the leaf loses its greenness.
At the same time, sugars build up. This is because they get trapped in the leaf. They cannot get past the ``abscission layer,'' a corky layer of cells that forms at the stem of the leaf and eventually causes it to drop to the ground. These sugars are needed to form the anthocyanin pigments that cause the red and orange coloration. The yellow pigments, the carotenoids, are in the leaf all along but are masked by the green chlorophyll.
The trees that don't turn red or orange simply lack the gene for the anthocyanin pigments, says Frank Santamour, a research geneticist with the U.S. National Arboretum. But there's no particular advantage to having one color or another: It's just our good luck that some trees are so colorful in the fall.
Santamour says one reason some trees drop their leaves is to prevent snow damage. If they kept their leaves and got smothered in a bunch of wet snow, branches would snap off. The broadleaf evergreens like the magnolia only grow in warmer climates where there is no snow threat.
As for cold climate evergreens, they're cone-shaped, basically. Think about it: They tend to have narrow tops and wide bases, as opposed to the broad crowns of deciduous trees. So evergreens have a sturdier structure when they are covered with snow.
From now on, don't think of trees as either deciduous or evergreen. Think of them as round-topped or cone-headed.
Q: Why does one bad apple spoil the whole barrel?
A: There was a time, years ago, when people stored food and fruits in large quantities because the nearest store was a two-day trip, by mule, through bear-infested forests. No one had yet mastered the art of going to the supermarket virtually every single day and, whenever the word ``apples'' appears on the grocery list, buying exactly two apples.
A couple of unfortunate things happen when an apple starts to rot, says Rick Heflebower, a fruit crop specialist with the University of Maryland. First, the rotting apple gives off a lot of ethylene gas. As you know, this is the gas that causes apples to ripen. It's only a bad thing when you want to store apples a long time; one rotten apple can cause them to turn prematurely mushy.
Second, apples rot by becoming overrun with fungus. A fungus, when extremely aroused, produces a bunch of spores, which drift onto other apples, turning them into additional fungal hosts, until finally you have a big nasty barrel o' fungus.
This is less of a problem now that we have refrigeration, but the truism survives due to its metaphorical usefulness.
The Mailbag:
Someone whose name we forgot already wrote in a while back to ask, ``Why do marshmallows have artificial coloring?''
DEAR SOMEONE: It violates our sense of color theory to think that there exists a pigment which can be added to something to make it white. But what's really happening with marshmallows is that there is an attempt to make sure that they don't skew yellow.
Dingy yellowness is the bane of the purity-obsessed American culture. It is not dirty we abhor; it is discoloration. Waxy yellow buildup was, next to communism, the great terror of the Cold War era.
Marshmallows are not immune, historically, to the yellowing problem. Marshmallows (so named, according to legend, when Egyptians invented a confection from a marsh-growing plant called the mallow - though this has the distinct odor of truthlessness about it) are made out of corn syrup, sugar, cornstarch, water, gelatin and artificial vanilla flavor. In the old days the corn syrup wasn't so pure, and gave the puffy treats a yellow cast unless a dye was added to whiten the product.
We are told that the dye used by one company to whiten marshmallows is none other than Blue 1. This raises the ancillary question of why was ``bluing'' used by laundries to make clothes whiter in the pre-Clorox era. Certain dyes, blue when concentrated, have the effect in a solution of removing yellow tones and whitening a product (though we are not sure how this works exactly).
We are told by Donna Fitzpatrick, sales administrator with Doumak Inc., which makes a lot of the private-label marshmallows sold in supermarkets, that her company a few years back decided that the corn syrup had gotten purer over time and no more bluing was necessary for intensive whitening. ``The quality of raw materials is just superior to what it used to be,'' she says.
The real question is, do people still roast marshmallows over campfires? Or does everyone just stay at home and microwave them?
- Washington Post Writers Group
by CNB