Q. In a recent column you mentioned that, on average, Americans consumed considerably more French fried potatoes than all other types combined. I was taken aback by that and would like to hear more about our potato-eating habits.

A. Data available from the USDA's Economic Research Service clearly indicate that we are eating a lot of fat with our potatoes. The consumption of processed potatoes has nearly tripled over the past two decades, rising from 24.6 pounds per person a year in 1960 to 64.4 pounds in 1980. Meanwhile, fresh potato consumption has dropped by more than one-third, from 83.8 to 51.4 pounds.

Processed potatoes have been around for a long time. Potato chips were first marketed commercially more than 130 years ago. But it was the introduction of commercially frozen potatoes in 1947 that has really changed our potato-eating habits. Consumption of other processed potatoes has grown, too, but their effect has been comparatively small.

For example, in 1960 the average American ate 6.6 pounds of frozen potatoes, 11.6 pounds of chips, 4.9 pounds of dehydrated and 1.5 pounds of canned potatoes. By 1980, on average, we were eating 33.8 pounds of frozen potatoes and 17.0 pounds of chips, 11.5 pounds of dehydrated and 2.1 pounds of canned potatoes. And while there are many different varieties of frozen potatoes, French fries account for 80 percent of all frozen potatoes (about a half pound per person per week), and 50 percent of all frozen vegetables consumed.

As you might expect, the greatest outlet is fast-food establishments. In 1980 an estimated 60 percent of all frozen French fries, or 2 billion of the 3.2 billion pounds produced that year, were sold through that route.

The fat content and the calories of French fries will depend on how they are processed from the frozen state. Potato chips are not nearly so variable. Thus we can tell you that the 17 pounds of potato chips consumed by the average American in 1980 provided 40,324 calories. That is 110 calories a day just from potato chips.

Q. I have often wondered what is meant by the term "pearled" barley. Is there another type?

A. No. "Pearling" is a processing technique. Unlike wheat or other grains, which have hulls that soften with heat, the tough outer layer on barley kernels does not yield even after long hours of cooking. So an abrasive must be used to strip it away.

Incidentally, if you have neglected barley because it just takes too long to cook, you might like to know a new quick-cooking variety is now available. And as for its nutritional value, barley provides about 185 calories per cup, mostly from carbohydrate. Like other grains, it also contains some protein, as well as some B vitamins and iron.

Q. Is it possible to freeze fruit with aspartame?

A. Apparently it is. M. Elizabeth Kunkel and Mildred Cody of Clemson University recently reported the results of studies comparing the acceptability of peaches and strawberries frozen without added sweetener and by the dry-pack method (that is, the sweetener is added "as is" rather than as a syrup) and sweetened with sugar or the equivalent sweetness of aspartame or saccharin.

The fruits were rated at the time they were frozen and again at intervals of one, two and six months after storage at 0 degrees Fahrenheit.

In analyzing their data, the researchers divided the panelists who rated the fruits into three groups: those who never used artificial sweeteners, those who used them infrequently and those who used them often. Here are some of the findings.

Regardless of previous use of artificial sweeteners, the panelists did not differentiate between the acceptability of peaches sweetened with either sugar or aspartame. Those who did not use sweeteners rated both sugar- and aspartame-sweetened berries frozen for six months or longer lower than did those who were artificial sweetener-users. The acceptability of the unsweetened and saccharin-sweetened fruits also decreased over time, and ratings remained significantly lower than those for the fruits frozen with the other two sweeteners.

Since the decrease in quality ratings over six months was similar for the sugar- and aspartame-sweetened fruits, the authors concluded that aspartame provides an acceptable alternative for people interested in freezing fruits without sugar.