It could cause the heart to skip a beat. The latest durum wheat crop projections--that the crop will be one-third shorter this year than last--might cause murmurs in food and athletic circles full of pasta lovers who depend on it to guarantee chichi dinner parties and successful marathons.

Not to worry, says Allen Schienbein, wheat analyst for the Department of Agriculture's Economic Research Service. Last year's crop was so huge they couldn't begin to sell it all. Farmers and grain elevators still hold enough carryover to make this year's actual supply equal to last, he assures.

Durum wheat is a very hard wheat, high in protein, used to make spaghetti, egg noodles and other pastas. People in this country consume only 20 percent of the crop that's grown here--the Italians, says Schienbein, buy almost as much as we do. The wheat grown here--in North and South Dakota, Minnesota and Montana--is of very high quality, and whenever the Italian crop falls a little short, they buy ours--16 million bushels last year (4 1/2 million went to France).

At a recent Food Marketing Institute convention, pasta machines contributed to the new look in supermarket gadgets. Machines that rolled, formed and extruded pasta, which allow the supermarket to provide the customer with fresh noodles, were conspicuous by their relatively recent presence at the annual food marketing show.

Schienbein says there's no real way to tell if these machines will make a difference in American pasta sales, which never really recovered after a drought two years ago caused prices to double. Prices have since fallen, but the slowed growth in pasta sales reflects cautious buying practices among supermarket managers, who want to avoid paying high interest rates on large inventories. Nevertheless, Don Vaillancourt, spokesman for Grand Union, which is selling fresh pasta from its Rockville food store, notes that fresh pasta sales have not caused a decrease in sales of dried pasta.

In any case, plenty of pasta will be available this year, says Schienbein, who calls it "a good buy" especially in hard economic times. Pasta helps to stretch food dollars and " durum is a high-protein wheat and we don't lose much of it in the milling," he adds.

Not only that, pasta is perfect for both hot and cold meals. Serve the following meal with sliced tomatoes and steamed zucchini flavored with butter, basil and salt and pepper to taste. Toss the dinner leftovers with vinaigrette for a cold salad lunch tomorrow. All it takes is a trip through the express lane at the supermarket.

And all you need to have at home is flour, sugar, salt, pepper and butter or oil.

EXPRESS LANE LIST: hot Italian sausage (large links, not in bulk), green peppers, onion, pasta, sliced tomatoes, zucchini and basil.

PEPPER SAUSAGE (4 servings) 4 large green and/or red peppers 8 hot Italian sausages (about 4 ounces each) 2 tablespoons olive oil 1 large onion, sliced 8 ounces thin spaghetti or fettucine

Broil the peppers on all sides until charred all over. Place in a paper bag, close the bag and set aside. Pierce the sausages several times with a fork. Place in a skillet and add water to just cover. Bring to a boil, cover and simmer about 15 minutes. Remove from pan and set aside. Discard water.

Wipe the skillet dry and set aside. When the peppers are cool enough to handle, peel and core them. Slice them lengthwise into strips and set aside. Heat olive oil in skillet and add sliced onion. Cook until soft. Add sausages and green pepper strips, cover and cook about 5 to 10 minutes over low heat (or while the pasta cooks).

Bring 5 quarts of water to a boil. Add pasta and cook to desired consistency. Drain and, if holding for a while, toss it with butter or olive oil to keep it from sticking.

Serve peppers and sausages with pasta, sliced tomatoes and steamed zucchini flavored with butter, basil, salt and pepper.