The humming motors, the miles of pipes, the enormous tanks and silos, the wafting vapors make the Clinton Corn Products Co.'s 42-acre spread look like just one more dreary outpost on the industrial frontier.

But beyond the well-guarded main gate, in the company's laboratories, biochemists and microbiologists working in secrecy, with urgency, put together the puzzle that brought a revolution to the American food-processing industry.

Odd setting for cloak-and-dagger stuff, this sprawling old plant on the west bank of the Mississippi, but that's what it was and this is where it happened.

The beginning was in 1965, when three Clinton executives flew home from Japan, each carrying in his coat pocket two test tubes swarming with microbes. The microbes were corporate gold, panned from the grasp of other American competitors.

Using the Japanese enzyme, the Clinton researchers found a way to convert corn into a syrup sweeter than sugar. It is called high fructose corn syrup (HFCS) and it is a multibillion-dollar discovery, now quickly shouldering aside traditional cane and beet sugar from their market dominance.

But syrup and corn sweeteners are only a part of this story. It is about corn, America's predominant grain, and the ingenious extremes to which corporate minds go to wring one more dollar and one more product from the golden kernel.

A key part in that is played by the dog-eat-dog wet milling industry, which uses a lot of chemistry and a bit of black magic to insinuate corn into every facet of daily life. This industry of a relatively few companies is to corn what the big petrochemical corners are to oil.

Their wet milling process, crushing and cooking and reorganizing the molecule of the grain, turns corn into sweeteners, starch, fuel, drugs, chemicals, animal feed, liquor, oil and margarine and thousands of other products without which the country would have difficulty functioning.

Last year, wet millers used about 500 million brushels of corn to produce this array. The hottest of their items right now is high fructose syrup, abetted by it acceptance by the major soft-drink bottlers as a sugar replacement. The industry in 1980 turned out about 4.3 billion pounds of HFCS for a market with a seemingly insatiable sweet tooth. HFCS and other corn sweetners last year accounted for a third of U.S. sweetener supplies.

The race to be first motivates the wet millers. Which returns the story to high fructose syrup and the intrigues and corporate dice-rolling that allowed Clinton scientists to crank out the first commercial batch of HFCS in 1967.

The industry's quest for sweeter syrups has been generated in part by ups and downs of the world sugar market and by sugar supply shortages during periods of war in the 20th century. Although some health-food purveyors make the debatable claim that fructose from corn is more healthful than sucrose from sugar, the competition is rooted more in economics.

The millers knew that corn could provide a sweetener that would challenge sugar in the marketplace -- if they could figure out a way to convert enough corn starch and thereby get a syrup sweet enough. Word came from Japan in the mid-1960s that a new enzyme -- a natural organic substance that could cause vigorous chemical reactions -- might provide the key.

The news set off a scramble among U.S. wet millers. If the enzyme worked, it could mean riches for the company that got it first. Officials at Standard Brands Inc., the parent of Clinton Corn Products, sensed the potential and dispatched a team to Tokyo to negotiate with the Japanese. So did the A.E. Staley Manufacturing Co. of Decatur, Ill., a pioneer in corn syrup. So did CPC International and Union Starch Co.

When Staley's Dr. Hans Wolff got to Japan in 1965, he found Clinton's team already there and bargaining hard for the enzyme licensing rights. Clinton won after several months of dickering and its negotiators flew home with their test-tube samples.

"People in our industry were aware that fructose would be very valuable -- but we didn't know how much," said Dr. Norman E. Lloyd, now head of research at Clinton. "We were going from acidic to enzymatic techniques in starch conversion. We had been seeking a way to do it for a long time. Some of us never had any doubt that it could be done, but we had to convince upper management to put out one helluva lot of money to market it."

Put most simply, the starch conversion techniques are not unlike the human digestive process. Traditionally, the refines put acid with the starch. The resultant reaction gave a syrup that was sweet, but not as sweet as sugar from cane and beets. The use of organic enzymes hastened the conversion process, intensified the breakdown of starch and produced fructose. Further processing intensifies the sweetness of the fructose.

Working overtime behind closed doors with their Japanese enzymes, the Clinton researchers found the process for quickly cleaving the starch molecule -- that is, changing the glucose (dextrose) to the sweeter fructose.

Within two years, Lloyd and his colleagues in the Clinton labs had their first big batch of the new HFCS ready for shipment to the baking industry. "While one team worked on the process, another group was working on applications," Lloyd said. "It was secretive. We weren't telling everybody what we were doing."

Staley, meanwhile, an also-ran in the race for the enzyme, did the next best thing: It paid Clinton more than $1 million for sublicensing rights to manufacture HFCS with Clinton's know-how. That was 1968. By 1971 Staley was shipping HFCS from Decatur while readying a large new fructose plant in Pennsylvania. It opened another in Indiana in 1977 and is planning a fourth in Tennessee.

Since the, the high fructose bonanza has grown by leaps and bounds, the new technology increasing the sweetness of the syrup. The other wet millers are into HFCS production in a big way. There are now 26 wet milling plants in operation, under construction or on the drawing boards -- including two opened recently by traditional sugar companies that see a future in corn sweeteners.

Existing plants represent a $3.3 billion capital investment, according to the Corn Refiners Assoication, with no real limits apparent on future growth -- a situation helped in large part by the soft-drink industry's acceptance of HFCS.

All major bottlers, from Coca Cola and Pepsi on down, now authorize partial or full use of HFCS in their beverage syrups, which the millers carefully price just below the going rate for sugar to stay competitive. Fructose prices, for example, doubled last year when sugar went up about 180 percent. Congress coincidentally helped the wet millers in 1977 when it forced an increase in wholesale sugar prices.

"This is a very capital intensive and volume sensitive industry," said Jack Anton, president of Clinto. "By 1985, we believe fructose will represent about 50 percent of U.S. sweetener needs. It's a very dynamic situation."

High fructose is now used in scores of products on the supermarket shelves -- bakery goods, soft drinks, canned fruit and juice, condiments, candies, frozen desserts, jams and jellies, pickles, wine.

But HFCS is only one of the items that a plant like Clinton Corn Products extracts from the kernel of corn, which it runs through its cookers, pipes and vats at a rate of 120,000 bushels a day, most of which comes from farms within a 100-mile radius of here in Iowa and Illinois.

That kernel, no bigger than your fingernail, is a marvel of nature. It is about 60 percent starch; 20 percent hull and gluten; 15 percent moisture and maybe 5 percent germ -- from which the oil is extracted.

Each of those components is used in the wet milling process. Anton and Lloyd estimate that less than 1 percent of the kernel finds its way into the Clinton waste-treatment plant. Otherwise someone's in trouble.

Multiply the kernel by millions upon millions and you get an idea of the mountains of corn that are processed in the Clinton plant, where every step in the procedure is monitored and controlled from a central computer room that seems more elaborate than that of a nuclear power station.

The corn first is soaked in warm water for two days. The "steepwater," as it is called, is piped off and saved for further processing into drugs, vitamins, proteins, minerals, lactic acid, carbohydrates, some of which will go into animal feed.

The softened kernels go into a milling process where they are broken down and the oil-bearing germ is removed. The germ is processed into oil for cooking and margarine.

What's left of the kernel -- starch, gluten and bran -- is run through screens for separation. Bran and hull go back toward the steepwater to become animal and poultry feed.

Centrifugal separators take the gluten from the starch, and that, too, heads toward the animal-feed section. (A point: the yellow skin of your chicken and the coloring of your egg yolk comes from the xanthophyll in the gluten, a vitamin and pigment that makes corn yellow.)

Before they're done with the gluten, a product called zein is removed. It's a binder used in inks, photographic paper, paints and floor finishes.

Next in the refining process is starch -- the major element in the kernel. Some of it is put through driers to become the corn starch used in hundreds of foods and industrial goods. Another part of it becomes dextrin, which goes into adhesives and explosives.

The rest of the starch, combined with acid or the newer enzyme processes, is made into dozens of kinds of syrup, either liquid or dried, from low-sweet to sweeter than sugar. It produces dextrose, which in turn can be converted into hydrol, an element in alcohol, gunpowder and synthetic rubber. Ferment the dextrose, you get lactic acid. Treat it other ways, you get sorbitol (for emulsifiers), mannitol (for dietetic sweetners) and methyl glucoside (urethan foam and insulation base).

Each of the wet milling plants devotes itself to some of most of these procedures. Here at Clinton, the array is impressive but by no means all-inclusive.

The gin and vodka that Standard Brands markets under the Fleishmann's label is produced here, alcohol distilled from the corn. The crude oil that becomes cooking oil and margarine with Standard Brands labels goes out in railroad tank cars to refineries elsewhere.

Three lines of high-fructose syrup are produced, along with tons of gluten meal for animals, food and industrial starches, crystalline dextrose and lactic acid, piped to another company on the Clinton tract that uses it to make caramel syrups.

Clinton Vice President Lloyd is a low-key fellow, but he goes down the list of products, looking across the wide river to the cornfields on the Illinois side, and he becomes almost rhapsodic.

"Most people don't realize what we're doing with that kernel of corn," he said. "But it's very exciting. Many in American history don't get to see the culmination of their work, but we do here at Clinton." KERNELS

The modern-day revolution in turning starch to sweetners has its roots in an 1811 discovery by a Russian chemist, G.S.C. Kirchoff. Looking for a gum arabic substitute, he found he could make a sweet substance by heating starch with dilute acid.

If you think the multibilliondollar corn refining industry is concentrated among relatively few companies, you are right. But at the turn of the century it was so concentrated that it was called the "Glucose Trust." The monopoly was broken up in 1916 by antitrust action, but one of the successors of the Corn Products Refining Co., the principal player back then, continues today under the flag of Cpc International, a company with corn-refining plants around the world.

Napoleon provided some of the first government support for starch-to-sweetner research, looking to beets and grapes as a sugar source. The British blockade had closed French ports to foreign sugar and the emperor was under pressure to satisfy the Gallic sweet tooth. The Battle of Waterloo put an end to the problem. Ports reopened and sugar poured freely again.