TTT Stood for Quality

TTT Stood for Time-Temperature-Tolerance. That was the name of the ambitious 8-year research project carried out in the 1950's at the ARS Western lab near San Francisco. Its aim was to improve frozen food quality.

Clarence Birdseye, a U.S. inventor, started the industry in 1925, when he quick-froze fish on a refrigerated moving belt. The frozen foods industry grew slowly but steadily until after World War II, when the renewed availability of home freezers boosted production to more than one billion pounds.

But there were consumer complaints over loss in flavor and changes in color and texture. The industry had production problems, too, and sought USDA research help. The Department accepted the challenge.

Building their own freezer plant inside the lab, Western researchers conducted painstaking experiments with every step in food freezing. These included selection of the right crop variety, handling produce between field and plant, blanching and freezing, packaging and storing, and transport of the products to market. They also invented processing equipment to improve frozen products. What scientists learned--and passed along to processors--helped beyond measure to ensure the survival and growth of America's frozen food industry. For today's consumer, TTT resulted in an almost unbelievable variety of quality frozen foods.

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Improving Frozen OJ

Some 50 years ago, orange juice concentrates were relatively flavorless--so insipid, in fact, that consumers opted instead for full-strength canned orange juice, which had a taste all its own. Meanwhile, Florida oranges were a surplus crop, with tons and tons going to waste every year.

The Florida Citrus Commission and ARS researchers at Winter Haven, Florida, partnered together to improve frozen concentrated orange juice.  They found that adding the fresh juice resulted in a vastly improved concentrate that could be easily frozen. USDA, as had been agreed in advance, took out a patent on the process and then licensed it nonexclusively to interested companies (USPN 2,453,109). So it was that the frozen concentrated orange juice industry was born--an industry today worth hundreds of millions of dollars a year in sales.

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Explosion Puffing

For a number of foods, dehydration is an unsatisfactory way to preserve them. Many dried foods rehydrate slowly in boiling water and contain tough and unappetizing areas. ARS researchers at Philadelphia modified and improved dehydration with a step they called "explosion puffing."

A partially dried piece of apple, for example, is subjected briefly to high temperature and pressure, then released into the atmosphere, where it expands instantly, or explodes. The result is a lightweight, porous piece of apple that can undergo further drying more quickly than an unexploded one. Researchers found that apples, celery, carrots, and potatoes so processed reconstitute in water quickly, fully, and evenly.

The technique has many applications. Explosion-puffed blueberries are suitable for inclusion in cereals and muffin mixes. Sliced mushrooms also can be explosion-puff-dried in a USDA-patented process (USPN 3,833,747 and USPN 3,408,209), retaining their nutrients and delicate flavor. The mushrooms can be stored for more than a year, then rehydrated in only five minutes. Used in dehydrated soup mixes and similar products, puff-dried mushrooms can also be eaten as is in salads in place of conventional croutons.

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Making More Corn Sugar

Corn sugar, or glucose, was once a possible substitute for cane sugar, but known methods for converting cornstarch to glucose either cost too much or produced too little sugar.

Screening fungi in a fungus collection housed Peoria, IL turned up a superior strain of Aspergillus. When combined with an improved growth medium this strain enabled ARS scientists to increase production of gluco-amylase (the enzyme that converts cornstarch to glucose). As a result, the corn processing industry could meet increased demand for corn sugar without costly expansion of facilities.

The enzyme research also resulted in a technique later adopted and modified by industry for production of high-fructose corn syrups. This syrup now sweetens hundreds of products, including many fruit drinks and practically every soft drink.

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Extraction Process

Carbon dioxide (C0₂), a gas that forms part of the air we breathe, can be heated and pressurized until it becomes what chemists call "supercritical." In this strange, intermediate state, it remains a gas but takes on some liquid properties. It can flow through such materials as ground coffee, corn germ, soybean flakes, hops and spices, dissolving their oil and sometimes their flavors. When the pressure is reduced, the carbon dioxide reverts to a gaseous state, leaving the oil behind with no solvent to dispose of or recycle.

Supercritical extraction can remove caffeine from coffee, extract the essence from hops to flavor beer, oil from soybeans and corn, and refine many spices. An Italian scientist visiting the Peoria lab used the technique to extract oil from the seeds of the evening primrose suggesting that it could be used in the perfume industry.

Peoria and University of Illinois scientists used the process to remove fat and 50 percent of cholesterol from freeze-dried hamburger patties. And University of Missouri researchers report removing up to 75 percent of cholesterol from freeze-dried ground beef and pork. The meat, they say, can then be rehydrated, cooked and eaten. While meat processors may be inhibited by the high initial cost of supercritical fluid extraction equipment, researchers believe the product may fill a market niche for low-cholesterol, low-fat, freeze-dried meats.

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Soap for Hard Water

When water is cold or where it is hard--loaded with calcium or magnesium salts--soap washes poorly. In hard water, it forms a curd-like substance called lime soap, the culprit behind the bathtub ring.

ARS scientists in Philadelphia modified soap by blending it with other substances derived from tallow called "lime soap dispensing agents." The resulting detergents clean well in hard, soft, cold, and hot water. They biodegrade completely, contain no phosphates, and are nontoxic to humans and animals. They also make use of a surplus product: tallow. The research has been applied in several U.S. toilet soaps, including Zest and Lever 2000, and is being used for laundry soaps in several foreign countries.

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Sourdough Leaves the Bay

ARS scientists found an unidentified bacterium in starter doughs from local San Francisoco bakeries. It worked cooperatively with a yeast to produce the bread's unusual crust, texture and slightly sour taste.

Subsequently, researchers on the other side of the continent, at the ARS lab in Philadelphia, worked with industry to develop a simple new procedure for making the bread. It used sour whey and vinegar instead of bacteria as sources of acetic and lactic acid. When the acids are added to a French bread formula in the quantities and proportions found in the traditional product, the result is a bread with the resilient body, robust flavor, coarse structure, and crisp chewy crust of the native San Francisco product. As a result, supermarkets everywhere today feature, not only sourdough breads, but also rolls and English muffins. And so does at least one fast-food chain--Wendy's.

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Instant Mashed Potatoes

At a 1954 press conference, ARS scientists in Philadelphia announced the development of the instant mashed potato flake.  The press was shown how the potatoes were precooked, cooled, cooked again under carefully controlled conditions, mashed, and spread onto a heated drum. Starch granules were undamaged in the process, an important key to product quality. The dried potatoes came off the drum in a thin sheet and were broken into flakes.

Subsequent market tests of the flake form of instant mashed potatoes indicated that consumers would buy and use the new product, and the first commercial production began in just three years. And three years after that, in 1960, six processors converted more than four million bushels of fall potatoes into flakes.

Improvements and new potato products followed. The ARS Western lab developed a satisfactory potato granule after first inventing a new kind of dryer. Later came explosion-puffed potatoes and a way to make crisper french fries using infrared lamps. Partly as a result of all these convenience foods, only one potato in three today is peeled at home.

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Easy Way to Peel Citrus

ARS researchers in Florida developed and patented (USPN 4,284,651; Docket #0644.87) a process that easily separates the peel from oranges and grapefruit without damaging the fruit or losing any juice or vitamins. The easy-peel process uses a mixture of pectinase, an enzyme, and water to soften the material that binds the peel to the fruit. 

Peeled and chilled citrus fruits have alonger shelf life than unpeeled fruit, allowing them to be dispensed in individual sealed plastic containers in vending machines in such places as schools and health clubs.

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Defatting Peanuts

ARS chemists in New Orleans, LA developed a defatting process that kees much of the peanut flavor intact in defatted peanuts. They also succeeded in restoring the lower calorie peanut to its original shape by expanding it in steam before roasting.

Using sensitive instruments, they identified and ranked a dozen compounds crucial to the aroma and flavor of peanuts. Peanut processors can use the findings to enrich their products, making them "pea-nuttier."

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Lower-Salt Pickles

A new and better way to make pickles has been developed by ARS technologists in cooperation with the pickle industry and North Carolina State University. Improvements include a new strain of lactobacillus plantarum, the bacterium that converts the sugar in cucumbers to lactic acid and gives pickles their characteristic sour taste. The microorganism, which was chemically mutated, allows cucumber pickling with less salt and is not as likely to cause softening of pickles during fermentation. It also permits using closed pickling tanks.

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Updated 7/15/03