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Milk goes arctic: freeze-concentrated milk is first major alternative to thermally evaporated milk.

The wraps have been coming off very slowly. But after seven years, an unlikely international consortium of corporations, associations and government agencies is readying what they believe will be the first freeze-concentrated milk with a chance of surviving -- even thriving -- in the food marketplace.

The group was planning to unveil its new freeze-concentrated milk by the end of the year after completion of a marketing study and its approval by the various entities in the consortium.

The group--the Dairy Research Foundation, the Electric Power Research Institute, Niro Process Technologies Inc., Galloway West Co. and the U.S. Energy Department--believes that its freeze-concentrated milk could become the first major alternative to thermally evaporated milk for both ingredient and consumer applications. Its success could have a major impact on markets that have been dominated by heat-dried milk.

Applications and benefits

Initial targets would be ingredient applications where non-fat dry milk now is the standard, such as sour cream, frozen dairy desserts and salad dressings. Several years from now, consortium members hope, their freeze-concentrated milk could be sold like orange juice concentrate is sold today.

"We feel it's viable for certain niche markets," says Dan Best, director of the Dairy Research Foundation in Elk Grove Village, III.

Adds Ammi Amarnath, process industries manager of the Electric Power Research Institute, a utility industry research organization based in Palo Alto, Calif.: "The potential is that our product could be used wherever non-fat dry milk or even fluid milk is being used now."

The U.S. dairy industry converts about 60 billion pounds of milk and whey to powdered products each year, according to the Energy Department. The advantages of concentrate include lower handling, storage and distribution costs.

Thermal evaporation is the most popular current method for "preconcentration" of dilute dairy liquids. But it's one of the most energy-intensive processes used in the food industry, the Energy Department says, and most of the evaporators in use today are old and relatively inefficient. What's more, all evaporators, regardless of age and condition, must be kept scrupulously clean to prevent bacteria growth. And the buildup of dairy solids in the evaporator reduces the efficiency of the heat transfer, resulting in higher operating and maintenance costs on top of high energy costs.

How it works

Researchers have been investigating freeze concentration as a possible alternative to evaporation since the 1960s. But Dairy Research Inc., a dairy-sponsored industry organization, refocused on the possibilities in 1986, teaming with EPRI. The Energy Department's Office of Industrial Technologies added its support in 1988. In 1990, the Dairy Research Foundation took over the responsibilities of Dairy Research Inc.

In the project's initial phase, the group used a small freeze concentration pilot unit to concentrate milk and whey products. In the process, as the Energy Department explains it, milk is cooled to the point where a mixture of milk concentrate and ice crystals forms. The crystal suspension is fed into the bottom of a wash column, then the concentrated milk is removed from the column through a filter. The resulting compact of ice crystals is then removed from the top of the column by a rotating scraper and is used to cool the milk entering the process.

The quality of the products of the pilot was superior to that of conventional products as determined by physical and chemical analyses, says the Energy Department. When reconstituted, the freeze-concentrated milk had a smoother, creamier taste than fresh unconcentrated milk. But the pilot unit wasn't able to concentrate the dilute product to the level possible with evaporators.

So the group began a second phase of the project in 1989 to "optimize the process and develop equipment capable of the high concentration needed to make commercially viable products," says the Energy Department. Grenco, now part of Niro A.S., built a process development unit with a water removal capability of 700 pounds per hour. Galloway West, a Fond du Lac, Wis., dairy that now is owned by the Irish food cooperative Waterford Foods PIc, agreed to become the demonstration site for the pilot's second phase, and a unit was assembled at Galloway West to use actual dairy products.

The group concluded, after numerous test runs with whole milk, skim milk and whey products, that the freeze-concentrated products were whiter than the derivatives of evaporation and had no cooked or caramelized flavors.

"The texture improvement shows potential," says Ray Ruemekorf, area manager for U.S. operations for consortium member Niro Inc., a Columbia, Md.-based division of Denmarkbased Niro A.S., the world's largest manufacturer of freeze-concentration equipment.

Ruemekorf says it isn't yet clear how much better the texture of freeze-concentrated milk could be because output by the prototype unit was short-term, often interrupted and frequently adjusted to test various production factors.

"We would like to go forward with a real commercial unit that would vary one parameter at a time instead of all the variables at once."

Concludes an Energy Department report: "Freeze concentrated products have been shown to be superior to those conventionally concentrated, both in taste and nutrition. There is no loss of aroma, flavor or other properties of the original product."

And other advantages of freeze concentration have emerged. For instance, the low operating temperatures involved don't harm heat-sensitive food constituents, enabling high-value liquid protein foods to be concentrated. The Energy Department says the lower temperatures also result in reduced microbiological and enzymatic activity, leading to better utilization of equipment and lower cleaning and sanitizing costs.

What's more, the process loses less food material than does evaporation because of the reduced frequency of cleaning the process equipment and the superior separation of product from machine with freeze concentration. And because freeze-concentration units are electrically driven, "they lend themselves to small installations and modular expansion," the Energy Department says.

Potential for energy savings

"The energy requirements of freeze concentration are roughly half those of evaporation," the Energy Department has concluded. The government said that if a single 50,000-pounds-an-hour evaporator were replaced with an equivalent freeze concentrator, a dairy would save about $100,000 a year through lower energy costs alone. And those savings don't include the costs recovered from keeping the nearly 1% of product lost each time evaporators must be shut down for cleaning, which occurs about every 20 hours.

More recently, however, Amarnath seemed to back away a bit from EPRI's initial finding, saying that the group "hasn't reached a definitive conclusion" about the energy savings of freeze concentration.

What has energized Amarnath and other group members are the possibilities for improving existing dairy products and creating new ones.

The Dairy Research Foundation's Best says that, once concentrated, the product could be freeze-dried, heat-dried through spraying or kept as a frozen, concentrated fluid. In any or all of these states, he says, the product would have appeal to food ingredients users.

"It could be shipped and stored just like non-fat dry milk," says Best, "but it is a better-quality product."

The Energy Department says ingredient users are likely to be attracted by the fact that freeze concentrate offers better control over product properties such as flavor retention and protein functionality than evaporated concentrate.

Amarnath says that sour cream, cream cheese, ice cream and other dairy products would be likely first target markets for freeze-concentrated milk, along with salad dressings and other non-dairy products that use dairy ingredients. He says another likely early product of the process could be high quality chocolate milk.

Within several years, group members say, the process could be used to make products with long shelf life, such as fresh-tasting reconstituted concentrated milk and high quality milk that would be shipped to foreign markets. Amarnath also envisions supplying restaurant chains, such as McDonald's, with concentrate and then having the product diluted and packaged at the point of sale.

Obstacles ahead

But "selling this product frozen like orange juice," cautions Best, "is way down the road."

Niro's Ruemekorf agrees the marketing obstacles will be substantial. "Breaking into the U.S. dairy industry is very difficult," he says. "Everyone says, 'We'll stay with what we have; we know it works.' One dairy processor told me, 'We're No. 2, and it ain't all that bad."
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Author:Buss, Dale D.
Publication:Food Processing
Date:Dec 1, 1993
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