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Freeze-Drying Gets Hot Revolution in f o o d processing looms on the horizon as attractive, tasty, d e h y d r a t e d dishes a p p e a r on consumer markets loi.LOWING
WORLD
W a r I I , food
processing a n d distribution underwent a major revolution as almost every type of fresh-frozen food— from orange juice to chow mein, a n d soup t o steak- -took over from conventional canned or packaged items. Freezer cabinets, once used only for ice cream, grew bigger and bigger as supermarkets steam-rollered m a n y less highly organized food-distribution systems. Today everything from an hors d'oeuvre to a complete meal comes o u t of the freezer. It looks now as though another food revolution is ready to take place : freeze-drying. This will m e a n n o refrigeration because these processed foods c a n be shelf-stored a t ambient temperatures. It will m e a n
less costly shipping because most of t h e water is removed. I t will m e a n more convenience for t h e housewife. T h e art of c o m m e n ç a i freeze-drying is a b o u t 25 years old. First used in developing vital antibiotics such as penicillin a n d streptomycin prior to World W a r I I , the process extended into production of various steroids, vaccines, sera, a n d bloodplasma preparations. T h e n it looked toward food as a lasting big-volume market. Foods H a v e Fresh Look
In preparing h u m a n food for sale to consumers, taste a n d a p p e a r a n c e seem to be far more i m p o r t a n t t h a n nutritive value. Early e q u i p m e n t left something to be desired, b u t
m o d e r n refrigeration engineering a n d v a c u u m technology arc producing freeze-dried foods virtually indistinguishable, after reconstitution, from fresh comestibles. T h e process involves freezing, lyophilization (sublimation of the ice directly to water vapor) a n d packaging (usually in nitrogen atmosphere) in moistureproof, light-tight containers (cans o r foil/plastic laminated bags) for u n refrigerated storage. Fruits a n d vegetables a r e first washed (some vegetables a n d seafoods a r e blanched), then c u t into optimum-size pieces for a d e q u a t e exposure to cold and vaccum treatment. M e a t c a n be ground o r filleted. Most foods a r e fast-frozen in conventional e q u i p m e n t o r in the freeze-drying cabinets themselves to inhibit growth of large ice crystals. For some not affected adversely b y slower freezing, t h e larger crystals actually help by opening the structure for faster drying. T h e n with gentle, controlled heating (hot water circulated through t h e cabinet shelves), the ice sublimes a t v a c u u m conditions of 1 to 0.1 m m . of mercury. T h e bulk of freeze-dried foods, both animal and vegetable, contains a b o u t 2 % moisture after processing. Original water content is m u c h h i g h e r — 8 0 % or more in some fruits a n d vegetables, 7 5 % in shrimp, a n d 60 to 7 0 % in meat. By proper t e m p e r a t u r e control in dehydration, general a p p e a r a n c e in dried foods— color, shape, size—is retained u n believably well. Meats get a slight graying on the surface, b u t most of their n a t u r a l color is restored b y reconstitution in water. Fruits, vegetables, a n d mushrooms look like t h e fresh a r t i c l e s - s l i c e d b a n a n a s , for example, retain their clean ivory look.
< The three Armour pork chops (freezedried) on the right pan w e i g h as much as the single unprocessed chop on the left. Normal weight is recovered upon r e constitution
Many ideas and projects—big and little—can influence you, give you ideas for use in your work, and provide useful information for "current awareness." Each month I/EC's field editors and Washington staff select for detailed report and analysis, designed for easy reading, some of the most timely, in research and commercial development, process design, engineering, production, and marketing areas in the chemical process industries. We present also our comments on other interesting happenings of business and professional interest.
The Chemical World Today
A.
Freeze-dried steak
Soups First on Market
A pioneer in commercial freezedrying equipment, F. J. Stokes Corp. (Philadelphia), is now indirectly represented on the consumer market by soup mixes. Lipton's mush room mix and chicken/rice mix come from a four-unit Stokes system at the food firm's Albion, Ν. Y., plant, the first truly "large-scale" vacuum freeze-drying plant in the country. Stokes equipment commercially produces a variety of dried foods for institutional use, too. After a decade of research, Wilson & Co. three years ago began turning out a number of private-label foods in a two-chamber system with a total input capacity of 1200 pounds per batch. Among presently available products for this market : • Rib eye steaks (fillets) • Boneless pork chops • Cube steak • Ground beef • Shredded chicken • Shrimp • Beef chop-suey mix (precooked) Because of the large quantities in volved in institutional use, most of these dried foods are bulk-canned, for convenience; some are foilwrapped. Late this spring Armour and Co. introduced its Star Lite line of freezedried foods, being marketed initially for campers and other outdoor types. The present selection (distributed
Β.
Reconstituted steak
now through sporting-goods stores, "outdoors" sections of department stores, and mail-order houses) in cludes steaks, pork chops, beef or chicken stew, ham patties, and pre cooked scrambled eggs. And a new United Fruit Co. subsidiary is installing a large Stokes freeze-drying plant at its existing San Carlos (Texas) food-processing location. This will be used on shrimp, for a major consumermarketing effort by United Fruit.
C.
Ready-to-eat steak
Vanadium — Cinderella Metal High V content in Venezuelan crudes makes oil ash a major basic source for this strategic refractory metal
V ANADIUM, AN alloying element used chiefly in specialty steels, plays a small but important role in modern Costs Getting Competitive metallurgical technology. Valued at a little over $3.50 per pound in The best present freeze-drying pure metallic form ($1.38 as V 2 O s ), systems designed for tonnage produc the refractory metal occurs in re tion can remove moisture from a coverable amounts associated with variety of foods for a total processing uranium deposits. U. S. production cost as low as 4 or 5 cents per pound of vanadium in ore and concentrate of water extracted. Improvements established an all-time record last in processing techniques should year (4971 tons of contained V), reduce this figure to 2.5 to 3.5 cents over one third higher than 1959 and within the next few years, in systems 29% above the previous record level processing 5 to 10 tons of food per in 1956. But with uranium stock hour. These costs include labor, piling now a reduced effort, eco power, heat, and 10-year amortiza nomic output of by-product vana tion on equipment. dium will naturally suffer. Conse The Military has been vitally in quently, a ubiquitous, unlikely, and terested in this development in food processing. Getting rid of 60 to not too exotic source—fly-ash, slag, and boiler-tube deposits from oil90% of food weight eases a logistical fired furnaces—is yielding more and problem regardless of cost. With more of this Cinderella metal. economics of the operation getting Actually, U . S. consumption competitive, the outlook is bright for (2016 tons of processed vanadium tastier food in the mess and easier last year) amounts to less than half preparation in the galley. V O L . 53, NO. 7 ·
JULY 1961
27 A
