Dehydration and Compression of Foods (1982) / Chapter Skim
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COST REDUCTION APPROACHES
COST REDUCTION APPROACHES
Pages 7-16
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From page 7... ...
The advantages offered by reductions in the weight and volume of food items, long-term shelf life without refrigeration, and ease of preparation, combined with high quality end products when rehydrated, justify the use of dehydrated and compressed foods for a variety of military missions. Currently, detailed systems cost analyses are being carried out on the dehydration and compression technology as a whole to provide accurate, timely information on the costs of each operation from raw material preparation to compression and packaging.
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From page 8... ...
, the one that has the least detrimental effect on quality, in most instances, is freeze-drying. Freeze-drying has proven to be a superior method of dehydration for most of the commonly used food items including green beans and other beans, peas, carrots, spinach, potatoes, beets, turnips, asparagus, parsnips, green and red peppers, okra, chives, corn, mushrooms, cottage cheese, coffee, cherries, blueberries, strawberries, and a variety of meat, poultry, and fish products.
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From page 9... ...
Hot air can be used to partially predry most dehydrated and compressed food items, the degree of prehydration that can be done without degrading the final product varies with each item. Frozen starting materials are less suitable for hot air predrying.
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From page 10... ...
If water is added to the dry product, the additional energy and time required for the rehydration and subsequent dehydration increase the cost of the dehydrated and compressed food item, limiting the military market and making dehydrated and compressed foods less attractive to the civilian market. A lesser degree of dehydration can be used before compression.
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From page 11... ...
. When, in a conventional freeze-drying process, the overall moisture content of a food item drops to the level that is considered optimal for compression, the item usually ends up with a wet unstable core and a dry outer region and will not compress satisfactorily.
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From page 12... ...
However, for most shipboard applications, this would be of little consequence. Results from a laboratory simulation in a large microwave oven containing the product in a stoppered flask connected to a vacuum source demonstrated that the moisture content of green beans could be reduced to 14 percent in 45 minutes.
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From page 13... ...
found that the rehydration rate for dehydrated carrots increased when the carrots were cooked in salted water prior to dehydration. Taking photomicrographs of the dehydrated carrot tissue with a scanning electron microscope, he noted the presence of sodium chloride crystals and concluded they were responsible for the increased rehydration rate because water has an affinity for crystalline salt.
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From page 14... ...
level in carrots prior to compression, found that the use of microwave heating produced a more uniform moisture distribution, minimizing the cellular compaction noted by Curry. The quality of the final product was found to be best when the moisture level was 10 to 15 percent after dehydration.
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From page 15... ...
. Poorer quality slices and chunks that contain gristle and connective tissue cannot be dehydrated satisfactorily by any method because the gristle and connective tissue become as hard as bone particles and do not rehydrate.
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From page 16... ...
ground sausage meat when transported over long distances, but these calculations are based on assumptions of capital costs and interest rates that are subject to change. Restructured Meat Products The poorer quality portions of a beef or pork carcass that contain gristle and connective tissue can be used for freeze-dried and compressed products if the meat is first cut into very small chunks or flaked and then "restructured." When this is done, the gristle and connective tissue are finely dispersed so the consumer does not notice that they have not rehydrated.
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