Food or edible material: processes – compositions – and products – Direct application of electrical or wave energy to food... – Heating by electromagnetic wave
Patent
1998-04-13
1999-08-17
Yeung, George
Food or edible material: processes, compositions, and products
Direct application of electrical or wave energy to food...
Heating by electromagnetic wave
34266, 34267, 426468, A23B 400, F26B 300
Patent
active
059391162
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a system for far-infrared drying food at reduced pressure and temperature.
BACKGROUND OF THE INVENTION
One method of preserving seafood for a relatively short period is natural drying, which is called "Overnight Drying". Fresh fishes are cut open to remove inner organs, and what remaines is rinsed from the opened fishes. The opened fishes are put on bamboo lattices to be dried all day and all night long. The "Overnight Drying" will put opened fishes in a semi-dried condition, and the so semi-dried products can be preserved for a relatively short period.
Such a natural drying method can be used in weather-permitting districts in limited seasons, and it requires a relatively large outdoor space for opened fishes to be set in order a and a lot of manpower is needed in drying.
In addition, there is a sanitary problem of contamination with dust and bacilli floating in the air, and there is a fear of deteriorating the taste of dried products due to oxidization. Usually it takes the whole day (24 hours) to dry opened fishes, and the opened fishes must be brought in houses when the weather is threatening. Therefore, a natural drying is a time-consuming and laborious work.
Alternatively indoor drying can be effected in sanitary rooms by using infrared lamps in place of sunlight. Such infrared heating will dry the surface of opened fishes and other foods in to a crisp condition, thereby confining free water inside to allow bacilli to breed. Otherwise, the oxygen gas remaining in the tissue of the food causes the surface of dried foods to detiorate due to oxidation.
Another drying method uses cold wind. Advantageously it takes 3 to 4 hours to dry foods in such a semi-dried condition as attained by the "Overnight Drying". The so dried products, however, are abundant in bacilli, and cannot be preserved for a long period without recourse to freezing preservation.
SUMMARY OF THE INVENTION
In an attempt to solve the problems described above, one object of the present invention is to provide a method of semi-drying a lot of food in a sanitary circumference in a relatively short period irrespective of weather and seasons. Another object of the present invention is to provide a food-drying system for semi-drying foods to provide bacilli-free semi-dried foods whose surface is not crisp, retaining good freshness and deliciousness.
According to the present invention, a method for far-infrared drying foods contained in an air-tight, insulating dryer comprises the steps of: the inner pressure to 560 mmHg to 160 mmHg in 1 to 10 minutes; spraying the ethanol onto the foods, and raising the inner pressure to 1.0 kg/cm.sup.2 G to 1.9 kg/cm.sup.2 G in 1 to 10 minutes to keep the so raised pressure for 1 to 10 minutes; within 30 minutes after stopping the feeding of the nitrogen gas containing ethanol to the insulating dryer; while keeping the inner pressure below 160 mmHg to 1 mmHg, thereby keeping the core temperature of the foods at 0.degree. C. to 10.degree. C. for 15 to 90 minutes; and reached atmospheric pressure.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a general arrangement of a low-pressure, low-temperature, far-infrared drying system according to the present invention;
FIG. 2 is a front view of a tray cart to be used in the drying system of FIG. 1; and
FIG. 3 shows how the inner pressure of the insulating dryer of FIG. 1 varies with time.
DESCRIPTION OF THE PREFERRED EMBODIMENT
A preferred embodiment of the present invention is described below with reference to the accompanying drawings.
Referring to FIG. 1, a low-pressure, low-temperature, far-infrared drying system according to the present invention comprises an air-tight, insulating dryer 1 having an air-feeding conduit 3 passing through its outer surrounding wall for supplying clean air to the inner space of the insulating dryer 1 through an associated filter, an inactive gas (nitrogen gas) feeding conduit 24 passing through its outer surrounding wall for supplying nitrogen gas to the inner space,
REFERENCES:
patent: 4612200 (1986-09-01), Sato
patent: 4860461 (1989-08-01), Tamaki et al.
Ono Foods Industrial Co., Ltd.
Yeung George
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