Food or edible material: processes – compositions – and products – Direct application of electrical or wave energy to food...
Patent
1989-05-09
1990-11-20
Yeung, George
Food or edible material: processes, compositions, and products
Direct application of electrical or wave energy to food...
426310, 426335, A23B 700
Patent
active
049718185
DESCRIPTION:
BRIEF SUMMARY
This invention relates to the treatment of harvested crops, such as fruit and vegetables.
Harvested crops are often treated, for example before storage or on removal for planting or sale, to inhibit decay or pest attack or control the maturing of the crop. A convenient technique is to spray the crop, such as potatoes for food or seed or a fruit such as oranges, while it is on a conveyor. Regulations for the use of chemicals put close limits on the dosage of the crop and for this reason, and for economy and effectiveness, it is desirable that only the minimum required amount of chemical be applied uniformly to each item of the crop. Such uniform application should be made rapidly as treatment is a seasonal requirement and large quantities of crop need to be handled quickly, for example to prevent spoilage. Furthermore the apparatus by which the crop is treated has to be robust to withstand an agricultural or warehouse enviroment.
It is an object of the present invention to provide an apparatus for the efficient economic treatment of harvested crops.
According to the invention there is provided a spray apparatus for the treatment of a harvested crop, the apparatus including a high voltage electrostatic sprayhead, a sprayhood surrounding the sprayhead and having an aperture opposite the sprayhead and insulating means to suspend the sprayhood with the aperture adjacent a region of a conveying path to establish and maintain the convering said region of sprayhood said conveying path, the sprayhood having on the outside an insulating surface and inside an extensive insulated electrode extending around and above said aperture, the electrode being energisable in operation to a potential similar to that applied to the sprayhead, whereby the suspension means and electrode together permit the application of an electrostatically charged spray from the sprayhead in a controlled manner throughout said region of the conveying path under the sprayhood to a quantity of crop conveyed past on the conveying path in a regular manner.
The sprayhood is conveniently provided with a frame of ribs having on the inside means to receive an insulated wire to form the electrode. The insulating surface is conveniently shaped from sheet material to fit closely over the ribs. The hood may be of generally rectangular or square form with an apex at which the sprayhead is placed and may be wound over the inside, on the ribs, with an insulated wire as the electrode. The means to suspend the hood may be insulated suspension links extending from the sprayhood. The suspension means may be attached near to the apex of the hood. There may be support means for the sprayhood to which the insulating links extend. The support means may include guide means to constrain the crop to the conveying path. The spray may be controlled to be a uniform or other pattern across the conveying path.
The voltage applied to the electrode is of the same polarity as that of the charge on the spray and of similar potential. The sprayhead is arranged to produce spray particles of a VMD less than 100 microns.
Embodiments of the invention will now be described with reference to the accompanying drawings in which:
FIG. 1 shows a cross-sectional elevation of a spray apparatus according to the invention,
FIG. 1a is an enlargement of a portion of FIG. 1, and
FIGS. 2a-2d and 3 show charts of results of treatment by the apparatus embodying the invention.
In FIG. 1 a roller table conveyor of conventional form is shown in outline at 10 and a roller indicated at 11.
A support frame generally indicated at 20 is fitted to the roller table with sloping guide plates 21, 22 and height adjustment clamps 23, 24. The guide plates are conveniently shaped to fit snugly to the roller table without any fastening. A support hoop 25 fits into the clamps to be held at a chosen height. Conveniently there are two hoops 25 spaced along the roller table in respective clamps on one set of guide plates. Each support hoop has two support point 26, 27. The four points are conveniently at the corners of a
REFERENCES:
patent: 2466906 (1949-04-01), Miller
patent: 2585799 (1952-02-01), Lawrence
patent: 3339840 (1967-09-01), Point
patent: 4818546 (1989-04-01), Whitford
National Research Development Corporation
Yeung George
LandOfFree
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