Food or edible material: processes – compositions – and products – Surface coating of a solid food with a liquid – Preserving
Reexamination Certificate
2000-01-04
2002-04-23
Corbin, Arthur L. (Department: 1761)
Food or edible material: processes, compositions, and products
Surface coating of a solid food with a liquid
Preserving
C426S321000, C504S304000, C504S357000, C514S485000, C514S765000
Reexamination Certificate
active
06375999
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to methods and compositions for treating stored potatoes including freshly dug potatoes.
2. State of the Art
A commercial sprout inhibitor has been chemically identified as Chloroisopropyl-N-carbamate (CIPC) which is a solid at room temperature. Various techniques and apparatus have been employed for distributing CIPC throughout a potato storage facility. Generally, CIPC is dissolved in a solvent, e.g., a polar solvent such as methanol, ethylene glycol, etc. and then atomized thermally or by other means and introduced, along with combustion products of the thermal fogging device, into an air stream which is generally the ventilation system for the potato storage facility in order to deposit a certain minor amount of CIPC evenly on all the potatoes in the storage shed.
The technique of distributing CIPC is frequently alluded to as “fogging,” especially because the solvent/CIPC solution vapor emanating form a “fogger” forms either minute liquid droplets in the air stream or very fine solid crystals which precipitate from the solution droplets. These droplets or crystals are suspended in air and appear as a fog or cloud. Thus, there is a phase difference between the gas (air) in the ventilating system and the CIPC which is either a liquid or a solid, even though in minute particle form.
It is necessary for CIPC to be in contact with the potato in a storage facility in order for it to be effective. Thus, during a typical storage, usually beginning in about October, one or more treatments of the storage facility with a “dusting” of CIPC via thermal fogging is done.
Prior patents which disclose apparatus and discuss the techniques of distributing CIPCs throughout the potato storage facility are Morgan U.S. Pat. No. 5,009,152, Morgan U.S. Pat. No. 4,887,525, Luck U.S. Pat. No. 4,078,480, and Sheldon U.S. Pat. No. 4,226,179, and Plant U.S. Pat. No. 3,128,170. Sheldon discloses an ultrasound technique for fogging CIPC solutions.
The chemical CIPC has been the principal sprout inhibitor used commercially in agriculture for the past 20 years or more. Other sprout inhibitors have been considered and experimental work has been done with chemicals such as coumarin, fenilin, dimethylnaphthalene (DMN), the latter having three isomers, the 1-4, the 1-6, and the 2-3 and other chemicals. Effectiveness of some of these other potential sprout inhibitors has been reported in the following journals:
Potato Res.
24 (1981) 61-76 Beveridge et al. “The Assessment of Some Volatile Organic Compounds as Sprout Suppressants for Ware and Seed Potatoes.”
Potato Res.
24 (1981) 77-88 Beveridge et al. “Dimethylnephthalene as a Sprout Suppressant for Seed and Ware Potatoes.”
Potato Res.
27 (1984) 383-392 Filmer et al. “An assessment of 1, 4, 6 -Trimethylnapthalene as a Sprout Suppressant for Stored Potato Tubers.”
Photochemistry v. 12 (1973) Mergh et al. “Growth-Inhibitory Volatile Isomatic Compound. Produced by Solanum Tuberosum Tubers.”
Although experimental work on such sprout inhibitors as DMN has shown promise, the commercial application of certain isomers DMN and other experimental sprout inhibitors has not been practiced.
In certain small scale experimental efforts, e.g., as described in Beveridge et al., the DMN was introduced into a small closed container by being absorbed on alumina and then allowed to evaporate, apparently to maintain a constant atmosphere of DMN in a closed environment. The alumina powder containing DMN was applied directly to the potatoes.
The potential usefulness of DMN as a potato sprout inhibitor has been disclosed in several publications, as indicated hereinabove.
Similarly, in British Patent Application 9117350, a technique was disclosed for measuring constantly the DMN concentration in the headspace of a potato storage facility. The DMN concentration measuring device interacted with a controller to cause more DMN to be introduced into the headspace when the concentration dropped below a certain minimum value (3 mg/m
3
) and to cease DMN introduction when it achieved a maximum value of about 6 mg/m
3
. This technique contemplated continuous introduction of DMN during an entire storage period.
Such a system requires a DMN applicator or injection unit for every storage shed. It also requires an expensive DMN concentration detection device for each storage shed. While such a system might be very appealing to the manufacturer of such an injection/monitor system, it would not be appealing to farmers who would have to buy such a system for each storage shed.
The profitability of storing potatoes for a period of time to await a more favorable potato price is such that it would not financially support the capital expenditure and regular maintenance and attention required of such a sophisticated injection and monitoring system.
The approach taken in B.P. Application 9117350, albeit an expensive one, is a direct application of the law of vapor pressure balancing. If the partial pressure of DMN in a potato storage facility equals the vapor pressure of DMN emanating from a potato, then the escape of DMN from the potato is prevented. Such an approach, straight forward scientifically, ignores a number of critical factors besides capital expenditure, maintenance, etc.
Potato storage facilities are rather large buildings with considerable headspace, voids (space between adjacent potatoes) and are not leak proof. Furthermore, neutralizing DMN respiration would not foreclose respiration of other ingredients from the potatoes. Respiration involves the release of heat. It is therefore necessary to ventilate and cool the potato pile during storage. This is well known and potato storage facilities are equipped with ventilation, duct work and humidifiers. The air inside a potato storage facility is changed very frequently during warm weather; but even during the coldest days of winter in Idaho and Maine, some ventilation may be necessary.
A potato storage facility is not under constant supervision. Most air handling and humidifying systems require infrequent attention. The DMN treatment system proposed in B.P. Application 9117350 would require frequent attention. A constantly operating injector/monitor system is not appropriate for a farm situation. If the monitor malfunctioned, an entire crop of potatoes could be lost. The present method of treating storage facilities with sprout inhibitors is treatment of the facility by skilled applicators with specialized equipment three or four times a year with each treatment, including set up, requiring less than one day.
Potatoes, when being dug are frequently bruised, cut and/or abraded. These injuries to the potatoes oftentimes cause spoilage during shipment, storage and the like. A process known as suberization occurs naturally which tends to heal many of these injuries. However, whenever potatoes are stored, which occurs with a particularly large portion of potatoes harvested in any given year, if healing occurs slowly a significant loss of potatoes can occur through spoilage.
For example, it is relatively common in the potato storage industry to treat potatoes with Chloroisopropyl-N-carbamate (CIPC) to prevent or retard development of sprouts in the potatoes. Even though potatoes are stored at a cool temperature, for example, generally between about 40° and 45° F., sprouting does begin to occur after a couple months of storage. Storage of upwards of six to eight months is typical for a stored potato harvest. Thus, without treatment of a chemical such as CIPC, the stored potatoes become entangled in sprouts and the whole stored lot of potatoes may become economically useless. Although early treatment with CIPC could be advantageous for sprout inhibition purposes, application of CIPC is typically delayed until after suberization has occurred inasmuch as CIPC tends to retard suberization, resulting in accelerated rot and spoilage.
BRIEF SUMMARY OF THE INVENTION
The instant invention involves a method and apparatus for introducing controlled quantities of a liquid sprout inhibito
Forsythe Darol
Forsythe John M.
Corbin Arthur L.
TraskBritt
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