WO2015199738A1 - Procédé et appareil commandés et corrélés pour limiter la perte d'eau à partir de matière végétale fraîche pendant un stockage et un transport hypobares - Google Patents

Procédé et appareil commandés et corrélés pour limiter la perte d'eau à partir de matière végétale fraîche pendant un stockage et un transport hypobares Download PDF

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Publication number
WO2015199738A1
WO2015199738A1 PCT/US2014/044759 US2014044759W WO2015199738A1 WO 2015199738 A1 WO2015199738 A1 WO 2015199738A1 US 2014044759 W US2014044759 W US 2014044759W WO 2015199738 A1 WO2015199738 A1 WO 2015199738A1
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air
plant matter
vacuum chamber
storage
pressure
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PCT/US2014/044759
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English (en)
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Stanley P. Burg
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American Management Group, LLC
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Priority to PCT/US2014/044759 priority Critical patent/WO2015199738A1/fr
Publication of WO2015199738A1 publication Critical patent/WO2015199738A1/fr

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    • A—HUMAN NECESSITIES
    • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
    • A23B—PRESERVATION OF FOODS, FOODSTUFFS OR NON-ALCOHOLIC BEVERAGES; CHEMICAL RIPENING OF FRUIT OR VEGETABLES
    • A23B7/00—Preservation of fruit or vegetables; Chemical ripening of fruit or vegetables
    • A23B7/14—Preserving or ripening with chemicals not covered by group A23B7/08 or A23B7/10
    • A23B7/144—Preserving or ripening with chemicals not covered by group A23B7/08 or A23B7/10 in the form of gases, e.g. fumigation; Compositions or apparatus therefor
    • A23B7/148—Preserving or ripening with chemicals not covered by group A23B7/08 or A23B7/10 in the form of gases, e.g. fumigation; Compositions or apparatus therefor in a controlled atmosphere, e.g. partial vacuum, comprising only CO2, N2, O2 or H2O

Definitions

  • the invention relates to a system and method for hypobaric (low pressure or "LP") storage of plant matter.
  • the method is characterized by controlling the correlated conditions of total pressure, oxygen partial pressure, air intake rate, and pumping speed, as described in U.S. Patent Nos.
  • the limit to how much water can be lost before fresh plant matter becomes unsalable varies from approximately 3% for lettuce to 10% for cabbage and celery, for most commodities is between 5 to 7%, and weight loss from cut- flowers must be kept below 10% to avoid senescence and a large decrease in vase-life.
  • Conduction, convection, radiation, and evaporation or condensation modulate the vapor pressure and temperature gradients which develop in systems containing plant matter, and heat transferred by evaporative cooling determines the amount of water the plant matter loses.
  • water loss depends on respiratory heat, sometimes augmented or reduced by additional heat transferred to or from the plant matter by convection and radiation. Respiratory heat is immediately available since it is generated within plant matter and does not have to be acquired from the environment.
  • Water loss by evaporative cooling lowers a stored commodity's temperature unless the latent energy used to change the state of water from liquid to vapor is replaced from a heat source.
  • Hypobaric storage systems are precisely controlled combinations of low pressure, low temperature, high humidity and ventilation that vastly extend the length of time a perishable commodity remains fresh. Atmospheres are tailored to each perishable item.
  • a 'metabolic humidification system' operates during every hypobaric storage, evaporating the amount of water from plant matter into the storage atmosphere that is needed to continuously transfer most of the respiratory heat plus any additional heat which the plant matter is receiving from the environment. Convection is ineffective in transferring these heat sources because the convective process is 80 to 90% inhibited at a low storage pressure according to Equations 6 and 7, infra.
  • the 'metabolic humidifier' is supplemented by a 'mechanical humidifier' (Fig. 1 - A) which warms and evaporates supplementary water (Fig. 1 - B) by means of electrical heat (Fig.
  • a low air velocity such as that occurring during LP storage, is one of the most important factors causing mist or fog to form on a heat exchanger's surface, and at a water vapor mass fraction between 0.05 and 0.45 condensation may occur and create fog in a stagnant wall film.
  • KOYAMA, S., YASHUHARA, K. and YARA, T. (2002) Study on mist formation from humid air cooled in a rectangular tube.
  • hypobaric storage mist formation is likely to occur in the stagnant gas layer beneath the storage space's roof because the flow is laminar, the temperature difference between plant matter and the wall is less than 2.5°C, and the vapor mass fraction in an empty chamber is 0.46 to 0.56. The vapor mass fraction is even higher when plant matter is present, and the roof is a refrigerated heat-exchange surface.
  • the heat transfer coefficient for condensation is greatly reduced when non-condensable air is present in the storage atmosphere, even in very small amounts.
  • the air is left behind when water vapor condenses on a cold surface and the incoming condensable water-vapor must diffuse through the air-enriched mixture collected in the vicinity of the condensate surface before reaching and condensing in the stagnant film layer at the cold surface.
  • the presence of non-condensable air adjacent to the condensate surface acts as a thermal resistance barrier to convective heat transfer, reducing the heat-transfer coefficient for condensation by at least an order of magnitude. See OZISIK, M.N. (1985) Heat Transfer. A basic approach.
  • Vacuum breakers control the pressure in a vacuum chamber by regulating the rate at which atmospheric air enters while the vacuum pump withdraws low-pressure air at a constant rate.
  • Vacuum regulators (Fig 1 - H and Fig. 2 - N) maintain a constant process pressure at their inlet by throttling flow from their outlet to the vacuum pump (Fig. 1 - N and Fig. 2 - P).
  • Breakers and regulators used in hypobaric storage systems are referenced to an absolute total vacuum to eliminate errors caused by fluctuations in a barometric reference pressure, and are able to control the pressure ⁇ 0.2 mm HgA.
  • the pressure in a VivaFresh hypobaric warehouse was measured with a Honeywell ASCX15AN absolute pressure transducer, and controlled by three Clippard EVP proportional solenoid valves acting as an absolute vacuum breaker in response to a proportional integral derivative computer-controlled algorithm. See EP20100267144.
  • the EVP system maintained the pressure ⁇ 0.2 mm Hg and had sufficient capacity to serve as a vacuum breaker in both hypobaric warehouses and VacuFresh hypobaric intermodal containers.
  • the EVP system's flow capacity is many hundred- fold too small for use as a vacuum regulator in a hypobaric warehouse or VacuFresh intermodal container.
  • Pressure in hypobaric storage systems also has been controlled by manually balancing needle valves which adjust the inflow of humidified air into a vacuum chamber vs. the rate at which the chamber air/water- vapor mixture is evacuated by the vacuum pump.
  • a static pressure regulating system employed in many Chinese hypobaric storage laboratory systems halts evacuation after the desired pressure has been reached, and intermittently resumes pumping to return the chamber to the set pressure after air has been intentionally reintroduced or has leaked into the chamber.
  • the box's transpirational resistance (rbox) depends on the storage pressure and water-vapor pressure according to Equation 4:
  • waxed cardboard boxes cannot be recycled they have been banned in Europe and replaced with water-resistant recyclable paperboard boxes ('Solidboard') capable of being hydrocooled without absorbing water and losing strength, and by plastic collapsible and returnable boxes.
  • Cardboard boxes such as International Paper's Climaseries or Interstate Container's GreencoatTM are impregnated with wax alternatives making them recyclable, compostable, re-pulpable, water-proof or water- resistant, and suitable replacements for waxed cardboard boxes.
  • EP20100267144 suggests that specialized packing boxes unable to absorb water can be used as 'an optional alternate feature' to prevent non- waxed cardboard boxes from absorbing enough water to reduce the humidity and increase water loss from plant matter during LP storage, but when roses were stored in non-waxed cardboard boxes inside an LP warehouse through which two water-saturated air-changes per hour were flowing, the chamber humidity reached 96% immediately after pump-down was completed, within 36 hours the RH increased to 98.5%, and soon thereafter water began to condense under the chamber roof (Fig. 4). Cardboard's ability to lower the humidity was overwhelmed by water vapor transpired from the roses.
  • U.S. Patent Nos. 3,958,028 and 4,061,483, to Burg and titled Low Temperature Hypobaric Storage Of Metabolically Active Matter disclose a method of overcoming evaporative cooling and providing a constant high relative humidity in a hypobaric storage space.
  • Incoming expanded atmospheric air is preconditioned to the pressure and temperature inside the storage space, and thereafter the air is contacted with a body of heated water to saturate the storage space atmosphere.
  • a relatively broad spectrum of correlated conditions is disclosed that is operational in preserving metabolically active matter at pressures ranging from 4 to 400 mm HgA.
  • the correlated conditions depend on the weight and density of plant matter relative to the chamber volume, the plant matter's respiration rate and heat production at the storage pressure and temperature, the rate at which humid low pressure air is flowing from the storage space to the pressure regulator, the rate at which low-pressure saturated air enters the system, and the type of plant matter.
  • a vacuum regulator operating at 25°C substituted for the vacuum breaker specified in U.S. Patent No. 4,685,305 for use in VacuFresh hypobaric intermodal containers humidified by evapo- transpired water, minimizes weight loss from transported plant matter by reducing the pumping speed and rate at which low-pressure humid air flows from the storage space to the vacuum pump responsive to a progressive natural reduction in the stored plant matter's respiratory heat production.
  • Microbes are killed by vacuum- infiltrating 0.5 to 25 ppm of hypochlorous acid vapor when the hypobaric warehouse or intermodal container is vented.
  • the system and method of the invention prevents transpired water vapor released by plant matter in a hypobaric storage space from super-saturating the storage atmosphere and condensing under the storage space's roof, dripping onto storage boxes, and weakening box stacks in LP systems which are humidified by contacting low-pressure air with heated supplementary water.
  • an absolute vacuum regulator operating at an elevated temperature is substituted in-place of the absolute vacuum breaker specified in U.S. patents 3,958.028, 4,061,483 and in Burg 2009 and US2010/0167144.
  • Pressure control by a vacuum regulator when used with hypobaric intermodal containers humidified exclusively by water transpired from stored plant matter reduces weight loss from stored plant matter by lowering the rate at which saturated low-pressure air is evacuated from the storage space in response to a natural progressive decrease in the amount of respiratory heat produced during storage.
  • Fig. 1 is a diagram of a hypobaric warehouse in which the pressure is controlled by an absolute vacuum regulator.
  • Fig. 2 is a diagram of a hypobaric intermodal container in which the pressure is controlled by an absolute vacuum regulator.
  • Fig. 3 is a diagram of a Fisher Y696VRM vacuum regulator manually controlled by an LJ model 329 self-relieving vacuum breaker, or computer controlled by a Clippard EVP proportional solenoid control valve in response to an absolute pressure transducer.
  • Fig. 5A depicts the effect of pressure on the air/water-vapor binary diffusion coefficient (D).
  • Fig. 6 is a diagram of a revised VacuFresh equipment package.
  • hypobaric warehouses and VacuFresh intermodal containers utilize a Fisher Y696VRM vacuum regulator (Fig. 3) to control the storage pressure.
  • the vacuum regulator has a blocked throat (Fig. 3 - C) and an O-ring seal on stem shaft D to isolate the reference pressure sensed above diaphragm F from the chamber pressure sensed below diaphragm F through external register J.
  • the tension in spring K is adjusted by spring adjusting nut B to permanently provide a bias pressure of approximately 90 mm Hg drawing diaphragm F upward toward spring K, and the reference chamber is sealed with closing cap A.
  • the reference pressure in the sealed reference chamber is computer controlled at an absolute value by a Clippard EVP control solenoid valve responsive to an absolute pressure transducer, as described in Burg et al. (2009), or manually controlled by LJ self-relieving model 329 vacuum controller H.
  • Orifice G provides a constant leak of filtered air to make EVP valve H self-relieving, but is not required when a 329 self-relieving vacuum breaker is used.
  • Changing the reference pressure in response to a computer generated signal to the EVP solenoid valve, or a manual adjustment of the LJ 329 self-relieving controller selects the operational pressure controlled by the Y696VRM vacuum breaker.
  • the LJ329 is able to control the Y696VRM at and below a 10 mm Hg operational pressure even though the LJ329 is unable to directly control a pressure that low.
  • Equation 2 predicts that the Y696VRM vacuum regulator is able to flow vastly more SCFH of air than is required to evacuate two air changes per hour from a hypobaric warehouse or VacuFresh intermodal container while developing less than a 1 mm Hg pressure differential across the vacuum regulator. Therefore the vacuum regulator will not significantly reduce the vacuum pump's efficiency or capacity.
  • Equation 2 assumes that only air is flowing, but the flowing mixture contains 46% water vapor at a 10 mm Hg, 0°C storage condition.
  • the actual flow at 10 mm Hg will be 20% higher than Equation 2 predicts because the density (mass/volume) of water vapor and air are 0.804 and 1.27 g/L, respectively, and Equation 2 assumes that the entire flowing mixture has the higher density.
  • LP systems that are humidified by air-changes saturated by contact with heated supplementary water should store plant matter in boxes which are unable to adsorb water and release the latent heat of water condensation.
  • the same type of box is suitable for use in VacuFresh hypobaric intermodal containers, but additional steps are required because the storage atmosphere in VacuFresh is metabolically humidified by evapo-transpiration.
  • the pumping speed in VacuFresh intermodal containers initially is adjusted so that product water evaporated in response to respiratory heat produced by the type and weight of the plant matter being transported saturates the incoming air-changes after they have expanded and dried during entry into the storage space. See U.S. Patent No. 4,685,305; Burg, 2004.
  • the pumping speed selected for each type of plant matter is estimated based on the amount of metabolic heat the plant matter initially produces at the storage pressure and temperature. Evaporation from the plant matter is not influenced by the lack of a mechanical humidifier because water loss is determined by the amount of metabolic heat produced and environmental heat acquired, independent of whether a mechanical humidifier is used. See Burg, 2004.
  • Weight loss from plant matter shipped in a VacuFresh hypobaric intermodal container can be decreased by taking advantage of the reduction in respiratory heat production which occurs during storage. See Hardenburg. This is accomplished by replacing the absolute vacuum breaker specified in U.S. Patent No. 4,685,305 with an absolute vacuum regulator operating at 25°C (Fig. 2 - N), and adjusting the air flow into the chamber with a thermal mass flow controller (Fig. 2 - M). Net radiative transfer of heat from the aluminum chamber wall to adjacent exterior boxes must be reduced to a minimum to ensure that decreased flow from the chamber to the vacuum regulator rather than increased plant matter evapo-transpiration caused by acquired environmental heat keeps the storage pressure at its initial value.
  • the radiation view factor 1 and radiation occurs from the container wall to outer boxes across two parallel surfaces.
  • Ti temperature of the chamber wall
  • T 2 box's surface temperature
  • Qi-2, watts the radiation energy leaving the wall that strikes the box minus the radiation energy leaving the box that strikes the wall:
  • Equation 5 If Ti is larger than T2 Equation 5 yields positive values indicating the intensity of aluminum wall to outer box net radiation if T2 is larger than Ti Equation 5 yields negative values indicating the net intensity of box to aluminum wall net radiation ⁇ Qi -1).
  • the aluminum wall should not be painted or anodized as this increases the wall's emissivity (Table 2), thereby enhancing net radiation from the aluminum to adjacent boxes by up to 2.8-fold.
  • Coating the outer surface of the cardboard boxes with a radiation retarding low emissivity barrier only costs 10 to 20 cents and decreases net radiation from the bare aluminum chamber wall to adjacent cardboard boxes by 58 to 96% (Table 2, Equation 5).
  • FIGs. 2 and 6 illustrate several improvements in the VacuFresh hypobaric intermodal container design not previously disclosed.
  • the cylindrical tank barrel is reinforced with an automatically welded spirally wrapped rectangular extrusion which replaces the circular stiffening rings, interconnecting piping between stiffening rings, and reinforcing bracing required for a considerable length along both sides of each stiffening ring where the integrity of the stiffening ring was broken to install interconnecting piping in the original VacuFresh design See Burg, 2004.
  • Five roof-mounted aluminum meat rails and a central meat trolley have been eliminated, and two full length heavy aluminum retractable shelves no longer are required because the container will in the future be loaded with plant matter packed in boxes that do not adsorb or absorb water and lose stacking strength.
  • the pneumatic air horn (Fig. 2 - J) discharges through an aluminum duct attached at the tank's upper center-line (Fig. 2 - K), instead of under a full-length shelf.
  • the new arrangement substantially reduces the manufacturing cost by decreasing the weight of aluminum and cost of hand labor.
  • Solid state controls are replaced by computer based systems, and to improve high ambient temperature performance an R-134a refrigeration scroll compressor is substituted for the R-404a compressor originally used in VacuFresh (Fig. 6).
  • hypobaric storage that cannot be duplicated by other storage methods is the elimination of the O2, CO2, and C2H4 gradients that develop at atmospheric pressure between the center and surface of plant matter's intercellular system. LP decreases these gradients because at a low pressure stomata open in darkness, respiratory O2 consumption is inhibited by 80-90%, and O2 and CO2 rapidly diffuse through the commodity's peel and intercellular air spaces due to the low pressure.
  • mangoes suffer I0W-O2 injury in CA at ⁇ 3% O2, in LP at and below 0.078% O2 (Table 3), and at the same temperature mangoes can be stored in LP for 8 weeks at 15 mm Hg (0.1% O2). Chrysanthemum blooms are well preserved for 42 days at 0°C, 10 mm Hg (0.14% O2), and green beans have been successfully stored for 38 days in 0.08% O2 at 7.2°C, 10 mm Hg, but green beans and chrysanthemums are severely injured in CA at 0.1% O2.
  • avocados have been stored in 0.1% O2 for 49 to 60 days at 13°C, 15 mm Hg, but in CA I0W-O2 injury occurs within one day in 0.1 to 0.4% O2. See Burg, 2004.
  • the steady-state O2 concentration within a hypobaric storage space can be precisely determined by measuring the O2 concentration in air exhausting from the vacuum pump.
  • the pump must be briefly operated without introducing gas-ballast air, and because air and water vapor present in the storage space's low-pressure atmosphere are not significantly soluble in vacuum pump oil they pass through into the pump's exhaust where the O2 can be accurately measured within a few minutes by means of a colorimetric gas detector tube or gas chromatography.
  • the O2 concentration in low-pressure storage air is increased in the vacuum pump exhaust proportional to the vacuum pump's compression ratio (atmospheric pressure/storage pressure).
  • VOCs volatile organic substances
  • Table 3A indicates that the amount of heat generated by fermentative CO2 emanation could only vaporize an amount of transpired water per hour which in a liquid state was able to dissolve and transport approximately 0.14% of the ethanol and acetaldehyde which emanated from mangoes during the LP and CA storages described in Table 3. This calculation demonstrates that ethanol and acetaldehyde did not escape dissolved in transpired water. Instead these VOCs passively diffused through the plasmalemma and cell wall, vaporized from the outer surface of the plasmalemma in response to metabolic heat, then passed through the intercellular system and exited through mango lenticles. Table 3A.
  • the apparent membrane permeability to ethanol, acetaldehyde and CO2 calculated as mmoles.kg ⁇ .h 1 of gas or vapor emitted from the fruit divided by the gas or vapor's mmole.kg "1 concentration in the tissue. Both in CA and LP the mmoles.kg ⁇ .h 1 emanated per mmole.kg 1 in the tissue was in the ratio 100:52: 1 for acetaldehyde, ethanol, and CO2, respectively.
  • the gradient which causes a small lipid soluble non-polar molecule to diffuse through the lipid portion of the plasma membrane is the difference between the molecule's aqueous concentration at the inner surface of the membrane minus the substance's concentration at the outer surface.
  • a partition coefficient is applied to estimate the concentration gradient moving solute molecules through the membrane lipid.
  • the dimensionless partition coefficient is the concentration in the membrane's lipid material vs. that in an adjacent aqueous phase. It is determined for each solute by measuring the ratio between the solute's concentration in a lipid material such as olive oil or octanol, which mimics membrane lipid, vs. the dissolved solute's equilibrium concentration in water.
  • EP20100267144 presents evidence indicating that a system resembling commercial pervaporation operates in plant matter during hypobaric storage. Pervaporation is unique among membrane separation processes in including a phase change from liquid to vapor.
  • a synthetic very strong membrane separates a solution containing one or more volatile liquids, usually at 1 atm pressure, on one side, from a vacuum condition, on the other side of the membrane. The liquid volatiles pass through the membrane at rates determined by their specific nature and the membrane's characteristics.
  • Heat is supplied to vaporize the permeating volatile liquid(s) at the evacuated side of the membrane, and to maximize mass transport across the membrane the vapor pressure of a component on the permeate side is kept low by evacuating (vacuum pervaporation) or purging the permeate (sweep gas pervaporation).
  • evacuating vacuum pervaporation
  • purging suction
  • permeate weep gas pervaporation
  • an amount of heat must be supplied that is at least as great as the permeate's heat of vaporization, and the permeate' s pressure must be kept lower than its saturation vapor pressure at the process temperature.
  • the separation is based on physical-chemical interactions between the membrane material and the permeating molecules, independent of vapor/liquid equilibrium.
  • the driving force for the mass transfer of permeants from the membrane's feed side is the volatile organic compound's chemical potential or partial pressure gradient across the membrane, not its volatility. Raising the feed pressure increases the chemical potential gradient and flux through a pervaporation membrane, ten-fold for a feed pressure elevation from 1 to 10 atmospheres. The permeation rate of a feed component also is increased by decreasing the pressure on the 'permeate' side of the membrane.
  • Boiling point of pure water, ethanol and acetaldehyde at various storage temperatures and pressures are Boiling point of pure water, ethanol and acetaldehyde at various storage temperatures and pressures.
  • HOCl plays an important role in the host defense microbiocidal reactions (oxidative burst pathway) of polymorphonuclear leukocytes (PMNs) after they engulf invading pathogens.
  • PMNs polymorphonuclear leukocytes
  • the gross features of the reactions are similar in phagocytosing PMNs, the cell-free MPOase-H202-Cl " system, and in the response to applied exogenous HOCl.
  • HOCl vapor generated by a method described in Canadian Patent 997,532, can be passed over the surface and vacuum- infiltrated into the intercellular spaces of stored plant matter present in a hypobaric intermodal container in order to kill bacteria and fungi.
  • a hypobaric intermodal container Immediately after the commodity has been cooled, packed in boxes, placed in an LP intermodal container, and the container has been evacuated, it can be vented with atmospheric air containing hypochlorous acid vapor generated by passing atmospheric air through a hypochlorite solution. Venting can be completed in 30 minutes, without damaging plant matter, and the chamber may be re-evacuated immediately thereafter, or a short time later, to begin hypobaric transportation in the VacuFresh container.
  • the chamber can again be vented with air containing HOCl vapor before the commodity is removed for distribution.
  • the HOCl vapor concentration within and around the plant matter progressively approaches the atmospheric concentration of HOCl vapor in the venting air.
  • the HOCl in the chamber is decreased by contact with the commodity and boxes.
  • the solution can be made to yield between 0.5 and 26 ppm ( ⁇ / ⁇ vokvol) of hypochlorous acid vapor.
  • a high enough HOCl vapor concentration can be maintained for long enough to kill up to 100% of bacteria, molds and virus's present on and within the stored plant matter, without damaging it.
  • the vacuum regulator's pressure sensing port (Fig. 3) can be sealed by a normally open solenoid valve, such as an ozone resistant 2 -SO012- 1/4A with a 24 VDC coil and NBR seals, rated for vacuum.
  • a normally open solenoid valve such as an ozone resistant 2 -SO012- 1/4A with a 24 VDC coil and NBR seals, rated for vacuum.
  • Hypochlorous acid (HOCl) is at least 100 times more effective than OCT 1 as a sanitizer and is responsible for most of the germicidal effect of active chlorine (Cl + ) both in air and chlorinated water.
  • Free available chlorine refers to the hypochlorous acid form of chlorine in a solution. Total free chlorine is the sum of associated hypochlorous acid (HOCl) and hypochlorite ion (OC1 ) present in the solution. All free chlorine would be in the form of hypochlorous acid if the pH was low enough. Above pH 8.0 the amount of available chlorine present in the solution, and the concentration of HOCl vapor in air that has passed through the solution and equilibrated with it, decreases 10-fold for a 1 unit pH increase:
  • the solution continues as a reservoir of associated HOCl over a long period of time with only a slight consumption of the hypochlorite ion. Evaporated water must be replaced, but the initial reservoir of hypochlorite and additives is so concentrated that it does not need to be replenished for weeks or months. As rapidly as hypochlorous acid vapor is lost from the solution it is regenerated from the large excess of hypochlorite ion present.
  • Hypochlorous acid vapor is a strong oxidizing agent that corrodes many materials, but not 5000 and 6000 series aluminum, or 316 stainless steel.
  • hypochlorous acid is thermodynamically unstable, it is much more stable than other hypohalite acids, and unlike the others can be distilled and recovered without extensive decomposition. This allows HOCl vapor to persist in air for long enough to control microbial development. HOCl vapor also decomposes when it contacts cardboard boxes or the commodity's surface, and at atmospheric pressure this causes the HOC1 vapor concentration within boxes to be much lower than it is in the storage air. Lowering the pressure to 10 mm Hg enhances the diffusion of HOC1 vapor 76-fold [Fig. 5A], and this should decrease the HOC1 gradient between the storage atmosphere and interior of a box. In a 20 ft. Fruehauf hypobaric intermodal container operating at 3°C and 160 mm Hg, 2.5 ⁇ / ⁇ of hypochlorous acid vapor was measured in the storage atmosphere and 1.0 to 1.5 ⁇ / ⁇ inside cardboard boxes containing Shasta strawberries.
  • HOC1 The EPA considers HOC1 to be non-toxic to human and animal tissues and non-deleterious to the environment.
  • the FDA has approved the use of high aqueous concentrations of HOC1 in contact with fresh foods and cut- flowers (Smith).
  • Fig. 1 depicts a diagram of a hypobaric warehouse in which the pressure is controlled by a vacuum regulator, the hypobaric warehouse comprising boiler A, boiler water B, boiler water level controller C, thermal mass air flow controller with remote digital readout D, wattage controlled boiler heater E, reverse osmosis + deionizing cartridge water purifier F, rotary oil-sealed air cooled gas ballasted vacuum pumps G, absolute vacuum regulator H, ball valves J, finned heat exchange tube K, vacuum regulator pressure sensing line (external register) L, inlet air duct M with duct holes sized and spaced to provide even longitudinal flow, exhaust duct N with duct holes sized and spaced to provide 5% pressure drop between the hypobaric warehouse and rotary oil-sealed air cooled gas ballasted vacuum pumps G and temperature controlled space P (at about 20 to 25°C).
  • the hypobaric warehouse comprising boiler A, boiler water B, boiler water level controller C, thermal mass air flow controller with remote digital readout D, wattage controlled boiler heater
  • FIG. 2 depicts a diagram of a hypobaric intermodal container in which the pressure is controlled by a vacuum regulator, comprising ethylene glycol heat exchange fluid A in surge tank, vented surge tank cap B, temperature controlled equipment compartment C (held at about 20 to 25°C), spirally wrapped rectangular cooling and reinforcing extrusion D, front aluminum head (door) E, neoprene door seal F that seats against an aluminum triangular cooling and reinforcing extrusion D, 5056- T6 marine aluminum circular vacuum tank G suspended between end frames by means of aluminum/fiberglass/T-1 steel mounting clips huck-bolted together and welded to the tank and end frames, floor duct H containing bottom holes sized and spaced to provide uniform uptake along the entire duct length with less than a 5% pressure drop between atmosphere in surge tank A and absolute vacuum regulator N, pneumatic air horn J discharging into longitudinal duct K, longitudinal duct K carrying pneumatic air horn discharge to front aluminum head E, cooling/heating coil L on front aluminum head E
  • FIG. 3 depicts absolute vacuum regulator (Fisher Y696VRM) computer controlled by a Clippard EVP series proportional solenoid control valve responsive to an absolute pressure transducer, or manually controlled with an LJ model 329 self- relieving vacuum controller, comprising closing cap A, spring adjusting nut B, blocked throat C, O-ring seal on valve stem D, lever assembly E, diaphragm F, orifice to make EVP solenoid valve (H) self-relieving G (not required with LJ self relieving model 329 vacuum controller), EVP proportional control solenoid valve H (can be computer controlled) or LJ self relieving 329 vacuum breaker (manually controlled) and external register J.
  • EVP solenoid valve H
  • G not required with LJ self relieving model 329 vacuum controller
  • EVP proportional control solenoid valve H can be computer controlled
  • LJ self relieving 329 vacuum breaker manually controlled
  • Fig. 4 depicts the air temperature, dew point temperature, RH, and the temperature of roses and cardboard boxes during storage in a hypobaric chamber in non-waxed cardboard boxes according to one embodiment of the invention. Arrows indicate times when the chamber was vented to atmospheric pressure for 2 to 4 hours to remove partial loads. The roses tolerated the extra water loss caused by the release of latent heat of water condensation during the initial 2 weeks. Vase life of the stored roses was only reduced by one day during the 35 day storage, whereas control roses stored in a high humidity refrigerated cold-room lost storage and vase-life so rapidly that they became unsalable after 5 to 7 days.
  • Fig. 5A depicts the effect of pressure on the air/water vapor binary diffusion coefficient (D).
  • Fig. 6 depicts VacuFresh equipment according to one embodiment of the invention, comprising copper fin and tube radiator 1; heat exchanger 2; cable 3 to scroll compressor; filter-drier 4; pressure controller 5; finbar heaters 6; receiver 7; air filter 8; injection expansion valve 9; brazed plate heat exchanger 10; vacuum pump oil filter 11; pressure sensing probe 12; line 13 from vacuum regulator 21 to pressure sensing probe 12; radiator fans 14; solenoid valve 15; vacuum pump 16; fork-lift slots 17; glycol tank connection 18; glycol supply 19; unloader solenoid valve 20; vacuum regulator 21; glycol pump 22; thermostatic valve 23; R-134a scroll compressor 24; economizer HX 25; silicone heating strips 26; cable storage 27; micro channel condenser coil 28; reinforcing gusset 29; axial condenser fan 30; spin-on air filter 31; low ⁇ flow meter + valve 32; heat exchanger 33; end frame 34; corner casting 35; discharge pressure regulator 36; transformer 37; check valve

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  • Agricultural Chemicals And Associated Chemicals (AREA)

Abstract

L'invention concerne un système et un procédé pour le stockage hypobare (basse pression ou ˝ LP ˝) d'une matière végétale. Le procédé est caractérisé par la commande des conditions corrélées de pression totale, de pression partielle d'oxygène, de débit d'admission d'air, et de vitesse de pompage et par la commande supplémentaire de la pression par le biais d'un régulateur de vide fonctionnant à une température plus élevée que l'espace de stockage; le stockage d'une matière végétale dans des boîtes de stockage qui ne sont pas aptes à adsorber l'eau et à libérer la chaleur de condensation d'eau; la protection des boîtes de stockage contre le rayonnement émis par la paroi des espaces de stockage; la protection de la matière végétale dans les boîtes de stockage contre le rayonnement émis par la surface intérieure des boîtes; et la diminution de la pression d'espace de stockage totale et de la pression partielle d'oxygène en régime permanent à une valeur minimale ne provoquant pas de lésion liée à la faible teneur en oxygène et présentant une efficacité optimale pour prolonger la durée de vie de stockage, réduire la chaleur métabolique et la production d'énergie biochimique, et empêcher la dégradation microbienne de la matière végétale.
PCT/US2014/044759 2014-06-28 2014-06-28 Procédé et appareil commandés et corrélés pour limiter la perte d'eau à partir de matière végétale fraîche pendant un stockage et un transport hypobares WO2015199738A1 (fr)

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PCT/US2014/044759 WO2015199738A1 (fr) 2014-06-28 2014-06-28 Procédé et appareil commandés et corrélés pour limiter la perte d'eau à partir de matière végétale fraîche pendant un stockage et un transport hypobares

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PCT/US2014/044759 WO2015199738A1 (fr) 2014-06-28 2014-06-28 Procédé et appareil commandés et corrélés pour limiter la perte d'eau à partir de matière végétale fraîche pendant un stockage et un transport hypobares

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Cited By (2)

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Publication number Priority date Publication date Assignee Title
RU171504U1 (ru) * 2016-05-11 2017-06-02 Федеральное государственное казенное военное образовательное учреждение высшего образования "Военный учебно-научный центр Военно-Морского Флота "Военно-морская академия им. Адмирала Флота Советского Союза Н.Г. Кузнецова" Устройство подачи диоксида углерода в барокамеру
FR3073367A1 (fr) * 2017-11-15 2019-05-17 Xeda International S.A. Procede et ensemble de traitement de l'atmosphere d'un stockage de produits vegetaux a haute humidite relative

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SU895386A1 (ru) * 1979-08-29 1982-01-07 За витель . УСТРОЙСТВО ДЛЯ ХРАНЕНИЯ СЕЛЬСКОХОЗЯЙСТВЕННЫХ ПРОДУКТОВ Д. Надыкта, В. П. Бел ков, Г. Талакин
US4685305A (en) * 1985-09-26 1987-08-11 Burg Stanley P Hypobaric storage of respiring plant matter without supplementary humidification
US4845958A (en) * 1985-12-28 1989-07-11 Mitsui & Co., Ltd. Method of and apparatus for preserving perishable goods
US20020012728A1 (en) * 1999-06-28 2002-01-31 Dr. Peter Carlson Hypobaric storage device

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SU895386A1 (ru) * 1979-08-29 1982-01-07 За витель . УСТРОЙСТВО ДЛЯ ХРАНЕНИЯ СЕЛЬСКОХОЗЯЙСТВЕННЫХ ПРОДУКТОВ Д. Надыкта, В. П. Бел ков, Г. Талакин
US4685305A (en) * 1985-09-26 1987-08-11 Burg Stanley P Hypobaric storage of respiring plant matter without supplementary humidification
US4845958A (en) * 1985-12-28 1989-07-11 Mitsui & Co., Ltd. Method of and apparatus for preserving perishable goods
US20020012728A1 (en) * 1999-06-28 2002-01-31 Dr. Peter Carlson Hypobaric storage device

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU171504U1 (ru) * 2016-05-11 2017-06-02 Федеральное государственное казенное военное образовательное учреждение высшего образования "Военный учебно-научный центр Военно-Морского Флота "Военно-морская академия им. Адмирала Флота Советского Союза Н.Г. Кузнецова" Устройство подачи диоксида углерода в барокамеру
FR3073367A1 (fr) * 2017-11-15 2019-05-17 Xeda International S.A. Procede et ensemble de traitement de l'atmosphere d'un stockage de produits vegetaux a haute humidite relative
WO2019096906A1 (fr) * 2017-11-15 2019-05-23 Xeda International S.A. Procédé et ensemble de traitement de l'atmosphère d'un stockage de produits végétaux à haute humidité relative

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