Apparatus and techniques for freezing and thawing of agricultural produce   

This application is a continuation of U.S. patent application Ser. No. 11/600,488, filed Nov. 15, 2006, entitled “APPARATUS AND TECHNIQUES FOR FREEZING AND THAWING OF AGRICULTURAL PRODUCE”, the contents of which are incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to system, apparatus and techniques for freezing and thawing of agricultural produce.

BACKGROUND OF THE INVENTION

The following published documents are believed to represent the current state of the art and the contents thereof are hereby incorporated by reference: U.S. Pat. Nos. 5,595,775; 5,256,438; 5,135,122; 5,020,237; 4,647,469; 4,551,384; 4,418,082; 4,390,550; 4,356,195; 4,350,711 and 4,332,824;

U.K. Published Patent Application No. 2005983A;

“Drying, shrinkage and rehydration characteristics of Kiwifruits during hot air and microwave drying”, M. Maskan, Journal of Food Engineering, 48, 177-182, (2001);

“Kinetics of moisture transfer during air drying of blanched and/or osmotically dehydrated mango”, A. Nieto, M. A. Castro and S. M Alzamora, Journal of Food Engineering, 50, 175-185, (2001);

“Analysis of shrinkage phenomenon of whole sweet cherry fruits (Prunus avium) during convective dehydration with very simple models”, M. R. Ochoa, A. G. Kessler, B. N. Pirone, C. A Marquez and A. De Michelis, Journal of Food Engineering, (2006); and

“Drying kinetics of pomegranate arils”, A. R. P. Kingsley and D. B. Singh, Journal of Food Engineering, (2006).

SUMMARY

The present invention seeks to provide improved apparatus and techniques for freezing and thawing of agricultural produce which maintains fresh-like qualities in the frozen produce when thawed.

There is thus provided in accordance with a preferred embodiment of the present invention a method for preserving uncut fresh agricultural produce including manually handling the uncut fresh agricultural produce, thereafter, removing moisture from the uncut fresh agricultural produce in an amount equal to between 5%-20% of the weight of the uncut fresh agricultural produce at a rate which does not exceed approximately 30×10−6 kg moisture/sec per area unit of the produce in meter2 and thereafter, freezing the uncut fresh agricultural produce.

Preferably, the manually handling is effective to generally eliminate damage to an outer peel of the uncut fresh agricultural produce.

There is also provided in accordance with another preferred embodiment of the present invention a method for preserving uncut fresh agricultural produce including non-manually handling the uncut fresh agricultural produce, thereafter, removing moisture from the uncut fresh agricultural produce in an amount equal to between 5%-20% of the weight of the uncut fresh agricultural produce at a rate which does not exceed approximately 60×10−6 kg moisture/sec per area unit of the produce in meter2; and thereafter, freezing the uncut fresh agricultural produce.

There is further provided in accordance with yet another preferred embodiment of the present invention a method for preserving fresh cut agricultural produce including removing moisture from the fresh cut agricultural produce in an amount equal to between 5%-20% of the weight of the fresh cut agricultural produce at a rate which does not exceed approximately 300×10−6 kg moisture/sec per area unit of the produce in meter2 and thereafter, freezing the fresh cut agricultural produce.

There is even further provided in accordance with still another preferred embodiment of the present invention a method of storing agricultural produce including removing moisture from the agricultural produce in an amount equal to between 5%-20% of the weight of the agricultural produce, thereafter, freezing the agricultural produce and thereafter, adding liquid to the agricultural produce and defrosting the agricultural produce in the presence of the liquid.

There is yet further provided in accordance with yet another preferred embodiment of the present invention a method for storing agricultural produce including removing moisture from the agricultural produce in an amount equal to between 5%-20% of the weight of the agricultural produce, thereafter, freezing the agricultural produce and storing it in a container for storing frozen agricultural produce and having a container opening, sealing the opening of the container, storing the container containing the agricultural produce under freezing conditions, unsealing the opening of the container, supplying a liquid to the agricultural produce in the container, defrosting the agricultural produce in the container in the presence of the liquid, removably attaching an apertured cap to the container and pouring out the liquid from the container through the apertured cap, thereby permitting the liquid, but not the produce, to pass out of the container.

Preferably, the removing moisture includes removing moisture in an amount equal to approximately 10%-14% of the weight of the agricultural produce. More preferably, the removing moisture includes removing moisture in an amount equal to approximately 12% of the weight of the agricultural produce.

Preferably, the removing moisture includes transporting the agricultural produce through a moisture removal chamber. Additionally, the removing moisture includes transporting the agricultural produce through a controlled temperature chamber. Additionally or alternatively, the removing moisture includes transporting the agricultural produce through a controlled air flow chamber. More preferably, the removing moisture includes transporting the agricultural produce through a controlled temperature and air flow chamber.

Alternatively, the removing moisture includes transporting the agricultural produce through a convection drying chamber. Alternatively, the removing moisture includes transporting the agricultural produce through at least one of a microwave chamber, an infrared chamber, a convection chamber, a chamber having fluidized bed technology and a chamber having vacuum drying technology.

Preferably, the method also includes, prior to the freezing, pre-cooling the agricultural produce to a temperature between 0° C. and 5° C.

Preferably, the freezing includes freezing the agricultural produce to a temperature between −40° C. and −35° C. Additionally or alternatively, the freezing includes quick freezing the agricultural produce. Alternatively or additionally, the freezing includes freezing the agricultural produce by employing IQF freezing technology.

Preferably, the method also includes, following the freezing, adding liquid to the agricultural produce and defrosting the agricultural produce in the presence of the liquid.

Preferably, the method for storing includes storing different types of the agricultural produce mixed together.

Preferably, the defrosting includes defrosting the agricultural produce at room temperature. Additionally, the defrosting the agricultural produce at room temperature includes defrosting the agricultural produce at room temperature for a duration of approximately 3 to 5 minutes. Alternatively, the defrosting includes defrosting the agricultural produce in a microwave oven. Additionally, the defrosting the agricultural produce in a microwave oven includes defrosting the agricultural produce in a microwave oven for a duration of approximately 15 to 30 seconds.

There is also provided in accordance with still another preferred embodiment of the present invention apparatus for preserving manually handled uncut fresh agricultural produce including a chamber operative to remove moisture from the manually handled uncut fresh agricultural produce in an amount equal to between 5%-20% of the weight of the manually handled uncut fresh agricultural produce at a rate which does not exceed approximately 30×10−6 kg moisture/sec per area unit of the produce in meter2 and at least one freezing device operative to freeze the manually handled uncut fresh agricultural produce.

There is further provided in accordance with another preferred embodiment of the present invention apparatus for preserving non-manually handled uncut fresh agricultural produce including a chamber operative to remove moisture from the non-manually handled uncut fresh agricultural produce in an amount equal to between 5%-20% of the weight of the non-manually handled uncut fresh agricultural produce at a rate which does not exceed approximately 60×10−6 kg moisture/sec per area unit of the produce in meter2 and at least one freezing device operative to freeze the non-manually handled uncut fresh agricultural produce.

There is even further provided in accordance with yet another preferred embodiment of the present invention apparatus for preserving fresh cut agricultural produce including a chamber operative to remove moisture from the fresh cut agricultural produce in an amount equal to between 5%-20% of the weight of the fresh cut agricultural produce at a rate which does not exceed approximately 300×10−6 kg moisture/sec per area unit of the produce in meter2 and at least one freezing device operative to freeze the fresh cut agricultural produce.

Preferably, the chamber is operative to remove moisture in an amount equal to approximately 10%-14% of the weight of the agricultural produce. More preferably, the chamber is operative to remove moisture in an amount equal to approximately 12% of the weight of the agricultural produce.

Preferably, the chamber is a controlled temperature and air flow chamber. Alternatively, the chamber is a controlled air flow chamber. Alternatively, the chamber is a controlled temperature chamber.

Preferably, the chamber is a convection drying chamber. Alternatively, the chamber is at least one of a microwave chamber, an infrared chamber, a convection chamber, a chamber having fluidized bed technology and a chamber having vacuum drying technology.

Preferably, the apparatus also includes a cooling device operative to pre-cool the agricultural produce prior to the freezing thereof, to a temperature between 0° C. and 5° C.

Preferably, the at least one freezing device is operative to freeze the agricultural produce to a temperature between −40° C. and −35° C. Additionally or alternatively, the at least one freezing device is operative to quick freeze the agricultural produce. Alternatively or additionally, the at least one freezing device employs IQF freezing technology.

There is still further provided in accordance with still another preferred embodiment of the present invention apparatus for storing agricultural produce including a container for storing the frozen agricultural produce and having a container opening, a seal formed over the opening of the container, a cap removably attached to the container and disposed over the seal, the cap being apertured to permit liquid, but not the produce, to pass therethrough and out of the container.

Preferably, the container has indicated thereon a line indicating a desired level to which the liquid should be added to the container prior to defrosting.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood and appreciated more fully from the following detailed description, taken in conjunction with the drawings in which:

FIGS. 1A, 1B and 1C are simplified illustrations of apparatus and techniques for preserving agricultural produce in accordance with three alternative embodiments of the present invention; and

FIGS. 2A, 2B and 2C are simplified illustrations of apparatus and techniques for freezing, packaging, storing, defrosting and utilizing agricultural produce in accordance with a preferred embodiment of the present invention.

DETAILED DESCRIPTION

Reference is now made to FIGS. 1A, 1B and 1C, which are simplified illustrations of apparatus and techniques for preserving agricultural produce in accordance with three alternative embodiments of the present invention.

Turning to FIG. 1A, there is seen a method and apparatus for preserving uncut fresh agricultural produce including manually handling the uncut fresh agricultural produce, thereafter, removing moisture from the uncut fresh agricultural produce in an amount equal to between 5%-20% of the weight of the uncut fresh agricultural produce at a rate which does not exceed approximately 30×10−6 kg moisture/sec per area unit of produce in meter2 and thereafter, freezing the uncut fresh agricultural produce.

In the illustrated method, pomegranate arils 100 are separated from fresh pomegranates by hand, as indicated at reference numeral 102, and placed on a conveyor 104 in a manner designed so as to generally eliminate or minimize damage to the outer peel 106 thereof.

The conveyor 104 transports the pomegranate ails 100 through a moisture removal chamber 108, preferably a controlled temperature and air flow chamber, in order to remove moisture therefrom, in an amount preferably equal to between approximately 5%-20%, and more preferably equal to between approximately 10%-14%, of the weight of the pomegranate ails 100, at a rate which does not exceed approximately 30×10−6 kg moisture/sec per area unit of produce in meter2. In the illustrated exemplary embodiment, moisture removal takes approximately 1.5 hours and preferably results in removal of moisture equal to approximately 12% of the weight of the pomegranate arils 100.

It is appreciated that moisture removal chamber 108 may be any suitable controlled drying chamber utilizing any suitable drying technology, such as microwave, infra-red, convection, fluidized bed or vacuum drying technologies and various combinations thereof. Convection drying is presently preferred.

Following moisture removal thereof as described hereinabove, the pomegranate ails 100 are preferably pre-cooled in a cooler 110 to a temperature between 0° C.-5° C. and are then preferably quick frozen, preferably to a temperature between −40° C. and −35° C., preferably in a freezer 112 employing IQF (individual quick frozen) freezing technology. Alternatively, the pre-cooling step may be obviated.

Turning to FIG. 1B, there is seen a method and apparatus for preserving uncut fresh agricultural produce including non-manually handling the uncut fresh agricultural produce, thereafter, removing moisture from the uncut fresh agricultural produce in an amount equal to between 5%-20% of the weight of the uncut fresh agricultural produce at a rate which does not exceed approximately 60×10−6 kg moisture/sec per unit area of produce in meter2 and thereafter, freezing the uncut fresh agricultural produce.

In the illustrated method, pomegranate arils 120 are separated from fresh pomegranates by use of a machine 122, such as, for example, the type described in published PCT application No. WO/2004/071249. Arils 120 are placed on a conveyor 124. The conveyor 124 transports the pomegranate arils 120 through a moisture removal chamber 128, preferably a controlled temperature and air flow chamber, in order to remove moisture therefrom, in an amount preferably equal to between approximately 5%-20%, and more preferably between approximately 10%-14%, of the weight of the pomegranate arils 120, at a rate which does not exceed approximately 60×10−6 kg moisture/sec per area unit of produce in meter2. In the illustrated exemplary embodiment, moisture removal takes approximately 50 minutes and preferably results in removal of moisture equal to approximately 12% of the weight of pomegranate ails 120.

It is appreciated that moisture removal chamber 128 may be any suitable controlled drying chamber utilizing any suitable drying technology, such as microwave, infra-red, convection, fluidized bed or vacuum drying technologies and various combinations thereof. Convection drying is presently preferred.

Following moisture removal thereof as described hereinabove, the pomegranate arils 120 are preferably pre-cooled in a cooler 130 to a temperature between 0° C.-5° C. and are then preferably quick frozen, preferably to a temperature between −40° C. and −35° C., preferably in a freezer 132 employing IQF freezing technology. Alternatively, the pre-cooling step may be obviated.

Turning to FIG. 1C, there is seen a method and apparatus for preserving fresh cut agricultural produce including manually handling the fresh cut agricultural produce, thereafter, removing moisture from the fresh cut agricultural produce in an amount equal to between 5%-20% of the weight of the fresh cut agricultural produce at a rate which does not exceed approximately 300×10−6 kg moisture/sec per area unit of produce in meter2 and thereafter, freezing the fresh cut agricultural produce.

In the illustrated method, fresh cut pieces 140 of mango are prepared from fresh mangos by hand, as indicated at reference numeral 142. Alternatively, fresh cut pieces 140 of mango may be non-manually prepared. Fresh cut pieces 140 of mango are placed on a conveyor 144. The conveyor 144 transports the fresh cut pieces 140 of mango through a moisture removal chamber 148, preferably a controlled temperature and air flow chamber, in order to remove moisture therefrom, in an amount preferably equal to between approximately 5%-20%, and more preferably between approximately 10%-14%, of the weight of the fresh cut pieces 140 of mango, at a rate which does not exceed approximately 300×10−6 kg moisture/sec per area unit of produce in meter2. In the illustrated exemplary embodiment, moisture removal takes approximately 40 minutes and preferably results in removal of moisture equal to approximately 12% of the weight of fresh cut pieces 140 of mango.

It is appreciated that moisture removal chamber may be any suitable controlled drying chamber utilizing any suitable drying technology, such as microwave, infra-red, convection, fluidized bed or vacuum drying technologies and various combinations thereof. Convection drying is presently preferred.

Following moisture removal thereof as described hereinabove, the fresh cut pieces 140 of mango are preferably pre-cooled in a cooler 150 to a temperature between 0° C.-5° C. and are then preferably quick frozen, preferably to a temperature between −40° C. and −35° C., preferably in a freezer 152 employing IQF freezing technology. Alternatively, the pre-cooling step may be obviated.

Although the invention has been described hereinabove with respect to pomegranate arils and fresh cut pieces of mango, it is appreciated that it is applicable to a great many types of agricultural produce. Data for various types of uncut produce appears in Table 1 hereinbelow and data for various types of fresh cut produce appears in Table 2 hereinbelow. It is seen that for each type of produce various drying rates and corresponding quality metrics, such as turgor, general taste, drip loss and dried tissue layer as a percentage by weight of produce weight, are indicated.

TABLE 1 UNCUT PRODUCE Parameter Drying Drying rate per Turgor on 0-5 General taste Drip Temp. unit area of product Dehydration, scale (5 is on 0-5 scale loss, Type (° C.) (kg m−2 s−1) × 10−6 % best) (5 is best) % Cherry 45 16 5 4 3.9 6.1 (Sweet) 45 16 8 4.4 4.4 4.3 Manually 45 16 12 4.7 4.8 0.2 handled 45 16 18 4.2 3.4 0.1 50 27 12 4.7 4.7 0.8 60 59 12 3.9 3.5 2.2 Control 0 3.3 3.1 7.3 Pomegranate 40 7 12 4.5 4.6 0.4 (Wonderful) 50 30 6 2.9 3.2 6.2 Manually 50 30 8 3.7 3.6 4.2 handled 50 30 10 4.1 3.9 3.9 50 30 12

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