BE1027379B1 - ESTABLISHMENT AND METHOD FOR PROCESSING FROZEN VEGETABLES - Google Patents

Abstract

The invention relates to a method for processing frozen vegetables, comprising: (a) feeding an amount of frozen vegetables, (b) optically sorting the frozen vegetables, (c) optionally, calibrating the frozen vegetables, (d ) glazing the deep-frozen vegetable, and (e) filling the deep-frozen vegetable in a suitable packaging material; wherein the deep-frozen vegetable is transported between the different steps a-e by means of one or more screw conveyors, said screw conveyor comprising at least one shaft and one screw, and wherein said shaft is at least partially thermally insulated. A second aspect relates to an apparatus for processing frozen vegetables, comprising a feeding device, an optical sorting device, a glazing device and a filling device, wherein at least two of the said parts are connected by one or more screw conveyors, which screw conveyors have at least one shaft and comprising a screw, and wherein said shank is at least partially thermally insulated.

Description

: BE2019 / 5397

DEVICE AND METHOD OF PROCESSING OF FROZEN VEGETABLES

TECHNICAL FIELD The invention relates to the processing of frozen vegetables. More specifically, the invention is located in the technical field of the refrigerated transport of frozen vegetables.

STATE OF THE ART In the vegetable processing industry, and particularly in the processing of frozen vegetables, the maintenance of the so-called cold chain is extremely important in order to guarantee the food safety and quality of the vegetables. However, maintaining deep-freeze temperatures over an entire industrial production and / or processing line is a particularly energy-consuming process. In particular, the transport between different sub-elements in the production and / or processing line is a weak link in maintaining the cold chain. A commonly used form of transport is the conveyor belt, which is frequently used in the food industry, but has the drawback that temperature control is only difficult to realize, since the use of a conveyor belt inherently leads to a multitude of heat losses.

From the current state of the art, some alternatives are already available which allow an accurate temperature control, although these are often based on active, and consequently energy-intensive, cooling, whereby the realized transport speeds are significantly low if good cooling is envisaged. In addition, known cooling methods are often not very suitable for maintaining deep-freeze temperatures. For example, CN 203 833 139 describes a transport method which may be suitable for transporting deep-frozen vegetables, and which is provided with a double cooling system. Here cooling water is led through a cooling jacket which is arranged around a screw conveyor. However, a cooling water based system as described in CN ‘139 is incapable of maintaining temperatures

° BE2019 / 5397 in the deep-freeze range, and can ideally be used purely to maintain cooling temperatures above freezing.

Furthermore, CN 203 633 413 describes a cooling system comprising a screw conveyor and an air cooling device suitable for cooling chicken. However, the cooling system described herein has active cooling and is therefore very energy consuming. There is therefore a need for a method for processing frozen vegetables, in which the cold chain is respected, especially in the transport between the different process steps, whereby a high transport speed is realized, and in which the need for active cooling is eliminated. In particular, a qualitative and safe food product is hereby obtained in an energy-efficient manner and with a generally high efficiency.

The present invention aims to solve at least some of the above-mentioned problems or drawbacks.

SUMMARY OF THE INVENTION To this aim, the invention provides in a first aspect a method for processing frozen vegetables according to claim 1, comprising the steps of: (a) feeding an amount of frozen vegetables, (b) sorting the frozen vegetables optically vegetable, (c) optionally, calibrating the frozen vegetable, (d) glazing the frozen vegetable, and (e) filling the frozen vegetable in a suitable packaging material, transporting the frozen vegetable between the different steps ae by means of one or more screw conveyors, said screw conveyor comprising at least a shank and a screw, and wherein said shank is at least partially thermally insulated. Preferred forms of the method are given in sub-claims 2 to

6. The at least partially thermally insulated shaft according to the present invention has the advantage that the heat loss through the various transport steps is minimized. The frozen vegetables can be processed in such a way by means of the relevant method, without interruption of the so-called cold chain, whereby risks regarding food safety and food quality are reduced. The thermal insulation according to the present method furthermore eliminates the need for actively refrigerated transport and guarantees the frozen state of the vegetable during the entire processing process. A second aspect of the present invention relates to a device according to claim 7, comprising a feeding device, an optical sorting device, a glazing device and a filling device, wherein at least two of said parts are connected by means of one or more screw conveyors, which screw conveyors have at least one shaft and comprising a screw, said shaft being at least partially thermally insulated. Preferred forms of the device are given in sub-claims 8 to

15.

DESCRIPTION OF THE FIGURES Figure 1 shows a perspective view of a screw conveyor according to the present invention. Figure 2 shows a schematic representation of an embodiment of the device for processing frozen vegetables according to the present invention.

DETAILED DESCRIPTION The present invention relates to a method for processing frozen vegetables. Unless defined otherwise, all terms used in the description of the invention, including technical and scientific terms, have the meaning as commonly understood by those skilled in the art of the invention. For a better assessment of the description of the invention, the following terms are explicitly explained.

+ BE2019 / 5397 “One”, ”the” and “it” refer in this document to both the singular and the plural unless the context clearly suggests otherwise. For example, “a segment” means one or more than one segment.

When “about” or “around” is used in this document for a measurable quantity, parameter, time or moment, and the like, it means variations of +/- 20% or less, preferably +/- 10% or less, more preferably +/- 5% or less, even more preferably +/- 1% or less, and even more preferably +/- 0.1% or less than and of the quoted value, to the extent that such variations of are applicable in the described invention. However, this should be understood to mean that the value of the quantity using the term “approximately” or “round” is itself specifically disclosed.

The terms “comprise”, “comprising”, “consist of”, “consisting of”, “incorporating”, “containing”, “containing”, “containing”, “containing” are synonyms and are inclusive or open terms that define the indicate the presence of what follows, and which do not exclude or prevent the presence of other components, features, elements, members, steps known from or described in the prior art.

Quoting numeric intervals through the endpoints includes all integers, fractions, and / or real numbers between the endpoints, including these endpoints.

In a first aspect, the present invention relates to a method for processing frozen vegetables, the processing comprising at least the following steps: (a) supplying an amount of frozen vegetables, (b) optically sorting the deep-frozen vegetables, (c) ) optionally, calibrating the frozen vegetable, (d) glazing the frozen vegetable, and (e) filling the frozen vegetable in a suitable packaging material. According to the present invention, the deep-frozen vegetable is transported between the different steps a-e by means of one or more screw conveyors, which screw conveyors comprise at least a shaft and a screw. The said shaft is at least partially thermally insulated.

The term “vegetable” denotes any crop, but is not limited to, the group of Jerusalem artichoke, onion, endive, artichoke, asparagus, eggplant, cauliflower, kale, green beans, green beans, string beans, broccoli, broccolini, mushroom, Chinese cabbage, zucchini, peas, celeriac, kohlrabi, bok choy, bell pepper, parsnip, pumpkin, leek,

> BE2019 / 5397 turnip, rhubarb, beetroot, red cabbage, savoy cabbage, salsify, celery, shallot, spinach, pointed cabbage, Brussels sprouts, fennel, chicory, white cabbage, carrot, or combinations thereof.

The present invention primarily wishes to focus on vegetables which are commonly frozen, such as onion, cauliflower, beans, green beans, string beans, broccoli, broccolini, peas, celeriac, paprika, leek, celery, spinach, carrot, or combinations thereof.

Vegetable according to the present invention may come in both cut and uncut form.

The term “deep-frozen” generally refers to the condition in which the vegetable has a temperature that is lower than 0 ° C.

In the context of the present invention, which falls within the context of the problem of food spoilage, this refers to the condition whereby the vegetable has a temperature which is lower than -18 ° C, in which spoilage under the influence of microorganisms is virtually absent.

The term “optical sorting” refers to sorting based on visual properties.

It may be sorted and / or classified based on size, color, consistency, or other appearance characteristics.

Preferably, the optical sorting is automated, this maximizes the yield while less waste is generated.

Moreover, throughout the production process of vegetables, for example, a reduction in energy consumption can be obtained and the use of chemicals is minimized.

Automated optical sorting also allows high productivity and throughput, and is an important link in ensuring consistent food security and food quality.

In the context of the present invention, the term "calibrate" refers to dividing the vegetable into one or more size classes.

For example, for beans a division can be made between beans of small, medium and large size.

Such size class division therefore allows further diversification of the vegetable supply.

The term “glazing” refers to the application and subsequent freezing of a water layer around the frozen vegetable.

Glazing prevents the vegetables from drying out during the storage period.

In the context of the present invention, the term "screw conveyor" refers to an elevator screw or screw pump, also known as the "Archimedes screw". Such a screw conveyor allows the transport of liquids, slurries,

© BE2019 / 5397 powders or, particularly applicable to the present invention, vegetables.

The lead screw usually includes a "shaft" in which a helical "screw" is suspended concentrically in bearings.

The intended transport is the result of the rotational movement of the spiral screw inside the shaft.

Such a screw conveyor is generally suitable for upward transport, although it can also be used for horizontal transport.

The terms “thermally insulated” or “thermal insulation” refer to the property of materials and / or structures to minimize the transfer of thermal energy, i.e. heat, between two sides of the material and / or structure.

Heat transfer by definition occurs as a result of (1) conduction or conduction, (2) air flow or convection, or (3) radiation.

The degree to which such heat transfer is reduced is further indicated by one of the following values.

The “U-value” or “heat transmission coefficient” expresses the amount of heat that is transmitted between the different sides of a material and / or construction, per unit of time, per unit area and per degree of temperature difference prevailing on both sides of the material and / or the construction.

The “R-value”, “thermal resistance” or “heat resistance” is related to the property of materials to slow down heat conduction.

Metals are good heat conductors, so they have a low heat resistance.

Air and plastic are examples of poor heat conductors, so with a high thermal resistance.

A value often used in the context of thermal insulation is the “lambda value”, “A value” or “thermal conductivity coefficient”. The thermal conductivity coefficient is a material constant that indicates how well a material conducts heat, and is determined independently of the prevailing temperature differences on both sides of a material and / or construction.

The at least partially thermally insulated shaft according to the present invention has the advantage that the heat loss through the different transport steps is minimized.

The frozen vegetables can be processed in such a way by means of the relevant method, without interruption of the so-called cold chain, whereby risks regarding food safety and food quality are reduced.

The thermal insulation according to the present method furthermore eliminates the need for actively refrigerated transport and guarantees the frozen state of the vegetable during the entire processing process. Although thorough isolation of the various screw conveyors entails a certain investment cost, the respective method allows a reduction in the operating costs. After all, production and / or processing lines generally have a considerable length in the processing of frozen vegetables, whereby active cooling entails great costs.

In some embodiments, the shaft is completely thermally insulated for this purpose. There are therefore no zones over the screw conveyor which entail an increased risk of heat loss. Possibly, in some embodiments, the deep-frozen vegetable is only transported between some of the steps mentioned by means of screw conveyors. Here, a selection can be made as to which steps pose the greatest risk of heat loss. Preferably, the temperature of the frozen vegetable supplied is comprised between -18.0 and -30.0 ° C. The risk of bacterial spoilage within this temperature range is hereby minimized during the entire process. In this way, a packaged end product is obtained that optimally complies with the applicable regulations regarding food safety for frozen vegetables. The maximum manageable temperature of - 18 ° C as included in the European directive 89/108 / EEC on "frozen products intended for human consumption" is hereby maintained. More preferably, the temperature of the frozen vegetable supplied is comprised between -18.0 and -25.0 ° C, even more preferably between -18.0 and -20.0 ° C. In this way, the criteria for food safety are met while the energy required for (fast) freezing of the vegetables is reduced. According to a further or different embodiment, each of the screw conveyors comprises a first and a second end, said screw conveyors transporting the frozen vegetable a transport distance extending from said first end to said second end. The temperature of the frozen vegetables increases by a maximum of 0.50 ° C over the transport distance. In order to meet the food safety criteria over the entire course of the processing, the limited temperature increase according to the present invention is particularly advantageous. The cold chain is respected at all times without the need for active cooling. As a result, the processing according to the present method is particularly energy-efficient.

Preferably, the temperature of the deep-frozen vegetable increases by a maximum of 0.25 ° C over the transport distance. A lower temperature increase further optimizes the energy efficiency of the method, while moreover the supply temperature of the vegetable can be closer to the permitted supply temperature. This not only eliminates cooling during processing, but also further reduces the energy required for (rapid) freezing of the vegetables prior to processing. More preferably, the temperature of the deep-frozen vegetable increases over the transport distance by a maximum of 0.20 ° C, even more preferably a maximum of 0.10 ° C. Each of the screw conveyors rotate according to one embodiment at a rotational speed comprised between 1 and 240 revolutions per minute. The "rotational speed" or "angular speed" according to the present invention may be expressed in various units, including radians per second, degrees per second, or revolutions per minute, also called "revolutions per minute (RPM). The latter unit is most common in motor and vehicle engineering. A rotational speed within the range according to the present invention ensures an optimal balance between transport speed and product quality. A higher conveying speed is desirable in order to minimize the time that the frozen vegetable spends in the conveyor screws. This further limits the temperature loss, which is desirable for food safety. However, a higher rotation speed entails quality risks, as the frozen vegetables may be damaged as a result of the faster rotation. Within the range according to the present invention, the frozen vegetable remains intact and the temperature loss over the screw conveyor is minimal. Preferably, the screw conveyors rotate at a rotational speed comprised between 5 and 210 revolutions per minute, more preferably between 10 and 180 revolutions per minute, even more preferably between 20 and 160 revolutions per minute, between 30 and 140 revolutions per minute, between 40 and 120 revolutions per minute, most preferably between 60 and 120 revolutions per minute. In a further or different embodiment, each of the screw conveyors transports the frozen vegetable at a linear speed which

? BE2019 / 5397 is between 0.05 and 5.00 m / s. The total throughput time of the method is optimal here in order to keep the temperature sufficiently low and not endanger the product quality. Preferably, the linear speed is comprised between 0.10 and 4.00 m / s, more preferably between 0.20 and 3.00 m / s, between 0.30 and 2.50 m / s, between 0.40 and 2.50 m / s, most preferably between 0.50 and 2.50. The frozen vegetable supplied is selected from the group of onion, cauliflower, green beans, green beans, string beans, broccoli, broccolini, peas, celeriac, bell pepper, leek, celery, spinach, carrot, or combinations thereof. Preferably, the vegetable is selected from the group of cauliflower, beans, green beans, string beans, broccoli, peas, celeriac, carrot, or combinations thereof. According to a further embodiment, the deep-frozen vegetable comprises a combination of two or more vegetables.

The filling of the deep-frozen vegetables in a suitable packaging material according to the present method preferably takes place semi-automatically or fully automatically. To this end, according to one embodiment, boxes and / or bags can be supplied on a suitable supply device, for instance a conveyor belt, wherein said boxes and / or bags are then filled and removed when they have exceeded a certain filling threshold.

Such control of the degree of filling may take place automatically by means of weighing and / or optically checking the filled boxes and / or bags. The semi or fully automatic filling of the deep-frozen vegetables contributes to a further reduction of the processing time, whereby as little heat loss as possible occurs.

In some embodiments, the steps of calibration and filling are combined by supplying, simultaneously or otherwise, a plurality of boxes and / or bags, filling different size classes of the frozen vegetable into the different boxes and / or bags. Combined calibration and filling can thus be obtained semi-automatically or fully automatically. The semi or fully automatic calibration and filling of the deep-frozen vegetables contributes to a further reduction of the processing time, whereby as little heat loss as possible occurs.

A second aspect of the present invention relates to an apparatus for processing frozen vegetables, comprising a feeding device, an optical sorting device, a glazing device and a filling device, wherein at least two of said parts are connected by one or more conveyor screws.

The conveyor screws of the present invention comprise at least one shank and one screw, said shank being at least partially thermally insulated.

The at least partially thermally insulated shaft according to the present invention has the advantage that the heat loss through the different transport steps is minimized.

When frozen vegetables are processed in the present establishment, the cold chain is therefore guaranteed at all times, whereby risks regarding food safety and food quality are reduced.

The thermal insulation according to the present device moreover eliminates the need for actively refrigerated transport and guarantees the deep-frozen condition of the vegetable throughout the entire processing process.

In some embodiments, the shaft is completely thermally insulated for this purpose.

There are therefore no zones over the screw conveyor which entail an increased risk of heat loss.

Possibly the frozen vegetable, in some embodiments, all parts of the device are connected via screw conveyors.

Preferably, the shaft is insulated with an insulating material, which insulating material has a thermal conductivity coefficient comprised between 0.01 and 1.50 W / mK.

The term "insulating material" in the context of the present invention includes any material capable of exerting some reduction in heat transfer.

To this end, such insulation material initially limits the thermal conductivity or conduction.

A suitable insulation material preferably has a low U and / or lambda value for this purpose.

Insulation materials, and by extension any material that sufficiently seals the shaft and / or screw from its environment, also limit thermal losses by limiting air flow or convection and / or limiting radiation effects.

Within the aforementioned ranges, a considerable reduction of the heat conduction is obtained, with optimum maintenance of the deep-freeze temperatures in the conveyor screw as a result.

A screw conveyor which is made of steel, which material has a thermal conductivity coefficient of approximately 50.00 W / mK, will consequently be considerably less exposed to heat losses due to insulation with the relevant insulation material.

More preferably, the u BE2019 / 5397 thermal conductivity coefficient of the insulation material is comprised between 0.01 and 0.50 W / mK. This has the advantage that the insulating material can be applied thinner around the shaft, while optimum thermal insulation is maintained.

Suitable insulating materials include fibrous, cellular and / or granular insulating materials including but not limited to mineral glass wool, cellulose glass, ceramic fibers, (expanded) perlite, mineral rock wool, vermiculite, cork, (expanded) nitrile rubber, phenolic foam, polyethylene foam, polypropylene, polystyrene, polyisocyanurate, polyurethane foam and / or (expanded) synthetic rubber. In some embodiments, the insulating material is selected from the group of cork, (expanded) nitrile rubber, phenolic foam, polyethylene foam, polypropylene, polystyrene, polyurethane foam, (expanded) synthetic rubber, or combinations thereof.

The screw according to a further or different embodiment has a (nominal) diameter which is comprised between 30.0 and 100.0 cm. A larger diameter allows the transport of larger quantities of frozen vegetables, while more insulation material is required for these larger dimensions. Within this range, an optimal balance is achieved between transport speed and insulation requirement so that the temperature loss during transport is minimal.

Preferably, the diameter is comprised between 50.0 and 100.0 cm.

In some embodiments, the screw has a pitch of between 10.0 and 50.0 cm. The term "pitch" denotes the rectilinear distance between two corresponding points of the same helix, it is the displacement along the axis per revolution. Preferably, the pitch is comprised between 25.0 and 45.0 cm, more preferably between 30.0 and 45.0 cm.

In some embodiments, the propeller includes a propeller blade of round shape, U shape, or omega shape. Preferably, the propeller blade has a U or omega shape. This has the advantage that a larger volume of frozen vegetables can be moved per revolution.

According to a further or different embodiment, the conveyor screws have a longitudinal angle of inclination which is comprised between 0 ° and 50 °, preferably between 0 ° and 40 °.

In some embodiments, the glazing device includes a glazing drum. A glazing drum is particularly suitable for continuous processing of frozen vegetables. Glazing prevents the vegetables from drying out during the storage period.

The presence of an optical sorting device makes it possible to check the frozen vegetables for visual defects and is an important link in guaranteeing consistent food security and food quality. In some embodiments, the device further includes a calibration unit. The calibration unit makes it possible to divide the frozen vegetables into one or more size classes. For example, for beans a division can be made between beans of small, medium and large size. Such size class division therefore allows further diversification of the vegetable supply.

The filling unit allows the semi-automatic or fully automatic filling of boxes and / or bags, wherein these boxes and / or bags are supplied on a suitable supply device, for example a conveyor belt. In some embodiments, the degree of filling is controlled by weighing and / or optically checking the filled boxes and / or bags. To this end, the filling device may be provided with a weighing or balance system, as well as one or more visual sensors. The semi or fully automatic filling of the deep-frozen vegetables contributes to a further reduction of the processing time, whereby as little heat loss as possible occurs.

In some embodiments, the calibration and filling device are combined, whereby different size classes of the frozen vegetable can be filled into the different boxes and / or bags. Combined calibration and filling can thus be obtained semi-automatically or fully automatically. The semi or fully automatic calibration and filling of the deep-frozen vegetables contributes to a further reduction of the processing time, whereby as little heat loss as possible occurs.

The apparatus, in some embodiments, is particularly suitable for processing frozen vegetables by the method of the present invention.

In what follows, the invention is described by means of non-limiting figures illustrating the invention, and which are not intended or should not be construed to limit the scope of the invention.

DETAILED DESCRIPTION OF FIGURES Figure 1 shows a perspective view of a screw conveyor (1) according to the present invention. The screw conveyor comprises a screw (2) and a shaft (3), which are thermally insulated by means of insulating material (4) arranged around it. The insulated screw conveyor allows the heat loss during transport of frozen vegetables to be minimized. The frozen vegetable can be processed in such a way by the method according to the present invention, without interruption of the so-called cold chain, whereby risks regarding food safety and food quality are reduced. This eliminates the need for actively cooled transport and guarantees the frozen state of the vegetables throughout the entire processing process. Figure 2 shows a schematic representation of an embodiment of the device for processing frozen vegetables according to the present invention. The device comprises a unit for optical sorting (5), a glazing unit (6), a calibration unit and two filling units (8). The different units are mutually connected by means of a conveyor screw (1) according to the present invention, which is at least partially insulated. In this way, heat losses during transport between the different units are limited, allowing continuous processing of frozen vegetables without the need for actively cooled transport.

Claims (15)

CONCLUSIONS 1. A method for processing deep-frozen vegetables, wherein the processing comprises at least the following steps: a. Supplying an amount of deep-frozen vegetables, b. optical sorting of the frozen vegetables, c. optionally, calibrating the frozen vegetables, d. glazing the frozen vegetables, and e. filling the frozen vegetable in a suitable packaging material; wherein the deep-frozen vegetable is transported between the different steps a-e by means of one or more screw conveyors, said screw conveyor comprising at least one shaft and one screw, and wherein said shaft is at least partially thermally insulated. A method according to claim 1, characterized in that the temperature of the frozen vegetable supplied is comprised between -18.0 and -30.0 ° C, preferably between -18.0 and -25.0 ° C. A method according to claim 1 or 2, wherein each of the screw conveyors comprise a first and a second end, and wherein said screw conveyors transport the frozen vegetable a transport distance extending from said first end to said second end, with the characterized in that the temperature of the deep-frozen vegetable increases by a maximum of 0.50 ° C over the transport distance, preferably increasing by a maximum of 0.25 ° C. A method according to any one of the preceding claims 1-3, characterized in that each of the screw conveyors rotate at a rotational speed comprised between 1 and 240 revolutions per minute, preferably between 5 and 210 revolutions per minute. A method according to any one of the preceding claims 1-4, characterized in that each of the screw conveyors transport the deep-frozen vegetable with a linear speed which is comprised between 0.05 and 5.0 m / s, preferably between 0.10. and 4.0 m / s. A method according to any one of the preceding claims 1-5, characterized in that the frozen vegetable supplied is selected from the group of cauliflower, beans, green beans, string beans, broccoli, peas, celeriac, carrot, or combinations thereof. 7. Device for processing deep-frozen vegetables, comprising a feeding device, a device for optical sorting, a glazing device and a filling device, characterized in that at least two of the said parts are connected by one or more conveyor screws, which conveyor screws have at least one shaft and a screw, said shaft being at least partially thermally insulated. A device according to claim 7, characterized in that the shaft is insulated with an insulating material, which insulating material has a thermal conductivity coefficient which is comprised between 0.01 and 1.50 W / mK, preferably between 0.01 and 0. , 50 W / mK. Device according to claim 8, characterized in that the insulating material is selected from the group of cork, (expanded) nitrile rubber, phenolic foam, polyethylene foam, polypropylene, polystyrene, polyurethane foam, (expanded) synthetic rubber, or combinations thereof. Device as claimed in any of the foregoing claims 7-9, characterized in that the screw has a diameter which is comprised between 30.0 and 100.0 cm, preferably between 50.0 and 100.0 cm. A device according to any one of the preceding claims 7-10, characterized in that the screw has a pitch which is comprised between 10.0 and 50.0 cm, preferably between 30.0 and 45.0 cm. 12. Device as claimed in any of the foregoing claims 7-11, wherein the screw comprises a screw blade, characterized in that the screw blade has a U-shape or omega-shape. Device according to any one of the preceding claims 7-12, characterized in that the screw conveyors have a longitudinal angle of inclination which is comprised between 0 ° and 50 °, preferably between 0 ° and 40 °. A device according to any one of the preceding claims 7-13, characterized in that the device further comprises a calibration unit. Device according to any one of the preceding claims 7-14 for processing frozen vegetables by means of a method according to any one of claims 1-6.