WO2020212680A1

WO2020212680A1 - Apparatus and method for washing plant products

Info

Publication number: WO2020212680A1
Application number: PCT/GB2020/050643
Authority: WO
Inventors: Scott Phillips
Original assignee: J.W. European Ltd
Priority date: 2019-04-18
Filing date: 2020-03-13
Publication date: 2020-10-22
Also published as: GB2583143A; GB2583143B; GB201905572D0; GB2583143A8

Abstract

The present invention discloses an apparatus for washing plant products, comprising an angled barrel, which is supplied with compressed air and water, within the barrel, a bank of air knives, which are configured to travel the length of the barrel, and to which the compressed air is supplied, within the barrel, water nozzles, which are configured to spay water to the inside of the barrel, and to which the water is supplied, and wherein the barrel has perforations or holes, through which water can exit the barrel. The water can also be applied outside the barrel. Further disclosed is a method of washing plant products, comprising the steps filling the products into an angled barrel, which is supplied with compressed air and water, tumbling the products through the barrel, by means of an air curtain created by a bank of air knives out of the compressed air, travelling the length of the barrel, moisturizing the products in the barrel, by means of spray water created by water nozzles out of the water, removing excess water through perforations or holes in the barrel.

Description

Apparatus and Method for Washing Plant Products

Field of the Invention

The present invention relates generally to an apparatus and a method for cleaning of cut plant material, and in particular to a process of washing plant material.

Background of the Invention

The following discussion of the prior art is intended to facilitate an understanding of the invention and to enable the advantages of it to be more fully understood. It should be appreciated, however, that any reference to prior art throughout the specification should not be construed as an express or implied admission that such prior art is widely known or forms part of common general knowledge in the field.

Herbs are available for sale in dried form (that is, desiccated form) or in fresh form. Fresh herbs are sold in pots as whole plants or typically cut in the field, chilled, transported and then packed into plastic film or bags, prior to stocking in a retail environment. Cut salad leaves, baby leaves and spinach are most commonly available for sale in fresh form in a washed or an unwashed state. Like fresh herbs, the leaves are typically cut in the field or glasshouse, chilled, transported and then packed into plastic film or bags, prior to stocking in a retail environment. In particular baby leaves are very sensitive to any cleaning treatment.

Prior art cleaning of baby leaves includes conventional washing or spraying with water jets. Also known is cleaning in root washers, where roots like carrot, potato or beetroot are washed. The full immersion of the product into water is detrimental to the durability of the product after the cleaning, which results in shortened shelf life of the finished product. Water jets are also not a good method of cleaning, because the water jets can violate the products and reduce their value thereby. Also, fixings and many parts and components on transport mechanisms, for example like screws, nuts, bolts etc. violate the products.

Conventional washing relies upon repeated immersion and usually centrifugal drying before packing straight into a bag. The object of the present invention is thus to overcome the above detailed drawbacks of the prior art, or at least to provide a useful alternative which allows for cleaning of cut plant products.

Summary of the Invention

Accordingly, the invention provides an apparatus and method for washing plant products, as defined in the independent claims. Further advantageous embodiments are defined in the dependent claims.

The present invention addresses that problem by providing a very gentle rinsing process to remove grit from plant products, avoiding immersion in water to maintain shelf life, and ensuring that no grit remained on the plant products.

Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise", "comprising", and the like are intended to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense, i.e. "including, but not limited to".

The invention provides in an alternative aspect a cut plant washing apparatus, comprising, an angled barrel, which is supplied with compressed air and water, within the barrel, a bank of air knives, which are configured to travel the length of the barrel, and to which the compressed air is supplied; within the barrel, water nozzles, which are configured to spay water to the inside of the barrel, and to which the water is supplied; and wherein the barrel has perforations or holes, through which water can exit the barrel.

Brief Description of the Drawings

Preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:

Figure 1 shows a plan exterior view of an apparatus according to the present invention;

Figure 2 shows a perspective view of an apparatus according to the present invention as shown in Figure 1 ;

Figure 3 shows a side view diagram of an apparatus according to the present invention; and Figure 4 shows a systematic diagram of an end view apparatus of Figures 1 - 3.

Detailed Description

In the figures, a barrel washer 1 is depicted. The washing apparatus comprises a barrel 10, surrounded by a carcass outer portion 12. The barrel 10 is supplied with compressed air on one side. The compressed air is delivered to the barrel 10 at a bank of air knives 20, which travel the length of the barrel 10. In use, the barrel 10 can be rotatable about an axis running through the centre of the barrel 10, using conventional motors, to aid the washing process. The barrel 10 may rotate at a constant speed. Alternatively, the speed of rotation of the barrel 10 may increase and/or decrease during operation. The barrel 10 may rotate at a speed of between 10 rpm and 40 rpm. For example, the barrel 10 may rotate at a constant speed of 15 rpm during operation. Alternative speeds are contemplated.

The barrel 10 can be constructed from three sections: a first section 10a, a second section 10b and a third section 10c. Each of the sections 10a, 10b, 10c generally include perforations. The perforations in the third section 10c are generally larger than the perforations of the first and second sections 10a, 10b. The perforations in the third section 10c can be twice the size of the perforations of the first and second sections 10a, 10b.

As an example, in the following the treated plant product will be leaves, like salad leaves, baby leaves or spinach leaves. However, other products can be washed in this apparatus as well.

The interior surface of the barrel may be continuous and/or uninterrupted. Accordingly, the barrel may not include a screw arrangement, which is conventionally used to push plant material along the barrel as the barrel rotates. Screw arrangements, and the like, have been found to damage the plant material. In this way, the plant material may remain relatively damage free and have a prolonged shelf life.

On the other side water nozzles 30 fire in from the outside to the inside of the barrel. The water nozzles 30 may be configured such that they each emit a water spray with an opening angle in the range 70° to 120°, preferably approximately 95°. Other opening angles are envisaged. The water nozzles 30 may comprise a plurality of individual nozzles, such as 10 to 20 nozzles, preferably 14 nozzles. The number of nozzles may be dependent on the size of the barrel, and a larger, or longer, barrel may require more nozzles than a smaller, or shorter barrel. The water nozzles 30 may each have an opening diameter in the range 0.125 inch to 0.5 inch, preferably approximately 0.25 inch. Water nozzles with openings of this diameter have been found to provide a preferable water flow rate and velocity, resulting in improved washing and plant product health.

Water may be provided to the water nozzles 30 such that water passes through each of the water nozzles 30 at a flow rate of between 1 litre/min and 2 litre/min. The flow rate may be constant during operation. Alternatively, the flow rate may increase or decrease during operation. The flow rate at a first nozzle may be different to the flow rate of a second nozzle. The first nozzle may be provided upstream or downstream of the second nozzle.

A spray bar can be put down the middle of the barrel 10 if directed water is required inside the barrel 10. Waste water is collected in the carcass 12 and transmitted down to the lower portion 60 of the barrel and carcass via a drain, which may be sieved, through the filter box 50 at the far end of the barrel 10. The barrel 10 can comprise one or several doors 70 for maintenance access. Each door may provide maintenance access to a respective section 10a, 10b, 10c of the barrel 10. As described above, the final section 10c of the barrel 10 has larger perforations to make sure most of the water goes down the drain and not onto the transferring conveyors. The larger perforations in the third section 10c of the barrel 10 also ensure that all debris have been removed.

Leaves are fed in to the barrel by means of an elevator and vibro feed. The barrel is angled to make use of gravity. The barrel is also perforated to allow water and air to move backwards and forwards. Along one side of the barrel are water nozzles 30, firing a controlled volume and pressure. The water may be cooled and/or potable. That is, the water may be of a temperature that is lower than room temperature and/or the water may be drinking water. Along the other side of the barrel are air knives 20 using a controlled volume and pressure of compressed air, to create an air curtain beyond which the leaves cannot travel. The air knives 20 may be configured to operate at least at 30 cfm, 40 cfm, 50 cfm, 60 cfm, 70 cfm, or 80 cfm, although alternative values are envisaged. Three air knives may be provided. Alternative numbers of air knives are envisaged. The compressed air may be cooled and/or filtered. That is, the compressed air may be of a temperature that is lower than room temperature and/or the compressed air may be filtered prior to being delivered to the barrel 10. A compressor may be provided to supply the compressed air. The compressor may comprise an air filter. The compressor may comprise an air cooler. The compressor may be configured to operate with food grade oil. The compressor may be configured to operate at least at 250 cfm, preferably 300 cfm, more preferably 320 cfm. In this way, the compressor may provide an adequate air supply to the air knives 20.

The leaves tumble through the barrel, rubbing against each other and the inside of the wet barrel, removing any grit. During the tumbling action, no direct spray of water is transferred onto the leaves. The compressed air prohibits the leaves sticking to the barrel. The compressed air also acts to distribute the water within the barrel, preventing pooling or over wetting of the plant produce. The washing apparatus disclosed herein also utilises less water than conventional systems, and thus mitigates the likelihood of microbial cross contamination.

After the washing treatment, the leaves or other plant products leave the apparatus at the exit opening and fall onto transferring conveyors, which transport the washed products away for further processing, like drying, sanitising, and packing. Shelf life is preserved by avoiding immersing the leaves in water.

Beneficial aspects of the present invention include the very gentle rinsing process to remove grit from the leaves and the avoidance of immersion in water to maintain shelf life. There is no direct spraying of the leaves with jets of water thereby violation of the products is avoided.

With the apparatus, the products are rinsed and then air dried. The products can be chilled. Afterward the products are held for a few hours to recover. Finally, the products are sanitised.

The products take about 2 minutes to travel through the washing apparatus, after which no grit remains on the leaves. After the treatment and the remaining process steps of drying, sanitising, and packing the shelf life of these products is improved, up to a doubling of the shelf life.

The apparatus may be used to batch treat plant material. Alternatively, the apparatus may be used in a continuous treatment process.

Prior to washing within the barrel, stones and other relatively large debris may be removed by sorting machines. The sorting machines may comprise at least one sensor or detector configured to detect at least one defect. The sorting machine may be configured to detect chlorophyll. Accordingly, the sorting machine may be able to differentiate between organic green products and inorganic products, such as green plastic. Additionally, or alternatively, the sorting machine may be configured to detect a morphological structure, such that rotten material may be detected. The sorting machine may comprise an infrared sensor for this purpose. Additionally, or alternatively, the sorting machine may comprise a visual detector, such as a camera. A visual feed from the visual detector may be analysed to identify defects. For example, a group of dark pixels may be identified as being a defect on a leaf. Accordingly, the defective leaf may be identified and removed. The sorting machine may be operable to separate healthy plant material from defective plant material and other foreign objects such as stones.

The barrel 10 may comprise at least one slit adjacent to the exit opening. The barrel 10 may comprise a plurality of slits distributed around the barrel 10 adjacent to the exit opening. In this way, water remaining in the barrel 10 may be removed before the leaves exit the barrel 10 via the exit opening.

It has been established and shown that washing cut plant material with the apparatus has been found to provide a 1 log reduction in microbe levels on the cut plant material.

Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment but may. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure, in one or more embodiments.

Furthermore, while some embodiments described herein include some, but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those skilled in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

Claims

1. A cut plant washing apparatus, comprising: an angled barrel, which is supplied with compressed air and water; within the barrel, a bank of air knives, which are configured to travel the length of the barrel, and to which the compressed air is supplied; in external communication with the barrel, water nozzles, which are configured to spray water from the outside to the inside of the barrel, and to which the water is supplied; and wherein the barrel has perforations or holes, through which water can exit the barrel.

2. A cut plant washing apparatus according to claim 1 , wherein within the barrel, the barrel further comprises water nozzles, which are configured to spray water to the inside of the barrel, and to which water is supplied.

3. A cut plant washing apparatus according to claim 1 or claim 2, further comprising:

within the barrel, a spray bar, which is located in the middle of the barrel.

4. A cut plant washing apparatus according to any of claims 1 , 2 or 3, further comprising one or more maintenance openings, preferably sealable by a door.

5. A cut plant washing apparatus according to any preceding claim, wherein the perforations of holes in the barrel are of increasing size towards the lower end of the barrel.

6. A method of washing cut plant products, comprising the steps:

filling the products into an angled barrel, which is supplied with compressed air and water;

tumbling the products through the barrel, by means of an air curtain created by a bank of air knives out of the compressed air, travelling the length of the barrel;

moisturizing the products in the barrel, by means of a spray of water;

removing excess water through perforations or holes in the barrel.

7. A method of washing cut plant products according to claim 6, wherein the step of moisturizing the products is with a spray of water generated outside the barrel.

8. A method of washing cut plant products according to claim 6 or claim 7, wherein the spray of water is generated by water from the outside of the barrel sprayed to the inside of the barrel.

9. A method of washing cut plant material according to claim 6, claim 7 or claim 8, wherein the step of moisturizing the products is with a spray of water created out of water supplied to the nozzles and sprayed out from the nozzles.

10. A method of washing cut plant products according to any one of claim 6, claim 7, claim 8 or claim 9, wherein the products are filled into the barrel from a conveyor belt, elevator, or vibro feed, or other transportation.