WO2018154290A1

WO2018154290A1 - Improved method for milling seaweed

Info

Publication number: WO2018154290A1
Application number: PCT/GB2018/050442
Authority: WO
Inventors: Craig Rose
Original assignee: Seaweed & Co. Limited
Priority date: 2017-02-23
Filing date: 2018-02-20
Publication date: 2018-08-30
Also published as: GB201702881D0

Abstract

The present invention relates to methods for milling seaweed, and in particular brown seaweed. More specifically,it refers to a method of milling seaweed using an air classifier mill. Further the method may include an authentication step that may act as a test of provenance of both the species of seaweed and the production process.

Description

Improved method for milling seaweed

The present invention relates to methods for milling seaweed, and in particular brown seaweed. More specifically, it refers to a method of milling seaweed, which includes the step of using an air classifier mill and related steps. Further the method may include an authentication step that may act as a test of provenance of both the species of seaweed and the production process.

Seaweeds are harvested or cultivated for a variety of different uses. In many cases it is seaweed extract that is of interest, for example alginate, agar and carrageenan gums are all extracted from seaweed (gelatinous substances collectively known as hydrocolloids). The food industry exploits their gelling, water-retention, emulsifying and other physical properties. Agar is used in foods such as confectionery, meat and poultry products, desserts and beverages and moulded foods. Carrageenan is used in salad dressings and sauces, dietetic foods, and as a preservative in meat and fish products, dairy items and baked goods.

However as seaweed contains minerals, vitamins, fibre, Omega 3 and protein there has been a recent upswell in interest in seaweed itself as a 'superfood'. Whilst in many cultures seaweed has been used in food preparation, for example nori in Japan and sushi wrap, it is becoming ever more desirable that seaweed is added to food, drink or nutrition products as a nutrient boost and flavour enhancer.

In order to include seaweed in food, drink or nutritional supplements, it generally needs to be provided in a powder or powder-like form. This typically involves milling the seaweed into relatively fine particles. However, the process for milling can be challenging, particularly when milling brown seaweeds (Class: Phaeophyceae), which includes species such as Ascophyllum nodosum and Fucus species and are relatively tough plants, with high fibre.

Typically, seaweed is harvested from the sea by specialist vessels and is stored in open cold-water cages until ready for collection (which is typically within 24 hours of the harvest and is tide dependent). The cages are then dragged to the shore by another boat, where the seaweed is removed and then transported for processing. Usually the first step for processing the seaweed is to shred it to reduce size, and then it is dried to required moisture levels. A hammer mill is then used to reduce the size of the seaweed and, if required, the milled product can be put through one or more screens or meshes. One problem that is faced with this technique is that, in order to obtain a relative fine milled product where all, or at least a substantial amount, of the seaweed fragments are below a desired size range, that is for example suitable for use in food or drink, the seaweed must be placed in the hammer mill for sufficient time, often many hours, such that the temperature that the seaweed is exposed to is relatively high. This can impact on the visual colour of the end product as the heat results in a darkening of the product. It also can effect the composition and quality of the product.

Another concern with the above hammer mill technique is that, if the product is in the mill for a significant time small amounts of the metal hammers flake off and can contaminate the end product. Whilst possibly not dangerous for consumption, the small filings from the metal hammers can affect mouth feel and overall product quality. An unrelated issue that is of increasingly importance to all foods and ingredients is that of, confirming provenance of the product. Analytical authentication provides more robust approval systems than a simple paper trail. Most milled seaweed products have no suitable analytical method for determining or indicating provenance.

The present invention aims to obviate or mitigate one or more of the problems associated with the prior art. According to a first aspect of the present invention there is provided a method for milling seaweed, comprising the steps;

obtaining seaweed with less than 20% moisture content;

performing a first milling step to give a particulate seaweed mixture;

removing particles of less than a pre-determined size from said particulate seaweed mixture;

performing a second milling and classifying step on the remaining particulate seaweed mixture using an air classifier mill. Advantageously, the first milling step and removal of particulate seaweed below a predetermined size acts to remove the more brittle outer portion of the seaweed that can be milled more easily. It can therefore also increase the potential removal of any contaminants adhered to the outer portion of the seaweed, such as sand and small crustaceans.

A further advantage is that by performing the second milling step in an air classifier mill the seaweed is not exposed to high temperatures for a significant period of time. A further advantage is that the milled material has been found to have higher levels of antioxidants and/or polyphenols than seaweed milled using hammer milling methods.

Preferably the seaweed is brown seaweed (Class: Phaeophyceae).

More preferably the seaweed is from the family Fucacae.

More preferably the seaweed is selected from the group comprising;

Seaweeds from the genus Fucus; and

Seaweeds from the genus Ascophyllum;

Seaweeds from the genus Pelvetia.

The group may also comprise Laminaria. Most preferably the seaweed is selected from the group comprising;

Ascophyllum nodosum;

Fucus spiralis;

Fucus vesiculosus;

Fucus serratus;

Pelvetia canaliculate.

Preferably the seaweed that is obtained has been shredded and dried. Alternatively, prior to the first milling step, the method may include the step of shredding the majority of the seaweed into pieces of less than 15cm.

In addition, prior to the first milling step, the method may include the step of drying the seaweed until it has moisture content of less than 20%.

Preferably the seaweed that is used for the first milling step has a moisture content of less than 15%. More preferably, the seaweed that is used for the first milling step has a moisture content of less than 14%. Most preferably, the seaweed that is used for the first milling step has moisture content of between 2%-14%.

Preferably in the step of removing particles of less than a pre-determined size from said particulate seaweed mixture, the predetermined size is less than 500pm. More preferably it is less than 400pm.

Preferably after the second milling and classifying step the size of the particulate seaweed material is <400microns. Preferably approximately 30% of material is within 0-200micron, 30% of material is within 200-300 micron and 30% of material is within 300-400micron.

Preferably the first milling step is carried out using a hammer mill. Preferably the first milling step is only for a relatively short period of time. Most preferably the material is milled in the first milling step for less than one hour. More preferably for less than 30 minutes. Optionally the method includes at least one step of testing the DNA of the seaweed material. Preferably this step comprises removing a portion of the seaweed material and carrying out DNA (deoxyribonucleic acid) profiling, including potentially partial sequencing of the DNA in the sample and then comparing to a reference to determine the provenance of the sample. The reference may be to fresh seaweed that has been identified by experts.

Most preferably, a first DNA profile is obtained prior to the first milling step. Most preferably this is obtained after harvesting the seaweed. Most preferably a second DNA profile is obtained after the second milling step. The second DNA profile is compared to the first DNA profile and/or to a reference library of DNA data.

According to a second aspect of the present invention there is provided a particulate seaweed material, where the particulates are less than 400pm in size, which comprises sufficient intact DNA for at least partial sequence information to be obtained.

The term 'seaweed' refers to several species of multicellular marine algae and includes some types of red, brown and green algae. The term 'mill' refers to a device that breaks materials into smaller pieces by grinding, crushing, or cutting.

The term 'milling refers to the grinding of solid matters by mechanical forces and to the process of breaking down material. It may include separating, sizing, or classifying said material. A hammer mill is a mill that uses the repeat blows of a plurality of hammers to crush material into smaller pieces. An air classifier mill applies impact grinding and air classification in a continuous step. The mill uses airflow to convey feed material to a grinding chamber where grinding or milling occurs, then classifies the milled material into fractions based on size. Material that is classified as larger/coarser is re-circulated for further grinding, whilst small enough, or fine, particles are conveyed out of the mill. Typically this is a continuous operation. The air classifier Mill utilises the fact that particle trajectory in a centrifugal field differs by particle size, and therefore allows for particle classification.

The dried seaweed then goes through the hammer mill to reduce the size to less than 2.5mm. Everything of 0-0.4mm is discarded (novel to our process, and to remove the more brittle, and most likely outer layer of the dried seaweed where any encrusting organisms and other contaminants may be). Then the 0.4-2.5mm material goes into our Air Classifier Mill.

In order to provide a better understanding of the present invention, an embodiment will be described, by way of example only, and with reference to the flowing figures in which;

Figure 1 a is a flow diagram showing various processing steps and identifying potential DNA authentication points; Figure 1 b is a more comprehensive diagram describing the process; and Figure 1 c is a diagram further detailing the milling steps;

Figure 2 is a table showing the amount of antioxidants present in a particulate seaweed product obtained using the method of the present invention compared to a similar product obtained using traditional means (e.g. use of a hammermill for a significant time); and

Figure 3 is a table showing the amount of polyphenols present in a particulate seaweed product obtained using the method of the present invention compared to a similar product obtained using traditional means (e.g. use of a hammermill for a significant time). A general overview of the process, including potential DNA testing points, is shown in Figure 1 a. More details of certain process steps are shown in Figures 1 b and 1 c. Ascophyllum nodosum seaweed is harvested from the sea, usually the Northern Atlantic Ocean off the coast of the United Kingdom, by specialist vessels and is stored in open cold-water cages until ready for collection (which is typically within 24 hours of the harvest and is tide dependent). The cages are then pulled to the shore by another boat, where a lorry cranes the seaweed into the back of it for transport to the factory where further processing is to occur.

At this stage a sample of seaweed can be removed and DNA testing carried out. This can be sequencing of the entire genome, or, more likely, obtaining sequence data or information for part of the genome sufficient to identify the seaweed and to provide an identifier which can be used for comparisons throughout the further processing.

Once it arrives at the factory, the seaweed is shredded to reduce the size as the initial seaweed can be in strands of up to a meter long or greater. The seaweed can be left to drain for a time to improve later drying. The pre-draining time can depend on weather, The seaweed is then dried until it has a moisture content of less than 14%.

The milling stages are shown in Fig 1 c. The dried seaweed then goes through the hammer mill for a relatively short period of time to reduce the size of the seaweed pieces to less than 2.5mm. Typically the seaweed is in the hammer mill for approximately 20mins for 100kg, ideally for no more than 30 minutes per 100kg. This equates to 200 minutes for 1 tonne (based on the input material being less than 2.5mm in size). Then everything that is less than 0.4mm is filtered out (typically using vibrating screens with meshes) and discarded. Surprisingly, it has been found that this first milling stage acts to remove the more brittle, and most likely outer layer of the dried seaweed where any encrusting organisms and other contaminants may be. Then the remaining 0.4mm-2.5mm material is fed into an Air Classifier Mill for the second milling stage. In this example a Hosokawa MikroPul™ Air Classifier Mill with independent mill rotor and classifier drives is used, however it would be understood that any appropriate Air Classifier Mill could be used. This is somewhat surprising as typically Air Classifier Mills are used for more brittle materials and for obtaining much smaller particle sizes. On the rare occasions that reference has been made to using air classifier mills for 'seaweed' this relates in fact to either the brittle, calcified remains of seaweed (e.g. from Lithothamnion red algae) or pre-processed agglomerates of algae found in the Far East. Size reduction takes place by the impact of material particles on the grinding surfaces. The cooling, conveying and classifying air drawn through the mill by the downstream fan entrains the metered feed material. The blades to the rotating classifier uniformly distribute the air/product mixture. Due to two opposing forces and the different masses of the material particles the separation into coarse and fine fraction is achieved in the classifying section. Those of high mass are thrown away from the wheel by centrifugal force. The rejected particles return to the milling zone. The fine material is carried with the air through the classifier to the outlet connection. The cut point is adjusted by means of the classifier speed and is variable even during grinding operation. Notf¾bSv ΟΠΘ skilled In iho ¾rt would un tersiHnd t ¾^ tno si o of t f* ΠΊ Ι Ι Ι c ¾n bo changed and that appropriate timings etc. would need to be re-optimised.

Notably, in this embodiment the material passes through the mill in a single pass with greater than 95% of the output material from the single pass being less than 400 microns. This is beneficial as it means far less heat/abrasion for the product during milling as it goes in and comes out to size, without a need for re-milling.

There are 4 main parameters that can affect the running of the air classifier mill:

1 . Mill speed (how fast the mill motor is rotating)

2. Fan speed (determines the suction of air pulling material through the mill)

3. Feeder speed (determines the rate at which material enters the mill)

4. Classifier speed (determines top size of particle by controlled what is pulled through) In this embodiment, the Air classifier Mill is ran at 50hz with the Classifier set to 7 (although could be used up to 10) and the feeder set to approximate^ 3.5 (although could be used down to 12). The fan runs at approximately 1757rpm (30hz).

The Air Classifier Mill is run until the majority of the particulates are sized at 400microns or less. It has been found that roughly 1/3 of material is within 0- 200micron, 1 /3 of material is between 200-300 micron and 1 /3 of the material is between 300-400micron.

At this stage a sample of the particulate seaweed material can be removed and DNA testing carried out. This can be sequencing of the entire genome, or, more likely, obtaining sequence data or information for part of the genome sufficient to identify the seaweed. The results are compared to the earlier test results to confirm that the two are the same. Alternatively, or in addition, the results could be compared to a library of information holding DNA data for a range of seaweeds. It is possible to carry out the DNA authentication steps on every fresh seaweed harvest, and then on every batch of dried seaweed ingredient produced via the method to show both accountability and traceability.

Notably, the DNA authentication testing is indicative of both species and the methodology being in accordance with the above description. Independent analysis of the same species, but that was not processed using the presently described techniques and technologies, did not allow for the extraction and subsequent identification of DNA. The analysis indicated that this could be due to the higher temperature and more abrasive techniques used in traditional milling processes for seaweed production that could denature the DNA present. Hence, DNA Authentication is a test of provenance of both species and unique production processes.

As a result of the above methodology it has been noted that there are a number of benefits to the resulting product that are not seen with products produced by standard methods. Firstly, it is possible to carry out DNA testing on the end product indicating that the nucleic acids present in the starting seaweed have not been denatured. This differs from seaweed products from traditional milling processes as the nucleic acid is denatured and sequencing or other nucleic acid identification or fingerprinting methods cannot be carried out.

Secondly, the processing method described herein retains more anti-oxidants than typical processing methods. This results in a product with higher levels of anti-oxidants. To confirm this, independent testing was carried out using ORAC (Oxygen Radical Absorbance Capacity), and the results are shown in Figure 2.

A similar finding is shown for polyphenols. Seaweed particulate material obtained using the methods of the present invention have more polyphenols than seaweed particulate material from other methods. Again independent testing was carried out to show that the level of polyphenols in the end product are higher when using the processing method of the present invention and the results are shown in Figure 3.

It will be appreciated that features from one embodiment may be appropriately incorporated into another embodiment unless technically unfeasible to do so. With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity. It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "includes but is not limited to," etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim recitation to embodiments containing only one such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an" (e.g., "a" and/or "an" should be interpreted to mean "at least one" or "one or more"); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should be interpreted to mean at least the recited number (e.g., the bare recitation of "two recitations," without other modifiers, means at least two recitations, or two or more recitations). It will be appreciated that various embodiments of the present disclosure have been described herein for purposes of illustration, and that various modifications may be made without departing from the scope and spirit of the present disclosure. Accordingly, the various embodiments disclosed herein are not intended to be limiting, with the true scope and spirit being indicated by the following claims.

Claims

1 . A method for milling seaweed, comprising the steps;

obtaining seaweed with less than 20% moisture content;

performing a first milling step to give a particulate seaweed mixture; removing particles of less than a pre-determined size from said particulate seaweed mixture;

performing a second milling and classifying step on the remaining particulate seaweed mixture using an air classifier mill.

2. A method as in Claim 1 wherein the seaweed is brown seaweed (Class:

Phaeophyceae).

3. A method as in Claims 1 or 2 wherein the seaweed is from the family Fucacae.

4. A method as in any of the previous Claims wherein the seaweed is selected from the group comprising;

Seaweeds from the genus Fucus; and

Seaweeds from the genus Ascophyllum;

Seaweeds from the genus Pelvetia.

5. A method as in Claim 4 wherein the group also comprises Laminaria.

6. A method as in any of Claims 1 to 4 wherein the seaweed is selected from the group comprising;

Ascophyllum nodosum;

Fucus spiralis;

Fucus vesiculosus;

Fucus serratus;

Pelvetia canaliculate.

7. A method as in any of the previous Claims wherein the seaweed that is obtained has been shredded and dried.

8. A method as in any of Claims 1 to 6 wherein, prior to the first milling step, the method includes the step of shredding the seaweed into pieces of substantially less than 15cm.

9. A method as in any of Claims 1 to 6 or 8 wherein the method may include the step of drying the seaweed until it has moisture content of less than 20%.

10. A method as in Claim 9 wherein the seaweed that is used for the first milling step has a moisture content of less than 15%.

1 1 . A method as in Claims 9 or 10 wherein the seaweed that is used for the first milling step has a moisture content of less than 14%.

12. A method as in any of Claims 9 to 1 1 wherein the seaweed that is used for the first milling step has moisture content of between 2%-14%.

13. A method as in any of the previous Claims wherein, in the step of removing particles of less than a pre-determined size from said particulate seaweed mixture, the predetermined size is less than 500pm.

14. A method as in any of the previous Claims wherein in the step of removing particles of less than a pre-determined size from said particulate seaweed mixture, the predetermined size is less than 400pm.

15. A method as in any of the previous Claims wherein after the second milling and classifying step the size of the particulate seaweed material is <400microns.

16. A method as in Claim 15 wherein approximately 30% of material is within 0-200micron, 30% of material is within 200-300 micron and 30% of material is within 300-400micron.

17. A method as in any of the previous Claims wherein the first milling step is carried out using a hammer mill.

18. A method as in any of the previous Claims wherein the material is milled in the first milling step for less than one hour per 250kg.

19. A method as in any of the previous Claims wherein the material is milled in the first milling step for less than 30 minutes per 100kg.

20. A method as in any of the previous Claims wherein the method includes at least one step of testing the DNA of the seaweed material.

21 . A method as in Claim 20 wherein the step of testing DNA comprises removing a portion of the seaweed material and carrying out DNA (deoxyribonucleic acid) profiling, including potentially partial sequencing of the DNA in the sample and then comparing to a reference to determine the provenance of the sample.

22. A method as in any of Claims 20 or 21 wherein, a first DNA profile is obtained prior to the first milling step.

23. A method as in Claim 22 wherein the first DNA profile is obtained after harvesting the seaweed and prior to the first milling step.

24. A method as in any of Claims 20 to 23 wherein a second DNA profile is obtained after the second milling step.

25. A method as in Claim 24 wherein second DNA profile is compared to the first DNA profile and/or to a reference library of DNA data.

26. A milled particulate seaweed material, where the particulates are less than 400pm in size, which comprises sufficient intact DNA for at least partial sequence information to be obtained.