AU2021106334A4

AU2021106334A4 - Method and Apparatus for Milling

Info

Publication number: AU2021106334A4
Application number: AU2021106334A
Authority: AU
Inventors: Leonard Grout
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-11-19
Filing date: 2021-08-21
Publication date: 2021-11-04
Anticipated expiration: 2029-08-19

Abstract

A method and apparatus for milling high-fat comestible products into a powder. The method comprising the steps of: applying solid C02 to a freeze-dried high-fat comestible product; cooling the freeze-dried comestible product below the melting temperature of the contained 5 fat; feeding the solid C02 and cooled freeze-dried comestible product mixture into a milling apparatus; wherein sufficient solid C02 is applied to the freeze-dried comestible product, such that solid C02 exists in the milling chamber to maintain the freeze-dried comestible product below the melting temperature of the contained fat during a milling operation; and wherein the milling operation produces a high-fat comestible powder. 10 2/4 200 210 Freeze-drying 220 Cooling 230 Confirming Solid C02 240 Milling 250 Packaging FIG. 2

Description

2/4

200 210 Freeze-drying

220 Cooling

230 Confirming Solid C02

240 Milling

250 Packaging

FIG. 2

METHOD AND APPARATUS FOR MILLING FIELD OF THE INVENTION

The present invention relates to methods and apparatus for milling, and in particular to

methods and apparatus for milling materials with a sufficiently high fat and/or oil content.

The invention has been developed primarily for use as a method of milling freeze-dried meat

product having a high fat content and will be described hereinafter with reference to this

application. However, it will be appreciated that the invention is not limited to this particular

field of use.

BACKGROUND OF THE INVENTION

Any discussion of the prior art throughout the specification should in no way be considered as

an admission that such prior art is widely known or forms part of the common general

knowledge in the field.

Milling machines generally rely on product being brittle, enabling the product to fragment as

they engage hammers or pins, until product particles become small enough to pass through a

mesh screen.

As high fat products are milled, they become more plastic (not brittle), with fats or oils from

the product coating particles. The presence of the fats and oils cause the particles to become

cohesive, thereby clogging and blocking the screen.

During milling of freeze-dried products having a high level of fat content, in conventional

milling machines, the milling hammers or blades become coated with fat that causes the

milled particles to mass or clump, which blocks the screens and prevents free-flowing powder

to be formed.

It will be appreciated that fat content can be desired in the end product for enhancing

nutritional value.

There is a need in the art to enable milling of product containing higher fat content in

conventional milling machines.

OBJECT OF THE INVENTION

It is an object of the present invention to overcome or ameliorate at least one of the

disadvantages of the prior art, or to provide a useful alternative.

It is an object of the invention in its preferred form to provide a method and/or apparatus for

milling materials with a sufficiently high fat and/or oil content.

SUMMARY OF THE INVENTION

According to an aspect of the invention there is provided a method for milling high-fat

comestible products into a powder, the method comprising the steps of:

(a) applying solid C02 to a freeze-dried high-fat comestible product;

(b) cooling the freeze-dried comestible product below the melting temperature of the

contained fat;

(c) feeding the solid C02 and cooled freeze-dried comestible product mixture into a

milling apparatus;

wherein sufficient solid C02 is applied to the freeze-dried comestible product, such that

solid C02 exists in the milling chamber to maintain the freeze-dried comestible product

below the melting temperature of the contained fat during a milling operation; and

wherein the milling operation produces a high-fat comestible powder.

Preferably solid C02 is in the form of dry ice pellets. Alternatively, solid C02 may preferably

be in the form of C02 snow. More preferably, the solid C02 is mixed (e.g. interspersed or

layered) through the freeze-dried comestible product.

Preferably, in step (a), the freeze-dried high-fat comestible product is layered between layers

of C02 snow in a tray or container device. More preferably, the product cools to below a

brittle point for the respective product. Most preferably, the brittle point for a product is a

temperature at which the respective product can be milled and pass through a milling screen

without causing a substantive blockage during the milling process.

According to an aspect of the invention there is provided a high-fat comestible powder

produced by a method as described herein.

According to an aspect of the invention there is provided an apparatus for milling high-fat

comestible products into a powder, the apparatus comprising:

a means for receiving a mixture of high-fat freeze-dried comestible product and solid

C02, such that sufficient contact time is provided between the substrates for the

temperature to sufficiently equilibrate;

a means for a milling operation that mills the mixture in a milling chamber;

wherein sufficient solid C02 exists in the milling chamber to maintain the freeze-dried

comestible product below the melting temperature of the contained fat during the

milling operation; and

wherein the milling operation produces a high-fat comestible powder.

Preferably the apparatus further comprises a means for injecting solid C02 into the milling

chamber.

Preferably, the apparatus further comprises a means for enabling excess solid C02 to

evaporate prior to packaging.

According to an aspect of the invention there is provided a high-fat powder produced by an

apparatus as described herein.

Preferably the high-fat freeze-dried comestible product is formed by freeze-drying a diced or

cubed comestible high-fat product.

Preferably the high-fat freeze-dried comestible product is substantially maintained up to 20

Deg C below the melting point of fat contained within the product. More preferably high-fat

freeze-dried comestible product is initially cooled to become brittle (by way of example, for

some products, less than -40 Deg C).

Preferably, the high-fat comestible powder is produced with a particle size less than 1000

micron.

Preferably, the high-fat comestible powder is a free-flowing powder.

The apparatus and method provides cost-effective milling of high-fat (or high-oil) freeze dried

product into powder with particle size less than 1000 micron, which is suited to small batch

1o size production for use in nutraceuticals and functional food.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the invention will now be described, by way of example only,

with reference to the accompanying drawings in which:

FIG. 1 is a schematic view of an embodiment apparatus for milling according to the

invention;

FIG. 2 is a flowchart of an embodiment method of milling according to the invention;

FIG. 3 is an image depicting a result of milling freeze-dried goat tongue without

utilising solid C02, shown clogging or blocking the milling chamber; and

FIG. 4 is an image depicting a result of milling freeze-dried goat tongue using the

present invention to produce free-flowing high fat comestible powder of less

than 1000 micron.

PREFERRED EMBODIMENT OF THE INVENTION

There is a preference to mill freeze-dried comestible product having a high fat content into a

free-flowing high fat powder of less than 1000 micron. This free-flowing powder may be

packaged or encapsulated for use in supplements and vitamins.

There has been a long felt want for freeze-dried high fat comestible powders, as they do not

require refrigeration, and reduce inventory, storage and logistics concerns.

The taught method enables milling of freeze-dried animal glands using conventional milling

apparatus without requiring expensive cryogenic milling/blending equipment.

It was identified that milling of high-fat freeze-dried comestible product into a free-flowing

1o food powder less than 1.0 mm particle size was not possible in conventional milling machines.

This is because the fats in the freeze dried product are released during milling to cause

massing (or clumping) of particles that blocks the screens and results in particle cohesion

within the milling apparatus.

It was identified that in milling high-fat freeze-dried comestible product (for example, animal

organs and glands) in conventional food grade milling apparatus, that friction from the

rotating milling hammers (or blades) causes release of fats from freeze-dried product - which

results in the milled particles being coated with fat and causes the particles to mass and clog

(or block) the milling screens, thereby preventing a free-flowing powder from being formed.

FIG. 1 shows a schematic view of an example embodiment apparatus 100.

Meat product 105 is typically cooled to 0 Deg C (or frozen). Excess fat may be removed by

knife trimming. The product can be minced by a mincing machine or diced (for example

cubed into 10mm-40mm pieces) by a dicing machine. By retaining sufficient fat content, yield can be improved.

The meat product then undergoes a freeze-drying process 110, to produce a freeze-dried

comestible product 115. A freeze-drying profile (vacuum/temperature) is typically adapted

and adjusted for the product.

Freeze drying is the process of drying food under vacuum and controlling the shelf

temperature of product in trays, so primary drying can be carried out below the critical

temperature (collapse temperature) of the product allowing frozen water to sublime and

collect on the ice condenser. The freeze-dry process and sub critical C02 application can

preferably reduce microbiological contamination and reduced water activity (aw) being

below 0.2.

1o Freeze-drying is typically accomplished within 24 to 48 hours.

Freeze-drying removes water from perishable raw food, while substantially retaining

nutritional value. Vitamins and minerals are concentrated, per gram of freeze-dried product,

when compared to the original product. Freeze-drying also typically extends shelf life, when

compared to alternative drying methods.

The freeze-drying process significantly enhances the efficiency of creating powder extracts,

and enhances access to useful vitamins, minerals and molecules that are not typically

available due to low concentration in the raw product.

Freeze-drying is a preferred method of dehydration because the low temperature process

preserves product quality and aromatics.

The freeze-dried comestible product is then collected 120. The freeze-dried comestible

product is preferably cooled below a brittle point for the product (for example, for some

products, -40 Deg C), and preferably temperature monitored (at 122).

In an embodiment, by way of example only, dry-ice pellets 130 are added to, and mixed in or

layered with, the freeze-dried comestible product to provide initial cooling. Atmospheric pressure dry ice pellets are about -78.5 Deg C, and contain no moisture. Typically, the cooling requires the dry ice pellets to be applied (in contact with the freeze-dried comestible product) for about 2 to 5 minutes prior to milling.

It will be appreciated that, for large volume freeze-dried product, it would be possible to mix

the dry ice pellets and freeze dried product in a ribbon blender.

It will be appreciated that the amount of dry ice pellets or snow required to cool the freeze

dried product to become brittle will depend on a range of factors, including: the mass of

freeze-dried product, initial temperature of freeze-dried product, temperature of the

processing room, and available cooling time.

It will be further appreciated that, adding too much dry ice can prolong sublimation, thereby

delaying packaging until sufficient C02 is removed from the milled powder.

It will be appreciated that processing of the products can be undertaken in a humidity

controlled room, for example, where relative humidity is typically maintained

<35% @20 Deg C for minimising atmospheric moisture forming on cold surfaces and freeze

dried product absorbing moisture.

Using dry ice pellets, being solid C02, introduces safety concerns. As gaseous C02 is denser

than air, sublimation of the dry ice pellets can result in an increased C02 level within the

processing room. Accordingly, the processing room will require a C02 monitor and

appropriate ventilation.

In an alternative embodiment, by way of example only, C02 snow is applied to, and mixed in

or layered with, the freeze-dried comestible product to provide initial cooling of the freeze

dried product. The C02 snow is generated using a snow horn 132 connected to a portable

liquid vessel 134 containing liquid C02.

The amount of dry ice pellets, or C02 snow, can be measured, for example, by placing tubs of

the freeze-dried product on weigh scales and measuring the increased weight of pellets or

snow applied.

Once the freeze-dried product is cooled to its respective brittle point, it is confirmed that

sufficient deposited dry ice pellets (or C02 snow) remains available within the product mix,

before being applied to a milling apparatus 140.

Successful milling of high-fat freeze-dried product has been achieved with a product pre

cooled below - 40 Deg C, with deposited dry ice (or snow) acting to cool (combat heat

through friction) within the milling apparatus and maintain a cooled product temperature

(e.g. below- 40 Deg C)

When running high mass flow rates through a milling apparatus, C02 pellets or snow may be

injected into the milling chamber to reduce heat generated from the milling friction and

maintain the product more than 20 Deg C below melting temperature of fat.

By way of example only, a preferred milling apparatus is a pan feed hammer mill with fixed

blunt hammer blades and variable rotor and hammers speed control. A product mix may

typically be fed into a milling apparatus at a suitable rate (for example, 0 to 5 Kg per minute)

depending on screen size, product characteristics, speed of rotor, hammer mill motor KW,

size of milling chamber and number of rotor blades (hammers).

The mill preferably produces a free flowing (preferably sub 1000 micron) powder. It will be

appreciated that solid C02 may still be present. Removal or elimination of solid C02 occurs

prior to packaging.

The powder is packed 150, preferably once all the C02 has evaborated and/or is expelled.

Typically, the powder is initially packaged into food grade bags or containers that are heat

sealed. The packaged freeze-dried animal organ and glandular powder is transported to

enable further encapsulation into vitamin supplements or capsules.

It will be appreciated that the milling apparatus 140 for milling high-fat comestible products

into a powder comprises:

a feed throat 142 for receiving a mixture of cooled high-fat freeze-dried comestible

product and solid C02;

a milling chamber 144 for milling the mixture;

milling operation; and

wherein the milling operation produces a high-fat comestible powder (at output 146).

1o Additional solid C02 can be injected into the milling chamber, for example, via the feed

throat. The high-fat freeze-dried comestible product in the milling chamber is typically

maintained up to 20 Deg C below the melting point of fat contained within the product.

It will be appreciated that a high-fat free flowing comestible powder, with a particle size less

than 1000 micron, can be produced by the milling apparatus 100.

It will e appreciated that a brittle point for a product is a temperature at which the respective

product can be milled and pass through a milling screen without causing a substantive

blockage during the milling process. By way of example only, a high-fat freeze-dried

comestible product can be cooled to less than -40 Deg C.

FIG. 2 shows a flowchart of an embodiment method 200 for milling high-fat comestible

products into a powder, the method comprising the steps of:

STEP 210: Freeze-drying a high-fat comestible product;

STEP 220: Applying solid C02 to the freeze-dried comestible product by cooling the

freeze-dried comestible product below the melting temperature of the

contained fat;

STEP 230: Ensuring sufficient solid C02 remains with the freeze-dried comestible

product;

STEP 240: milling the mixture of solid C02 and freeze-dried comestible product to

produce a high-fat comestible powder.

wherein sufficient solid C02 remains with the freeze-dried comestible product, such that

below the melting temperature of the contained fat during a milling operation.

It will be appreciated that solid C02 can be in the form of dry ice pellets or C02 snow

(typically produced with a snow horn) and is typically mixed (e.g. interspersed or layered)

through the freeze-dried comestible product.

It will be further appreciated that the method can provide a high-fat comestible powder.

It will be appreciated that the high-fat comestible product is typically minced, diced or cubed

prior to freeze-drying.

than 1000 micron, can be produced by this milling method 200.

Sufficient solid C02 can be maintained in the milling chamber to ensure that the high-fat

freeze-dried comestible product remains brittle up to 20 Deg C below the melting point of fat

contained within the product. Preferably, the high-fat freeze-dried comestible product is

cooled so as not to block the milling screen during the milling process..

It will be appreciated that, the above methods and apparatus teaches a cost-effective solution

to cooling and maintaining freeze dried high-fat comestible products to up to 20C below the

fat melting temperature during a milling operation. It has been shown that freeze dried

comestible products with fat content more than 30% can be milled into a free-flowing powder

using conventional milling apparatus.

FIG. 3 shows, by way of example only, a failed result 300 of milling freeze-dried goat tongue

(comprising 49% fat) without utilising solid C02, shown clogging or blocking the milling

chamber; and

FIG. 4 shows, by way of example only, a successful result 400 of milling freeze-dried goat

tongue (comprising 49% fat) using the present invention to produce free-flowing high fat

comestible powder of less than 1000 micron.

From extensive trials, it has been found that hammer mills are generally preferred in

producing a free-flowing high fat comestible powder based on the method disclosed herein.

It will be appreciated that a hammer mill is adapted to mill material into smaller particles by

1o repeated blows of a plurality of hammers.

Trials further identified that pin mills were generally not successful. It will be appreciated that

a pin mill is adapted to mill materials by the action of a plurality of pins that repeatedly move

past each other. It was found that pin mills introduce increased localised friction caused by

the pins, causing fat molecules to melt and resulting in milled particles cohering together

and/or blocking (or clogging) the mill.

By way of example only, scaling up production volumes of high-fat comestible powders (for

example, milled from animal glands and organs) a fit for purpose blender can be provided to

blend the freeze-dried product and solid C02 (e.g. dry-ice pallets) for a specified time, until

the freeze-dried product reaches the respective brittle point. This process can occur in a

dehumidified room with appropriate ventilation. Once product reached the desired

temperature, the mixture can be adjusted to ensure sufficient solid C02 (e.g. 5-10% C02

pellets by weight - or volume). The blender can be stopped and product mixed discharged

from the blender to an auger feeder that feeds the product mixture into a pan feed tray of a

hammer mill for milling into a powder. It would be appreciated that much of this process can

be automated for improving output and reducing labour requirements.

In an embodiment, it will be appreciated that freeze dried product can be pre frozen by

freezing in a -20 to -60C freezer. However, freeze dried product has a very low density

enabling it to heat up quickly when removed from a freezer environment, thereby requiring a

secondary means of temperature control.

In an embodiment, it will be appreciated that a secondary source of freezing is needed during

milling. The volume of low-density frozen freeze-dried material passing through the milling

chamber is insufficient to keep the product brittle and the fat below the melting temperature

during milling. To keep product sufficiently brittle and below the melting point of the fat, for

the hammer mill to break particles into small enough size, requires addition of solid C02 to

1o the milling operation. Adjusting a hammer mill rotor speed via a variable frequency drive can

improve milling performance and powder production. Producing a free-flowing high fat

powder means the powder can be easily poured from one container into another without

scooping.

In an embodiment, safety measures in the milling room for use of C02 can include: a suitable

ventilation system HVAC performs necessary fresh air changes in the room; C02 monitors for

detecting increased levels of C02. For example, a C02 gas monitor can measure a time

weighted average of <0.5% C02 over 8 hrs, providing a low warning alarm at 1.5%

(15,000ppm) C02 and an evacuation emergency alarm at 3% (30,000ppm) C02.

It will be appreciated that the taught apparatus and method can operate equally on first

grade (prime) foods or second grade (secondary) foods. Using second grade food (e.g.

bruised, damaged, aesthetically affected, off-cuts, etc.) can reduce waste while providing the

same nutritional properties. Agricultural yields for high-fat products (animal and./or plant

based) can be improved.

It will be appreciated that, by avoiding the need to heat the product to 70 Deg C for removing

high-fat content can improve nutritional value and/or enzyme retention in the produced

powders.

In an embodiment, the method (and apparatus) can include the step of interspersing solid

C02 amongst freeze-dried product as placed in a container. It will be appreciated that the

solid C02 can be in the form of dry-ice pallets or C02 snow (typically produced with a snow

horn).

The container is selected, and the solid C02 (e.g. dry ice pellets or C02 snow) is layered with

layers of the freeze-dried product to effect the cooling (or freezing). It will be appreicted that

interspersing dry ice with freeze dry product can be achieved with a plastic scoop that mix

and layers dry ice snow evenly amongst the freeze-dried product to maximise contact surface

area.

1o An embodiment dry-ice interspersion freezing milling method is performed using two (or

more) containers (or tray devices) at a time. It will be appreciated that, while a first container

is being actively loaded (or fed) into the milling machine, a second container can be loaded

with interspersed dry ice and the freeze-dried product and is temporarily idle while cooling

(or freezing) of the freeze-dried product is achieved. Then, once the first container is fed into

the milling machine, this container is reloaded with interspersed dry ice and the freeze-dried

product, and becomes the idle container while cooling (or freezing) of the freeze-dried

product is achieved. The second container that was the idle container now becomes the

active container being fed into the mill. Then, once the second container is fed into the

milling machine, the cycle continues.

An advantage of the dry-ice interspersion freezing milling method is provision of a low-cost

milling operation of high fat freeze dried food into powder.

It will be appreciated that the illustrated apparatus and methods provide a means for milling

high-fat comestible products into a free-flowing powder.

Although the invention has been described with reference to specific examples, it will be

appreciated by those skilled in the art that the invention may be embodied in many other

forms.

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.

In the claims below and the description herein, any one of the terms comprising, comprised

1o of or which comprises is an open term that means including at least the elements/features

that follow, but not excluding others. Thus, the term comprising, when used in the claims,

should not be interpreted as being limitative to the means or elements or steps listed

thereafter. For example, the scope of the expression a device comprising A and B should not

be limited to devices consisting only of elements A and B. Any one of the terms including or

which includes or that includes as used herein is also an open term that also means including

at least the elements/features that follow the term, but not excluding others. Thus, including

is synonymous with and means comprising.

Similarly, it is to be noticed that the term coupled, when used in the claims, should not be

interpreted as being limitative to direct connections only. The terms "coupled" and

"connected", along with their derivatives, may be used. It should be understood that these

terms are not intended as synonyms for each other. Thus, the scope of the expression a

device A coupled to a device B should not be limited to devices or systems wherein an output

of device A is directly connected to an input of device B. It means that there exists a path

between an output of A and an input of B which may be a path including other devices or

means. "Coupled" may mean that two or more elements are either in direct physical, or that

two or more elements are not in direct contact with each other but yet still co-operate or

interact with each other.

As used herein, unless otherwise specified the use of the ordinal adjectives "first", "second",

"third", etc., to describe a common object, merely indicate that different instances of like objects are being referred to, and are not intended to imply that the objects so described must be in a given sequence, either temporally, spatially, in ranking, or in any other manner.

As used herein, unless otherwise specified the use of terms "horizontal", "vertical", "left",

"right", "up" and "down", as well as adjectival and adverbial derivatives thereof (e.g.,

"horizontally", "rightwardly", "upwardly", etc.), simply refer to the orientation of the

illustrated structure as the particular drawing figure faces the reader, or with reference to the

orientation of the structure during nominal use, as appropriate. Similarly, the terms

"inwardly" and "outwardly" generally refer to the orientation of a surface relative to its axis

of elongation, or axis of rotation, as appropriate.

1o Similarly it should be appreciated that in the above description of exemplary embodiments of

the invention, various features of the invention are sometimes grouped together in a single

embodiment, figure, or description thereof for the purpose of streamlining the disclosure and

aiding in the understanding of one or more of the various inventive aspects. This method of

disclosure, however, is not to be interpreted as reflecting an intention that the claimed

invention requires more features than are expressly recited in each claim. Rather, as the

following claims reflect, inventive aspects lie in less than all features of a single foregoing

disclosed embodiment. Thus, the claims following the Detailed Description are hereby

expressly incorporated into this Detailed Description, with each claim standing on its own as a

separate embodiment of this invention.

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 in the art. For example, in the following claims, any of the claimed

embodiments can be used in any combination.

In the description provided herein, numerous specific details are set forth. However, it is

understood that embodiments of the invention may be practiced without these specific

details. In other instances, well-known methods, structures and techniques have not been

shown in detail in order not to obscure an understanding of this description.

Thus, while there has been described what are believed to be the preferred embodiments of

the invention, those skilled in the art will recognize that other and further modifications may

be made thereto without departing from the spirit of the invention, and it is intended to claim

all such changes and modifications as fall within the scope of the invention. For example, any

formulas given above are merely representative of procedures that may be used.

Functionality may be added or deleted from the block diagrams and operations may be

interchanged among functional blocks. Steps may be added or deleted to methods described

within the scope of the present invention.

It will be appreciated that an embodiment of the invention can consist essentially of features

1o disclosed herein. Alternatively, an embodiment of the invention can consist of features

disclosed herein. The invention illustratively disclosed herein suitably may be practiced in the

absence of any element which is not specifically disclosed herein.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. A method of milling high-fat comestible products into a powder, the method comprising

the steps of:

(a) applying solid C02 in the form of C02 snow to a freeze-dried high-fat comestible

product;

contained fat;

(c) feeding the mixture of solid C02 and cooled freeze-dried comestible product

mixture into a milling apparatus;

wherein the milling operation produces a high-fat comestible powder.

2. The method according to claim 1, wherein the freeze-dried high-fat comestible product is

produced by freeze-drying a high-fat comestible meat product that had been chopped or

cubed.

3. The method according to claim 1 or claim 2, wherein, in step (a), the freeze-dried high-fat

comestible product is layered between layers of C02 snow in a tray or container device.

4. The method or apparatus according to any one of the preceding claims, wherein the

high-fat freeze-dried comestible product is initially cooled to less than its respective

brittle point; and wherein the high-fat freeze-dried comestible product is maintained up

to 20 Deg C below the melting point of the fat during the milling operation.

5. A high-fat free-flowing powder less than 1000 micron produced by the method according

to any one of the preceding claims.