AU720848B3 - Rendering and refining animal fat - Google Patents

Description

P/00/012 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION PETTY PATENT Invention Title: RENDERING AND REFINING ANIMAL FAT The following statement is a full description of this invention, including the best method of performing it known to me: 1 Document4 2 RENDERING AND REFINING ANIMAL FAT The invention relates to a method of rendering and refining animal fat and to refined animal fats, such emu oil, produced by the method.

The invention is particularly useful for rendering and refining emu oil and although the invention may be used to prepare other fats it will be described herein with reference to this preferred exemplary application.

Refined animal fats are used in a wide range of applications including in cosmetics, pharmaceutical and agro-chemical compositions as well as in cooking and food products. During the rendering process oil can become contaminated with bacteria and needs to be treated in a manner which minimises degradation or other processes which can reduce the beneficial properties of the oil. This is particularly a problem with emu oil which is difficult to prepare without bacterial contamination and with high purity.

The invention provides a method of rendering and refining animal fat from a raw fat-containing material including the steps of: mincing the fat-containing material; heating the minced fat-containing material in a vessel with a food grade antioxidant and filter aid; centrifugally separating the crude fat as an oil from unwanted animal products and the filter aid; heating the separated oil in a vessel under vacuum with addition of a filter aid to at least partially dry the oil; and subjecting the dried oil to centrifugal filtration to remove filter aids and to provide a refined fat; and wherein the filter aid removed from the separated oil by centrifugal filtration is re-used as at least part of the filter aid for treating said minced fat.

The vessel used for heating the minced fat and separated oil is preferably provided with a steam jacket to allow indirect heating of the vessel contents by steam. It is also preferred that the refined oil is filtered under C:AMy ooumntseanne pecesO5973.doc 3 pressure through a multiplicity of filter plates having microfine pores. Microfine porous filter plates will preferably filter under pressure to remove particles at least as small as 1.5 microns and more preferably at least as small as 1 micron.

One example of a suitable filter is the "EQUIP" brand filter which includes two stacks of paper plates for removing particles of size at least as small as 1 micron. The oil will in most cases be fed through the filter using a pneumatic pump. The filtering process will preferably be carried out on warm oil. More preferably the oil will be filtered at a temperature of from 50 to 100 0

C.

We have found that efficiency of the process is significantly improved if.

the raw fat-containing material is frozen prior to mincing. For example frozen blocks of fat-containing material can be cut into strips using a band saw or the like. The frozen strips can be prepared in a size suitable for a heavy duty industrial mincer. Without wishing to be bound by theory we believe that the mincing of the fat-containing material in a frozen state enhances breakdown of fat tissues to provide a product that is more easily rendered. This enables lower temperatures to be used which also helps to retain the desirable properties of the oil.

The process of the invention includes at least two steps in which the product is heated preferably in a steam jacketed vessel. The product is typically heated to a temperature up to 100C and more preferably is heated in the range of from 35 to 100C and most preferably from 60 to 1000C.

In the second heating step the separated oil is heated under vacuum to remove water. We have also found that this step helps enable the adsorbent to act on the oil. It is therefore particularly preferred that an adsorbent is present during the second heating step. The adsorbent may and preferably will be present during the first heating step. Suitable adsorbents are known in the industry and include clays such as bentonite clay and Fuller's Earth. The crude fat product may contain about 5% or more by weight of water. Typically water will be removed to provide no more than 0.5% by weight of water and more preferably no more than 0.1% by weight of water.

C:VAy D ntslannespeddeS~O5973.doc The process of the invention uses antioxidants at an early stage in the process to avoid degradation of the oil during the rendering and refining stages.

The antioxidant may be any of the antioxidants known in the food industry.

Examples of preferred antioxidants include one or more of hydroxy anisole, butylated, vitamin E, rosemary extract and grape seed extract.

Following the centrifugal separation to remove the crude fat as an oil from unwanted animal products and particulate materials including the filter aid and adsorbent, further filter aid and adsorbent is added and the oil is heated in a vessel under vacuum to remove water. The filter aid added at this stage is removed in the second centrifugal filtration step and are re-used as the filter aid in separating the crude fat from unwanted animal products. Examples of suitable filter aids include one or more selected from silicates such as calcium silicate and calcium aluminium silicate, diatomaceous earth and cotton flock, precipitated silicate and crystalline silicates. The particle range of the silicate may be determined based on the nature of the filter, which is generally a cloth, used in the centrifugal filtering process. The filter aids will be of a size to be retained by the filter.

A preferred embodiment of the invention will now be described with reference to the attached drawings in which: Fig. 1 is a flow diagram illustrating the preferred sequence of steps used in the invention.

The raw fat is collected at the abattoirs at the time of slaughter from the Emu's back and some internal fat as well. The amount of fat collected is typically 8-10 kg/bird. This fat is then cartonised and frozen to -18 deg C and stored in cool stores/ice works till required for rendering. Firstly the frozen blocks are band sawed into strips to a size so that a heavy duty industrial mincer can mince the frozen fat through a fine grate at the end of the mincer.

This process breaks down the fat tissues into very easily renderable product and allows the primary rendering to be done at low temperatures which help retain the required qualities of the oil.

C:VMy Doumentseannespedes=5973.doc The minced fat is transferred to a steam jacketed stirred stainless steel vessel where it is heated indirectly by the steam jacket adding no extra water to the rendering process to a temperature of about 100'C to produce oil. A percentage of food grade antioxidant is added to the vessel to help preserve the refined oil, filter aids and free fatty acid/odour reducers are added at this time along with used filter aids collected from a later stage of centrifuging which is hereafter discussed. The addition of antioxidants, filter aid and adsorbent help in the refining process and aid in the economy of the processing.

When this mixture has reached its temperature/time settings it is pumped at a regular rate into a continuous centrifuge (commonly used in the rendering industry) to separate the oil from the gristle/meatlfeathers/sinews/filter aids/purifiers which are discarded at this stage.

The separated oil then goes into a second agitated jacketed stainless steel vessel that has the capacity to be put under vacuum and has temperature control. A prescribed amount of filter aids and oil purifiers are also put into this vessel before the primary refined oil starts coming into this vessel. The indirect steam heating, vacuum, agitation and time all act on the oil to remove water to no more than 0.5% by weight and to also remove undesirable free fatty acids and odour. The water can be removed at lower than the boiling point due to the vacuum which aids in retaining the desired qualities of the oil and helps the adsorbents act on the oil.

The mixture is pumped into a bowl type centrifuge which spins at high speed allowing the perforated bowl and filter cloth to retain the filter aids, thus separating the filter aid and adsorbent from the refined oil. The filter aid and adsorbent are re-used in the first heating step referred to above.

The refined oil is then pumped into a heated stirred stainless holding vat for holding the oil from steps 1-5 repeated over and over. This consolidated oil is then kept at a temperature that allows for the final filtering process.

C:WMy Dmntseanniespcces65973.doc 6 Final filtering is done through a double stack plate and frame type filter with minus 1 micron disposable filters stacked inside the frames. The oil is pumped at a constant pressure and temperature so that it will go through this very fine filter giving the final refined product high clarity and substantially bacteria free purity. The high quality of the oil produced allows it to be used as an ingredient in cosmetic and therapeutic products such as arthritic rubs, muscular sports rubs, back rubs, day and night creams, sun screens, soaps and exotic oil products etc.

The invention will now be more fully described with reference to the following examples. It should be understood, however, that the following examples are illustrations only and should not be taken as in any way restricting generality of the invention described above.

Example 1 The procedure described above and illustrated in Fig. 1 was used to process a 320 kg. batch of emu fat using the following specific steps.

320 kgs. of frozen fat was band sawed into strips which were minced into a steam jacketed vat to which was added 250 gms of food grade antioxidant, kgs. of "Englehard" adsorbent, 4 kgs of "Britesorb", 0.5 kgs calcium aluminium silicate. All filter aid and the adsorbent from the second centrifugal step of a previous batch using this process were also added. The fat was heated in the vat until boiling.

The contents of the vat were transferred by a transfer pump to a centrifugal filter which removed unwanted animal products (eg gristle, meat, feathers and sinews) and the filter aid and adsorbent which were discarded.

The filtered oil was transferred to an inlet of a second steam jacketed vat which was connected to a vacuum pump and stirred by an impellor.

Before transferring the filtered oil to the second vat, 50 gms of antioxidant, 5 kgs. of "Englehard", 4 kgs. of "Britesorb", 3 kgs. of"Celite", 1 kg of cotton flock and 0.5 kgs. of calcium aluminium silicate were added. The product C:VAy DumentseannlspeiSe%605973.doc was heated in the vat under vacuum to a temperature of 950C to remove water from the product and allow the filter aid and adsorbent components to act on the oil.

The oil was then transferred via a transfer pump to a screened high speed centrifugal filter which removed the filter aids and other particulate material including the adsorbent. The filter aids removed in this step are reused by adding them to the minced fat of a subsequent batch.

The filtered oil was then transferred to a stirred holding tank before final filtration under pressure at 60C through an "EQUIP" brand double stack plate and frame filter with minus 1 micron disposable filters.

The resulting oil was clear and of a suitable quality for cosmetic or topical pharmaceutical use.

The invention described hereinabove is susceptible to variations, modifications and/or additions other than those specifically described and that the invention includes all such variations, modifications and/or additions which fall within the.spirit and scope of the above description.

C:VWy DomentsIeannlespeWs'605973.dc

Claims (3)

1. A process for rendering and refining animal fat from a raw fat- containing material including the steps of: mincing the fat-containing material; (ii) heating the minced fat-containing material in a vessel with. a-food grade antioxidant and a filter aid; (iii) centrifugally separating the crude fat as an oil from unwanted animal products and the filter aid; (iv) heating the separated oil in a vessel under vacuum with addition of a filter aid to at least partially dry the oil; subjecting the dried oil to centrifugal filtration to remove the filter aid and provide a refined fat and wherein the filter aid removed by filtration in step is re-used as at least a portion of the filter aid for treating said minced fat in step (ii).

2. A process according to claim 1 wherein the vessels used in each of steps (ii) and step (iv) are steam jacketed vessels and the refined oil is pumped under pressure through a plurality of microfine pore filters.

3. A process according to claim 1 or claim 2 wherein the raw fat is minced in a frozen state and the composition of the filter aid includes one or more filter aids selected from the group consisting of cotton flock, diatomaceous earth and precipitated and crystalline silicates. DATED: 6 January, 2000 PHILLIPS ORMONDE FITZPATRICK Attorneys for: ANDREW JAMES BAKER and LINDA MARY BAKER C:%My Doame sleanniesped-s\605Q73.do