GB2244999A

GB2244999A - Extraction of fish oil

Info

Publication number: GB2244999A
Application number: GB9013464A
Authority: GB
Inventors: David Davis
Original assignee: BRAINSTORM INVESTMENTS Ltd
Current assignee: BRAINSTORM INVESTMENTS Ltd
Priority date: 1990-06-15
Filing date: 1990-06-15
Publication date: 1991-12-18
Also published as: GB9013464D0

Abstract

In a method of extracting oil from fish fragments, for example from fragments of smoked salmon, fish fragments, after removal of skin and bones in a reclaimer (10), are compressed in a press (12) and the expressed liquid collected. The oil is separated from the remainder of the liquid in a separator (14) and is subsequently packaged (16). The compression of the fish fragments, collection of the expressed liquid, and separation of the oil from the expressed liquid all take place in an atmosphere of carbon dioxide to prevent oxidation. The press (12) and associated collecting channels for the expressed liquid are maintained at a low temperature, of, for example, between 0 DEG C and 5 DEG C. <IMAGE>

Description

DESCRIPTION OF INVENTION Title: "Extraction of fish oil" THIS INVENTION relates to the extraction of fish oil and particularly, but not exclusively, to extraction of oil from smoked salmon trimmings.

In the processing of smoked salmon, there is produced a quantity of trimmings and fragments of the smoked fish which are not directly saleable, but nevertheless incorporate useful nutrients and vitamins, etc. particularly in the oil present in the trimmings. It is an object of the present invention to provide a method of reclaiming such oil and converting it to a saleable form.

According to the invention there is provided a method of extracting fish oil comprising compressing fish fragments in a press, collecting the expressed liquid, and separating the oil from the remainder of the liquid.

Preferably the fish fragments are pressed in the press whilst cold (between 0 and 50 C.).

The fish fragments may be compressed and the expressed liquid collected, in a non-oxidising atmosphere, for example a mixture of CO2 and nitrogen.

An embodiment of the invention is described below by way of example with reference to the accompanying diagram.

Referring to the diagram, smoked salmon trimmings are introduced to a meat reclaimer 10 which separates the meat in the trimmings from the bones and skin. The meat, which contains the oil, is processed further, as described below.

The bones and skin represent a by-product which may be used for the manufacture of fertiliser or pet food, for example.

Anti-oxidant is added to the meat from trimmings and the meat is taken to a press 12, where the meat is pressed to express the oil therefrom. The press 12 is similar to a conventional cider press, a stack comprising alternate layers of fish meat and fluid-permeable sheets being arranged between a base of the press and a press platen thereof, whereafter the press platen is forced towards the press base, for example hydraulically, to express the liquid component from the fish meat. An atmosphere of CO2 and nitrogen mixture is maintained around the press during this phase to minimise oxidation.For the same reason, and to avoid the destruction of essential fatty acids in the oil, and of other valuable dietary components, the press and its surroundings and the surfaces, channels, conduits and the like which receive the expressed liquid are maintained at a low temperature, for example by means of a cold water jacket.The smoked salmon trimmings used should be fresh, preferably not more than a week or two old, and in particular should be fresh enough to ensure that the protein in the trimmings has not gone into suspension in the water therein.

The expressed liquid, which comprises a mixture of water, fish waste, protein and natural oil is passed to a separator vessel 14 where the oil is separated from the remainder, for example, simply by allowing the oil, which is less dense than the remainder, to rise to the top of the fluid in the vessel. The oil is drawn off from the vessel 14 and is packed, still under an atmosphere comprising a mixture of CO2 and nitrogen. Whilst it is contemplated that the oil will eventually be packed in sealed capsules, each representing a "unit dose such encapsulation need not, of course, take place at the oil extraction plant and, indeed, the oil may leave the extraction plant in containers of relatively large size.

It will be appreciated that the method described above with reference to the drawings may be applied to the extraction of oil from fish fragments other than smoked salmon, for example fresh salmon or fresh or smoked fish of other species. However, it has been noted that oil reclaimed from smoked salmon is much more stable than oil reclaimed from fresh salmon, although the reason for this is not known.

Claims

1. A method of extracting fish oil comprising compressing fish fragments in a press, collecting the expressed liquid and separating the oil from the remainder of the liquid

2. A method according to claim 1 wherein the compression of the fish fragments, collection of the expressed liquid, and separation of the oil from the expressed liquid all take place in an atmosphere of carbon dioxide.

3. A method according to claim 2 wherein said nonoxidising atmosphere comprises a mixture of carbon dioxide and nitrogen.

4. A method according any of claims 1 to 3 wherein the press and associated collecting channels for the expressed liquid are maintained at a low temperature.

5. Apparatus for extracting fish oil comprising a press for compressing fish fragments, means for collecting the liquid expressed from the fish fragments in the press, and means for separating the oil from said liquid.

6. A method of extracting fish oil, substantially as hereinbefore described with reference to the accompanying drawing.

7. Apparatus for extracting fish oil, substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

8. Fish oil obtained by the method of any of claims 1 to 4 or 6 or using the apparatus of claim 5 or claim 7.

9. Any novel feature or combination of features described herein.