PROCESS FOR THE PREPARATION OF MARINE OILS

Description

Field of the invention

[0001] The present invention relates to a process for the preparation of marine oils, in particular marine oils such as fish oil, algae and/or microbial oils and concentrates thereof.

Background to the invention

[0002] Recently the use of marine oils as food ingredients has attracted increased interest especially because of the presence of long chain fatty acids such as EPA and DHA.

[0003] It is well known that these marine oils, in particular marine oils and/or microbial oils and marine oils/concentrates, may be free of odor and smell when fresh, but reversion through oxidation occurs very rapidly.

[0004] Many attempts have been made to stabilize marine oils. For example a common method is to store and transport the marine oils at low temperature, for example in the frozen state. At these low temperatures the marine oils are solid and are less prone to degradation effects. However the storage in the frozen form has the disadvantage that long periods are needed for the freezing and the thawing of the product leading to an undesired increase in storage time. Also the freezing of the oil and the subsequent transport at low temperature requires an undesired ongoing input of energy.

[0005] Another problem in the storage and transport of marine oils is the fact that marine oils tend to solidify during storage and/or transport at ambient temperature. Such solidification renders the marine oil less suitable for handling under factory conditions because the solid oil can generally not be pumped at ambient temperature or the oil requires an undesired heating step before it can be handled.

[0006] Another problem in the storage and transport of marine oils is the fact that marine oils due to their relative high solid fat content tend to form a solid fat and wax containing phase which during storage and transport often sediments to the bottom of the storage vessel. This sediment generally is non-pumpable and therefore cannot be used under standard factory conditions. In practice therefore this sediment layer is often discarded as waste leading to an undesired loss of material and an increase of costs.

[0007] Winterization has been used to separate the solid fat from the marine oil prior to storage or transport. This indeed may result in a decrease of the above problems of solidification and sedimentation, however winterization causes an undesired delay and also leads to the removal of the hard fat fraction, which -unless a suitable economic use of this solid fat fraction can be found- significantly increases the cost of the resulting winterized marine oil.

[0008] US-A-5 436 021 discloses a process to provide pumpable oleaginous composition, which involves exposing oils/fats to relatively high temperatures for an extended period of time. US-A-2 999 022 discloses a process for making a stable liquid shortening. The process comprises the steps of: heating oil to a temperature high enough to melt all solid material and crystal nuclei; cooling to a temperature just above the alpha melting point of the fat, let beta-prime crystalline grow and agitating; heating to form stable beta crystals and agitating; cooling and agitating; packaging. US-A-5 211 981 discloses a process for making a uniform liquid pourable shortening. The melted composition is rapidly cooled in a first zone (15.5-26.6 °C) in a scraped surface heat exchanger, and then worked by agitation in a second zone. US-A-3 395 023 discloses a process for preparing a liquid shortening comprising the steps of heating a fat mixture, pumping into a cooling tank, where, while being stirred, it is cooled for a period of several days.

Summary of the invention

[0009] It is therefore an object of the invention to improve the keepability of marine oil. Another object of the present invention is to bring marine oil in a form wherein it remains pumpable after storage without the unacceptable formation of sediment and without the need for winterization.

[0010] Surprisingly it has been found that a specific cooling regime for the marine oil leads to the formation of a stable suspension of a solid fat fraction in a liquid fraction without the occurrence of undesired solidification and sedimentation and without the need of prior winterization.

[0011] Accordingly the present invention involves a process for the handling and storage of marine oils comprising the steps of:

(a) optionally heating the marine oil to a temperature of 20-45 C to ensure that the marine oil is fully liquid;

(b) Cooling the fully liquid marine oil in one or more scraped surface heat exchangers to a temperature of -5-10 C;

(c) maintaining the cooled marine oil obtained in step (b) in one or more a steered vessels at a temperature of -5-10 C for a total period of 15 seconds to 10 minutes;

(d) Storing the marine oil thus obtained in a closed container at a temperature below 15 C.

Detailed description of the invention

[0012] The oil prepared according to the invention is a non-winterized marine oil i.e. an oil which is easily oxidized, developing off-taste. Examples of marine oils are: fish oils for example obtained from fatty fish such as mackerel, salmon, tuna, squid, whale, menhaden, pilchard, anchovy, sardine and herring, or microbial oils as algae oil, obtained from marine micro algae or krill oil. Preferably the marine oil has an iodine value of 100 or more, more preferably 120 or more. Preferably the marine oil has a C20+C22 content of 1wt.% or more. More preferably the marine oil is fish oil, such as oil from Tuna, Herring, salmon, tuna, Menhaden, anchovy, sardines, Skipjack or concentrates made thereof.

[0013] Marine oils as used in the present invention may be refined according to well-known refining procedures like neutralization to remove the free fatty acids, bleaching to remove colored components and contaminants, and deodorization to remove odiferous components. Variations on the existing procedures are also well known. Fatty acids can also be physically removed by means of a short path distillation equipment. The bleaching step can also be carried out in various manners. Silica, carbon and bleaching earth in various grades and concentrations are frequently used in the bleaching step.

[0014] The marine oils of the invention preferably are non-winterized marine oils generally having a solid fat content (SFC) of 5 to 25 wt% % at 5 C, preferably 5 to 20 wt%, more preferably 5 to 17 wt% and even more preferably 5 to 12 wt%. SFC is a well known parameter of fat and can be determined by conventional methods. It will be appreciated that the SFC at 5 C of the marine oil may vary depending on the source and the natural variation of the marine oil, but generally a SFC at 5 C of 5 wt% or more for marine oils is indicative of the non-winterized nature of said marine oil.

[0015] The first step of the process of the invention involves the optional heating of the marine oil to a temperature of 20-45 C to ensure that the marine oil is fully liquid.

[0016] It will be appreciated that if the starting oil is already fully liquid at ambient temperature, for example because a fully fresh oil is used, the heating step (a) can be omitted and the liquid oil can directly be used in the other steps of the process.

[0017] In the second step of the process of the invention the fully liquid marine oil is cooled in a scraped surface heat exchanger to a temperature of -5 to10 C.

[0018] Scraped surface heat exchangers are commonly used in the processing and cooling of food products such as oils, ice-cream and margarine and are often referred to as so-called A units. A units are conveniently used in the second step of the invention whereby the fully liquid marine oil is cooled to a temperature of -5 to 10 C, preferably to a temperature of 0-10 C, more preferably from 1 to 10 C. Depending on the size of the scraped surface exchanger the time to effect the cooling may vary but will generally be from 5 to 1000 seconds, more general from 10 to 100 seconds. Preferably the rate of cooling in the second step is from 0.1 to 1 degree per second, for example 0.5 to 2 C per second. If appropriate two or more A units may be used for example for sequential cooling.

[0019] After the cooling of step (b) the cooled marine oil is maintained in a steered vessel at a temperature of 3-10C for a period of 1-10 minutes.

[0020] A commonly used steered vessel in the food industry is a pin-steered unit which is often referred to as a C-unit. Preferably a C-unit is used in step c for maintaining the cooled marine oil. If desired more than one C-unit can be used for the steered maintenance, for example 2 A units may be used for cooling while 2 C units may be used for steered keeping, for example in the sequence A C A C.

[0021] The keeping time in the steered vessel is 15 seconds to 10 minutes while the temperature is maintained at a low temperature of 1-10 C, for example 2-6 minutes.

[0022] After the cooling for example in an A-unit and maintaining the oil, for example in a C-unit, the marine oil thus obtained is filled in a container, for example an oil drum, where after the container is closed and stored below 15 C for example in the cooled state (say at 3-10 C).

[0023] Surprisingly it has been found that the above process leads -even after 28 hours of storage to products which have a low viscosity. Generally products obtained by the process of the invention are uniquely characterized by a combination of a relatively high SFC (solid fat content) and a relatively low viscosity of less than 1000 mPa.s at 30 rpm at 10 C.

[0024] Although applicants do not wish to be bound by any theory it is believed that the specific processing sequence of the invention leads to the formation of an under cooled marine oil after step b wherein little to no fat crystals are yet formed, while step C results in the controlled crystallization of said under cooled marine oil leading to the formation of a stable suspension of small fat crystals with little to no crystal growth upon storage in the remainder of the liquid marine oil.

[0025] Surprisingly the suspension thus obtained does not suffer from an unacceptable increase in viscosity and/or sedimentation upon storage at ambient temperature.

[0026] In a second aspect the present invention relates to a marine oil obtainable by the process as described above.

[0027] Said marine oil is characterized by a solid fat content at 5 C of from 5 to 25 wt% in combination with a viscosity at 30 rpm and 10 C of less than 1000 mPa.s. Preferably the SFC at 5 C of said marine oil is from 5 to 20 wt%, more preferably 5 to 17 wt% and even more preferably 5 to 12 wt%.

[0028] The invention will now be illustrated by means of the following examples.

Viscosity measurement

[0029] A Brookfield Rotovisco meter Model DV-I+ was used to measure viscosity. Spindle LV3 was chosen as measuring probe. The viscosity was measured by lifting the sample and make sure the spindle was covered by the oil precisely to the indication level on the spindle, applying 30 rpm and waiting for 1 minute to read the viscosity at that shear rate.

EXAMPLE 1 (invention)

[0030] Fish oil obtained from Ocean Nutrition and having an SFC of 10.2 at 5C was heated to 40 C and processed as follows:

the oil was cooled in 32 seconds to 5C in an A unit followed by maintenance in a C-unit at 5C for 264 seconds. The resulting suspension was filled into pre-cooled containers at 5C and stored at this temperature.

[0031] After 28 hours of storage the suspension still was liquid and has a viscosity of 650 mPa.s measured at 10 C and 30 rpm.

EXAMPLE 2 (comparison)

[0032] Example 1 was repeated while using a fish oil having a SFC of 9.7 but omitting step c (maintenance in the C-unit). The resulting fish oil was fully solid after storage and the viscosity could not adequately be determined at 10 C.

EXAMPLE 3 (invention)

[0033] The fish oil of example 2 was cooled and stored in accordance to the method of example 1. The resulting suspension was after storage still fully liquid and has a viscosity at 10 C and 30 rpm of 676 mPa.s.

EXAMPLE 4 (invention)

[0034] A fish oil obtained from Ocean Nutrition Canada and having a SFC of 5.7 wt% at 5C was processed in accordance to example 1 resulting after storage in a liquid suspension having a viscosity of 600 mPa.s at 30 rpm and 10 C.

EXAMPLE 5 (comparison)

[0035] Example 2 was repeated while using the fish oil of example 4, resulting in a solid fish oil composition for which the viscosity at 10 C could not adequately be determined.

Claims

1. A process for the handling and storage of marine oils comprising the steps of:

(a) optionally heating the marine oil to a temperature of 20-45 C to ensure that the marine oil is fully liquid;

(b) Cooling the fully liquid marine oil in one or more scraped surface heat exchangers to a temperature of -5-10 C;

(c) maintaining the cooled marine oil obtained in step (b) in one or more a steered vessels at a temperature of -5-10 C for a total period of 15 seconds to 10 minutes;

(d) Storing the marine oil thus obtained in a closed container at a temperature below 15 C.

2. Process according to claim 1, wherein step (b) is carried out in one or more A units and step (c) in one or more C-units

3. Process according to claim 2, involving the use of 2 or more A units for cooling and 2 or more C units for steering.

4. Process according to claim 1, wherein the marine oil is a fish oil having an SFC at 5 C of 5 to 25 wt%, preferably 5 to 20 wt%, more preferably 5 to 17 wt% and even more preferably 5 to 12 wt%.

5. Marine oil suspension obtainable by the process of claim 1, 2 or 3.

6. Marine oil according to claim 5

having a SFC at 5 C of from 5 to 25 wt% and having after storage for 24 hours at 10 C a viscosity at 10C and 30rpm of less than 1000 mPa.s.

7. Marine oil according to claim 6 having a SFC at 5 C of from 5 to 20 wt%, more preferably 5 to 17 wt% and even more preferably 5 to 12 wt%.

Ansprüche

1. Verfahren zur Handhabung und Lagerung von Meeresölen, umfassend die Schritte:

(a) optionales Erhitzen von Meeresöl auf eine Temperatur von 20 bis 45°C, um sicherzustellen, dass das Meeresöl vollständig flüssig ist,

(b) Kühlen des vollständig flüssigen Meeresöls in einem oder mehreren Kratzwärmetauschern auf eine Temperatur von -5 bis 10°C

(c) Halten des in Schritt (b) gewonnenen gekühlten Meeresöls in ein oder mehreren gesteuerten Gefäßen auf einer Temperatur von -5 bis 10°C für eine Gesamtdauer von 15 Sekunden bis 10 Minuten,

(d) Lagern des so gewonnenen Meeresöls in einem geschlossenen Behälter bei einer Temperatur unter 15°C.

2. Verfahren nach Anspruch 1, wobei der Schritt (b) in einer oder mehreren A-Einheiten und der Schritt (c) in einer oder mehreren C-Einheiten durchgeführt wird.

3. Verfahren nach Anspruch 2, das die Verwendung von zwei oder mehreren A-Einheiten zum Kühlen und von zwei oder mehreren C-Einheiten zum Steuern einbezieht.

4. Verfahren nach Anspruch 1, wobei das Meeresöl ein Fischöl mit einem SFC bei 5°C von 5 bis 25 Gew.-%, vorzugsweise 5 bis 20 Gew.-%, bevorzugter 5 bis 17 Gew.-% und sogar bevorzugter 5 bis 12 Gew.-%, darstellt.

5. Meeresöl-Suspension, erhältlich durch das Verfahren nach Anspruch 1, 2 oder 3.

6. Meeresöl nach Anspruch 5 mit einem SFC bei 5°C von 5 bis 25 Gew.-% und nach Lagerung während 24 Stunden bei 10°C mit einer Viskosität bei 10°C und 30 U/min von weniger als 1000 mPa.s.

7. Meeresöl nach Anspruch 6 mit einem SFC bei 5°C von 5 bis 20 Gew.-%, bevorzugter von 5 bis 17 Gew.-% und sogar bevorzugter von 5 bis 12 Gew.-%.

Revendications

1. Procédé pour la manipulation et le stockage d'huiles marines comprenant les étapes de :

(a) chauffage éventuel de l'huile marine à une température de 20-45°C pour s'assurer que l'huile marine est complètement liquide ;

(b) refroidissement de l'huile marine complètement liquide dans un ou plusieurs échangeurs de chaleur à couche mince à une température de -5-10°C ;

(c) maintien de l'huile marine refroidie obtenue dans l'étape (b) dans une ou plusieurs cuves orientées à une température de -5-10°C sur une période totale de 15 secondes à 10 minutes ;

(d) stockage de l'huile marine ainsi obtenue dans un récipient fermé à une température inférieure à 15°C.

2. Procédé selon la revendication 1, dans lequel l'étape (b) est réalisée dans une ou plusieurs unités A et l'étape (c) dans une ou plusieurs unités C.

3. Procédé selon la revendication 2, impliquant l'utilisation de 2 unités A ou plus pour le refroidissement et de 2 unités C ou plus pour l'orientation.

4. Procédé selon la revendication 1, dans lequel l'huile marine est une huile de poisson ayant un SFC à 5°C de 5 à 25 % en masse, de préférence de 5 à 20 % en masse, encore mieux de 5 à 17 % en masse et bien mieux encore de 5 à 12 % en masse.

5. Suspension d'huile marine pouvant être obtenue par le procédé selon la revendication 1, 2 ou 3.

6. Huile marine selon la revendication 5 ayant un SFC à 5°C de 5 à 25 % en masse et ayant après stockage pendant 24 heures à 10°C une viscosité à 10°C et 30 tr/min inférieure à 1 000 mPa.s.

7. Huile marine selon la revendication 6 ayant un SFC à 5°C de 5 à 20 % en masse, encore mieux de 5 à 17 % en masse et bien mieux encore de 5 à 12 % en masse.