Composition comprising cholesterol

Abstract

Disclosed is a process for producing a cholesterol concentrate including the steps of (a) distilling a fish oil having no more than 2% free fatty acids in an admixture with an auxiliary fluid in a vacuum distillation column to obtain a first distillate and a first residue; and (b) distilling the first distillate in a vacuum distillation column to obtain a second distillate and a second residue, wherein the second residue includes the cholesterol concentrate.

Claims

1. A process for producing a composition comprising at least 20% by weight of cholesterol, based on 100% total weight of the composition, the process comprising the steps of: (a) distilling a fish oil having at most 2% by weight of free fatty acids, based on 100% total weight of the fish oil, in an admixture with an auxiliary fluid in a vacuum distillation column to obtain a first distillate and a first residue; and (b) distilling the first distillate in a vacuum distillation column to obtain a second distillate and a second residue, wherein (i) the second residue comprises the composition comprising at least 20% by weight cholesterol, based on the total weight of the composition, and (ii) the composition has a lower content of anthropogenic contaminants than the fish oil.

2. The process according to claim 1, wherein the weight ratio of the auxiliary fluid to the fish oil in the admixture is about 1:100 to 10:100.

3. The process according to claim 1, wherein the vacuum distillation column is a short-path distillation column.

4. The process according to claim 1, wherein the admixture is fed into the vacuum distillation column in step (a) at a rate, based on an auxiliary fluid free basis, of 1 to 150 kg/h per m.sup.2 of evaporator area.

5. The process according to claim 1, wherein step (a) is conducted at an evaporation temperature of 150 to 300 C. and a column pressure of 0.0001 to 0.5 mbar.

6. The process according to claim 5, wherein the evaporation temperature in step (a) is 180 to 280 C. and the column pressure is 0.001 to 0.1 mbar.

7. The process according to claim 1, wherein the first distillate is fed into the vacuum distillation column in step (b) at a rate of 10 to 350 kg/h per m.sup.2 of evaporator area.

8. The process according to claim 1, wherein step (b) is conducted at an evaporation temperature of 100 to 250 C. and a column pressure of 0.0001 to 0.5 mbar.

9. A process for producing a composition comprising at least 20% by weight of cholesterol, based on 100% total weight of the composition, the process comprising the steps of: (a) distilling a fish oil having at most 2% by weight of free fatty acids, based on 100% total weight of the fish oil, in an admixture with an auxiliary fluid in a vacuum distillation column to obtain a first distillate and a first residue; and (b) distilling the first distillate in a vacuum distillation column to obtain a second distillate and a second residue, wherein (i) the second residue comprises the composition comprising at least 20% by weight cholesterol, based on the total weight of the composition, (ii) the composition has a lower content of anthropogenic contaminants than the fish oil, and (iii) the auxiliary fluid is a fluid that distills at a temperature between about 150 C. and about 300 C. at a pressure of between about 0.0001 mbar and 5 mbar, and is miscible with cholesterol.

10. The process according to claim 9, wherein the auxiliary fluid comprises one or more ethyl esters of fatty acids.

11. The process according to claim 10, wherein the fatty acids are selected from myristic acid, palmitic acid, palmitoleic acid, stearic acid, oleic acid, linoleic acid, alpha-linolenic acid, and any combination thereof.

12. The process according to claim 10, wherein the fatty acids are unsaturated fatty acids.

13. A process for producing a composition comprising at least 20% by weight of cholesterol, based on 100% total weight of the composition, the process comprising the steps of: (a) distilling a fish oil having at most 2% by weight of free fatty acids, based on 100% total weight of the fish oil, in an admixture with an auxiliary fluid in a vacuum distillation column to obtain a first distillate and a first residue; and (b) distilling the first distillate in a vacuum distillation column to obtain a second distillate and a second residue, wherein (i) the second residue comprises the composition comprising at least 20% by weight cholesterol, based on the total weight of the composition, (ii) the composition has a lower content of anthropogenic contaminants than the fish oil, and (iii) the auxiliary fluid comprises one or more ethyl esters of fatty acids.

14. The process according to claim 13, wherein the fatty acids are selected from myristic acid, palmitic acid, palmitoleic acid, stearic acid, oleic acid, linoleic acid, alpha-linolenic acid, and any combination thereof.

15. The process according to claim 13, wherein the fatty acids are unsaturated fatty acids.

16. The process according to claim 13, wherein the distilling in step (b) is performed without the further addition of an auxiliary fluid.

17. The process according to claim 1, wherein step (a) is conducted at an evaporation temperature of about 180 to about 280 C. and a column pressure of about 0.001 to about 0.1 mbar.

Description

DETAILED DESCRIPTION OF THE INVENTION

(1) Fish oil contains, on the average, about 1% of total (free and esterified) cholesterol but this does not suffice alone to satisfy the cholesterol requirements of the shrimp or prawn, because as mentioned above, fish oil is included typically at 2 to 3% in the feed, and would thus contribute at most 0.02-0.03% of cholesterol only, instead of the 0.5 to 1.0% range for the dietary requirements of cholesterol for shrimp and prawn.

(2) As used here, the term fish oil refers to oils obtained from wild and farmed fish, crustaceans and other marine animals. Such oils are obtained from the whole body of the fish or from its by-products such as liver, head etc. Examples of such oils comprise anchovy oil, sardine oil, salmon oil, jack mackerel oil, menhaden oil, tuna oil, krill oil, squid oil, pollock oil, herring oil, capelin oil, cod liver oil and squid oil. Fish oils may be derived from a single species or mixtures of fish oils.

(3) Fish oil also refers to any fish oil from fish oil/meal factories, including degummed or bleached fish oil. Such oils, in addition to triglycerides, their main component, typically comprise between 1 to 10% of free fatty acids and about 2% or less of non-saponifiable matter composed primarily of cholesterol, glyceryl ethers, fatty alcohols, squalene and saturated hydrocarbons. (Young, F.V.K. The Chemical & Physical Properties of Crude Fish Oils for Refiners & Hydrogenators Fish Oil Bulletin No. 18, 1986). The average cholesterol content of fish oil is about 1%.

(4) In addition, conventional fish oils contain a great variety of toxic and/or harmful anthropogenic contaminants like polychlorinated biphenyls (PCB), DDT and its metabolites, dibenzo-dioxins (PCDDs), and dibenzo-furans (PCDFs), poly-aromatic hydrocarbons (PAH), pesticides and their degradation products, also known as persistent organic pollutants or POP's, which are resistant to environmental degradation and thus bio-accumulate.

(5) It is a surprising feature of the present invention that the cholesterol containing compositions obtained according to the process described below have a lower content of anthropogenic contaminants than the fish oils these compositions are obtained from.

(6) In the present invention a fish oil having low content of free fatty acids means a fish oil comprising at most 2% of free fatty acids. Such fish oil might come directly from a fish oil/meal factory or might correspond to a neutralized fish oil.

(7) Neutralized fish oil is a fish oil that has been processed through an alkali refining or neutralization step to reduce its free fatty acid content (FFA) to an acid value less than 2 mg KOH/g. Commonly referred to as neutralization, an alkali, e.g., NaOH or KOH, is added to the fish oil in a reactor and heated to react with the free fatty acids to form soaps, which are then centrifuged out. Washing with water completes the neutralization of the oil. Typically, fish oil is first subjected to a degumming step with phosphoric acid to reduce its phospholipids content, and then is neutralized with caustic soda to reduce its FFA content.

(8) In the present invention a vacuum distillation column may be a short-path distillation column having an internal condenser at the proximity of the heated surface or evaporator. The short-path distillation column is also known as a molecular distillation column when the distance between the evaporator and the condenser is comparable to the mean free path of the distillate molecules under the operating conditions. Therefore, in the present invention a vacuum distillation column may be a short-path distillation column, a molecular distillation column, or an equivalent thereof.

(9) a) Distilling the Admixture of Auxiliary Fluid with Fish Oil Having Low Content of Free Fatty Acids.

(10) Cholesterol having a melting point of 136 C. at the temperature of the condenser, which is preferably lower than 60 C., may form a very viscous slow flowing film at the condenser or may even solidify, thus clogging the condenser.

(11) An auxiliary fluid (AF) includes any fluid or mixture of fluids which distills at the vacuum distilling conditions disclosed below, and is also in a liquid state at the condenser temperature and dissolves or is miscible with cholesterol, thus reducing its concentration in the condensed film, therefore forming a free downward flowing fluid mixture at the condenser, and preventing clogging or fouling of the condenser. Any fluid or fluid mixture fulfilling the above requirements can be used as an auxiliary fluid, though preferred auxiliary fluids for the present invention include ethyl esters of unsaturated fatty acids or mixtures of ethyl esters of fatty acids mostly composed of unsaturated fatty acids, because such auxiliary fluids allow the use of lower condenser temperatures, which in turn improves the vacuum system performance and reduces the re-evaporation rate of the condensates, thereby improving the overall removal yield of the desired distillate.

(12) The admixture in an auxiliary fluid free basis is fed into the vacuum distillation column, generally at a rate from 1 to 150 kg/h per m.sup.2 of evaporating surface, preferably from 10 to 100 kg/h per m.sup.2.

(13) The proportion of auxiliary fluid relative to the fish oil having low content of free fatty acids can be from 1 to 10%, preferably from 2 to 8%.

(14) In an embodiment, the evaporation temperature is between 150 C. and 300 C., preferably between 180 C. and 280 C. In an embodiment, the column pressure is between 0.0001 mbar and 0.5 mbar, preferably between 0.001 and 0.1 mbar. In an embodiment, the evaporation temperature is between 150 C. and 300 C., preferably between 180 C. and 280 C. and the column pressure is between 0.0001 mbar and 0.5 mbar, preferably between 0.001 and 0.1 mbar.

(15) The distillation process results in the separation of a first distillate comprising cholesterol, other non-saponifiable matter of the fish oil and anthropogenic contaminants, and a first residue comprising fish oil with decreased content of cholesterol, non-saponifiable matter and anthropogenic contaminants. The first distillate condenses at the internal condenser. The first distillate and the first residue leave the column separately and are collected at the column exit. The first residue is a high quality fish oil suitable for human an animal consumption or for the elaboration of EPA and DHA concentrates.

(16) b) Distilling the First Distillate

(17) The first distillate is fed into a vacuum distillation column at a rate from 10 to 350 kg/h per m.sup.2 of evaporating surface, preferably from 50 to 200 kg/h per m.sup.2.

(18) In an embodiment, the evaporation temperature is between 100 C. and 250 C., preferably between 140 C. and 220 C. In an embodiment, the column pressure is between 0.0001 mbar and 0.5 mbar, preferably between 0.001 and 0.1 mbar. In an embodiment the evaporation temperature is between 100 C. and 250 C., preferably between 140 C. and 220 C., the column pressure is between 0.0001 mbar and 0.5 mbar, preferably between 0.001 and 0.1 mbar.

(19) The distillation process of the first distillate results in the production of a second distillate which condenses at the internal condenser, and a second residue comprising cholesterol and a content of anthropogenic contaminants, such as POPs and heavy metals, that is less than the fish oil.

(20) The second distillate and the second residue leave the vacuum distillation column separately and are collected at the column exit.

(21) The second residue is a composition comprising at least 20% of cholesterol and can be used as a cholesterol-containing ingredient for shrimp and prawn feed.

(22) A better understanding of the present invention may be obtained in light of the following examples which are set forth to illustrate, but are not to be construed to limit the present invention.

Comparative Example

(23) Cholesterol Concentrates from Anchovy Oil According to the Process of Patent GB 489623.

(24) Anchovy oil was processed according the to process disclosed in patent GB 489623, as embodied in Example 1 of GB 489623 for whale oil.

(25) 100 kg of the anchovy oil having a total cholesterol content of 7.4 mg/g was fed to a VK 83 short path distillation column and distilled at the temperature of 90 C. and the pressure of 0.003 mbar. The condenser temperature was set at 50 C. A distillate D1 in the amount of 1.6 kg was obtained together with a residue R1, the residual anchovy oil of the first distillation. The content of cholesterol of D1 was below 0.1%.

(26) Next, R1 was fed to a VK 83 short path distillation column and distilled at the temperature of 130 C. and the pressure of 0.002 mbar. The condenser temperature was set at 50 C. A distillate D2 in the amount of 1.1 kg was obtained together with a residue R2, the residual anchovy oil of the second distillation. The content of cholesterol of D2 was 0.8%.

(27) As the D2 split was low, around 1%, the following distillations were done using an auxiliary fluid of the composition shown in Table 1 below. It should be noted, that in similar circumstances, use of an auxiliary fluid may help prevent the clogging of the condenser, as disclosed in U.S. Pat. No. 2,126,467.

(28) R2 was admixed with 5 kg of auxiliary fluid of the composition shown in Table 1 and the mixture was fed to a VK 83 short path distillation column and distilled at the temperature of 180 C. and the pressure of 0.002 mbar. The condenser temperature was set to 20 C. A distillate D3 in the amount of 5.8 kg was obtained together with a residue R3, the residual anchovy oil of the third distillation. The content of cholesterol in D3 was 6.6%.

(29) Next, R3 was admixed with 5 kg of auxiliary fluid of the composition shown in Table 1 and the mixture was fed to a VK 83 short path distillation column and distilled at the temperature of 220 C. and the pressure of 0.002 mbar. The condenser temperature was set to 20 C. A distillate D4 in the amount of 5.3 kg was obtained together with a residue R4, the residual anchovy oil of the third distillation. The content of cholesterol in D4 was 6.2%.

(30) TABLE-US-00001 TABLE 1 Auxiliary fluid composition in Comparative Example. Fatty acid ethyl ester Composition concentration, % Myristic acid (C14:0) ethyl ester. 6.6 Palmitic acid (C16:0) ethyl ester 8.2 Palmitoleic acid (C16:1) ethyl ester 46.4 Stearic acid (C18:0) ethyl ester 1.9 Oleic acid (C18:1) ethyl ester 29.3 Linoleic acid (C18:2) ethyl ester 4.1 Alpha-linolenic acid (18:3) ethyl ester 3.5

(31) The total amount of cholesterol in the combined distillate fractions D2, D3 and D4 is 720.2 g, which is tantamount to a cholesterol recovery yield of 97.3%. However, the concentration of cholesterol in the combined distillate fractions is only 5.9%, therefore to provide 1% of cholesterol in the shrimp and prawn feed, 17 g of the combined distillate fractions is needed (per 100 g of feed), which rules out its use for such purpose, without further processing to achieve a cholesterol content of at least 20%.

(32) In addition, the total poly aromatic hydrocarbons (PAH) in the combined distillate fractions amounted to 88.5 ppb, which is higher than in the original anchovy oil.

(33) Concerning the residual fish oil of each distillation, Table 2 shows the combined EPA and DHA content, trans fatty acid content and acid number of each residue.

(34) TABLE-US-00002 TABLE 2 Combined EPA and DHA content, trans fatty acid content and acid number Anchovy Oil R1 R2 R3 R4 EPA + DHA, % 26.7 26.8 26.2 25.1 24.3 Trans Fatty Acids, % 0.3% 0.3% 0.4% 0.6% 0.7% Acid Number, mg KOH/g 6.3 0.3 0.1 <0.05 <0.05

(35) As can be observed in Table 2, the obtaining of cholesterol fractions by fractionation of the fish oil as disclosed in patent GB 489962, leads to an increase of the trans fatty content and a loss of (EPA+DHA), presumably due to polymerization in the residual fish oil. After four successive distillations, the trans fatty acid content increased by about 130% and the EPA+DHA content decreased by about 9%.

Example 1

(36) Cholesterol Concentrate from Neutralized Anchovy Oil

(37) Anchovy oil (same as used in Comparative Example) was neutralized with caustic soda and washed with hot water to yield to a neutralized anchovy oil with an acid number of 0.2 mg KOH/g.

(38) 250 kg of the neutralized anchovy oil was admixed with 15 kg of auxiliary fluid of the composition shown in Table 1.

(39) The admixture was fed to a VK 83 short path distillation column and distilled at the temperature of 253 C. and the pressure of 0.008 mbar. The condenser temperature was set at 20 C. A distillate D1 in the amount of 18 kg was obtained together with a residue R1, the residual anchovy oil of the distillation.

(40) Next, 15 kg of distillate D1 was fed to a VK 83 short path distillation column at the temperature of 155 C. and the pressure of 0.007 mbar. The condenser temperature was set to 20 C. A residue R2 in the amount of 3.5 kg was obtained. Table 3 below presents the analytical results for Example 1.

(41) TABLE-US-00003 TABLE 3 Analytical results for the Example 1. Neutralized Anchovy oil Distillate D1 Residue R2 Free cholesterol, mg/g 7.0 92.7 311.2 Total cholesterol, mg/g 7.4 93.0 325.4 Cholesterol ester.sup.1, mg/g 0.8 0.5 23.9 Non-saponifiable matter, % 1.38 13.40 33.12 Acid number, mg KOH/g 0.2 2.6 10.2 Dioxins, Furans and Dioxin like 1.41 12.83 0.21 PCBs, TEQ ppt (lower bound) PCB 209, ppb (lower bound) 18.53 225.27 2.95 Total PAHs, ppb 14.11 133.6 0.7 Pesticides, ppb 18.4 241.3 <LOQ .sup.1As mg of cholesteryl oleate/g of sample; LOQ: Limit of Quantification

(42) As can be observed, a formulated pellet comprising at most 3% of residue R2, a product of the process, is enough to meet the cholesterol requirement of shrimp and prawn. In addition, given that the total fat or lipid content in the formulated pellet for shrimps and prawns is from 6 to 9%, there remains an ample choice for additional sources of lipids, like fish and vegetable oils, to satisfy essential fatty acid requirements of the crustaceans, linoleic acid (LA), and alpha-linolenic acid (ALA), EPA and DHA.

(43) The concentration of cholesterol in residue R2 is 32.5% and the recovery yield was 73.8%.

(44) In addition, the cholesterol composition derived from the fish oil having a low free fatty acid content according to the process of the present invention has a lower contaminant content than the starting fish oil the composition is obtained from.

(45) Table 4 shows the combined EPA and DHA content, trans fatty acid content and acid number of residue R1 of Example 1.

(46) TABLE-US-00004 TABLE 4 Combined EPA and DHA content, trans fatty acid content and acid number of residue R1. Anchovy Neutralized Oil Anchovy Oil R1 EPA + DHA, % 26.7 26.9 27.0 Trans Fatty Acids, % 0.3% 0.3% 0.3% Acid Number, mg KOH/g 7.1 0.2 <0.05

(47) Superior results are demonstrated in Example 1, contrary to the process of GB 489623 which is unable to achieve such results.

(48) All references cited and/or discussed in this specification are incorporated herein by reference in their entireties and to the same extent as if each reference was individually incorporated by reference.