JP7737518B2 - lipid composition - Google Patents

Description

The present invention relates to a lipid composition containing polyunsaturated fatty acids.

In recent years, there have been many reports on the health benefits of polyunsaturated fatty acids, leading to increased demand. This is particularly evident in the popularity of canned seafood products among consumers. Many foods approved under the Functional Food Labeling System also boast the health benefits of these polyunsaturated fatty acids. Polyunsaturated fatty acids in this context refer to, for example, docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and alpha-linolenic acid. Fish oil, extracted and refined from seafood, is attracting attention as a material that is rich in these polyunsaturated fatty acids, especially DHA and EPA.

Oil and fat compositions containing polyunsaturated fatty acids may contain moisture. For example, Patent Document 1 describes a method for producing long-chain polyunsaturated fatty acid-containing oils and fats with a moisture content of 3% by weight or less, which includes a contact treatment step with rosemary and an adsorption treatment step with chemically activated activated carbon. The document states that the effect of this production method is to produce a long-chain polyunsaturated fatty acid-containing oil and fat with improved oxidation stability and good flavor using a simple method. Furthermore, Example 1 describes that 100 parts of deoxidized tuna oil (acid value = 0.10, peroxide value = 5.5, iodine value = 184, EPA + DHA content = 28.0%) was subjected to rosemary treatment, bleaching, and deodorization, and that the moisture content of the oil and fat was 0.01-0.10% throughout these steps. Furthermore, Patent Document 2 describes an oil having a fishy odor of less than 1.5, which oil comprises (i) at least about 30% by weight of one or more polyunsaturated fatty acids having at least four carbon-carbon double bonds; (ii) at least one first antioxidant; and (iii) a means for improving oxidative stability. This document also describes, as an example, an oil having a content of a predetermined polyunsaturated fatty acid of at least about 400 mg/g oil, with a moisture and volatile matter percentage of a maximum specified value of 0.02, resulting in a value of less than 0.01.

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) have been used in industrial and household products since the 1940s, but they are known to be difficult to decompose in the environment and to be persistent and bioaccumulate. In recent years, their health effects and environmental risks have been discussed in various countries.

Japanese Patent Application Publication No. 2017-171942 Japanese Patent Publication No. 2020-2364

Polyunsaturated fatty acids contain many double bonds in their chemical structure, and generally have poor oxidative stability and rapid flavor deterioration. This is because the double bonds of fatty acids easily react with active oxygen in the air through the generation of free radicals to form hydroperoxides. These hydroperoxides then continuously react with new free radicals, such as active oxygen, and decompose to produce compounds with distinctive odors, such as unsaturated aldehydes and ketones. The inventors' studies have found that moisture in oil and fat compositions may accelerate the decomposition of polyunsaturated fatty acids during storage. Therefore, a low moisture content in an oil and fat composition is desirable.
Conventional lipid evaluations based on acid value, peroxide value, and measurements by the Rancimat method measure compounds generated during decomposition (peroxide compounds, unsaturated aldehydes, ketones, etc.), but these do not necessarily reflect the unpleasant odors that humans perceive from degraded lipids. There are few reports that use odor components that contribute significantly to degraded lipids as indicators.

It is also desirable that PFAS be reduced in lipid compositions.

The inventors have discovered that the generation of odorous components can be reduced by controlling the moisture content of lipid compositions. They have also discovered that when the amount of a specific component (PFOS) is within a specific range, the distinctive odor of the oil composition upon deterioration is reduced, leading to the completion of the present invention.

The inventors also searched for components that contribute to the odor of lipids, and found approximately 100 components that can be detected by the human nose out of the hundreds of aroma components contained in lipids whose constituent fatty acids are polyunsaturated fatty acids. From these, they further identified important components that can be detected as odors even in small amounts (with a relatively low threshold). Furthermore, by individually measuring the concentrations of such components in lipids, they determined the degree to which it is important to suppress odorous components, and discovered that compositions with suppressed odors can be provided as described below.

The present application provides the following:
[1] A lipid composition comprising a lipid having a polyunsaturated fatty acid as a constituent fatty acid, wherein the composition ratio of polyunsaturated fatty acids to the total constituent fatty acids of the lipid is 15% or more;
The moisture content is 600 ppm or less,
A composition having 0.1 ppb or less of perfluorooctanesulfonic acid and 0.1 ppb or less of perfluorooctanoic acid.
[2] The composition according to 1, wherein the moisture content is 300 ppm or less.
[3] The composition according to any one of [1] and [2], further comprising an antioxidant.
[4] The composition according to any one of [1] to [3], wherein the content of 2,4-heptadienal is less than 2,600 ppm.
[5] The composition according to any one of [1] to [4], wherein the content of 2-(2-pentenyl)furan is less than 0.0095 ppm.
[6] A method for inspecting the degree of deterioration of a lipid composition containing a lipid having a polyunsaturated fatty acid as a constituent fatty acid, using as an indicator any one selected from the group consisting of 1-penten-3-one, 2,6-nonadienal, 2-methyl-2-cyclopentene-1-one, 2-(2-pentenyl)furan, 2,4-decadienal, 4-heptenal, and 2,4-heptadienal.

[7] A method for producing a lipid composition having a reduced unpleasant odor, comprising the steps of:
Obtaining from the feedstock a fraction having a water content of 600 ppm or less, a 2-(2-pentenyl)furan content of less than 0.0095 ppm, and a 2,4-heptadienal content of less than 2,600 ppm.
[8] A method for reducing an unpleasant odor in a lipid composition containing lipids having polyunsaturated fatty acids as constituent fatty acids, wherein the composition ratio of polyunsaturated fatty acids to the total constituent fatty acids of the lipids is 15% or more, characterized by obtaining a fraction that satisfies the following from a raw material:
The water content is 600 ppm or less, the 2-(2-pentenyl)furan content is less than 0.0095 ppm, and the 2,4-heptadienal content is less than 2.600 ppm.
[9] A lipid composition comprising a lipid having polyunsaturated fatty acids as its constituent fatty acids, wherein the composition ratio of polyunsaturated fatty acids to the total constituent fatty acids of the lipid is 15% or more, the water content is 600 ppm or less, the 2-(2-pentenyl)furan content is less than 0.0095 ppm, and the 2,4-heptadienal content is less than 2,600 ppm.
[10] A lipid composition comprising a lipid having a polyunsaturated fatty acid as a constituent fatty acid, wherein the composition ratio of the polyunsaturated fatty acid to the total constituent fatty acids of the lipid is 15% or more;
an acid value of 0.5 or less and a peroxide value of 2.0 meq/kg or less;
1. A composition having a water content of 600 ppm or less, a 2-(2-pentenyl)furan content of less than 0.0095 ppm, and a 2,4-heptadienal content of less than 2.600 ppm.

According to the present invention, a lipid composition with little unpleasant odor can be provided.
According to the present invention, a lipid composition can be provided in which organic perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA), which are types of perfluoroalkyl and polyfluoroalkyl compounds (PFAS), are below the detection limit.

Changes over time in the oxidized odor component (2,4-heptadienal) or 2-(2-pentenyl)furan in fish oil

When referring to the present invention, percentages, composition ratios, and concentrations (ppm, %, etc.) are indicated, they are based on mass unless otherwise specified.

<Lipid composition>
The present invention relates to a lipid composition containing a lipid having polyunsaturated fatty acids as its constituent fatty acids, in which the composition ratio of polyunsaturated fatty acids to the total constituent fatty acids of the lipid is relatively high.

(Fat)
Lipids include fats and oils, phospholipids, and glycolipids. Fat and oil include substances with triacylglycerol (triglyceride), diacylglycerol, or monoacylglycerol structures, fatty acids, and fatty acid esters. Phospholipids are lipids that contain phosphorus in the form of phosphate, and include glycerophospholipids and sphingosine phospholipids. Glycolipids include glyceroglycolipids and sphingosine glycolipids.

(Polyunsaturated fatty acids, fatty acid composition)
In the composition of the present invention, the composition ratio of polyunsaturated fatty acids to the total fatty acids constituting the lipid is relatively high.

Polyunsaturated fatty acids (polyenoic acids, PUFAs) are unsaturated fatty acids with two or more unsaturated bonds, particularly double bonds. Examples of polyunsaturated fatty acids include the n-6 fatty acids linoleic acid (C18:2), gamma-linolenic acid (C18:3), and arachidonic acid (C20:4), as well as the n-3 fatty acids alpha-linolenic acid (C18:3), eicosapentaenoic acid (EPA) (C20:5), and docosahexaenoic acid (DHA) (C22:6). Preferred examples of polyunsaturated fatty acids are n-3 polyunsaturated fatty acids or polyunsaturated fatty acids with four or more unsaturated bonds, more preferably five or more. Even more preferred examples are EPA and/or DHA, with DHA being even more preferred. In the following, we will use as an example lipids containing DHA as a constituent fatty acid among lipids containing polyunsaturated fatty acids, but the explanation also applies to lipids containing other polyunsaturated fatty acids.

The lipids contained in the compositions of the present invention may contain fatty acids other than polyunsaturated fatty acids, i.e., saturated fatty acids (SFA) and monoenoic fatty acids (monounsaturated fatty acids, MUFA), as constituent fatty acids. Examples of such constituent fatty acids include myristic acid (C14:0), palmitic acid (C16:0), stearic acid (C18:0), oleic acid (C18:1, n9c), and eicosenoic acid (C20:1).

In a preferred embodiment, the composition ratio of polyunsaturated fatty acids in the total fatty acids of lipids is 15% or more, preferably 18% or more, more preferably 20% or more, even more preferably 22% or more, and even more preferably 50% or more, regardless of the type of polyunsaturated fatty acid.The upper limit of the composition ratio of polyunsaturated fatty acids in the total fatty acids is not particularly limited, regardless of the type of polyunsaturated fatty acid, but for example, it may be 82% or less, 80% or less, preferably 75% or less, more preferably 70% or less, and even more preferably 60% or less.In some cases, it may be 46% or less, preferably 40% or less, more preferably 35% or less, and even more preferably 30% or less.This composition ratio is particularly suitable when polyunsaturated fatty acid is DHA.
In the present invention, when the composition ratio of a specific fatty acid to the total constituent fatty acids of a lipid is expressed as a percentage, it is based on the area of the chart obtained when the fatty acid composition is analyzed by gas chromatography, unless otherwise specified.

The content of components other than lipids in the composition of the present invention is, for example, 10.0% or less, preferably 8.0% or less, more preferably 7.5% or less, and even more preferably 7.0% or less.

The iodine value of the lipid composition of the present invention is, for example, 155 g/100 g or more, preferably 160 g/100 g or more, and, for example, 250 g/100 g or less, preferably 220 g/100 g or less, more preferably 210 g/100 g or less. The iodine value can be measured by the WIJS method.

The acid value of the lipid composition of the present invention (the number of mg of potassium hydroxide required to neutralize the free fatty acids contained in 1 g of fat or oil) is, for example, 0.5 or less, preferably 0.4 or less, more preferably 0.3 or less, and even more preferably 0.2 or less.
The lipid composition of the present invention preferably has a peroxide value (sometimes referred to as "POV") of 2.0 meq/kg or less, more preferably 0.5 meq/kg or less. The peroxide value represents the amount of peroxides, which are primary products formed in the early stage of autoxidation of fats and oils.
The acid value and peroxide value can be measured by the method described in the Standard Methods for the Analysis of Fats, Oils and Related Materials, 2003 edition (compiled by the Japan Oil Chemists' Society).

The saponification value (the number of mg of potassium hydroxide required to saponify 1 g of fat or oil) of the lipid composition of the present invention is, for example, 220 or less, preferably 210 or less, more preferably 200 or less, and even more preferably 190 or less. Regardless of the upper limit, the lower limit may be, for example, 150 or more, 160 or more, or 170 or more.

(raw materials)
The composition of the present invention can be prepared using various natural products containing lipids whose constituent fatty acids are polyunsaturated fatty acids as raw materials. Examples of raw materials include fish oil and microorganisms. Fish oil includes those obtained from fish meat and fish eggs. Examples of microorganisms include Labyrinthulae. Labyrinthulae are closely related to algae such as brown algae and diatoms, but are heterotrophic eukaryotic microorganisms that do not perform photosynthesis and are known to accumulate lipids whose constituent fatty acids are polyunsaturated fatty acids such as DHA and EPA within their cells.

The type of fish from which the fish oil is derived is not particularly limited, as long as it contains a large amount of lipids whose constituent fatty acids are polyunsaturated fatty acids, but it is preferable that the fish be from the Scombrinae, Swordfish, Marlinidae, Salmonidae, Clupeidae, Gadidae, or Carangidae families. The subfamily Scombrinae includes the tribe Scombridae (genus Tumerica, genus Scombridae), the tribe Scombridae (genus Scombridae, Scombridae, genus Scombridae), the tribe Scombridae (genus Dogtoothfin, Scombridae, genus Cybiosarda, genus Orcynopsis), the tribe Scombridae (genus Bonito, Scombridae, Scombridae, Scombridae, Scombridae, genus Thunnus), but more preferably tuna (bluefin tuna, albacore tuna, yellowfin tuna, Indian tuna), swordfish, skipjack tuna, Scombridae (big mackerel, flat mackerel), yellowfin tuna, chub mackerel, yellow mackerel, and Scombridae. The family Salmonidae includes the genera Salmonella, Salmonella, Salmonella, and Sakhalin, but more preferably fish of the genera Salmonella or Salmonella. Examples of fish in the genus Salmon include chum salmon, coho salmon (coho salmon, silver salmon), pink salmon, cherry salmon, yamame salmon, Taiwan salmon, satsukimasu, amago, Biwa trout (ame-no-uo), rainbow trout (steelhead), king salmon, sockeye salmon, kokanee, and kunimasu. Examples of fish in the genus Salmon include Atlantic salmon and brown trout. The Clupeidae family includes the subfamilies Clupeinae, Clupeinae, Sardininae, and Ehiravinae, with Clupeinae and Clupeinae being preferred. Examples of fish in the genus Clupe include herring, Atlantic herring, and sardines (pilchard, round herring, and anchovy). The Gadidae family includes the genera Gadus, Micromesistius, Gadiculus, Trisopterus, Microgadus, Eleginus, Merlangius, Melanogrammus, Pollachius, Boreogadus, and Arctogadus, with fish in the genus Gad being preferred. Examples of fish in the genus Gad include Alaska pollock, Pacific cod, Pacific cod, and Greenland cod. The Carangidae family includes the subfamily Caranginae, Bonitoinae, Caranginae, and Caranginae, with fish in the Caranginae being preferred. The Caranginae subfamily includes the genera Siberian amberjack, Siberian amberjack, Seriola serricola, and Seriola serricola, with fish in the Seriola genus being preferred. Examples of fish in the Seriola genus include yellowtail, amberjack, and amberjack.

In the present invention, the term "fish roe" refers to any degree of processing, unless otherwise specified. Therefore, in the present invention, the term "fish roe lipid composition" also includes lipid compositions made from fish roe extract, fish roe oil, purified fish roe oil, or any of their dried products. In a particularly preferred embodiment, the composition of the present invention is prepared from salmon roe, salmon roe, herring roe, herring roe, or any of their processed products.

When the raw material is a microorganism, the type of microorganism is not particularly limited, as long as it contains a large amount of lipids whose constituent fatty acids are polyunsaturated fatty acids. Labyrinthula microorganisms are broadly divided into Labyrinthulids (Labyrinthulidae) and Thraustochytrids (Thraustochytrids) (Thoraustochytrids), with the former being more suitable in terms of growth and lipid accumulation. More specific examples of Labyrinthula microorganisms include microorganisms belonging to the genera Aurantiochytrium, Thraustochytrium, Ulkenia, Parietychytrium, Labyrinthula, Aplanochytrium, Oblongichytrium, and Schizochytrium.

(moisture)
The moisture content of the composition of the present invention is preferably low. According to the studies of the present inventors, when moisture in the lipid composition exceeds a certain concentration, deterioration is accelerated, the amount of aroma components increases, and the oxidized odor is felt more strongly. Regardless of the concentration of other components, the moisture content in the composition is 600 ppm or less, preferably 500 ppm or less, more preferably 400 ppm or less, even more preferably 350 ppm or less, even more preferably 300 ppm or less, and even more preferably 250 ppm or less. The lower limit of the moisture content in the composition, regardless of the upper limit, is 10 ppm or more, preferably 20 ppm or more, more preferably 30 ppm or more, even more preferably 40 ppm or more, even more preferably 50 ppm or more, even more preferably 80 ppm or more, even more preferably 100 ppm or more, even more preferably 120 ppm or more, and even more preferably 150 ppm or more.

In the present invention, the amount or concentration of water refers to a value measured using a method for measuring water in foods, unless otherwise specified. Those skilled in the art will be able to select an appropriate measurement method depending on the form of the oil or fat composition and the level of water contained therein. Examples of measurement methods include the Karl Fischer method, a method using a water activity measuring device (water activity measurement method), and a method using a moisture meter (loss on drying method). There are two Karl Fischer methods: volumetric titration and coulometric titration. Generally, volumetric titration is selected when the water content is 1% or more, and coulometric titration is selected when the water content is 1% or less.

(oxidized odor indicator component)
The present invention relates to components that indicate oxidized odor (sometimes referred to as unpleasant odor) in lipid compositions containing lipids whose constituent fatty acids are polyunsaturated fatty acids. The following seven components were identified by the inventors as components that can be detected even in small amounts (relatively low threshold) and serve as indicators of the oxidized odor of polyunsaturated fatty acids. This application is the first to clarify the relationship between these components and the oxidized odor of polyunsaturated fatty acids. Furthermore, this application is the first to show the absolute amount, rather than a relative value, of 2-(2-pentenyl)furan and/or 2,4-heptadienal contained in lipid compositions with an oxidized odor (see the Examples section).

1-penten-3-one,
2,6-nonadienal,
2-methyl-2-cyclopentene-1-one,
2-(2-pentenyl)furan,
2,4-decadienal,
4-heptenal, and
2,4-heptadienal

In the case of a component that contains optical isomers based on asymmetric carbons or geometric isomers based on double bonds, unless otherwise specified, any one of these may be used as an indicator of oxidized odor, or a mixture of these may be used as an indicator of oxidized odor. Below, the concentration of each of the seven components in the composition is explained, but in the case of a component that contains optical or geometric isomers, this concentration refers to the total concentration of those isomers unless otherwise specified.

From the standpoint of ensuring that the oxidized odor is acceptable for food, the concentration of 2-(2-pentenyl)furan in the composition is less than 0.0095 ppm, preferably 0.0088 ppm or less, more preferably 0.0086 ppm or less, even more preferably 0.0083 ppm or less, and even more preferably 0.0080 ppm or less, regardless of the concentrations of other ingredients.

Furthermore, the concentration of 2,4-heptadienal in the composition is less than 2.600 ppm, preferably 2.400 ppm or less, more preferably 2.350 ppm or less, even more preferably 2.300 ppm or less, even more preferably 2.200 ppm or less, and even more preferably 2.100 ppm or less, regardless of the concentrations of other components. More specifically, the concentration of (E,Z)2,4-heptadienal in the composition is less than 2.590 ppm, preferably 2.350 ppm or less, more preferably 2.280 ppm or less, even more preferably 2.240 ppm or less, even more preferably 2.200 ppm or less, and even more preferably 2.100 ppm or less, regardless of the concentrations of other components. The concentration of (E,E)2,4-heptadienal in the composition is less than 0.028 ppm, preferably 0.026 ppm or less, more preferably 0.025 ppm or less, even more preferably 0.024 ppm or less, and even more preferably 0.023 ppm or less, regardless of the concentrations of other components.

It is preferable that either 2-(2-pentenyl)furan or 2,4-heptadienal satisfy these requirements, and it is even more preferable that both satisfy these requirements.

The concentration of 1-penten-3-one in the composition is less than 0.139 ppm, preferably 0.138 ppm or less, more preferably 0.130 ppm or less, even more preferably 0.1 ppm or less, and even more preferably 0.07 ppm or less, regardless of the concentrations of other ingredients.

The concentration of 2,6-nonadienal in the composition is less than 0.005 ppm, preferably 0.0045 ppm or less, more preferably 0.004 ppm or less, even more preferably 0.0035 ppm or less, and even more preferably 0.003 ppm or less, regardless of the concentrations of other ingredients.

The concentration of 2,4-decadienal in the composition is less than 0.11 ppm, preferably 0.1 ppm or less, more preferably 0.075 ppm or less, even more preferably 0.05 ppm or less, and even more preferably 0.025 ppm or less, regardless of the concentrations of other ingredients.

The amount or concentration of oxidized odor components can be measured using techniques well known to those skilled in the art, such as analyzing components collected using the dynamic headspace method with a gas chromatograph-mass spectrometer (GC-MS).

The above seven components can be used as indicators when testing the degree of deterioration of lipid compositions containing lipids whose constituent fatty acids are polyunsaturated fatty acids. The above values, shown as concentrations in the composition, can be used as appropriate to determine the judgment value for each component. For example, when judging a lipid composition using 1-penten-3-one as an indicator, the concentration of this component in the target lipid composition is measured, and if it is less than 0.139 ppm, preferably 0.138 ppm or less, more preferably 0.130 ppm or less, even more preferably 0.100 ppm or less, and even more preferably 0.070 ppm or less, it can be determined that there is no oxidative deterioration.

Conventional lipid evaluations based on acid value, peroxide value, and measurements by the Rancimat method measure the total amount of oxidation products. In contrast, the evaluation of lipid compositions using indicator components of oxidized odor disclosed in this application directly measures components that contribute significantly to oxidized odor, allowing for evaluations that are closer to sensory characteristics.

(Per- and polyfluoroalkyl substances (PFAS))
The composition of the present invention has reduced perfluoroalkyl and polyfluoroalkyl compounds (PFAS). PFAS is a general term for over 4,730 types of organic fluorine compounds. Representative PFAS include perfluorooctane sulfonic acid (PFOS) (the prefix "per" is sometimes referred to as "per"; the same applies below), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorohexanesulfonic acid (PFHxS), perfluorobutanesulfonic acid (PFBS), perfluorobutanoic acid (PFBA), perfluoropentanesulfonic acid (PFPeS), perfluoropentanoic acid (PFPeA), perfluorohexanoic acid (PFHxA), perfluoroheptanesulfonic acid (PFHpS), perfluoroheptanoic acid (PFHpA), and perfluorooctane sulfonic acid. Perfluorooctanoic acid (PFOSA), perfluoro-3,7-dimethyloctanoic acid (PF-3,7-DMOA), perfluorodecanesulfonate (PFDS), perfluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUnA), perfluorododecanoic acid (PFDoA), perfluorotridecanic acid (PFTrA), perfluorotetradecanoic acid (PFTA), 7H-dodecafluoroheptanoic acid (HPFHpA), 2H,2H-perfluorodecanoic acid (HPFDA), 2H,2H,3H,3H-perfluoroundecanoic acid (HPPFUnA), 1H,1H,2H,2H-perfluorohexanesulfonic acid (4:2FTS), 6:2 fluorotelomer sulfonate (6:2FTS).

In one embodiment of the composition of the present invention, the concentration of at least one of the PFASs, PFOS and PFOA, is, for example, 1 ppb or less, preferably 0.1 ppb or less, more preferably 0.05 ppb or less, and even more preferably 0.01 ppb or less. In a preferred embodiment, the concentration of the PFASs, PFOS and PFOA, is, for example, 1 ppb or less, preferably 0.1 ppb or less, more preferably 0.05 ppb or less, and even more preferably 0.01 ppb or less.

The concentration of PFAS in a composition can be measured using methods for measuring PFAS in food. An example of a measurement method is liquid chromatography-mass spectrometry (LC-MS/MS).

PFAS in compositions can be reduced by treatment with adsorbents such as activated carbon. PFOS and PFOA, two representative PFASs, are water-soluble and have an affinity for proteins, so they can be reduced by washing with water, separating oil from water, and treating with activated carbon.

(Adjustment of water content, method for producing lipid composition)
The water content of the composition can be adjusted by treatment with an adsorbent such as activated carbon or by a distillation process. One preferred treatment is a combination of treatment with an adsorbent such as activated carbon and distillation, or a repeated treatment of these.
The composition of the present invention can be prepared, for example, by subjecting oils and fats containing highly unsaturated fatty acids obtained from seafood or microalgae, which have been deoxidized and degummed as necessary, to a combined treatment of reduced pressure distillation, adsorption, and steam distillation. There are no limitations on the oil and fat treatment conditions, and general-purpose conditions applicable to oils and fats containing highly unsaturated fatty acids can be used.
For example, vacuum distillation can be carried out at 1 to 100 mTorr, preferably 5 to 50 mTorr, with short residence times.
For example, adsorption can be carried out by treating the oil with 0.05 to 10% by weight, preferably 0.1 to 5% by weight, of activated carbon and/or activated clay at a temperature of 50 to 120°C, preferably 50 to 100°C, for 5 to 120 minutes, preferably 10 to 80 minutes.
For example, steam distillation can be carried out using a steam amount of 0.5% by weight or more, preferably 1 to 10% by weight, based on the oil, at a temperature of 120 to 220°C, preferably 130 to 200°C, at 10 Torr or less, preferably 8 Torr or less, for 30 to 180 minutes, preferably 60 to 180 minutes.
Each step can be repeated as necessary. In a preferred embodiment, steam distillation is performed, followed by vacuum distillation and treatment with an adsorbent. It is more preferred to perform vacuum distillation and treatment with an adsorbent before steam distillation.

(Antioxidant)
The composition of the present invention may contain an antioxidant (also referred to as an antioxidant). The antioxidant is not particularly limited, and various antioxidants can be used as long as they are acceptable as food additives. Examples of antioxidants include butylhydroxytoluene (BHT), butylhydroxyanisole (BHA), vitamins (e.g., tocopherol, retinol, β-carotene, ascorbic acid), vitamin derivatives (e.g., retinyl acetate, retinyl palmitate, ascorbyl palmitate, magnesium ascorbyl phosphate, tocophoryl acetate), flavonoids, polyphenol compounds, citric acid, nordihydroguaiaretic acid, thioctic acid (lipoic acid), dihydrolipoic acid, glycolic acid, and esters thereof. Preferably, it is one that is highly effective against polyunsaturated fatty acids, and examples of such include BHT, tocopherol (vitamin E, V.E), BHA, rosemary extract (obtained from rosemary leaves or flowers and containing carnosic acid, carnosol, and rosmanol as main components), catechin, gallic acid, and propyl gallate.

The amount of antioxidant in the composition can be adjusted appropriately. Specifically, it can be 50 ppm or more, preferably 100 ppm or more, more preferably 200 ppm or more, and even more preferably 300 ppm or more. There is no particular upper limit, but it can be, for example, 30,000 ppm or less, 20,000 ppm or less, preferably 15,000 ppm or less, more preferably 10,000 ppm or less, and even more preferably 9,000 ppm or less. When multiple types of antioxidants are used, it is recommended that they be used in such a way that the total amount is the above amount.

<Others>
(Route of administration, etc.)
The compositions of the present invention are suitable for oral ingestion or administration.

(Application)
The composition of the present invention can be used for ingesting polyunsaturated fatty acids. Furthermore, the composition can be used for various applications based on the functions of polyunsaturated fatty acids. Known functions of DHA, a type of polyunsaturated fatty acid, include platelet aggregation inhibition, blood triglyceride reduction, blood cholesterol reduction, brain function improvement, memory maintenance, and sleep quality improvement. Known functions of DHA-bound phospholipids include allergy suppression, liver function improvement, erythrocyte deformability improvement, stroke prevention, skin whitening, and cognitive function improvement. It has also been reported that DHA-bound phospholipids, such as PDPC, affect the differentiation and proliferation of HL-60 human promyelocytic leukemia cells (J. Jpn. Oil Chem. Soc. 46(4), 1997).

In a preferred embodiment, the composition can be used to improve metabolic syndrome, lipid metabolism, glucose metabolism, and cognitive function. Metabolic syndrome refers to a condition in which visceral obesity, combined with high blood pressure, hyperglycemia, or dyslipidemia, predisposes to heart disease, stroke, and other conditions. This condition is diagnosed when a patient's waist circumference is 85 cm or greater in men and 90 cm or greater in women, and two or more of the following three variables are outside the normal range: blood pressure (systolic (maximum) blood pressure) ≥ 130 mmHg and/or diastolic (minimum) blood pressure ≥ 85 mmHg; blood glucose (fasting blood glucose) ≥ 110 mg/dL; and lipids (hypertriglyceridemia, i.e., blood triglycerides ≥ 150 mg/dL and/or hypo-HDL cholesterolemia, i.e., blood HDL < 40 mg/dL). Targets for improving cognitive function include patients with Alzheimer's disease.

(subject)
The compositions of the present invention are suitable for ingesting or administering polyunsaturated fatty acids to subjects, including infants, children, adults (15 years of age or older), middle-aged and elderly people (65 years of age or older), those currently recovering from illness, pregnant women, women who have just given birth, men, and women.

(dose)
The intake/administration amount of the composition of the present invention can be 100 mg to 10,000 mg per day, preferably 300 mg to 5,000 mg, and more preferably 500 mg to 2,500 mg. According to the "Dietary Reference Intakes for Japanese (2015 Edition)" published by the Ministry of Health, Labor and Welfare, the dietary reference intake amount for n-3 fatty acids is 2.1 to 2.4 g/day for men aged 15 years or older, 1.6 to 2.0 g/day for women aged 15 years or older, and 1.8 g/day for pregnant and lactating women. The composition of the present invention can also be used within these ranges.

The composition of the present invention may be administered or ingested once a day, or multiple times a day, for example, three times with each meal. Because the composition uses active ingredients derived from fish eggs, which are widely consumed, it is suitable for long-term ingestion. Therefore, it may be ingested repeatedly or over a long period of time, for example, for three days or more, preferably one week or more, more preferably four weeks or more, and particularly preferably one month or more.

(form)
The composition of the present invention can be used as a raw material in the production of general foods, health functional foods, pharmaceuticals, and quasi-drugs. General foods, etc., include not only those for humans but also those for non-human animals, unless otherwise specified. Health functional foods include foods for specified health uses, foods with nutrient functions, and foods with functional claims. Foods, unless otherwise specified, include not only solids but also liquids, such as beverages, energy drinks, liquid diets, and soups. Foods encompass all health foods, including special-purpose foods, nutritional supplements, health supplements, supplements (e.g., various dosage forms such as capsules and tablets), and beauty foods (e.g., diet foods).

In one preferred embodiment, a food composition or pharmaceutical composition in the form of a supplement or beverage containing the composition of the present invention is provided.

(Other ingredients, additives)
The composition of the present invention, and food or pharmaceutical compositions containing the composition of the present invention, may contain other active ingredients or nutritional components acceptable for use as foods or pharmaceuticals. Examples of such ingredients include vitamins (e.g., vitamin A, vitamin B1, vitamin B2, vitamin B6, vitamin B12, vitamin C, vitamin D, vitamin E, vitamin K, biotin, folic acid, pantothenic acid, and nicotinic acids), minerals (e.g., copper, zinc, iron, cobalt, and manganese), amino acids (e.g., lysine, arginine, glycine, alanine, glutamic acid, leucine, isoleucine, and valine), carbohydrates (glucose, sucrose, fructose, maltose, trehalose, erythritol, maltitol, palatinose, xylitol, and dextrin), dietary fiber, proteins, and other lipids.

The composition of the present invention, and food compositions or pharmaceutical compositions containing the composition of the present invention, may further contain additives acceptable for use as foods or pharmaceuticals. Examples of such additives include antioxidants, stabilizers, colorants, preservatives, inert carriers (solid or liquid carriers), excipients, surfactants, binders, disintegrants, lubricants, solubilizers, suspending agents, coating agents, buffers, pH adjusters, emulsifiers, sweeteners, flavors, acidulants, and natural products.

(others)
The present invention can be applied to foods containing a large amount of lipids containing polyunsaturated fatty acids as constituent fatty acids. The amount of DHA contained per 100 g of edible portion can be 500 mg or more, preferably 1000 mg or more, more preferably 1250 mg or more, even more preferably 1500 mg or more, even more preferably 2000 mg or more, and even more preferably 2500 mg or more.

The composition of the present invention or a food composition containing the same can be labeled with information about the presence of polyunsaturated fatty acids, the functions of these components, and the fact that it can be used for ingesting them. It can also be labeled with information about specific targets for which it is recommended (e.g., those concerned about triglycerides, those wanting to take DHA, etc.). Labeling can be direct or indirect. Examples of direct labeling include inscriptions on tangible objects such as the product itself, packaging, containers, labels, and tags. Examples of indirect labeling include advertising and promotional activities by place or means such as flyers, pamphlets, exhibitions, in-store displays, websites, books, newspapers, magazines, television, radio, mail, email, and voice.

The present invention will be explained in more detail below using examples, but the present invention is not limited to the following examples.

[Search and determination of key aroma components responsible for the oxidized odor of lipids containing polyunsaturated fatty acids]
1. Estimation of important oxidized odor components <Accelerated deterioration>
A fish oil product sold by Maruha Nichiro Corporation that met the following specifications (DHA content in the oil is 19% by mass or more, and contains gamma-tocopherol as an antioxidant) was filled into 110 mL glass vials (product number: 9-852-10) manufactured by AS ONE Corporation and stored in an incubator set at 40°C for two weeks. After storage, oxygen was sealed in and the vials were stored at 40°C for an additional week.

The products used meet the following standards:
Acid value: 0.5 mg/g or less Iodine value: 160-200 g/100 g
Saponification value: 170 to 200 mg/g
Peroxide value: 2.0 meq/kg or less Color: 4 or less (Gardner)

The resulting deteriorated oil had a pungent, metallic smell and was confirmed to have an oxidized odor. The DHA content was measured using the following method.

<DHA content measurement>
Six mg of methyl tricosanoate was weighed into a stoppered test tube as an internal standard, followed by 30 mg of lipid. Next, 1.5 mL of 0.5 mol/L NaOH methanol solution was added, and after nitrogen purging, the mixture was heated at 100°C for 9 minutes (the step of forming the free form from the glyceride). After cooling, 2 mL of boron trifluoride methanol complex/methanol solution was added, and after nitrogen purging, the mixture was heated at 100°C for 7 minutes (the step of methyl esterification of the free form). After cooling, 3 mL of trimethylpentane (containing 0.1% dibutylhydroxytoluene) was added and stirred for 3 minutes. 7 mL of distilled water was added and stirred for 30 seconds. The supernatant trimethylpentane layer was separated and diluted 50-fold with trimethylpentane (containing 0.1% dibutylhydroxytoluene) (the purification step). The mixture was dehydrated over anhydrous sodium sulfate and analyzed by gas chromatography. The DHA content was calculated from the area value and weight value of methyl tricosanoate and the area ratio of DHA (g/100 g). The composition ratio of DHA to all constituent fatty acids was the ratio of the area value corresponding to DHA to the area value of the total peak area of the chromatogram excluding the peaks derived from the dilution solvent, methyl tricosanoate, and dibutylhydroxytoluene.

Gas chromatograph operating conditions Model: GC-17A (Shimadzu)
Detector: FID
Column: J&W DB-23 0.25 mm x 30 m
Temperature: Inlet 250℃
Column 50℃ (1 min) → 170℃ (10℃/min) → 210℃ (1.2℃/min)
Detector 250℃
Gas flow rate: He (carrier gas) 113 kPa (1 min) → 164 kPa (4.2 kPa/min) →
181 kPa (0.5 kPa/min)
Nitrogen (make-up gas) 90 kPa
Hydrogen 60 kPa
Air 50 kPa

<Aroma extraction>
The above deteriorated oil (40 g) was placed in an Erlenmeyer flask, and dichloromethane (Junsei Chemical, pesticide analysis grade) (120 mL) was added to extract the aroma of the deteriorated oil using the Solvent-Assisted Flavor Extraction (SAFE) method. The resulting extract was concentrated and made to a constant volume of 10 mL.

<Aroma analysis method 1>
An Agilent Technologies GC-MS (7890-5977 MSD) and Gerstel MPS, DHS, and TDU were used. The GC-MS was equipped with a Gerstel ODP3 and single PFC (described below). 300 μL of aroma extract solution placed in a 10 mL glass vial was heated to 80°C under a nitrogen stream and circulated for 30 minutes to adsorb the aroma components onto a TDU tube (Gerstel Carbopack B). The aroma components were then desorbed at 280°C in the TDU, re-trapped in a CIS, and desorbed at 250°C. The aroma components were then desorbed by heating the CTS2 to 280°C and introduced into an analytical column (InertCap Pure Wax, length 60 m, inner diameter 0.25 mm, film thickness 0.25 μm).
The temperature was raised to 230°C at a rate of 5°C/min and maintained at this temperature for 20 minutes. The average linear velocity was 20.6 cm/sec.
The components were estimated using the NIST library, and the compounds were identified by measuring commercially available standards. For 2-(2-pentenyl)furan, the standard compound was synthesized according to the method of Smagla et al. (MS Smagla, et al. J. Am. Oil Chem. Soc. 1979, 56, 516.).

<Synthesis of 2-(2-Pentenyl)furan>
Under a nitrogen atmosphere, furan (2.5 mL) and tetrahydrofuran (30 mL) were added to a 100 mL two-necked round-bottom flask and cooled to -25°C using a dry ice-ethanol mixture. 25 mL of n-butyllithium (1.6 M in hexane) was then added dropwise and stirred at -15°C for 4 hours. After stirring, (E)-1-bromo-2-pentene (5 g) was added dropwise and stirred at -15°C for 1 hour, followed by overnight reaction at room temperature.
The next morning, ice was added to the reaction solution in small portions to quench the reaction. The mixture was extracted twice with diethyl ether (30 mL), and the organic layer was dehydrated over anhydrous sodium sulfate. Gravity filtration was performed, and the filtrate was purified by atmospheric and reduced-pressure distillation to obtain 2.21 g (48% yield) of 2-(2-pentenyl)furan (a colorless, clear solution with a boiling point of 65-67°C (3.0 kPa)). This 2-(2-pentenyl)furan was used as a trans-enriched standard in the following analyses.

<Aroma analysis method 2>
An Agilent Technologies GC-MS (7890-5977 MSD) and a Gerstel MPS and TDU were used. After transferring the TDU tube (2,6-diphenylene oxide polymer) to the TDU, the aroma compounds were desorbed at 300°C, re-trapped in a CIS, and desorbed at 250°C. The aroma compounds were further trapped in a cold trap (Gerstel CTS2, trapping temperature -100°C), and then heated to 280°C to desorb the aroma compounds. The desorbed aroma compounds were then introduced into an analytical column (InertCap Pure Wax, length 60 m, inner diameter 0.25 mm, film thickness 0.25 μm).
The temperature was raised to 230°C at a rate of 5°C/min and maintained at this temperature for 20 minutes. The average linear velocity was 20.6 cm/sec.

<GC-Olfactometry analysis>
The analysis was conducted by seven evaluators involved in the development of lipids containing polyunsaturated fatty acids. The analysis was performed using the above-mentioned GC-MS equipped with a Gerstel ODP3 odor sensor. The evaluators regularly received basic taste and smell training, regularly handled fish oil products, and had a thorough understanding of their odors. The evaluators had previously compiled and summarized descriptions of the oxidized odor of fish oil (Chemistry and Biology. 50(11):818-824, 2012), and shared their understanding of each evaluation term before commencing the evaluation.

<Aroma Extract Dilution Analysis (AEDA)>
AEDA is described, for example, in Chemistry and Biology Vol. 55, No. 11, 2017, pp. 743-749. Following this, the following procedure was performed. The dilution ratio of the extract in this method was determined to be the lowest concentration that did not change the odor characteristics perceived from the original solution. Specifically, the original extract was diluted with dichloromethane (4, 8, 16, 32, and 64 times), and the odor characteristics were compared by an evaluator using odor paper (Daiichi Pharmaceutical Co., Ltd.). The results confirmed that the 8-fold diluted solution retained the odor characteristics of the original solution, while the 16-fold diluted solution lost the characteristics. Based on these findings, the 8-fold diluted solution was selected as the concentration to be used for AEDA.

<Results>
155 aroma characteristics were detected in the undiluted solution, and 56 components were detected in the 8x diluted solution. Of these, the 10 aromas shown in the table below were detected by more than 43% (3 people) of the evaluators in the diluted solution, and these 10 components were identified as candidates for important aroma components of the oxidized odor of lipids containing polyunsaturated fatty acids. The breakdown of the aroma characteristics included components characteristic of oxidized odors such as "sour, grass, plastic, metal, stink bug," and components related to chemical odors such as "disinfectant."

2. Repeated concentration and omission tests using a fractionator
The 10 compounds discovered by AEDA are candidates for important odor components of lipid oxidation odors containing polyunsaturated fatty acids. However, because some of them are unidentified, and because humans generally detect odor components as a complex odor consisting of multiple compounds, which may have different odor characteristics than odors detected from individual compounds, analysis of the odor mixture of these 10 compounds is necessary to identify the compounds with particularly high contributions. Therefore, we investigated odor collection using a GC-MS equipped with a fractionation mechanism (Gerstel single PFC) and an aroma baking device (Gerstel Thermal Extractor).

<Fractionation and collection of aroma components>
The basic analytical method was the same as described above in <Aroma Analysis Method 1>, except that the samples used were degraded oils and fats (500-1000 μL). To fractionate the compounds listed in the table above, a single PFC (Gerstel) was used to capture the compounds in a TDU tube. A flow path switching mechanism (valve switching) was installed in the flow path from the column outlet, and the flow path was switched to match the elution time of the target compound. A TDU tube (2,6-diphenylene oxide polymer) for aroma collection was installed at the outlet (ODP3) of the switched flow path, allowing the target compound to be captured.

<Thermal Extractor conditions>
Total Flow 163 mL/min, Vent: 11.3 mL/min
Flow meter scale: 200 mL, pressure: 0.4 MPa
Initial temperature: 100°C, held for 0 min, heated at 20°C/min → 160°C, held for 3 min Collection bag: AS ONE odor bag (250 mm x 250 mm, capacity 3 L)
The heating and nitrogen gas flow conditions were set as described above, the TDU tube that had captured the aroma was set in the main body, and an odor collection bag was placed on the opposite side of the main body, and the fractionated aroma was captured in the bag.

<Results>
(Omission test of deteriorated aroma using PFC (Preparative Fragment Collector))
Degraded oil (500 μL) was used as a sample, and the 10 target components were separated 10 times. The collected TDU tubes were again subjected to GC-MS analysis (analysis method described above in "Aroma Analysis Method 2"), confirming that all of the target peaks had been collected. The collected TDU tubes were again fractionated and baked in a thermal extractor, and the collected aroma was confirmed by the seven evaluators. The results showed that the sample had the odor characteristics characteristic of an oxidized odor, as well as the characteristics of lipids containing degraded polyunsaturated fatty acids. In other words, it was confirmed that the complex odor composed of the 10 target components already exhibited the same odor characteristics as degraded fish oil.

Next, to determine which of the key aroma components identified contributed most to the complex odor, an omission test using fractional collection was conducted in the test plots shown in the table below (in the table, "+" indicates a compound that was fractionally collected, and "-" indicates a compound that was not collected). The results showed that when unknown compounds (test plots 2 and 3) were omitted, the resulting complex odor was no different from the control (test plot 1; hereafter referred to as the control). This indicates that the unknown compounds contributed little to the oxidized odor complex. On the other hand, when 2-(2-pentenyl)furan was omitted (test plot 4), the aroma characteristics were significantly different from the control. This indicates that 2-(2-pentenyl)furan contributes significantly to the oxidized odor component identified in this AEDA study, making it an especially important component as an indicator. This compound has not previously been reported as a key oxidized odor component in complex odor analysis of lipids containing degraded polyunsaturated fatty acids. Furthermore, considering that a trans-rich standard obtained by organic synthesis was used and that the retention time (RT) matched that of the standard, it was strongly suspected that this 2-(2-pentenyl)furan contained the trans isomer.

Based on these results, (1), (3), (4), (5), (6), (7), and (10) shown in the table above were determined to be the key aroma components responsible for the oxidized odor of lipids containing polyunsaturated fatty acids.

(Publicly known literature on 2-(2-Pentenyl)furan (supplementary information))
Elmore et al. analyzed the aroma components of grilled muscle from beef cattle fed diets containing different types of oil. The results showed that 2-(2-pentenyl)furan (analyzed as an E/Z mixture) was significantly higher in grilled meat from beef fed diets containing fish oil (highest C22:6 content) than in beef fed a control diet (no ω-3). However, the authors speculated that this compound may have a high threshold for its contribution to the key aroma components of grilled meat (J.S. Elmore, et al. J. Agric. Food. Chem. 1999, 47, 1619).

[Preparation of lipid composition with adjusted water content]
In order to obtain a deoxidized and degummed fish oil with a peroxide value of 0.5 meq/kg or less and an acid value of 0.5 or less (both the peroxide value and acid value were determined by the analytical method described in the 2003 edition of the Standard Methods for the Analysis of Fats, Oils and Related Materials (compiled by the Japan Oil Chemists' Society)), the fish oil was purified by a combination of vacuum distillation, adsorption, and steam distillation according to the method described in the above section (Adjustment of water content, method for producing lipid compositions). Analysis of the obtained purified fish oil revealed that the composition ratio of DHA to all constituent fatty acids was 22.6%, EPA was 5.9%, the peroxide value was 0.1, and the acid value was 0.1.

The resulting fish oil (20 mL) was placed in a 50 mL glass vial, and 10 μL or 40 μL of ultrapure water was added and stirred well to prepare fish oil with 500 ppm or 2000 ppm of water added, respectively.

A sample was also prepared by thoroughly removing water from the resulting fish oil. Specifically, 30 mL of the fish oil was placed in a 50 mL round-bottom glass container, and 6 g of anhydrous sodium sulfate (odorless) was added. The mixture was then thoroughly stirred, centrifuged (3000 rpm, 5 minutes), and the supernatant was collected.

These products were subjected to moisture content analysis and accelerated aging tests.

<Water content analysis>
Measurements were conducted by the Karl Fischer method (volumetric titration) at the request of the Japan Food Research Center or JFE Techno Research.

The results are shown in the table below. The water content of fish oil without added water was 200 ppm. The water content of fish oil with added water at 500 ppm or 2000 ppm was 700 ppm and 2200 ppm, respectively. This means that the amount of water added is reflected directly in the content, suggesting that fish oil with an adjusted water content had been prepared.

<PFAS analysis>
(method)
We commissioned Eurofins Food Testing Co., Ltd. to analyze the PFASs in the above fish oil without adding water using an analytical method using LC-MSMS.

(Analysis results)
Perfluorooctane sulfonic acid (PFOS) was less than 0.10 ng/g, and perfluorooctanoic acid (PFOA) was less than 0.10 ng/g.

<Accelerated Deterioration Test>
The four types of fish oil (no water added, 500 ppm water added, 2000 ppm water added, and dehydrated fish oil with anhydrous sodium sulfate added) were left to stand in an incubator at 50°C for three days. The vials (AS ONE screw cap bottles, 9-852-09) were capped and stored without any special replacement of the headspace with a nitrogen stream or the like.

After leaving the fish oil for three days, anhydrous sodium sulfate (6 g) was added to each sample, which was then left to stand for a while (excluding fish oils that had already been dehydrated). The supernatant (10 mL) was then collected in a 50 mL glass vial and used for the sensory evaluation and aroma component analysis described below. The reason for adding anhydrous sodium sulfate to dehydrate the fish oil was (1) to prevent a decrease in sensitivity due to moisture being detected from the fish oil during the sensory evaluation, (2) because storing fish oil samples while they still contain moisture can cause deterioration during storage, and (3) because the presence of moisture in the fish oil during analysis can interfere with measurement. However, removing the moisture after deterioration does not affect the evaluation results. Fish oil without added water still had a slightly detectable oxidized odor even after the deterioration test, but was evaluated as acceptable for food use.

Regarding the discrimination evaluation method, aluminum foil was wrapped around the glass vials to prevent the evaluators from seeing the properties of the oils. The fish oils were also heated in a water bath heated to 50°C before being served. The evaluators were presented with two types of fish oil and asked to compare their aromas, and to present the sample that they perceived as having the strongest oxidized odor. In other words, the "water-free" product was used as the comparison standard, and the oxidized odor intensity of each fish oil shown in the table above was evaluated.

The results are shown in the table below. Compared to fish oil without added water, both the fish oil with added water and the dehydrated fish oil had a stronger oxidized odor.

<Analysis of Aroma Components>
The amount of oxidized odor components in the four types of fish oil shown in the table above was calculated as a relative quantitative value against a standard deteriorated fish oil of known concentration. That is, first, commercially available fish oil was deteriorated under certain conditions, and then quantitative values of aroma components were obtained as the component analysis results of the standard deteriorated fish oil using SAFE extraction and GC-MS analysis.

(Preparation of standard degraded fish oil)
A fish oil product sold by Maruha Nichiro (the same as that used in Section 1, "Estimation of Important Oxidized Odor Aroma Components") (100 mL) was placed in an IWAKI screw-cap bottle (1 L; product number 2-077-05), oxygen was sealed in the headspace, and the bottle was then wrapped in aluminum foil and stored at 50°C for two days.

(Aroma Extraction (SAFE Extraction))
The degraded fish oil (40 g) was placed in an Erlenmeyer flask, and three volumes (120 mL) of dichloromethane 5000 (Junsei Chemical, pesticide analysis grade) were added. The aroma components were extracted using a SAFE extraction device manufactured by Kiriyama Seisakusho. The resulting extract was adjusted to a constant volume of 100 mL to prepare the aroma extract. The extract was then concentrated 10 times using a nitrogen stream to prepare the measurement sample.

(Aroma Analysis Method 1)
An Agilent Technologies GC-MS (7890-5977) and Gerstel MPS, DHS, and TDU were used. 300 μL of the standard solution and measurement sample in a 10 mL glass vial were heated to 80 °C under a nitrogen stream and circulated for 30 minutes to adsorb the aroma components onto a TDU tube (Carbopack B). The aroma components were then desorbed at 300 °C, re-trapped in a CIS, and desorbed at 250 °C. The resulting mixture was further trapped in a cold trap (Gerstel CTS2, trapping temperature -100 °C), heated to 280 °C, and desorbed. The aroma components were then introduced into an analytical column (GL Sciences InertCap Pure Wax, 60 m long, 0.25 mm inner diameter, 0.25 μm film thickness).

The temperature was maintained at 40°C for 10 minutes, then increased to 230°C at a rate of 5°C/min and held there for 20 minutes. The average linear velocity was 20.6 cm/sec.

(Analysis results of standard deteriorated fish oil)
The results are shown in the table below.

Next, the four types of fish oil shown in Table 6 were each analyzed by GC-MS, and the aroma component values of the hydrated fish oil, the unhydrated fish oil, and the dehydrated fish oil were obtained from the ratio of the area value and content of each component peak obtained to that of the standard degraded fish oil.
The analysis results for the oxidized odor components in each deteriorated fish oil are shown below (table below).
(1) In fish oil with added water, the amount of both 2-(2-pentenyl)furan and 2,4-heptadienal, which are aroma compounds, increased after accelerated aging compared to fish oil without added water. This supports the results of the sensory evaluation. In other words, when the water content in fish oil exceeds a certain concentration, the deterioration is accelerated, the amount of aroma compounds increases, and the oxidized odor is felt more strongly.
(2) On the other hand, the amount of 2,4-heptadienal in dehydrated fish oil with the addition of anhydrous sodium sulfate increased after accelerated aging compared to fish oil without added water. This supports the results of the sensory evaluation. In other words, even when the water content in fish oil falls below a certain concentration, the aging process accelerates, the amount of aroma components increases, and an oxidized odor is perceived as being stronger.

From the above, we found that adjusting the water content in fish oil to a certain concentration range is important in terms of suppressing the production of oxidized odor.

<Changes in 2-(2-pentenyl)furan and 2,4-heptadienal over four days in accelerated aging tests>
The headspace of a glass vial containing fish oil (a fish oil product sold by Maruha Nichiro Corporation (same as the one used in Section 1. Estimation of Important Oxidized Odor Aroma Components, except that it did not contain antioxidants)) was filled with oxygen, and the container was wrapped in aluminum foil and stored in an incubator at 40°C. Analytical samples (500 μL) were taken into glass vials (10 mL) at 3 h, 1 d, 2 d, 3 d, and 4 d after the start of storage. After opening, the vial was refilled with oxygen and allowed to deteriorate again under light-blocking aluminum foil. The headspace of the collected fish oil was filled with nitrogen and stored at −80°C until analysis began. The amounts of 2-(2-pentenyl)furan and 2,4-heptadienal generated at each time point are shown in Figure 1.

[Analysis of High DHA Refined Fish Oil]
According to the above-mentioned "Preparation of lipid composition with adjusted water content", a refined fish oil (high-DHA refined fish oil) was obtained with a composition ratio of DHA of 55.5% and EPA of 7.5% of the total fatty acids, a peroxide value of 0.2, and an acid value of 0.1. The evaluators did not detect an oxidized odor when smelling the high-DHA refined fish oil.

The moisture content was also analyzed in the same manner as in the above-mentioned <Analysis of Moisture Content>. The moisture content was 200 ppm, which was below 600 ppm. Furthermore, the aroma components of the high-DHA refined fish oil were analyzed instead of the deteriorated fish oil according to the sections (Aroma Extraction (SAFE Extraction)) and (Aroma Analysis Method 1) in the <Analysis of Aroma Components>, and the following results were obtained.

These results demonstrate that even lipid compositions with a high ratio of polyunsaturated fatty acids exhibited trends similar to those observed in this application.

[Food manufacturing example]
<Capsules (food composition in the form of a supplement)>
Fish oil (derived from tuna, DHA content 20%, moisture content 200 ppm or less) and antioxidant are mixed until homogeneous to prepare a mixture with a final antioxidant concentration of 4060 ppm. The resulting mixture is filled into prepared soft capsule shells using standard methods to obtain soft capsules. Taking four capsules per day provides a combined intake of more than 503 mg of DHA and EPA.

Claims (5)

A lipid composition comprising a lipid having DHA and/or EPA as a constituent fatty acid, wherein the composition ratio of DHA and/or EPA to the total constituent fatty acids of the lipid is 20% or more;
The moisture content is 150 to 250 ppm,
The peroxide value is 0.5 meq/kg or less,
2-(2-pentenyl)furan is less than 0.0095 ppm;
2,4-heptadienal is less than 2,600 ppm;
A composition having 0.1 ppb or less of perfluorooctanesulfonic acid and 0.1 ppb or less of perfluorooctanoic acid. The composition of claim 1, having an iodine value of 155 g/100 g or more. The composition of claim 1, further comprising an antioxidant. A method for producing a lipid composition having reduced unpleasant odor, which comprises lipids having DHA and/or EPA as constituent fatty acids, and in which the composition ratio of DHA and/or EPA to the total constituent fatty acids of the lipids is 20 % or more, the method comprising the steps of:
obtaining from the raw material a fraction having a water content of 150 to 250 ppm, a peroxide value of 0.5 meq/kg or less, 2-(2-pentenyl)furan less than 0.0095 ppm, 2,4-heptadienal less than 2,600 ppm , perfluorooctanesulfonic acid less than 0.1 ppb, and perfluorooctanoic acid less than 0.1 ppb . A method for reducing an unpleasant odor in a lipid composition containing lipids having DHA and/or EPA as constituent fatty acids, wherein the composition ratio of DHA and/or EPA to the total constituent fatty acids of the lipids is 20 % or more, characterized by obtaining a fraction that satisfies the following from a raw material:
The water content is 150 to 250 ppm, the peroxide value is 0.5 meq/kg or less, the 2-(2-pentenyl)furan is less than 0.0095 ppm, the 2,4-heptadienal is less than 2,600 ppm, the perfluorooctanesulfonic acid is 0.1 ppb or less, and the perfluorooctanoic acid is 0.1 ppb or less .