FATS AND OILS HAVING SUPERIOR DIGESTIBILITY AND ABSORPTIVITY

Abstract: Fats and oils having a superior digestibility and absorptivity are provided, which fats and oils are com­ posed of a triglyceride having a C₈ to C₁₄ fatty acid residue at the 2-position of the triglyceride and residues of C₁₈ or higher fatty acids at the 1- and 3-positions thereof, examples of the C₁₈ or higher fatty acids being linolic acid, linolenic acid, arachidonic acid, eicosapentenoic acid, docosahexenoic acid, etc.

Description: 1. Field of the Invention This invention relates to fats and oils having superior digestibility and adsorptivity, and more particularly it relates to fats and oils consisting of triglycerides having a short chain fatty acid of C₁₄ or less at the 2-position thereof. 2. Description of the Related Art Natural fats and oils include plant fats and oils represented by soybean oil, rape oil, safflower oil, etc. and animal fats and oils such as beef tallow, fish oils, etc. and they have specific features that the former contains a large quantity of linoleic acid as an essential fatty acid, while the latter contains short chain and C₂₀ or higher highly unsaturated fatty acids such as eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), etc. In particular, in view of the fact that linoleic acid exhibits an effectiveness of reducing serum cholesterol, while EPA and DHA have a function of inhibiting thrombocyte agglutination as well as a function of reducing serum cholesterol and exhibit an effectiveness of preventing brain thrombus, it has been urged that intake of these long chain highly unsaturated fatty acids is important for health maintenance. Thus, use of safflower oil and purified products of fish oils for various foods has been increasing, but the digestibility and absorptivity of fats and oils containing a large quantity of these fatty acids cannot be said to be so good. In particular, the problem of the digestibility and absorptivity has been becoming more serious for persons having reduced digestion function as in patients and old men. On the other hand, it has been known that unlike such long chain fatty acids, fats and oils composed only of short chain fatty acids of 8 to 12 carbon atoms i.e. medium chain fatty acid triglycerides are very rapid in the absorption and also easy in the metabolism; hence they have been used as the lipid source of fluid foods, etc. However, such medium chain fatty acid triglycerides (MCT) have often caused side effects such as acosmia of alimentary canals such as diarrhea accompanying the rapid absorption and metabolism, formation of ketone substances at the time of intake of a large quantity thereof, etc. Thus, since it is difficult to use a large quantity of medium chain triglycerides as an energy source, it has been recommended to simultaneously use medium fatty acid triglycerides with long chain fatty acid triglycerides (LCT). As a process for such simultaneous use, a process of merely mixing the both and a process of mixing the both, followed by random ester exchange therebetween have been proposed. However, these processes have also been still insufficient in the aspect of digestibility and absorptivity. A method of producing an improved glyceride by interesterification in the presence of lipase as a catalyst is disclosed in GB-A-2 042 579. The lipase used therein has a selectivity for reacting at the 1- and 3-position of the triglyceride. The triglycerides disclosed therein are either substituted by C₁₀₋₁₄ fatty acid residues at the 1- and 3-position, or exhibit a ratio of C₁₀₋₁₄ fatty acid residues to C₁₈ or higher fatty acid residues of 2:1. SUMMARY OF THE INVENTION The object of the present invention is to provide fats and oils having overcome drawbacks as seen in conventional products and having improved still insufficient effectiveness thereof, and having superior digestibility and absorptivity. The present invention is directed to fats and oils having superior digestibility and absorptivity, composed of a triglyceride having a fatty acid of C₈ to C₁₄ at the 2-position of the triglyceride and fatty acids of C₁₈ or higher at the 1- and 3-positions thereof. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS As the fatty acid at the 2-position, those of C₈ to C₁₄ are required and those of C₈ to C₁₂ are preferred. The degree of unsaturation of these fatty acids has no particular limitation, but saturated or monounsaturated acids are preferred in the aspect of stability, etc. The fatty acids at the 1- and 3-positions have no particular limitation as far as they are of long chain type of C₁₈ or higher, and various kinds thereof may be used depending on the aimed properties and physiological effect of the fats and oils. The upper limit of carbon atoms of the above fatty acid is preferably 24. For example, linoleic acid and linolenic acid as essential fatty acids, EPA and DHA having been noted to exhibit effects of preventing brain thrombus, arachidonic acid as a precursor of prostaglandin having various physiological functions, etc. may be used. The fats and oils of the present invention wherein linoleic acid or linolenic acid is used as the fatty acids at the 1- and 3-positions in the triglycerides are higher in the absorption rate of linoleic acid or linolenic acid than the case of intake of safflower oil or soybean oil (most of the fatty acids of these triglycerides being long chain fatty acids of C₁₈ or more and having few specificity at the sites linked to glycerol). Further, since arachidonic acid, EPA and DHA each have a large molecular diameter, they are further inferior in the digestion and absorption rates to fatty acids of C₁₈ so that even if fish oils, etc. containing a large quantity thereof are administered as they are, effectiveness is difficultly exhibited, whereas according to the fats and oils of the present invention, it is possible to achieve a higher effectiveness even in the same dose. In the production of the fats and oils of the present invention, since the position specificity of the 1- and 3-positions and 2-position is required, it is preferred to employ an ester exchange process by means of a lipase having a specifity at the 1- and 3-positions. Namely, to one mol of a triglyceride composed only of short chain fatty acids such as synthesized medium chain fatty acid triglycerides, cocoa butter, palm fat, etc. are added 2 to 3 mols of fatty acids such as linoleic acid, EPA, etc. or fatty acid esters or nearly the same mols of triglycerides followed by carrying out ester exchange with a lipase having a 1-and 3-position specificity. After completion of the ester exchange, free fatty acids, fatty acid esters, glycerine, triglycerides, etc. are removed according to a conventional method such as alkali washing, steam distillation, molecular distillation, treatment with high molecular membranes, treatment with ion exchange resins, column chromatography, etc. to thereby obtain the aimed fats and oils. As the lipase having a specificity at the 1- and 3-positions, commercially available products such as LIPOZYME (tradename of a product manufactured by NOVO Company), TALIPASE (tradename of a product manufactured by Tanabe Seiyaku Company), lipase (manufactured by Seikagaku Kogyo Company),Lipase D, Lipase F-AP, Lipase M-AP, Lipase AP and Lipase R (tradenames of products manufactured by Amano Seiyaku Company, respectively), etc. may be used. In addition, the fats and oils may also be produced according to synthetic methods. Since the fats and oils of the present invention are usually in the form of liquid at room temperature, it is possible to use them in various forms. For example, in the case of foods, they may be used for dressing, mayonnaise, etc. or as a fat or oil component of fluid foods for remedy. Further, as pharmaceuticals, when they are used as a fat or oil component of oral or intravascular nutrients, a substrate for suppository, a fat or oil component of transfusion (fatty emulsion for intravenous injection), etc., it is possible to produce a product having a superior absorption effectiveness compared with conventional LCT or simultaneous use of LCT with MCT. Further, the fats and oils of the present invention may also be used as those to be added to feedstuffs for fisheries or stock-raising. Namely, mammals and fishes are generally weak in the digestibility and absorptivity at their infant period so that unless fats and oils are adequately fed, obstacles such as diarrhea may often occur. Thus, even in such a case, use of the fats and oils of the present invention is effective. In addition, in various use applications, it is not always necessary to singly use the fats and oils of the present invention. It is optional to blend other fats and oils with those of the present invention to such an extent that the effectiveness of the present invention is not harmed, and use the resulting blend. The present invention will be described in more detail by way of Examples. Example 1 Six mols of safflower oil fatty acid (the content of linoleic acid in the total fatty acid: 70%) were added to an equimolecular triglyceride of a mixture of capric acid (C₁₀) with caprylic acid (C₈), followed by subjecting the resulting mixture to the following two kinds of ester exchange reactions: (1) Ten parts of a lipase having a specificity at the 1- and 3-positions (LIPOZYME, tradename of a product manufactured by NOVO Company) were added to 100 parts of the above-mentioned mixture, followed by carrying out reaction with weak stirring at 60°C for 5 hours. (2) Ten parts of a lipase having no specificity at the 1- and 3-positions (Lipase OF, tradename of a product manufactured by Meito Sangyo Company) were added to 100 parts of the above-mentioned mixture, followed by carrying out reaction at 40°C for 5 hours. After completion of the reaction, the enzymes were filted off, followed by washing the resulting material with an alkaline aqueous solution in a conventional manner to remove free fatty acids, further washing with purified water, dehydrating with sodium sulfate to obtain two kinds of ester exchange fats and oils (a product by way of the reaction (1) being referred to as SE and a product by way of the reaction (2) being referred to as RE). The respective fatty acid compositions of SE and RE are shown in Table 1. Next, 5 kinds of fats and oils of SE, RE, MCT, safflower oil and a mixture of MCT/safflower oil (1:2) were each subjected to a digestibility and absorptivity test with rats. As the rats, those of SD genus (body weight 100 g, male) were used. Rats of test sections were bred with a non-fatty food for 3 days, followed by further breeding them with feedstuffs obtained by adding the above-mentioned respective fats and oils each in 15% by weight to the above non-fatty food for 3 days and collecting the respective total feces during 6 days. On the other hand, rats of control sections were bred with the non-fatty food for 6 days, followed by similarly collecting the respective total feces. In addition, 10 rats were used in each of the respective test sections and the control sections. The compositions of the above-mentioned non-fatty food and the above food having the fats and oils added are shown in Table 2. The collected total feces was freeze-dried and subjected to lipid extraction with a mixed solvent of hexane/ethanol (2:1). The respective total quantities of fatty acids in the total feces were measured according to gas chromatography. The numeral values obtained by subtracting those of the control sections from those of the test sections were presumed to be the quantities absorbed and rendered as the percentages of digestion and absorption of the respective fats and oils. The results are shown in Table 3. Digestivities and absorptivities of various triglycerides Percentage absorption of fats and oils taken (%) Presence or absence of diarrhea SE 93.8±0.52 - RE 74.3±0.40 - MCT 70.3±1.20 + + Safflower oil 78.6±1.58 + MCT/safflower oil 80.4±0.46 + Example 2 Ester exchange reaction was carried out in the same manner as in (1) and (2) of Example 1 except that as the fats and oils used at the time of ester exchange of Example 1, MCT was changed to trimyristin and safflower oil fatty acids were changed to EPA (eicosapentaenoic acid) having a purity of 95%, followed purification to obtain two kinds of ester exchange reaction fats and oils (those obtained according to the above reaction (1) being referred to as SE-2 and those according to the reaction (2) being referred to as RE-2). However, in the case of use of EPA, the temperature was made 35°C and the reaction time was made 12 hours. Further, with 5 kinds of fats and oils of SE-2, RE-2, trimyristin, EPA triglyceride (purity: 95%) and a mixture of trimyristin/EPA triglyceride (1:2), digestion and absorption tests were carried out in the same manner as in Example 1. The results are shown in Table 4. Example 3 With the fats and oils (SE and SE-2) prepared in Examples 1 and 2, performance comparisons thereof with mother's milk lipid and lard, both having been said to have a very good digestibility and absorptivity were carried out. The measurement method of digestibility and absorptivity are the same as in Example 1. The results are shown in Table 5. Digestibilities and absorptivities of various kinds of triglycerides Percentage absorption of fats and oils taken (%) Presence or absence of diarrhea SE 93.8±0.52 - SE-2 92.8±0.96 - Mother's milk lipid 90.3±0.56 - Lard 88.6±0.48 Example 4 With (1) a lipase having a specifity at the 1- and 3-positions (Talipase, tradename of a product manufactured by Tanabe Seiyaku Company) or (2) a lipase having no specifity at the 1- and 3-positions (Lipase P, tradename of a product manufactured by Amano Seiyaku Company), 3 mols of linoleic acid (a reagent manufactured by Wako Junyaku Company, purity 95%) were reacted with one mol of a medium chain fatty acid triglyceride (composition ratio of MCT: fatty acid, C₈/C₁₀ = 75/25) to subject these in the same manner as in Example 1 to ester exchange reaction, followed by removing the lipases and free fatty acids in a conventional manner, to obtain two kinds of ester exchange fats and oils according to a combination of solvent-fractionation process with column chromatography process (product by means of (1) being referred to as SE-3 and that by means of (2) being referred to as RE-3). The fatty acid compositions of SE-3 and RE-3 are shown in Table 6. Fatty acid distribution of SE-3 and RE-3 Total fatty acids Fatty acids at 1- and 3-positions Fatty acid at 2-position SE-3 RE-3 SE-3 RE-3 SE-3 RE-3 C 8:0 26.5 24.5 5.0 23.0 72.6 20.2 C 10:0 9.9 8.0 2.6 17.7 21.0 18.1 C 14:0 - - - - - - C 16:0 - - - - - - C 16:1 - - - - - - C 18:0 - - - - - - C 18:1 3.0 2.4 1.5 0.6 0.1 0.8 C 18:2 63.0 64.3 90.4 58.5 5.8 60.5 C 18:3 - - - - - - Others 1.0 0.8 0.5 0.2 0.5 0.4 Next, with 3 kinds of fats and oils of SE, SE-3 and RE-3, digestibility and absorptivity tests were carried out in the same manner as in Example 1. The results are shown in Table 7. Digestibility and absorptivity of various triglycerides Percentage absorption of fats and oils taken (%) Presence or absence of diarrhea SE 93.8±0.52 - SE-3 98.1±0.29 - RE-3 73.0±0.51 - The fats and oils of the present invention have a far higher digestibility and absorptivity than safflower oil, fish oils, etc. Thus, the fats and oils of the present invention have a higher efficiency of absorption of linoleic acid, EPA, etc. than safflower oil, fish oils, etc.; hence they are very useful. Further, there is no fear of diarrhea and side effects as observed in the case of MCT.

Claims: Fats and oils having superior digestibility and absorptivity, consisting of a triglyceride having a C₈ to C₁₄ fatty acid residue at the 2-position of the triglyceride and residues of C₁₈ or higher fatty acids at the 1- and 3-positions thereof. Fats and oils according to claim 1 wherein said fatty acid residue at the 2-position of said triglyceride is that of a C₈ to C₁₂-fatty acid. Fats and oils according to claim 1 or 2 wherein said fatty acid residues at the 1- and 3-positions of said triglyceride are linoleic acid or/and linolenic acid residues. Fats and oils according to claim 1 or 2, wherein said fatty acid residues at the 1- and 3-positions of said triglyceride are residues of arachidonic acid, eicosapentaenoic acid or mixtures thereof. Fats and oils according to any of the claims 1 to 4, producible by an ester exchange reaction in the presence of a lipase having specificity for the 1- and 3-positions. An oral or intravascular nutrient composition for the treatment of insufficiency of digestion and absorption, comprising fats and oils according to any of the claims 1 to 5.

Inventors: SETO, AKIRA, YAMADA, OSAMU
Applicants: THE NISSHIN OIL MILLS, LTD.
Application year: 1987
Main classification: C11C3
IPC codes: A23D9, C07C69, C11C3, A61K31, C12P7