United States Patent:  6,054,494

Assignee:  Q. P. Corporation (Tokyo-To, JP)

Filed:  July 13, 1998

The present invention relates to a phospholipid composition comprising two or more phospholipids, the electric conductivity and pH of a 5 wt. % suspension of the phospholipid composition in deionized water being in the range of 130 to 220 .mu.S/cm and in the range of 6.5 to 9.5, respectively; a process for producing the same; and the use of the same.

SUMMARY OF THE INVENTION

We have made extensive studies in order to attain the above object, and, as a result, finally accomplished the present invention.

The present invention provides a phospholipid composition comprising two or more phospholipids, the electric conductivity and pH of a 5 wt. % suspension of the phospholipid composition in deionized water being in the range of 130 to 220 .mu.S/cm and in the range of 6.5 to 9.5, respectively.

Further, the present invention provides a process for producing the above-described phospholipid composition, and an emulsifier comprising the phospholipid composition.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will be described in detail hereinbelow.

In the present invention, phospholipids include those consisting of phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, phosphatidylserine, phosphatidic acid, or sphingomyelin. Further, phospholipid compositions are compositions comprising two or more phospholipids described above, in which the phospholipid content is 20% or more and in which the remainder is mainly composed of neutral lipids.

Specific examples of such phospholipid compositions include a phospholipid composition comprising ordinarily at least 20% of phospholipids extracted from egg yolk with an organic solvent (an alcohol), or the one obtained by purifying this phospholipid composition to a phospholipid content of 80% or more; and a phospholipid composition comprising ordinarily at least 50% of phospholipids obtained by dehydrating a water-containing gummy substance obtained in the degumming step in the production process of soybean salad oil, or the one obtained by purifying this phospholipid composition to a phospholipid content of at least 80%.

The phospholipid composition of the present invention has an electric conductivity in the range of 130 to 220 .mu.S/cm and a pH in the range of 6.5 to 9.5 when measured as a 5 wt. % suspension of the phospholipid composition in deionized water. The term "deionized water" as used herein means purified water containing no dissolved ions, specifically, purified water whose electric conductivity is not greater than 2 .mu.S/cm. Further, the phrase "a 5 wt % suspension of the phospholipid composition in deionized water" means a suspension obtained by dispersing 5 parts by weight of the phospholipid composition in 95 parts by weight of deionized water by using, for example, a homogenizer. Furthermore, in the present invention, the electric conductivity is a value obtained by measuring the electric conductivity of the above-described 5 wt. % suspension of the phospholipid composition at 20^oC. by using an electric conductivity meter (e.g., "Conductivity Meter DS-14" manufactured by HORIBA, LTD., Japan); and the pH is a value obtained by measuring the pH of the above-described 5 wt. % suspension of the phospholipid composition at 20^oC. by using a pH meter (e.g., "pH Meter F-22" manufactured by HORIBA, LTD., Japan).

When the electric conductivity is lower than 130 .mu.S/cm, the pH of an emulsion prepared by using the phospholipid composition as an emulsifier tends to be greatly lowered while the emulsion is sterilized by heating. On the other hand, when the electric conductivity is higher than 220 .mu.S/cm, the emulsion tends to be demulsified while it is sterilized by heating. For this reason, the phospholipid composition of the present invention is essentially required to have an electric conductivity in the above-described range. The preferable range of the electric conductivity is from 150 to 200 .mu.S/cm.

Further, when the pH is lower than 6.5, an emulsion prepared by using the phospholipid composition as an emulsifier tends to be demulsified while the emulsion is sterilized by heating even if the electric conductivity is in the range of 130 to 220 .mu.S/cm. On the other hand, when the pH is higher than 9.5, not only the emulsion tends to be demulsified while it is sterilized by heating, but also the pH of the emulsion tends to be greatly lowered. Therefore, it is also essential for the phospholipid composition of the present invention to have a pH in the above-described range. The preferable range of the pH is from 7.0 to 9.0.

Furthermore, the phospholipid composition of the present invention comprises two or more phospholipids. A phospholipid composition containing only one phospholipid gives, when used as an emulsifier, an emulsion which is easily demulsified during heat sterilization even if the electric conductivity and pH of a 5 wt. % suspension of the phospholipid composition in deionized water are in the range of 130 to 220 .mu.S/cm and in the range of 6.5 to 9.5, respectively.

A typical process for producing the phospholipid composition of the present invertion will be described hereinbelow.

A crude phospholipid composition (phospholipid content: approximately 20 to 60%) obtained by extracting phospholipid components from dried egg yolk by allowing an alcohol to act on it, and removing the alcohol from the extract, or a phospholipid composition having a high phospholipid content of 80% or more, for example, 95 to 99%, obtained further by removing neutral lipids (triacylglycerol, cholesterol, etc.) from the above crude phospholipid composition by treating it with acetone in an amount 1 to 10 times the amount of the crude phospholipid composition, is dissolved in a polar solvent (methanol, ethanol, dichloromethane, acetone, water, or the like) or in a solvent mixture of a polar solvent and a non-polar solvent (n-pentane, n-hexane, chloroform, ethyl acetate, ether, benzene, or the like) in an amount 3 to 20 times the amount of the phospholipid composition, and then the resultant solution is brought into contact with an ion exchange resin so that the electric conductivity and pH will be in the range of 130 to 220 .mu.S/cm and in the range of 6.5 to 9.5, respectively, whereafter the solvent is distilled off under reduced pressure to produce the desired phospholipid composition.

Examples of the ion exchange resin for use in the above-described process include strongly acidic or weakly acidic cation exchange resins (Examples of the former include "Amberlite IR 120B" and "Amberlite IR 200C" manufactured by Rohm & Haas Co., "Dowex 50W" and "Dowex MSC-1" manufactured by Dow Chemical Co., and "DouLite C-20" and "DouLite C-25D" manufactured by Diamond Shamrock Corporation; and examples of the latter include "Amberlite IRC 50", "Amberlite IRC 84", "Dowex CCR-2", and "DouLite CC-4"), and strongly basic or weakly basic anion exchange resins (examples of the former include "Amberlite IRA400", "Amberlite IRA 900", "Dowex 1", and "DouLite A-101D", and examples of the latter include "Amberlite IRA 68" and "Amberlite IRA 45"). These ion exchange resins can be used either singly or in combination of two or more members, as needed.

Claim 1 of 4 Claims

1. An emulsifier comprising a phospholipid composition having a phospholipid content of at least 20% which comprises two or more natural phospholipids having an electric conductivity and pH of a 5 wt. % suspension of the phospholipid composition in deionized water in the range of 130 to 220 .mu.S/cm and in the range of 6.5 to 9.5, respectively, the phospholipid composition having been obtained by dissolving, in a solvent, a crude phospholipid composition obtained by means of extraction, or a purified phospholipid composition obtained further by purifying the crude phospholipid composition to remove neutral lipids,

bringing the resultant solution into contact with one or more ion exchange resins until the specified electric conductivity and pH in the 5 wt. % suspension is achieved,

removing the ion exchange resin(s) from the solution, and

removing the solvent from the solution.

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