Organic compounds -- part of the class 532-570 series – Organic compounds – Fatty compounds having an acid moiety which contains the...
Reexamination Certificate
1997-03-19
2001-07-03
Carr, Deborah (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Fatty compounds having an acid moiety which contains the...
C435S134000, C435S132000, C435S171000, C435S252100
Reexamination Certificate
active
06255505
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a polyunsaturated fatty acid-(PUFA) containing oil, especially to a pure and stable microbial oil containing at least one polyunsaturated fatty acid. This oil can be obtained from a biomass or fermentation broth that has been subjected to pasteurisation.
BACKGROUND OF THE INVENTION
There has been a growing tendency to include lipid products containing polyunsaturated fatty acids derived from fermentation, processes in various foodstuffs. Of importance is the recently established need to incorporate polyunsaturated fatty acids in infant formula.
Various processes have been described for the fermentative production of lipid or oil containing polyunsaturated fatty acids. Examples are EP-A-0155420 for the production of &ggr;-linolenic acid- (GLA) containing lipid from Mortierella; EP-A-0223960, EP-A-0276541 and WO-A-92/13086 for the production of arachidonic acid- (ARA) containing oil from Mortierella and/or Pythium; WO-A-91/07499 and WO-A-91/11918 for the production of docosahexaenoic acid-(DHA) containing oil from Crypthecodinium cohnii or Thraustochytrium, and WO-A-91/14427 for the production of eicosapentaenoic acid-(EPA) containing oil from Nitzschia; and U.S. Pat. No. 5,539,133 for production of ARA and EPA from microalgae.
Typically, a microbial species producing a lipid containing the desired polyunsaturated fatty acid(a) is cultured in it suitable medium, the biomass in then harvested and pretreated to enable subsequent extraction of lipid from the microbial biomass with a suitable solvent. The thus-extracted lipid is in a crude form and so is often subjected to several refining steps.
The pretreatment of the wet biomass cake is usually by drying, such as spray drying or lyophilization and/or by mechanical disintegration, such as homogenisation or milling. Drying of the biomass is desirable in order to reduce the amount of solvent and to prevent troublesome emulsions. If all oxidation- and thermo-sensitive lipid, such as a polyunsaturated fatty acid-containing lipid, needs to be isolated, special care needs to be taken to ensure that exposure to unfavourable conditions, which stimulate oxygen-induced degradation, is avoided as much as possible. However, the biomass pretreatment methods used in the art do not avoid such unfavourable conditions.
Yamada et al, Industrial applications of single cell oils, Eds. Kyle and Ratledge, 118-138 (1992) describe an arachidonic acid-containing oil purified from
Mortierella alpina
with a triglyceride content of 90%. In the recovery process, the harvested biomass is dried and crushed by a ball mill prior to hexane extraction. This method also does not minimise exposure to unfavourable conditions.
Thus, polyunsaturated fatty-acid-containing lipids isolated from microbial biomass according to methods known in the art are exposed to oxidation-stimulating conditions which negatively affect the quality of the oil.
DESCRIPTION OF THE INVENTION
According to a first aspect of the present invention there is provided a microbial oil, comprising at least one polyunsaturated fatty acid (PUPA), which has a triglyceride content of greater than 90%. This oil has been found to be particularly stable in comparison with prior art PUPA-containing oils The PUFA is produced by one or more microorganisms, suitably in a fermentation process. The PUFA is recovered by various process steps, from the biomass, which is essentially the material resulting from the fermentation process in which the PUFA is produced.
Since the oil of the present invention can be microbially, derived, it will be appreciated that this oil does not cover synthetic oils. Although not wishing to be bound by theory, the applicant believes that there may be a number of explanations as to why the oil of the present invention is more stable than those described before the present invention.
The oil may contain one or more compounds that were present: in the biomass. While more of these compounds may act as an anti-oxidant. Alternatively or in addition, one or more of the compounds may inactivate (partially, or at least inhibit) one or more oxidising (or pro-oxidant) substances present in the oil.
A number of substances may be responsible for degradation of PUPA containing oils. These include metals, that may act as an catalysts, for example copper, iron and/or zinc. Other, similar metals, may act as radical initiators. Other degrading influences are light and heat. There may be one or mores substances that may, for example, may be able to complex with one of these metals, or they may act as a radical scavenger.
Alternatively, the process for obtaining the oil of the invention may remove one or more oxidative or oxidation-causing substances that may have originally been present in the biomass.
It is believed that degradation is particularly high when the PUFA is ARA, and therefore a substance in the oil may inhibit or prevent degradation of this PUFA.
The process of obtaining the oil of the invention, which will be described in more detail later, can involve the formation of a granular particulate form, or even dried granules, which may render the PUFA inside the granules or granular forms less accessible to the atmosphere, and in particular oxygen, thereby reducing the chances of oxidation.
In the process of the invention the sterol content maybe reduced, so that the maximum amount of sterols (such as 5-desmosterol) is 1.5% by weight.
The oil may therefore contain one or more radical inhibitors, radical scavengers and/or antioxidants.
The present invention thus relates to a microbial polyunsaturated fatty acid(PUPA)- containing oil with a high triglyceride content (e.g. at least 90%), and a high Rancimat induction time (e.g. at least 5 hours at 80° C.). The polyunsaturated fatty acid can be a C18, C20 or C22 &ohgr;-3 and C18, C20, or C22 &ohgr;-6 polyunsaturated fatty acid. Preferably it is a C20 or C22 &ohgr;-3, or a C20 &ohgr;-6 polyunsaturated fatty acids. In particular the PUFA is arachidonic acid (PUPA), eicosapentaenoic lo acid (EPA) docosahexaenoic acid (DHA). Examples of such oils are arachidonic acid-containing oil from Mortierella or a docosahexaenoic acid-containing oil from Crypthecodinium.
The oil of the invention can advantageously be used in foods, foods stuffs or food compositions or serve as a nutritional supplement, for humans as well as for animals. In addition, the oil of the invention can be used in cosmetics. The granular particles or granules may find use as a food or feed composition or supplement.
The oil of the present invention contains one or more polyunsaturated fatty acids and can have a high triglyceride content. This oil has a much higher oxidative stability than the microbial polyunsaturated fatty acid-containing oils described in the art.
The oil of the invention preferably has the following characteristics. It has a triglyceride content >90%, preferably a triglyceride content ≧93%. However, suitably the triglyceride content is a ≧5%, optionally a triglyceride content ≧97%. It may further have a Rancimat induction time which is ≧5 hours at 80° C., preferably an induction time of 5-16 hours at 80° C. More suitably it can have an induction time of 7-16 hours at 90° C., optionally an induction time of 10-16 hours at 80° C. The Rancimat induction times are measured at a temperature of 80° C., since this temperature is better suited for oils containing polyunsaturated fatty acids. When measured 35 at 100° C., the oil of the invention may have an induction time of from 3 to 5 hours.
It should be noted that the Rancimat induction time of the oil of the invention is measured without the presence of exogenously added stabilizing compounds, such as antioxidants. Obviously, the presence of stabilizing additives in an oil will increase its Rancimat induction time. Stabilizing additives, such as antioxidants, may originate from additions to certain steps of the oil recovery process, for instance to the medium wherein the microorganism is cultured, or from additions to the oil itself. The Rancimat test
Bijl Hendrik Louis
Schaap Albert
Visser Johannes Martinus Jacobus
Wolf Johannes Hendrik
Carr Deborah
Gist-Brocades B.V.
Morrison & Foerster / LLP
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