Food or edible material: processes – compositions – and products – Products per se – or processes of preparing or treating... – Extract
Reexamination Certificate
2000-05-09
2002-02-05
Hendricks, Keith (Department: 1761)
Food or edible material: processes, compositions, and products
Products per se, or processes of preparing or treating...
Extract
C426S656000, C435S255400
Reexamination Certificate
active
06344231
ABSTRACT:
TITLE OF THE INVENTION
A composition of yeast extract and yeast for obtaining the same, and a process for production of the composition of yeast extract.
FIELD OF THE INVENTION
This invention relates to a composition of yeast extract having taste, of kombu (Laminariales, kelps) and mushrooms and flavor thereof, new yeast strain for obtaining the same, and a process for production of the composition of yeast extract.
PRIOR ARTS AND PROBLEMS TO BE SOLVED BY THE INVENTION
Conventionally used extracts of mushrooms and kombu (Laminariales, kelps, hereinafter designated as kombu) have good flavors, but addition of these natural extracts to the foods can only show simple taste. In order to increase richness in flavor, heaviness of the taste and better taste, various seasonings have simultaneously to be added. Consequently, the said extracts are not satisfactory for the purpose of commonly used or all-purpose seasonings.
Recently, the use of natural seasonings is being recognized once again according to the natural food-oriented minds of the general consumers. For expanding applicable fields of natural seasonings, yeast extracts have widely been used, and demands for higher level of quality of the yeast extracts are increasing.
Generally, raw materials of yeast extracts include genus Saccharomyces such as baker's yeast and brewery yeast. The yeast extracts from Saccharomyces yeast have a specific yeast flavor. The yeast flavor is preferable for increasing meat taste, but is disadvantageous for taste of Japanese style cuisine.
The yeast extracts from genus Candida (hereinafter designated as Candida yeast extracts) have almost no yeast flavor which is specific to yeast extracts originated from yeast belonging to genus Saccharomyces. Furthermore, Candida extract can be used in all-purpose seasonings preferable to the taste of Japanese cuisine having savory (umami) by using nucleic acids which are rich in Candida yeast. (Japanese Patent Unexamined Publication No. 62-201595), Japanese Patent Examined Publications No. 7-93871 and No. 56-46824).
These prior technologies have objective to increase the taste of nucleic acids. For this purpose, the yeast is treated in order to increase the content of nucleic acids by enzymatic decomposition. Consequently, the content of free amino acids is relatively low and this gives simple taste and flavor.
In order to improve this disadvantage, the invention of Japanese Pat. Unexam. Publ. No. 9-294581 discloses an increased intracellular glutamic acid content by obtaining yeast belonging to genus Saccharomyces which is resistant to glutamic acid antagonist. The yeast extract of the invention is, however, not able to improve flavor due to removing Saccharomyces yeast flavor.
For masking undesirable yeast flavor of the yeast extracts and adding specific good flavor to foods and cooking, a method is conventionally practiced which adds flavors such as dried bonito flavor and smoke flavor, other than yeast extract whose origin is not yeast extracts. This method is, however, complicated due to processing and causes higher production cost. Consequently, it is preferable for the yeast itself to have a specific good flavor in yeast. No trials have been made to add or to generate specific good flavor and taste in the composition of Candida yeast extract per se.
Furthermore, a method for preparing sea tangle (kombu)-like taste using sugar alcohol, potassium and glutamic acid is known (Japanese Pat. Exam. Publ. No. 6-75479 and ibid. 7-114646). This method is only a combination of chemical compounds for preparing a taste composition, and the resulting seasonings are different from the natural flavor. Therefore, the method can not provide a seasoning with a natural complex flavor. Consequently, in order to prepare sea tangle (kombu)-like natural flavor, sea tangle (kombu) extract and/or residue of sea tangle (kombu) extract should be added.
MEANS FOR SOLVING PROBLEMS
As a result of extensive studies in order to solve these problems, we have found that Candida yeast having both aspartate hydroxamate resistance and low temperature sensibility, could provide yeast extracts which contain over a certain content of mannitol, glutamic acid, alanine, 5′-IMP and 5′-GMP. We have also found that the said yeast extract showed strong taste of sea tangle (kombu) and mushrooms-like taste, and have completed the present invention.
An object of the present invention is to provide a composition of yeast extract from genus Candida comprising contents in a dried yeast extract being mannitol above 0.5%, glutamic acid above 2.0%, alanine above 0.5%, 5′-IMP above 1.5% and 5′-GMP above 1.5%.
Another object of the present invention is to provide a yeast from genus Candida resistant to aspartate hydroxamate and taking within 48 hours to grow colonies at 30° C. on a nutrient agar medium, but taking over 96 hours to grow colonies at 15° C.
Further object of the present invention is to provide
Candida utilis
AHR21 (FERM BP-6099).
A still further object of the present invention is to provide a process for production of a composition of yeast extract comprising culturing said yeast in a medium containing molasses as a main carbon source, isolating the cultured yeast, disrupting the yeast cells and treating the thus obtained destructed cell suspension with enzyme.
The present invention will be explained in detail herein below.
In the yeast extract of the present invention, contents of mannitol, glutamic acid, alanine, 5′-IMP and 5′-GMP are essentially above 0.5%, above 2.0%, above 0.5%, above 1.5% and above 1.5%, respectively. These are preferably above 1.0%, above 3.0%, above 1.0%, above 2.0% and above 2.0%, respectively.
Candida yeast extracts prepared by a conventional enzymatic digestion method have been known to contain glutamic acid, alanine and 5′-1 G. However, the fact that coexistence of over a certain level of glutamic acid, alanine and 5′-1 G with mannitol in Candida yeast can produce sea tangle (kombu)-like or mushroom-like taste, has not been known.
We have found that when the above concentration of each component is simultaneously satisfied, sea tangle (kombu)-like and mushroom-like taste and flavor are felt strongly and with good balance. Namely, addition of nuclease to the yeast which contains mannitol, glutamic acid and alanine may result to enhance taste of glutamic acid with coexisting alanine, 5′-IMP and 5′-GMP, thus to produce sea tangle (kombu)-like taste.
In this invention, a taste means, when the extract is held in the mouth, feelings of full body of the taste or spread of the taste, for example, richness or thickness in taste. A flavor means, when the extract is held in the mouth, feelings of first taste and flavor in the tongue and the nose.
A process for production of a yeast extract of the present invention is explained hereinbelow.
A yeast derived from genus Candida which is resistant to aspartate hydroxamate and takes within 48 hours to grow colonies at 30° C. on a nutrient agar medium, but takes over 96 hours to grow colonies at 15° C., is obtained. A mother strain of the yeast from genus Candida is preferably
Candida tropicalis, Candida lypolitica
and
Candida utilis
. Most preferable strain is
Candida utilis
IFO 0626. These yeasts can be obtained from Institute for Fermentation Osaka, Japan.
(1) [Production of a Strain Resistant to Aspartate Hydroxamate]
Cultured broth of genus Candida is treated by mutagen, such as nitrosoguanidine, UV or X-ray irradiation to produce survival rate of yeast about 0.01-1%. Thus obtained mutant of yeast resistant to aspartate hydroxamate is selected. The yeast strain resistant to aspartate hydroxamate can be selected by the following procedure. The mutant yeast hereinabove is cultured in complete synthetic medium (glucose 1%, ammonium sulfate 0.35%, potassium monophosphate 0.1%, magnesium sulfate 0.05%, sodium chloride 0.05%, calcium chloride 0.05%, and trace metal ions and vitamins), which contains aspartate hydroxamate about 500-1000 &mgr;g/ml, then coloni
Nakajo Yukihiro
Sano Hiroyuki
Birch & Stewart Kolasch & Birch, LLP
Hendricks Keith
Nihon Tobacco Inc.
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