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Beer yeast cell bodies containing high ribonucleic acid content and their production method

a technology of ribonucleic acid and yeast, which is applied in the field of brewers yeast cell bodies containing can solve the problems of not being able to achieve the high ribonucleic acid conten

Inactive Publication Date: 2007-02-08
SAPPORO BREWERIES
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides a method for producing a brewer's yeast cell body with a high content of ribonucleic acid (RNA) based on the weight of the cell body. This is achieved by immersing the cell body in a medium containing an ingredient for activating the yeast, and adding an inorganic salt, such as sodium chloride, to the immersion. The immersion is then stirred at a predetermined temperature to carry out aerobic activation treatment on the cell body. The resulting cell body contains 10% or more RNA by weight. This method can also be used to increase the RNA content of a brewer's yeast cell body.

Problems solved by technology

Nevertheless, the yeast cell bodies recovered after beer production contain ribonucleic acid as much as at a level of about 4 to 6% in their solid masses; therefore, they have been considered as materials that are inadequate to extract ribonucleic acid on a commercial scale.
The Candida yeast cell bodies, however, cannot necessarily be said to be non-toxic to the health of humans and animals and adequate precautions will be needed in the utilization of their products as foodstuff or feed additives.
However, it was again only possible to attain the high ribonucleic acid content by limiting the strain for use in culturing as described above.
Nor has there been an accomplished method for increasing the ribonucleic acid content of a brewer's yeast cell body to the aforementioned level.

Method used

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  • Beer yeast cell bodies containing high ribonucleic acid content and their production method
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Examples

Experimental program
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Effect test

example 1

[0036] The recovered brewer's yeast (which was collected after beer production) was subjected to the treatment according to this invention in a batch system in a 30-L fermentation tank. The medium for use containing nutrient ingredients consisted of the following composition, for example: 400 g ammonium sulfate, 1620 g liquid sugar, 30 g KH2PO4, 200 g NaCl, 50 g yeast extract, 16 L water and other additives such as a defoaming agent.

[0037] The yeast recovered after beer production was washed by sieving and exchanging for fresh water, and centrifuged at 3000 rpm. The obtained yeast precipitate, 4 Kg, was added to the 30-L fermentation tank containing the medium. Under aeration the activation treatment of the yeast was carried out. The treatment conditions were a pH of 4.0, a temperature of 15° C., the quantity of airflow of 1 VVM and an agitation rate of 200 rpm; and the treatment continued for 7 hours. Subsequently, the yeast cell body was recovered by centrifugation. The yeast cel...

example 2

[0038] Following the method described in Example 1, the activation treatment was carried out under the identical conditions except that only the treatment temperature of yeast was changed from 15 to 19° C. Here, the treatment time was set to be as long as 24 hours, which exceeded 7 hours in Example 1. Sampling was conducted at 0, 2, 4, 6, 8, 12, 16, 20 and 24 hours after the start of treatment and the contents of ribonucleic acid were determined. As FIG. 2 shows, the content of ribonucleic acid increased in proportion to the treatment time with the peak of the content (exceeding 10% but less than 12%) appearing 12 hours later, but showed the tendency to decrease thereafter. Therefore, the level of the increase of ribonucleic acid in weight was lowered at a treatment temperature of 10° C. relative to the 15° C. used in Example 1. The content of ribonucleic acid at the peak point reached greater than about three times that at the start of treatment. The timing for recovery under these...

example 3

[0039] The media similar to that used in Example 1 were prepared in different types, but none of them contained NaCl (sodium chloride). NaCl (200 g) was added to the media after the lapses of predetermined times from the start of treatment and the activation treatment of yeast was carried out on the respective media according to the method described in Example 1. The timing of NaCl addition was set at 2, 4, and 6 hours after the start of treatment. The contents of ribonucleic acid for the dried yeast cell bodies recovered from the respective lots were determined and plotted in FIG. 3. The content of ribonucleic acid was highest in the lot where NaCl was added 4 hours after the start of treatment and it was increased by about 40% compared to the case where NaCl was added at the time of start (Example 1). Accordingly, it has become apparent that the content of ribonucleic acid can be enhanced more by establishing the timing of NaCl addition as appropriate.

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Abstract

By using a medium containing an ingredient for activating brewer's yeast, a brewer's yeast cell body is immersed in the medium in the presence of an added inorganic salt; and the immersion is stirred at a predetermined temperature to concurrently carry out an aerobic activation treatment, resulting in the formation of a brewer's yeast cell body containing a high ribonucleic acid content comprising 10% by weight or more of ribonucleic acid based on the weight of the cell body.

Description

TECHNICAL FIELD [0001] This invention relates to a brewer's yeast cell body containing high ribonucleic acid content and a method for its production. BACKGROUND ART [0002] Ribonucleic acid (RNA) is available as a raw material for a drug or a flavor enhancer such as 5′-inosinic acid (IMP) or 5′-guanylic acid (GMP). In general, the ribonucleic acid production employs yeast cell bodies that are cultured using waste molasses or liquid sugar as a major carbon source. Especially, yeasts are utilized for this purpose, including Candida utilis and Saccharomyces cerevisiae. In an approach to increasing the ribonucleic acid content of yeast, attempts have been made, which include culturing in antibiotic-added media, the examination of major carbon sources and the isolation of mutant strains. Specifically, as U.S. Pat. No. 3,909,352 reports, a yeast of a Candida species is mutated, a strain having KCl susceptibility is then isolated, and a yeast cell body containing a ribonucleic acid content ...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C12N15/74C12N1/18A23L27/10
CPCC12N1/18
Inventor YAMASHITA, SHINJIKADO, HISAOMASUDA, TAIJU
Owner SAPPORO BREWERIES