Pichia kudriavzevii yeast low in urea yield and capable of producing flavor and application thereof to food fermentation

A technology for yeast and food, applied in the field of wine brewing and food safety, to reduce the formation of urea and EC, and to produce strong flavor

Active Publication Date: 2016-08-17
JIANGNAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] Recent studies have found that Pichia kudriavzevii is an important urea-producing strain, and the large amount of urea produced during the fermentation process will lead to the formation of EC during the fermentation process, resulting in safety issues

Method used

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  • Pichia kudriavzevii yeast low in urea yield and capable of producing flavor and application thereof to food fermentation
  • Pichia kudriavzevii yeast low in urea yield and capable of producing flavor and application thereof to food fermentation

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0033] Example 1: Screening and identification of yeast Pichia kudriavzevii with low urea production

[0034] Get 10g Daqu and dissolve it in 100ml sterile normal saline, shake it for 30min and carry out gradient dilution, coat WL solid plate, according to the morphological characteristics of colonies on the plate ( figure 1 ), pick a single colony of Pichia kudriavzevii yeast for high-throughput liquid fermentation, carry out molecular biology identification on the obtained potential low-urea-producing Pichia kudriavzevii yeast, and use yeast-specific classification and identification primers NL1 and NL4 to amplify the 26S rDNA fragments of the yeast respectively , gel electrophoresis detection ( figure 2 ). Sequencing comparisons were then performed to confirm that the screened low-urea-producing yeasts all belonged to Pichia kudriavzevii yeasts in taxonomy. Finally, a strain of Pichia kudriavzevii with low urea production was obtained, which was named Pichia kudriavzevii...

Embodiment 2

[0036] Embodiment 2: the function of bacterial strain metabolism producing flavor

[0037] Seed medium: Take a 25ml test tube, fill it with 5ml sorghum medium, and inoculate it with the strain Pichia kudriavzevii JZ523 obtained in Example 1 above, at natural pH, 30°C, 200rpm, and carry out aerobic culture for 48h.

[0038] Fermentation medium: Inoculate the cultivated seed culture medium into a 250ml Erlenmeyer flask containing 50ml sorghum medium, at natural pH, inoculum size is 5%, 30°C, 200rpm, ferment for 48h.

[0039] Using headspace solid-phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS) methods to analyze volatile products, take 8mL samples, put them into a headspace vial containing 3g NaCl, add 10 μL of 4-methyl-2-pentanol with a concentration of 42.60 mg / L was used as the internal standard. The headspace vial was extracted at a constant temperature of 50°C for 45 minutes, and analyzed by GC-MS after the extraction was completed.

[004...

Embodiment 3

[0041] Example 3: Pichia kudriavzevii JZ523 Yeast Low Production of Urea

[0042] Seed medium: take a 25ml test tube, fill it with 5ml sorghum medium, and inoculate the strain obtained in the above-mentioned Example 1, and carry out aerobic culture at natural pH, 30°C, 200rpm for 48h.

[0043] Fermentation medium: Inoculate the cultivated seed culture solution in a 250ml Erlenmeyer flask equipped with 50ml of sorghum medium (adding 500mg / L of arginine precursor and 2% ethanol), the inoculum size is 5%, 30°C , 200rpm, fermented for 96h, and measured the yeast growth situation (OD 600 ) and urea formation. It was found that the strain entered the stationary phase (OD 600 1.8), the maximum urea yield reached 227.42μg / L (48h) during the fermentation process.

[0044] Urea detection: the content of urea in the fermentation broth was determined by pre-column derivatization high performance liquid chromatography fluorescence detector (HPLC-FLD). The specific operation is as follo...

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Abstract

The invention discloses pichia kudriavzevii yeast low in urea yield and capable of producing flavor and application thereof to food fermentation and belongs to the fields of wine brewing and food safety. The pichia kudriavzevii yeast is separated from a baijiu fermentation environment (yeast for making hard liquor), named as Pichia kudriavzevii JZ523 and preserved in the General Microbiology Centre of Microbial Preservation Management Committee in China on May 6th, 2016 with the preservation number being CGMCC NO.12418. The strain has the advantages of being low in urea yield, capable of producing flavor, resistant to ethyl alcohol and resistant to acid, is an excellent liquor-making functional strain and can be applied to the fields of fermented wine, distilled liquor and other food, and food safety is guaranteed.

Description

technical field [0001] The invention relates to a Pichia kudriazvii strain with low urea production and flavor production and its application in food fermentation, belonging to the fields of wine brewing and food safety. Background technique [0002] Traditional food will inevitably produce a metabolic by-product during the fermentation process, namely ethyl carbamate (EC). The production of urethane is due to the microbial metabolism in the fermentation process or the spontaneous chemical reaction of urea, citrulline, etc. from raw materials with ethanol. The precursor substances for the formation of EC mainly include urea, cyanide and citrulline, and urea is currently recognized as the main precursor substance for the formation of EC in alcoholic beverages, such as rice wine and wine. In the fermentation process of Chinese liquor, the main precursor of EC formation has also been confirmed to be urea, and its content in the fermented grains is 26-80 mg / kg. [0003] Urea i...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C12N1/16C12G3/02C12G3/12C12G1/022C12R1/84C12H6/02
CPCC12G1/0203C12G3/02C12N1/16C12H6/02C12N1/165C12R2001/84
Inventor 吴群徐岩林建春
Owner JIANGNAN UNIV
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