Yeast for pear wine brewing, preparation method and fermentation completion judgment method

[0026] Example 1

[0027] The special yeast used for brewing pear wine of the present invention is the wild yeast isolated from pear fruit.

[0028] Example 2

[0029] A preparation method of the yeast used for brewing pear wine: S1: taking pear juice: crushing fresh pears, beating, filtering and extracting the juice to obtain fresh pear juice; S2: proliferating and culturing: taking the The obtained fresh pear juice is cultivated at 28-30°C for 48-72 hours to achieve the purpose of multiplying the number of bacteria in the fresh pear juice; S3: selection culture: the selection medium is made into a plate, sterilized and cooled, and the "marker" is used to Line method" to paint the pear juice cultured in step S2 on the plate, place it at 28-30°C for 60-72 hours, and isolate bacteria from no less than 8 plates each time; the selection medium needs to be pressed frequently. Boil, sub-package, and sterilize at 105°C for 30 minutes before use; S4: purification and proliferation: after the cultivation in step S3, according to the characteristics of yeast colonies (these characteristics are the usual morphological characteristics of most yeasts, such as The shape is spherical, oval, elliptical or lotus root-shaped, etc. The individual cells are large, generally 1-5 microns or 5-20 microns. The yeast has no flagella and cannot swim; the surface of the colony is smooth, moist, sticky, It is easy to stir up, the colony texture is uniform, the color of the front and back, the edge and the central part are very uniform, and the colonies are mostly milky white, etc.) to carry out aseptic operation, pick a single colony with strong growth (that is, the growth from a single cell) The bacterium cells of pure colonies) are inoculated in the slant medium, and continuously cultivated at 28-30° C. for 60-72 hours; the components of the slant medium and the contents of various components are the same as the selection medium. S5: Domestication: multiple generations of domestication are carried out in the domestication medium to enhance the stability of its performance; the number of domestication is not less than 10 generations; the components of the domestication medium and the contents of various components are the same as the selection medium same. S6: Screening: Separate and cultivate the single bacterial strain (i.e. purified strain) continuously acclimated and cultivated according to the method in steps S3-S4 again, and select the single bacterial colony (i.e. pure bacterial strain) with the most robust growth Inoculate into slant medium for culture; then carry out a series of performance measurements (growth potential, reproduction rate, fermentation power, wine production rate, wine flavor, etc.) Inoculate on the carrier (for example, inoculate on the bran), and then pass small-scale laboratory tests and production medium-scale tests to finally screen out pears with strong growth potential, high reproduction rate, strong fermentation ability, high wine yield, and excellent aroma and flavor of pear wine. Saccharomyces cerevisiae strain is used as a special yeast for brewing pear wine; S7: the yeast obtained in step S6 is made into a yeast for brewing pear wine with bran as a carrier.

[0030] Example 3

[0031] The composition of the selective culture medium described in the present invention can be following composition (mass percentage): 1. the wort+2% agar of 5 Baume degree; 2. 5 Baume degree wort juice 48%, agar 2%, 1.7 Baume Fresh pear juice 50%; ③ 1.7 Baumé fresh pear juice 98% + 2% agar.