Fermentation Strain Screening And Processing Technology For Prunuus Mume Wine

Fruit of Prunus mume Sieb. et Zucc. has rich nutrients and it is the food with functions of nourishing the kidney, improving eyesight, scavenging free radical and antioxiditive effects, delaying senescence, while wine can effectively maintain the nutrients in the fruit. Prunus mume wine made from fermenting the fruit juice has typical features of nutrient-rich, mellow taste, fruity smell, and effectively regulating body pH balance, and is regarded as a wholesome drink. Currently, the Prunus mume wine is fermented by yeast specified for grape wine, however, its quality turns poor. Therefore, it has significant meaning to screen fermentation strains for producing Prunus mume wine with high quality and improve the taste and mouthfeel of the wine. In this paper Prunus mume fruits were chosen as the main raw material to ferment into fruit wine, to sreen strains with high fermentation-speed and good flavor product, and fermentation technology for the wine was investigated and determine.(1) With the fruits ripe stage increasing from 70% to 90%, the color of fruit changed from green to reddish yellow one, the flavor of the juice changed from unripe fruity aroma to fragrant aroma similar to peach flavor, total sugar content in the juice increased from 1.85 g/L to 12.49 g/L, protein content increased from 2.70 g/L to 5.40 g/L, and total phenol content increased from 0.41 g/L to 0.78 g/L. While total acidity content decreased from 3.84% to 2.92%, among which, citric acid content decreased from 16.44 g/L to 13.49 g/L, malic acid decreased from 6.51 g/L to 1.81 g/L, and sugar-acid ratio increased from 1.03 to 2.15 with increasing ripeness. Ripe stage had no effect on varieties of amino acid, however, content of each amino acid increased with advanced ripeness, resulting a rise from 191.66 mg/100g to 260.25 mg/100g in total amino acid content.17 volatile compositions were detected in juice from 70% ripe fruits while 20 ones from 90% ripe fruits. The aroma of juice changed with increasing ripness, from green fruity type to floral-fruity one, with the two characteristic flavor components of Prunus mume, bezaldehyde and linalyl alcohol increasing from 2.60% to 5.04% and 1.13% to 14.95% respecitively, while the content of 1-hexanol decreased from 69.42% to 46.23%.(2) 9 yeast strains were screened from overripe Prunus mume fruits, which had greenish ivory morphological character in WL test and red morphological character in TTC test, high rate of weight loss, high heredity stability, and pure flavor of fermentation. The strains were identified as Saccaromyces cerevisae by the micrograph morphology observation, physiological and biochemical tests, and 18S rDNA sequence analysis, and named as S. cerevisae QM2524, S. cerevisae QM2518, S. cerevisae QM258, S. cerevisae QM235, S. cerevisae QM247, S. cerevisae QM213, S. cerevisae QM5236, S. cerevisae QM2410, S. cerevisae QM2515 respectively. Among those, after repeated trials and a comparison with commercial yeast, S. cerevisae QM5236 was found to tolerate 15% alcohol and 16 g/L acidity, ferment normally in 45% sucrose. The strain had high stability of heredity and could adapt to the system of Prunus mume juice, and produce a wine with rich fruity and distinctive characteristics of Prunus mume fruit.(3) The fermentation technology of Prunus mume wine was investigated. The primary fermentation condition were 25% content of juice(V/V),30% content of sugar (W/V),7% amount of yeast inoculation. The main ferment was finished at 28℃ for 8 d, after first racking, the wine was conducted in stationary at 25℃ for 15 d, after the second racking, the wine was conducted in stationary at 10-20℃ for 60 d avoid light, then the bright and yellowish in color and fruity of Prunus mume wine was abtained. Besides part of the flavor compouds in the raw juice retained in the wine, some new volatile occurred by biochemical reaction during the femetation process were also found. The main volative flavor components of the wine were alcohols and esters, among which, benzyl carbinol was the highest, followed by ethyl caproate. Compared with raw juice, the content of alcohols in the wine decreased from 81.3% to 57.14%, while the content of esters increased from 6.74% to 39.71%, including characteristic flavor components of the wine such as benzyl carbinol, ethyl caprylate, which render the wine flavor to that of roses and brandy bouquet reapectively.