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• EFFECTS OF YEAST STRAINS, pH AND FERMENTATION TEMPERATURE ON WINE MADE FROM RhodomyrtustomentosaFRUIT (MANG DEN, KONTUM PROVINCE)

  NguyenMinh Thuy, Nguyen Phu Cuong, Nguyen Thi My Tuyen, Dinh Cong Dinh

  Received: 24-10-2013 / Accepted: 24-02-2014

   Abstract PDF (VIETNAMESE)

  The effects of yeast strains, fermentation temperature and pH on quality of Rhodomyrtus tomentosa wine were examined. At ambient temperature (28±2oC), the fermentation was induced by inoculation with Saccharomyces cerevisiae strains isolated, purified and screened from sugar palm (Borassus flabellifer) and pineapple juice in comparison with commercial yeast (initial populations of yeast raging from 104107 cells/ml). The medium was adjusted before fermentation to five different pH values (3.44.2). The effect of fermentation temperature (20 and 28±2°C) on strain population was also studied. The resulting wines were chemically analyzed. Pure cultures of Saccharomyces cerevisiae isolated from sugar palm significantly yielded in ethanol production higher than other strains in the fermentation at 28±2°C.. Yeast strains performed better at low temperatures with high alcohol yield. At 20±2°C, the fermentation was dominated by the growth of S. cerevisiae in Rhodomyrtus tomentosa juice with maximum ethanol concentrations (13.43%Vol.) The methanol and SO2 concentrations met the Vietnamese Standards (QCVN 6-3 2010/BYT). In addition, the total acid, ester and aldehyde concentration were also low.

• Functional Roleof Mould Strains in Production of Rice Wine

  Nguyen Ngoc Hoa, Dang Xuan Nghiem

  Received: 07-03-2012 / Accepted: 17-05-2012

   Abstract PDF (VIETNAMESE)

  This investigation on the possible role of mould in production of traditional rice wine was carried out with the 4 candidate mould strains which were selected from 21 mould strains isolated from traditional rice wine starters and traditional soysauce starters. The 4 mould strains were preliminarily identified and named as M3 (Rhizopus spp.), M10 (Rhizopus spp.), M16 (Aspergillus oryzae), and M18 (Endomycopsisfibuliger). M10, M16 and M18 strains expressed very strong extracellular enzyme activities (amylase, protease, cellulase), while M3 strain had weak extracellular protease and cellulase activity and no extracellular amylase. Noteably, the yield of rice wine of the traditional alcoholic fermentation was not increased when large amounts of the biomass of the 4 isolated mould strains were added. There was a strong correlation between the pH of fermention liquid and the final yield of wine. The lower the pH of fermentation liquid was, the lower the yield of wine. Moreover, all 4 mould strains were determined to have no role in the formation of aldehyde, methanol and higher alcohol in rice wine products.

• Fermentation of Agricultural Wastes after Harvesting by Microbes Combination for Bioethanol Production

  Nguyen Thi Minh, Nguyen Thi Sang, Nguyen Thi Quyen

  Received: 13-04-2012 / Accepted: 26-08-2012

   Abstract PDF (VIETNAMESE)

  The aim of this study was executive the fermentation by microbes to produce Bioethanol from Agricultural wastes after harvesting in order to reuse the wastes in most efficiency, forward to develope the subtainable Agriculture and contribute into environmental protection. The results obtained suggested that two microbescombination were chosen, which suitable for fermentation process including: combination of bacteria and molds with high abilities in organic degradation could use in period of pretreatment and decomposing raw materials and yeasts combination with ability in fermentation of saccharose into ethanol.The test of inoculation and fermentation of Agricultural wastes by microbes combination proved that activities of useful microbes in fermentation lead to increasing nutrients content in remain wastes, especially effect of ethanol production was preeminentin treatment of inoculation in anaerobic condition, at the same time supplying microbes by interrupted way,which suitable with fermentation process, the ethanol content increased 12 - 15 times comparing to control.

• Isolation, Screening and Identification of Yeast Strain for Producing a High Quality Fermented Watermelon (Citrullus lanatus)Juice

  Do Thi Bich Thuy, Tran Thanh Quynh Anh

  Received: 19-09-2022 / Accepted: 02-03-2023

   Abstract PDF (VIETNAMESE)

  This research was conducted to isolate, screen and identifyyeast strain capable ofproducing high quality fermented watermelon juice. The strain Saccharomyces cerevisiae M11 was selected basedon the content of alcohol, aldehyde, phenolic total, anthocynine, and antioxidant capacity in fermented watermelon juice and identified by sequencing region of ITS (Internal Transcribed Spacer Regions). The results showed that the strain M11produced highest content of alcohol (11.6 ± 0.1), phenolic total (0.06mg GAE/ml), anthocynine (0.589 ± 0.012 mg/l), and antioxidant capacity (0.589 ± 0.012 mg/l) while theanother strains (M2, M7 and M14)producedlowest content of aldehyde (57.7 ± 2.68 mg/lethanol 100)in fermented product.