Defined fungal starter granules for purple glutinous rice wine

The Mekong Delta region ofSouth Vietnamis particularly known as a production area of purple glutinous rice wine ( RuouNepThan ). The latter differs from regular rice wine for its sherry-like taste and flavour and its attractive brown-red colour. Wine is made from purple glutinous rice at home or by small cottage industries, by washing, soaking, steam-cooking, cooling and inoculation of the cooled rice with powdered rice-wine starter ( Men ). The fermentation takes place in two stages, i.e. an aerobic phase which is dominated by mycelial fungi from Men that convert rice starch into glucose, and an anaerobic phase during which an active alcoholic fermentation is caused by the yeasts originating from Men . Of pure isolates from Vietnamese rice wine starters Amylomyces rouxii (CBS 111757) and Saccharomyces cerevisiae (LU 1250) were selected as a powerful glucose producer and a superior fermentative strain, respectively. These were shown to be compatible in mixed cultures, which is of importance for the production of starters with good quality.The development of a laboratory-scale process to formulate defined mixed-culture starter granules was established.The process was based on traditional starter manufacturing methods and modified where appropriate, as determined by optimization experiments. Theherbs "Tieu Hoi" (Fennel: Foeniculum vulgare Miller) and "Dinh Huong" (Clove: Syzygium aromaticum L.) as supplementary ingredients were observed to stimulate the yeast and mould growth. Starter mould viability and its enzymatic activity were found to be quite stable during a 3 months storage test. Yeast activity is most likely the limiting factor for shelf-life and stability of starter. The dry matter content of starter granules is one of the factors influencing the shelf-life of the starter. Based on Vietnamese standard 3215-79 the wine produced with experimental dehydrated defined mixed-culture starter was assessed as superior compared with commercially available rice wines, particularly because of its flavour and overall acceptability.