Establishment of microbial succession of starter culture for rice wine (tapuy) processing

Shelf stable IFST [Institute of Food Science and Technology, University of the Philippines Los Baños, College, Laguna, Philippines] bubod [starter for rice wine production] was developed from Ifugao and Baguio City [Philippines]. Bubod isolates consisting of Rhizopuz oryzae 1, R. oryzae 2, Saccharomyces fibuligera and Saccharomyces cerevisiae. IFST bubod packed in polycthylene plastic bag remained constant in viable microbial count up to 5 months when stored at room temperature and up to 6 months at refrigerated temperature. Microbial succession study in rice wine making using IFST bubod and Ifugao bubod revealed that at an initial stage of solid state fermentation, presence of mold was noted up to 3rd and 4th day and totally disappeared when there was considerable starch liquefaction. Saccharomycopsis sp and lactic acid bacteria (LAB) were also found during the 1st week of fermentation. Yeast count increased from 10 sup 5 - 10 sup 9 CFU/g sample up to 6th to 7th day of fermentation. Bacterial count also increased from an initial value of 10 sup 4 to 10 sup 9 but disappeared on the 7th day. Results were revalidated using IFST bubod starter and two rice varieties (NSIC Rc 160 and Bungkitan) in rice wine processing which gave the same trend of microbial succession. Laboratory scale and bench scale production of rice wine using IFST bubod and three rice varieties (NSIC Rc 160, Bungkitan and Sungsung) showed that NSIC Rc 160 had the lowest yield. The highest yield was obtained from Bungkitan followed by Sungsung. However, Sungsung gave the highest alcohol content in both laboratory scale and bench scale process. IFST bubod, when used in traditional rice wine processing obtained higher yield (1:1.7 rice:wine ratio), conversion efficiency (46%), amino nitrogen (0.019%) and alcohol content (12%) compared to rice wine prepared using bubod from Ifugao. Multi-parallel technique of rice wine processing gave higher values for yield (1:3.5 rice:wine ratio), conversion efficiency (78%) but lower alcohol content (10%), TSS [total soluble solids] (5 deg Brix), protein content (0.54%), amino nitrogen (0.0047%) and total phenolics (58.53 mg FAE [ferrulic acid equivalent]/150 ml wine) compared to traditional method. The use of multi-parallel technique in rice wine processing considerably inhibited browning of rice wine during storage. Sensory evaluation of stored rice wine samples from traditional and multi-parallel methods of fermentation were not significantly different in terms of aroma, flavor and body but significantly different in color, sweetness, acidity, astringency and general acceptability. Rice wine from traditional method has fish sauce/soy-like aroma and addition of pandan flavor did not improve its flavor and aroma. Addition of pandan flavor, adjusting the alcohol content to 8% and increasing TSS to 15 deg Brix greatly increased the acceptability of rice wine from multi-parallel technique. Cost analysis showed the use of multi-parallel technique was more profitable than the traditional technique of rice wine processing.