Abstract
Deep Sea Water (DSW) can be pumped up from a depth of 200 meters at Muroto in Kochi. Since DSW is known to be unspoiled by pollution and contain various minerals, it is used for a variety of fermented foods. To investigate the effects of DSW on sake production, we carried out small-scale (1-2L) fermentation tests. As a consequence, the addition of DSW led to elevated levels of aroma components, including isoamyl acetate, ethyl caproate and ethyl caprylate. To elucidate further the mechanism underlying this phenomenon, we used cDNA microarray for studying yeast gene expression during fermentation. As a result, the addition of DSW substantially increased the transcript levels of several genes known to be involved in higher alcohol and fatty acid biosynthesis. It is therefore suggested that the rise in transcription of these genes caused the increased aroma production. Sensory evaluation revealed that the addition of DSW to fermentation resulted in a significantly superior flavor profile of final products compared with the addition of NaCl, a major component in seawater. Interestingly, the microarray analysis demonstrated that the addition of NaCl by itself induced stress during fermentation as indicated by mRNA levels in sake yeast. The addition of DSW appeared to ameliorate the negative effect induced by NaCl. Taken together, these results indicate that addition of DSW to the fermentation processes provides unique advantages for sake production.
