UNLIKE wine, sake has no tannins and acid to protect it from oxidation, so it can only be aged at very low temperatures.
After two decades of testing, Noriyoshi Nagai, president and CEO of Nagai Sake, has determined that minus two degrees is ideal for allowing sake to mature for up to 10 years, while minus five degrees will take it to 20.
The results are on display at dinner over an irori or sunken hearth in Kura Cafe, located next to the brewery. The cafe, which only opens to the public for lunch, was designed by Mr Nagai, a trained architect.
The top-tier Nagai Style range of sakes accounts for only 8 per cent of his company's total annual production, equivalent to one million 720 ml bottles.
Toasting with Mizubasho Pure sparkling sake, he says Nagai Style is served in wine glasses for those who are more familiar with wine culture.
"But it still tastes best in an ochoko (small sake cup)."
The first fermentation of Pure is in the tank, before it is aged for two years in the bottle. It is clear, with very fine bubbles, and dry on the palate, with traces of melon, white peach and a faint hint of lychee.
Slabs of Toriyama wagyu are grilled as Mr Nagai decants the Mizubasho 2005 vintage. At about 28,000 yen (S$353) a bottle, it is over 10 times more expensive than the usual premium sake.
But its special quality is immediately recognisable.
It is light golden in colour, with a bouquet of green grapes, pear and honey. According to Mr Nagai, the fragrance comes from the rice and yeast, with each passing year changing its character further.
But why decant? Because when drunk 30 minutes later, the Mizubasho 2005's flavour deepens. Served at room temperature - Japan's 20 deg Celsius, not Singapore's 34 - it smells even sweeter and more honeyed, with the key factor being its longer finish.
"Its taste is solely due to good quality rice. If you have that, you only have to give it time to develop."
It is perfectly paired with the rich A3 Toriyama beef, which packs the same amount of umami with less marbling.
Some juicy Gunma chicken thighs and shiitake mushrooms follow, the latter "topped up" with some Mizubasho daiginjo while roasting over the charcoal fire.
Next is some al dente cold udon, followed by the dry and slightly sweet Mizubasho Dessert Sake 2009 and vanilla ice cream served with sake lees sauce. Nagai Sake also uses sake lees to make delicious sable-style cookies and sake jelly, as well as soap and a variety of other products.
But the highlight of the night has to be the Nigori sake. Unfiltered and cloudy, this bottle of Mizubasho premium junmai daiginjo is listed at 6,000 yen but it is priceless because only 12 bottles are produced, three times a year.
The moromi or fermented mash, is not pressed but allowed to drip naturally. Dubbed the "president's sake" for its rarity, it has hints of white peach, green apple and pineapple on the nose. A sip reveals it to be slightly dry but very fresh, with good acidity and effervescence.
But like the range of Nagai Style matured sake, it represents the quality and refinement of this very special brand.
- Mizubasho sake is served at Hashida Sushi Singapore