WHAT IS GINJO-KA AND WHERE DOES IT COME FROM?
FERMENTATION TEMPERATURE
In the early days of sake, almost every sake tended to
smell grainy as the main material came from the rice itself.
Subsequently there was a period of time when sake aroma
was primarily woody, because all vessels for sake production
were made from Japanese cedar. However nowadays there
is a wide choice of materials for sake vessels ranging from
enamel, stainless steel tanks or traditional Japanese cedar
tanks. Therefore sake aromas are no longer limited by the
vessel and breweries can have more control in achieving the
sake aroma they desire - whether rice-based and grainy as
in traditional sake, or with amazing fruity or floral aromas.
During the fermentation process, sake yeast will happily
do its job at around 20 degrees Celsius to create alcohol.
Below 6 degrees or above 35 degrees yeast will stop
working. When the temperature is higher than the
optimum, fermentation will speed up. Sake made in this
quick-fermentation style tends to have cereal aromas
and a fuller body.
However, when the fermentation temperature is lowered,
enzyme activity also slows down and less ‘food’, ie. sugar is
produced for the yeast to consume. The interesting thing
is that although the yeast doesn’t like these uncomfortably
low temperatures, the stress of low temperature and
shortage of food stimulates the yeast cells to create weak
acids to protect themselves from the cold and starvation.
These weak acids don’t have much effect on the acidity
of the sake, but they do combine with ethanol to create
amazing aromas such as melon, apple and banana- know
as ginjo aroma. Over one hundred kinds of aroma have
been discovered, but well-known ginjo aromas are isoamyl
acetate which creates banana fragrances and ethyl caproate
which creates aromas of green apple and melon.
15°
FERMENTATION
SPEEDS UP
CO
2
CO
AT
AL
2
CO
YEAST
YEAST
12-18°
GENERAL SAKE
HE
AT
AL
<6° OR >35°
YEAST STOPS
WORKING
HE
CO
HO
L
HO
L
Fruity and floral aromas can be created by sake yeast, but
only under certain conditions. Determining factors include
a low fermentation temperature of around 6 to 12 degrees
Celsius, reduced effects from nutrients and the potential
of the yeast type to create a specific type of aroma.
6-12°
FERMENTATION
SLOWS DOWN
CEREAL AROMA &
FULLER BODY CREATED
CREATES WEAK ACID
EFFECT WITH ETHANOL
GINJO AROMA
LIGHTER BODY
TEMPERATURE EFFECT
MUSEUM OF SAKE JOURNAL 34
‘STRESSED
OUT’ BY LOW
TEMPERATURE