The scents of sake

If you’ve already heard about how sake is evaluated in Japan (covered in previous posts) you know it’s very different from the positive, wine-based model people learn if they study with WSET. Regional and national evaluations are focused on sake being free from faults, with little more than a nod to balance and degree of aroma.

So it’s interesting to see what aromas and flavours some of the official Japanese assessors are expecting to find, and how they train. [Apologies for a second Brewing Society of Japan story, I wasn’t expecting them to release the course this week!]

Sake flavor wheel for professional purposes 
(“A Comprehensive Guide to Japanese Sake“, National Research Institute of Brewing, p.21)

The Brewing Society of Japan (BSJ) have a sensory training set, based on the NRIB flavour wheel above, designed to help assessors recognise sake aromas and create a common vocabulary so they can compare their findings. They promote the set as particularly useful for people working in sake production and release/shipping. 

The chemical name and type of aroma for the 19 vials in the set are:

• ethyl acetate: nail polish remover or adhesive (in excess)
• isoamyl acetate: one of the esters that defines ginjō-ka
• ethyl caproate: one of the esters that defines ginjō-ka
• ethanol: the main component of alcoholic drinks
• higher alcohols: key aroma of sake, similar to whiteboard markers
• phenethyl alcohol: key aroma of sake, similar to roses, sweet floral scent
• acetaldehyde: light aroma reminiscent of wood or grass, or green apple
• isovaleradehyde: irritating smell produced when unpasteurised sake is stored at room temperature
• 4-vinylguaiacol (4VG): reminiscent of smoke or spice, found in junmai
• caramel: produced when sake is in storage
• mercaptan: similar to onion or natural gas
• dimethyl trisulfate (DMS): reminiscent of ao-nori or corn soup, found in sake made from old rice
• polysulfide: like takuan pickles
• mould (tricholoroanisole, TCA): same mouldy smell as cork taint in wine*
• diacetyl: sweetish aroma like cultured butter or yoghurt
• fatty acids: oily or resin-like smell found in some ginjō
• acetic acid: vinegar
• butyric acid: gingko or cheese
• isovaleric acid: sweaty smell similar to nattō

The 5 mL vials come with an explanatory booklet, and can be smelled blind either on test strips or by mixing into water or neutral sake.

The tasting set is available from the BSJ site (Japanese), priced at JPY 49,500, but needs to be ordered by fax and with ID for private buyers. Refrigeration is also recommended, so it is unlikely to be available for international shipping, but other companies providing sensory training kits for beer, wine, coffee, etc. may be able to supply some of the compounds.

* For more on TCA in sake, see Hannah Kirschner’s episode for the Proof podcast (Season 13, episode 5).