The natural salmon roe season is the autumn. Does this mean that most of the roe eaten during the off-season is artificial Salmon roe. Not necessarily. As stated in his biography, even at the famous sushi restaurant Sukiyabashi Jiro, frozen roe is thawed as necessary.
Long ago this was an extremely expensive topping that ordinary people couldn’t afford, so artificial roe was used. There was a time when this was the case. But nowadays salmon roe is regularly imported from overseas and can be obtained cheaper, eliminating the need to use artificial roe instead.
However, we cannot overlook the commercial law for passing off artificial roe as natural roe. In Japan, the non-perishable properties of artificial salmon roe made from chemical substances (mainly sodium alginate) is utilized and used mainly in hospitals, but not sold to the general public. I’ll also tell you that it is very rare to find a sushi restaurant that serves artificial roe. Cheap roe is generally made from eggs of trout, other related species, or imported from Canada and other countries.
Unfortunately I’m not familiar with the state of things outside of Japan, but I can tell you how to tell the difference. All it takes is hot water and a moment of observation. Artificial salmon roe will show no changes in hot water, but natural roe will start to turn white on the surface. This is due to the protein reacting and changing with the heat. That said, this is not an experience you can just set up at the sushi restaurant. Just for your own information.
We hope this information will be helpful.
Revision date: November 6, 2017