It has a very unpleasant, bitter taste. Better to use Fee Brothers Fee Foam or Vegg White. Please click "See more cocktail foamers" above.
Thank you for such prompt and useful advice. I probably throw away 80% of all the egg white I buy and don't always have it in the fridge when I need it, so in principle finding a foamer with a long shelf life is a handy option. I shall try the Fee Bros. or Vegg White product.