Free and protein-bound N ε-carboxymethyllysine and N ε-carboxyethyllysine in fish muscle: Biological variation and effects of heat treatment. ... cut into small cubes and ground at low speed for 20 s and then high speed for 10 s in a homogenizer (8010 s; Waring, Inc., Torrington, CT). All samples were kept in sealed plastic bags and buried in ...