Jones' factors in cronometer database(s)
I'm having some doubts about protein contents in food databases (especially so those used by cronometer). When a food is analyzed, AFAIK its nitrogen content is determined, then it's converted into protein content by the use of specific conversion factors, known as Jones' factors. Now, are the protein values in food databases derived from the use of Jones' factors as determined in its classic 1931 article? Or more recent Jones' factors as in Mariotti et al., 2008? Or even crudely by the overall pre-Jones factor of 6.25?