Interesting reads about sattvic diet:
B.K.S. Iyengar, The Path To Holistic Health (2001), edited version of 2008, page 178 (Food and Nourishment).
Yoga Makaranda First Part (1934), Sri T. Krishnamacharya, english translated version of 2006, page 34 & 35 (Dietary Restrictions for the Yogabhyasi)