For procyanidins analysis with a degree of polymerization >2,
the method of Robbins et al. (2009) was used. Briefly, 2 g of rice
seeds were homogenised with 5 mL of acetone/water/acetic acid,
(70:29.5:0.5, v/v/v). Samples were centrifuged at 3000g for
15 min at 4 C and supernatants were collected.