The composition of the dried substrate was determined through a quantitative acid hydrolysis under standard conditions. Briefly, aliquots from the homogenized lot were taken and submitted to a treatment with a sulphuric acid mass fraction of 72% at 30 C during 1 h and then, after dilu- tion to a sulphuric acid mass fraction of 3%, the reaction mixture was submitted to 121 C for 1 h [18].