For the microwave digestion of cashew apple fibre crushing of
the samples was performed followed by drying in an oven at
60 C/24 h and then maceration until a powder was obtained.
Two hundred milligrams of the sample were digested with the
diluted oxidant mixture (1 mL of H2O2, 1 mL of HNO3 and 1 mL
of Milli Q water). After the complete oxidation of the organic
matter, the samples were diluted to 10 mL with deionised water
and the copper, iron and zinc were measured by ICP OES in the
same way as described for the cashew apple juice using the
heating program for microwave digestion as described in
Table 1.