For measuring zinc content in the final products, canned pears
were pureed by use of a blender and dried in a mechanical convection
oven at 80 °C for 4 d and then ground into powders. About 0.2
g of dried pear powder was put into a fluorocarbon microwave vessel
with 2 mL H2O2 (30%) and 2 mL HNO3 (70%)