2.2. Sampling
Only mechanically and physiologically undamaged healthy
tubers weighing 20–80 g were used. The field sample consisted
of randomly chosen tubers making up 30 kg, which was later
reduced in the laboratory to a sub-sample of twenty tubers. All
plant material has been stored for 5 months in a forced-air cooling
storage room in the dark at 4 C and 85–90% relative humidity.
Chemical analyses were performed within 1 month after the storage
period.