Enzyme extraction was carried out according to the
method of Yemenicioglu et al. (1997). Fresh turmeric
pieces (100 g) were cut into small pieces and homogenised
with cold acetone ()20 C). The homogenate was
filtered through a Buchner funnel using Whatman No.1
filter paper. The residue was washed again with acetone
and the colourless solid residue was dried overnight at
room temperature and then stored at )60 C until use.
For polyphenol oxidase (PPO) extraction, 1 g of
acetone powder was suspended in 0.05 m sodium
phosphate buffer (pH 6.8). The suspension was mixed
well for 20 min at 4 C. Then it was centrifuged at
9000 · g for 15 min and the supernatant (crude enzyme
extract) was separated. All the procedures were carried
out in triplicate and at 4 C.