Hydrothermal process
In blanching process, fresh leaves (100 g) were
blanched in 1000 ml of water at 85ºC in a stainless
steel pan and cooked for 30 s. The samples were
drained off and cooled rapidly on plenty of ice. For
boiling, the water temperature was set at 80ºC prior to
the samples were immersed and reached the boiling
temperature. A 100 g portion of leaves were added to
1000 ml of water in stainless steel pan and cooked
for 10 min. After cooking, the cooked tissues were
drained and cooled rapidly on ice. For steaming, a
100 g portion of leaves were placed on tray in steam
rack over boiling water in a closed water bath for 10
min under atmospheric pressure. The steamed leaves
were removed and cooled on ice.