Abstract
Kaffir lime leaf is one of important spices used in eastern cuisines especially in Thai food
and that has been cooked in many ways. Our present study investigated the effect of cooking
methods on phenolic compounds and antioxidant properties as well as volatile compounds of
kaffir lime leaf. Six commonly used cooking methods including three hydrothermal processes,
namely blanching, boiling and steaming, and three non-hydrothermal processes, namely frying,
roasting and drying, were evaluated. The results showed steaming provided the highest values
of total phenolic and total flavonoid contents along with antioxidant activities determined by
in vitro DPPH and FRAP assays while drying with hot air gave the lowest values of those
parameters tested. Critonella was the predominant volatile compound in fresh leaf (56%) which
was enhanced by all non-hydrothermal processes however it was significantly decreased by all
water involving processes. In contrast, beta-citronellol was increased by blanching and boiling
but decreased by other cooking processes. Our findings suggest that different cooking methods
caused various effects on the phenolic compounds and antioxidant properties of kaffir lime leaf.
The presence of different volatile compounds in kaffir lime leaves cooked by each process may
be a reason of a unique flavor to the food.