In the present work, two oils are selected for the formulation
of the frying oil: sunflower oil and soybean oil. These oils
and fresh potatoes for sensorial analysis were purchased from
a local market. The Rosemary leaves (Rosemarinus Officinalis L.)
used in this study were collected in October from the region of
Zaghouan in the north-east of Tunisia. Vouchers specimens are
kept in the herbarium of the National Institute of Applied Science
and Technology (Tunis, Tunisia). All chemical reagents used were
of analytical grade. HPLC-grade acetonitrile and methanol were
both from Carlo-Erba (Rodano, Italy), and formic acid was from
Interchim (Montluc¸ on, France). All of them were used without any
further purification.