2.2.1. Isolation of the essential oil
Prior to distillation, the fruits (about 200 g) were
crushed. The crushed materials (200 g) were subjected to
hydrodistillation for 4 h using a Clevenger-type apparatus
(Clevenger, 1928). The essential oil obtained was dried over
anhydrous sodium sulphate. The oil yield calculated on a
dry weight basis was 0.02%.
2.2.2. Determination of dimethyl sulfite (DMS) contents
Working conditions of ICP-AES:
About 1 g crushed fruit was put into a small glass bottle
and 1.1 ml 1 N NaOH was added and cooled at 0 C for
1 h. Then, a 2.5 ll samples was injected into a gas chromatograph
(Kolb, 1989). Total DMS contents using an
internal Standard (Etil Metil Sulfid; Fuluka ID: 04490)
was directly printed from the integral printer (Perkin–
Elmer GP 100 graphics printer). Results were given as
lg/kg.