Chitosan of low molecular weight (MW; 340) in powder form from
crab shells was purchased from Aldrich Company (Athens, Greece).
Moisture content was less than 10% and chitosan had a deacetylation
degree of 75–85% (Manufacturer's data). A stock solution of chitosan
was prepared by dissolving 1.5 g in 100 ml of 1% (w/v) glacial acetic
acid and stirred overnight at room temperature (final chitosan concentration=
1.5% w/v). Pure oregano oil (Kokkinakis S.A., Athens, Greece)
was used (see below). The oil consisted of (major components): Carvacrol:
57.7%; p-cymene: 28.7%; γ- terpinene: 6.4% and thymol 2.8%
(Manufacturer's data).