The film forming solutions were prepared using highly viscous chitosan from crab shells where MW = 310,000–375,000 g/mol, with a dynamic viscosity of >400 mPa·s in 1% acetic acid (20 °C). The chitosan film-forming solution was prepared by dissolving 2 g of chitosan per 100 mL of a 5% acetic acid aqueous solution. Food grade essential oils (clove, thyme, rosemary, and tea tree oils) were incorporated in a proportion of 0.75 mL/g chitosan, and Tween 80 (Sigma-Aldrich, Darmstadt, Germany) (0.125 g/g chitosan) was added as an emulsifying agent. The essential oil-added film-forming solution was homogenized with an ultrasonic processor UP50H (Hielscher—Ultrasound Technology, Teltow, Germany) using a power of 50 W at 30 kHz). The films were obtained by casting 50 mL in glass Petri dishes (153 cm2) and drying first at 25 °C in a forced-air oven for 24 h and then at 40 °C in a vacuum oven to yield a uniform thickness in all cases. Prior to analyses, the films were conditioned in desiccators for 2 days at 22 °C over a saturated solution of NaBr (58% relative humidity) [56].