Liposome-entrapped essential oils on in vitro and in vivo antioxidant activity in leafy vegetables

Enzymatic browning in vegetables can cause undesirable quality changes during handling, processing and storage. Because of antioxidant properties of essential oils, effects of rosemary (Rosmarinus officinalis L.) and lemon (Citrus limonum L.), and their liposomal derivatives, were evaluated on reduction of peroxides and polyphenoloxidase activities, enzymes that promotes enzymatic browning and nutritional damage in plant tissues, in spinach (Spinacia oleracea L., cv. Inner), lettuce (Lactuca sativa L., cv. Dark green cos) and red cabbage (Brassica oleracea L. capitata, cv. Danish bull head). Multillamelar liposomes were prepared using a thin film hydration method. Antioxidant activity of the essential oils was compared with liposomal oils. Antioxidant activity of oils were maintained in the liposomal derivatives, and enhanced at low oils concentration. The highest percentage of antioxidant activity reduction was achieved in vitro and in vivo using a 0.1 mg/ml concentration of liposomal rosemary oil in all vegetables. Since essential oil is a natural compound in aromatic plants and residues have been successfully encapsulated in liposomes, the liposomal of essential oil hold potential of becoming a safe and effective method to prolong shelf-life of vegetables.