Optimization of physical, barrier and antioxidant properties of Kefiran-nanoclay bionanocomposite film containing alphatocopherol by using surface response method

In this research, Kefiran based bionanocomposite active film containing nanoclay and alpha-tocopherol was prepared. The effect of kefiran content (3.5, 4.25, 5.75 and 6.5 gr), nanoclay content (0, 1.75, 3.5, 5.25 and 7 %wt. of kefiran) and concentration of alpha-tocopherol (0, 50, 100, 150 and 200 ppm) on the barrier, mechanical and color properties and also antioxidant effect of film on the increasing of oxidative stability of soybean oil were investigated by using surface response method. Results indicated that water solubility and water vapor permeability were increased by increasing kefiran content and were decreased by nanoclay increasing. Also, tensile strength and young’s modulus of films were increased by increasing nanoclay content. But alpha-tocopherol had no effect on mechanical properties. Total color difference and yellowness index of films were also increased by addition of nanoclay and alpha-tocopherol. The antioxidant activity of films was decreased by increasing of their retention inside the oil. But increasing of nanoclay and alpha-tocopherol caused to increase of antioxidant activity. Also, nanoclay caused to increase the peroxide value of soybean oil by release controlling of antioxidant. For optimization purpose, the desirability function method was employed. The optimum film was obtained by 6.2 g kefiran, 2.64% nanoclay and 200 ppm alpha-tocopherol. The best retention time of film in oil was achieved as 31.81 days. At this condition, the overall desirability of 60% was achieved.