Application of Gellan Gum-black Rice Anthocyanin-titanium Dioxide Composite Film in the Coating Preservation of Blueberry

Abstract

An edible film using gellan gum, black rice anthocyanins, and titanium dioxide as raw materials were prepared. The effect of edible film on blueberries coating preservation was investigated. Firstly, scanning electron microscopy revealed that there were no obvious cracks or delamination in the cross sections of the gellan gum film (GG), gellan gum, and black rice anthocyanin, composite film (GG-BRA), and gellan gum, black rice anthocyanin, and titanium dioxide composite film (GG-BRA-TiO2). Fourier transform infrared spectroscopy further showed that gellan gum was interacted with black rice anthocyanin and titanium dioxide through non covalent bond. The antibacterial experiment indicated that the GG-BRA-TiO2 composite film had a good antibacterial activity, in which size of the antibacterial circle for Staphylococcus aureus, E. coli and bread's yeast were 4.14, 2.77 and 3.55 (mm), respectively. Secondly, the composite film was used for the preservation of blueberries. The results showed that the GG-BRA and GG-BRA-TiO2 coating groups could slow down the rate of physicochemical properties changes during blueberry fruit storage. Among them, the preservation effect of GG-BRA-TiO2 composite film was better than that of GG-BRA composite film. After 10 days of storage, the weight loss rate, hardness, anthocyanins, total phenols, and the activity of polyphenol oxidase were decreased by 1.56%, 23.69%, 18.44%, 12.71%, and 14.00% compared to the control group, respectively. Therefore, GG-BRA-TiO2 composite film showed good water resistance and antibacterial properties and could be used as a promising coating and preservation material in food packaging.

Keywords

• blueberry
• edible coating
• gellan gum
• black rice anthocyanin
• titanium dioxide