Effect of kaolin impregnated with calico plant extract on properties of starch films.

Starch film has poor tensile properties and poor water resistance. We aimed to improve these properties by adding kaolin impregnated with calico plant extract (CP-Kaolin). UV-Vis spectrophotometry showed that the calico plant extract (CPE) contained 4867.52 mg/L of total phenolic compounds and betacyanins were the predominant constituents. CP-Kaolin was characterized by Fourier transform infrared spectroscopy (FTIR), zeta potential, scanning electron microscopy (SEM) and x-ray diffraction (XRD) analysis. FTIR analysis showed that betacyanins were adsorbed on kaolin via hydrogen bonding. Zeta potential analysis confirmed the adsorption of betacyanins on kaolin. The intercalation of betacyanins between kaolin platelets was observed by XRD. SEM revealed that CP-Kaolin was well dispersed and embedded within the starch matrix. It was found that the addition of 10 wt% of CP-Kaolin increased the water resistance, tensile strength and thermal stability of starch film. Moreover, starch film containing 10 wt% of CP-Kaolin was sensitive to the change in pH of the fish during storage. Therefore, the addition of CP-Kaolin improved the properties of starch film and starch film composite with CP-Kaolin could be applied as a smart packaging in the food industry.

Characterization of starch film incorporating Hom Nil rice extract for food packaging purposes.

Poor water resistance, mechanical properties and stability limit the food packaging applications of starch films. Since the properties of starch films are improved by incorporating phenolic compounds and anthocyanins from natural plant extracts, Hom Nil rice (HN) extract was incorporated into cassava starch solution to produce a starch-based packaging film. We evaluated the extraction condition to optimize the total phenolic and anthocyanin contents of the HN extract. The optimal ratio of ethanol solution:Hom Nil rice powder was 5:1 v/w% and the optimal extraction time was 60 min. The influence of HN extract on the viscosity of the film solution and the properties of the obtained films were investigated. The results showed that the HN extract increased the viscosity of the starch solution. A film containing 8 wt% of HN extract produced the highest water contact angle and tensile strength, and hindered the retrogradation process. Therefore, cassava starch film modified with the proposed HN extract has the potential to be used as a food packaging material.