The insect-repelling effect of cinnamon oil incorporated into LDPE films was more effective with microencapsulation. The system developed in this research with LDPE film may also be extended to other food-packaging films where the same coating platform can be used. This platform is interchangeable and easy to use for the delivery of insect-repelling agents. The films can protect a wide variety of food products from invasion by the Indian meal moth.

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Plodia interpunctella is a major storage pest that penetrates into food packaging and causes serious economic losses, as well as posing health risks. The goal of this study was to develop effective anti-insect polymer strips against P. interpunctella by using plant essential oil (EO) and polyvinyl alcohol (PVA). The EO of cinnamon (Cinnamomum zeylanicum, CO) bark was used as an insect repellent, and fumigant mortality and the repellent activity of CO were measured to evaluate subsistent anti-insect properties through newly designed traps. Repellent activity was also examined with several foods to simulate the storage environment. The mortality rate with CO after fumigation for 120 h was 63%. In the repellent assay, CO-treated strips, but not control strips, effectively repelled P. interpunctella in both "with foods" and "without foods" groups. A PVA-CO strip sachet (PCO sachet) was developed to control the volatility of CO, and the PCO sachet demonstrated robust repellent activity. The loading contents of CO at the center and edges of strips were 39.41% and 39.59%, respectively, and through the results of FT-IR, it inferred that CO was physically diffused in the PVA polymer matrix, not forming chemical bonds. In a release test using a gas chromatography, the PCO sachet showed remarkable controlled release of CO. These results demonstrate that the anti-insect effects of CO can be maintained throughout the distribution and storage periods of foods using PCO sachets.

The aims of this study were to develop insect-proof halloysite nanotubes (HNTs) and apply the HNTs to a low-density polyethylene (LDPE) film that will prevent Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae), commonly known as Indian mealmoth, from infesting the food. Clove bud oil (CO), an insect repellent, was encapsulated into HNTs with polyethylenimine (PEI) to bring about controlled release of CO. Chemical composition and insecticidal effect of CO were examined. The Fourier transform infrared (FTIR) spectrum of encapsulated CO was confirmed. The surface charges of uncoated HNTs (HNTs/CO) and coated HNTs with PEI by the layer-by-layer (LBL) method (HNTs/CO/LBL) were determined to be -37.23 and 36.33 mV, respectively. HNTs/CO/LBL showed slow, controlled release of CO compared to HNTs/CO. After 30 d, the residual amounts of CO in HNTs/CO and HNTs/CO/LBL were estimated to be 13.43 and 28.66 mg/g, respectively. HNTs/CO/LBL showed the most sustainable repellent effect. HNTs applied to gravure printing ink solution did not affect mechanical, optical, or thermal properties of the developed film. Gravure-printed LDPE film containing HNTs/CO/LBL displayed the greatest preventive effect on insect penetration, indicating its potential for use as insect-resistant food packaging materials.

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