Development of Natural Insect‐Repellent Loaded Halloysite Nanotubes and their Application to Food Packaging to Prevent Plodia interpunctella Infestation

Abstract

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.

Prolonged Insecticidal Activity of Clove oil‐Loaded Halloysite Nanotubes on Plodia interpunctella Infestation and Application in Industrial‐Scale Food Packaging

“…As a result, the sustained release profile of HNTs/CO/LBL was elucidated, suggesting that an inhibitory effect of HNTs/CO/LBL film on P. interpunctella larvae invasion was caused by gradual release of CO. From the results, the ink only‐printed LDPE film, the CO, and HNTs/CO films displayed no insecticidal properties during the 60‐day test period. Nevertheless, compared with our previous 30‐day test (Kim et al, ), the insecticidal characteristics of HNTs/CO/LBL film tended to be decreased by day 60. This phenomenon might have been caused by loss of CO during storage.…”

“…However, Figure shows there was no repellency among the three samples after 90 d due to the non‐significances ( P > 0.05). The correlation between the results from the GC analysis (Figure ) and the repellent test (Figure ) was determined previously (Kim et al, ); therefore, we decided that the minimal released CO should be <70% to show insecticidal effects against P. interpunctella larvae. Based on this, it was estimated that the insecticidal properties of HNTs/CO/LBL would be lost before day 50 (Figure ).…”

“…The percentage of released CO compared with the initial concentration was calculated. Since the major single compounds of CO were previously shown to be eugenol (61.00%), eugenol acetate (11.73%), and β ‐caryophyllene (17.90%) (Kim et al., ), released CO was quantified by integrating each peak area of the three compounds as follows: where, , and indicate the peak areas of each compound at the specific time. All analyses were performed in triplicate.…”

“…The percentage of released CO compared with the initial concentration was calculated. Since the major single compounds of CO were previously shown to be eugenol (61.00%), eugenol acetate (11.73%), and β-caryophyllene (17.90%) (Kim et al, 2016), released CO was quantified by integrating each peak area of the three compounds as follows:…”

Thyme Oil Encapsulated in Halloysite Nanotubes for Antimicrobial Packaging System

“…HNTs have geometry similar to that of carbon nanotubes; however, they are low‐priced, environmentally friendly, nontoxic, and biocompatible. In addition, kaolin clay, including kaolinite and HNTs, is classified as generally recognized as safe for food packaging materials by the U.S. Food and Drug Administration (Lee and Park ), hence HNTs have been studied as an additive in the production of nanocomposites to enhance mechanical and barrier properties of the film (Liu and others ; Gorrasi and others ) and to give functional properties such as antioxidant, antimicrobial, and insect repellent (De Silva and others ; Biddeci and others ; Kim and others ). Owing to their unique tubular structure, HNTs have been also studied as a nanosized container for loading functional ingredients like drugs, pesticides, antifouling agents, and cosmetics (Levis and Deasy ; Abdullayev and others ; Suh and others ; Bielska and others ).…”