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The purpose of this review is to provide an overview of current packaging systems, e.g. active packaging and intelligent packaging, for various foods. Active packaging, such as modified atmosphere packaging (MAP), extends the shelf life of fresh produce, provides a high-quality product, reduces economic losses, including those caused by delay of ripening, and improves appearance. However, in active packaging, several variables must be considered, such as temperature control and different gas formulations with different product types and microorganisms. Active packaging refers to the incorporation of additive agents into packaging materials with the purpose of maintaining or extending food product quality and shelf life. Intelligent packaging is emerging as a potential advantage in food processing and is an especially useful tool for tracking product information and monitoring product conditions. Moreover, intelligent packaging facilitates data access and information exchange by altering conditions inside or outside the packaging and product. In spite of these advantages, few of these packaging systems are commercialized because of high cost, strict safety and hygiene regulations or limited consumer acceptance. Therefore more research is needed to develop cheaper, more easily applicable and effective packaging systems for various foods.

The integration of electrochromic (EC) and thermochromic (TC) systems is important for realizingmultifunctional smart windows, which can adaptively control light transmittance and solar energy in response to diverse external stimuli. In this study, we developed an all-solid-state multifunctional smart window, in which tungsten oxide (WO3)-based EC and vanadium oxide (VO2)-based TC cells were integrated into a single device. In hybrid smart windows, the WO3-based EC layer modulates optical transmission in response to electrical voltage, while the VO2-based TC layer regulates solar energy transmission responding to the surrounding temperature. Therefore, such windows can control optical transmission and solar energy transmission  in response to an electric stimulus and temperature change simultaneously or independently, allowing for a selective modulation of light in the visible and near-infrared regions. We demonstrated the viability of the proposed integrated smart window system by varying its optical transmission in four different optical states depending on its EC reaction and TC behavior. The concept for the integration of EC and TC cells into a single device can pave the way for next-generation multifunctional smart window systems.

Since most goods are transported and stored in a unit-load form in today’s global supply chain, there has been a growing concern regarding the compression strength of corrugated paperboard boxes for packaging of agricultural products. The best predictor of the compression strength of corrugated boxes is the edgewise compression test (ECT) value; therefore, its efficient measurement or prediction is crucial for the design of more efficient corrugated boxes for food and agricultural and industrial products. This study investigated the edgewise compression behavior (load vs. displacement plot, ECT, and failure mechanism) of corrugated paperboard based on different types of testing standards and flute types using finite element analysis (FEA) and experimental analysis. The results of this study showed that the magnitude of the ECT values produced by the FEA was different from the values produced by the experiment. The difference in the ECT can be possibly explained by layer thickness approximations, together with glue line width assumptions between fluting and the liners in the numerical models. However, the trends of the values were the same. If the material properties of corrugated paperboard components and modeling methods of the corrugated paperboard are further studied, the FE (finite element)-based simulation technique will be a useful alternative tool that can replace the edgewise compression test.

We developed an on-packaging colorimetric sensor label that can detect the aldehyde emission of apples based on Methyl Red. The sensor label was constructed using printable inks on paper medium and relied on the change in basicity caused by the nucleophilic addition reaction between aldehyde and hydroxide via the Cannizzaro reaction. The sensor can be used to detect aldehyde in solution and vapor. Sensitivity and stability toward changes in humidity were achieved by altering the concentration of OH. Under exposure to ripening apples, the label changed color from yellow to orange, and then to red. The degree of ripeness was estimated by a sensory test and texture analysis. The color change of sensor label had showed a similar tendency to the changes in the parameters of the sensory test, soluble solid content, and hardness. Therefore, the sensor label can be used for real time on-package ripeness monitoring of apples during their shelf life.

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Here, we show that chemical vapor deposition growth of graphene on copper foil is strongly affected by the cooling conditions. Variation of cooling conditions such as cooling rate and hydrocarbon concentration in the cooling step has yielded graphene islands with different sizes, density of nuclei, and growth rates. The nucleation site density on Cu substrate is greatly reduced when the fast cooling condition was applied, while continuing methane flow during the cooling step also influences the nucleation and growth rate. Raman spectra indicate that the graphene synthesized under fast cooling condition and methane flow on cool-down exhibit superior quality of graphene. Further studies suggest that careful control of the cooling rate and CH4 gas flow on the cooling step yield a high quality of graphene.

Graphene synthesized via chemical vapor deposition is a notable candidate for flexible large-area transparent electrodes due to its great physical properties and its 2D activated surface area. Electrochromic devices in optical displays, smart windows, etc are suitable applications for graphene when used as a transparent conductive electrode. In this study, various-layer graphene was synthesized via chemical vapor deposition, and inorganic WO(x) was deposited on the layers, which have advantageous columnar structures and W(6+) and W(4+) oxidation states. The characteristics of graphene and WO(x) were verified using optical transmittance, Raman spectroscopy, x-ray photoelectron spectroscopy and scanning electron microscopy. The optimum transparent conductive electrode condition for controlling graphene layers was investigated based on the optical density and cyclic voltammetry. Electrochromic devices were fabricated using a three-layer graphene electrode, which had the best optical density. The graphene in the flexible electrochromic device demonstrated a potential for replacing ITO in flexible electronics.