Leaching-Resistant Carrageenan-Based Colorimetric Oxygen Indicator Films for Intelligent Food Packaging

Abstract

Visual oxygen indicators can give information on the quality and safety of packaged food in an economic and simple manner by changing color based on the amount of oxygen in the packaging, which is related to food spoilage. In particular, ultraviolet (UV)-activated oxygen indicators have the advantages of in-pack activation and irreversibility; however, these dye-based oxygen indicator films suffer from dye leaching upon contact with water. In this work, we introduce carrageenans, which are natural sulfated polysaccharides, to develop UV-activated colorimetric oxygen indicator films that are resistant to dye leakage. Carrageenan-based indicator films were fabricated using redox dyes [methylene blue (MB), azure A, and thionine], a sacrificial electron donor (glycerol), an UV-absorbing photocatalyst (TiO2), and an encapsulation polymer (carrageenan). They showed even lower dye leakage in water than conventional oxygen indicator films, owing to the electrostatic interaction of anionic carrageenan with cationic dyes. The MB/TiO2/glycerol/carrageenan oxygen indicator film was successfully bleached upon UV irradiation, and it regained color very rapidly in the presence of oxygen compared to the other waterproof oxygen indicator films.

An overview of the intelligent packaging technologies in the food sector

“…The most widely known gas indicators are used to check oxygen and carbon dioxide concentrations. Due to the importance of these gases in food applications, much research has been devoted to the development of O 2 and CO 2 indicators over the last decade and in more recent years (Roberts, Lines, Reddy, & Hay, 2011;Jung, Puligundla, & Ko, 2012;Lee & Ko, 2014;Vu & Won, 2014). Most devices are based on redox dyes (e.g., methylene blue, 2,6-dichloroindophenol, or N,N,Nꞌ,Nꞌ-tetramethylp-phenylenediamine), a reducing compound (e.g., reducing sugars), and an alkaline compound (e.g., sodium hydroxide) (Kuswandi et al, 2011).…”

Self-adhesive graphene oxide-wrapped TiO2 nanoparticles for UV-activated colorimetric oxygen detection

“…For reference, this upward trend in the dye leakage continued beyond the 70 min around which we observed the hydrophilic polymer (HEC) starting to dissolve with the naked eye. It should be possible to suppress the dye leakage of the MB/GO-TiO 2 -based film in water to a greater degree by employing anionic polymers to interact with cationic MB as the encapsulating polymer [12,13].…”

“…When in contact with water contained in food, however, the oxygen indicator film suffers from the migration of redox dyes into food, which is prohibited under the regulation; it can lead to health problems [7,8]. Many attempts have been made to address such problems [9][10][11][12][13]; for example, the use of hydrophobic sulfonated polystyrene (SPS) as the encapsulating polymer made the film highly resistant to dye leaching, but the MB/TiO 2 /glycerol/SPS film showed very slow recovery of the color (5 days in ambient air) because of its hydrophobic property [9].…”

Smart monitoring of gas/temperature changes within food packaging based on natural colorants

“…Up to now, for smart packaging design based on natural food colorants, some gases such as oxygen, carbon dioxide, hydrogen sulfide, ethylene, and volatile ammonia compounds have been applied. For instance, the UV-activated oxygen concentration indicator film is an improved and easy to use oxygen GI that was prepared using an encapsulating polymer with zein as a redox dye, thionine, and P25 TiO 2 , for the detection of oxygen and maintaining the dyes from leaching out in the packaging material and incorporation of biopolymeric hydroxyethyl cellulose with anthraquinone dye, Remazol brilliant blue R, and P25 TiO 2 for multifunctional anthraquinone-based sensors (UV, O 2 , and time) (Khankaew et al, 2017;Vu & Won, 2014). Also, Yanxiao et al (2015) reported a new room temperature gas sensor based on pigment-sensitized TiO 2 thin film (as the sensing layer) and natural pigments extracted from spinach, red radish, winter jasmine, and black rice.…”