Search

[Display omitted] • Excellent utilization of visible light by photosensitive substances. • Structural Characterization and Possible Reaction Sites of Alizarin Calculated by DFT. • Addition of pectin modulates the size of alizarin. • Alizarin's antimicrobial properties significantly improved after photoactivation. • Alizarin – Pectin coating effectively resisted microbial contamination and extended shelf-life. Most photosensitizers have limited responsiveness to visible light, however, visible light is a light source with a wide range of wavelengths and the most common in daily life, and making full use of visible light can help to enhance the photodynamic antimicrobial properties of photosensitizers. To tackle this issue, this study confirmed that alizarin has a good absorption capacity for visible light by UV-DRS analysis. Theoretical calculations showed that alizarin might be excited through the charge transfer (CT) mechanism. Under simulated light conditions, alizarin exhibited significant photodynamic inactivation, with a bactericidal efficiency of 99.91 % against S. aureus and L. monocytogenes within 40 min. Meanwhile, the cytolytic rate of alizarin was less than 5 % and the free radical scavenging rate was more than 90 %. To improve the freshness of fresh-cut fruits, we prepared alizarin-pectin (Ali-Pec) coatings using a one-step synthesis method. FT-IR spectroscopic showed the possible presence of hydrogen bonding. It was further found that during storage, the coating-treated fresh-cut apples in the experimental group showed an 8 % reduction in the variation of L-value and a 50 % reduction in the variation of a*-value, and effectively maintained the pH, VC, PPO, and T-AOC levels of the fresh-cut apples, which prolonged the shelf-life of the fresh-cut apples. [ABSTRACT FROM AUTHOR]

In this study, a double-layer intelligent packaging, which is designed by a layer-by-layer casting strategy, is employed for efficient food preservation and high contrast monitoring. Specifically, novel zein/tannic acid (TA) composite colloidal particles (ZTs) were prepared by manipulating the non-covalent interaction between zein and TA using an easy antisolvent method. The stable oregano essential oil (OEO) Pickering emulsion (ZTOEO) with varying concentrations of ZTs (0.1%–1.0%) was successfully prepared. The optimized ZTOEO, containing 0.8% ZTs, was then integrated into the emulsified hydrophobic layer of the konjac glucomannan (Kgm) matrix. Finally, the carrageenan (Car) matrix containing alizarine (Al) as an indicator was added to construct the bilayer structure. The outer Car/Al layer serves as an acid/base responsive indicator layer, while the inner Kgm/ZTOEO layer functions as a high-barrier bacteriostatic layer. The double-layer Kgm/ZTOEO-Car/Al is integrated through intermolecular hydrogen bonding and dehydration condensation. Kgm/ZTOEO-Car/Al exhibits excellent slow-release antibacterial and antioxidant activity, with a sensitive, repeatable and accurate visual response to pH/NH 3. The composite film demonstrates good mechanical strength, thermal stability, light blocking, and water vapor and oxygen permeability. The individual inner Kgm/ZTOEO film effectively prolonged the shelf-life and quality of fruits, which the double-layer Kgm/ZTOEO-Car/Al film showed minimal changes in TVB-N (16.65 mg/100 g) even after monitoring and maintaining the shrimp freshness for 48 h. It can be easily processed on a large scale into packaging bags and indicator labels. This packaging is expected to be an eco-friendly, low-cost, bacteriostatic, suitable for applications requiring real-time monitoring and maintenance of fruit/seafood freshness. [Display omitted] • An antibacterial, antioxidant and slow-release bilayer intelligent packaging was designed. • Novel zein/tannic acid (TA) composite colloidal particles (ZTs) were prepared. • Outer Car/Al layer serves as an acid/base responsive indicator layer. • Inner Kgm/ZTOEO layer functions as a high-barrier bacteriostatic layer. [ABSTRACT FROM AUTHOR]