A simple time temperature indicator for real time microbial assessment in minimally processed fruits

Effect of gamma irradiation on different components of onion (Allium cepa) skin waste and enhancement of bioactive potentials

The current study was aimed to use gamma irradiation (10-25 kGy) as pre-treatment technique for improved extraction of phenolics and oil from onion dry skin powder (OSP) which was evaluated by TLC, FT/IR and GC/MS methods. Gamma irradiation (10 kGy) enhanced the extractability of oil and phenolics by 80 % and 50 %, respectively. The ethyl acetate extract (EAE) of irradiated (10 kGy) OSP showed significant anti-cancer activity by inhibiting proliferation, migration and inducing apoptosis in mice breast cancer cell line (4T1) at lower concentration of 0.01 % in comparison with pure quercetin. In addition, compositional changes in oil showed oleic, linoleic and palmitic acids as major among eight identified fatty acids. The surface morphology of isolated MCC was also characterized using SEM. These findings demonstrated the valorization of OSP in a zero waste approach using gamma irradiation (10 kGy) which concomitantly improved yield and bioactivities of phenolic constituents for various health applications.

Development and application of a time-temperature hydroxyethyl cellulose ink based on Clitoria ternatea L. blue petals anthocyanin and N-Hydroxyphthalimide for food freshness monitoring

A novel, sustainable time-temperature indicator (TTI) ink based on natural pigments is introduced for food freshness monitoring. The ink, composed of hydroxyethyl cellulose (HEC), Clitoria ternatea anthocyanin, and N-hydroxyphthalimide (NHPI), was applied to art paper using screen printing. The inks were characterized through FT-IR, particle size analysis, and rheological measurements, with optimal performance achieved at Clitoria ternatea anthocyanin to NHPI ratios of 9:1 and 7:1. The color change of the ink followed the Arrhenius equation, correlating with food degradation activation energies ranging from 0 to 75 kJ/mol. The ink was applied to monitor pork freshness, demonstrating high sensitivity and accuracy in tracking food quality. This TTI ink offers a cost-effective, environmentally friendly solution for food freshness assessment, with potential applications in reducing food waste and enhancing consumer confidence in food safety.

Application of laccase-inorganic nanoflowers based time-temperature integrator to real-time monitor the freshness of pasteurized milk

A time-temperature integrator (TTI) based on laccase@Cu3(PO4)2 nanoflowers (laccase@NFs) was created to monitor the freshness of pasteurized milk during storage. To address the challenges of easy inactivation, poor stability, and high use-cost of laccase in the application of TTI, laccase@NFs were synthesized by ultrasonic-assisted biomineralization. The laccase@NFs-based TTI was created through the enzymatic reaction between laccase and 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid ammonium salt), and the effects of laccase@NFs addition amount on the reaction rate, discoloration lifetime and activation energy (Ea) were discussed. Furthermore, the spoilage pattern and kinetic properties of pasteurized milk were explored based on titratable acidity. The measurement of the Ea was determined as 49.98 kJ/mol, and an investigation was conducted to assess the suitability of the TTI with pasteurized milk under both constant and variable temperature conditions. This research aims to contribute valuable insights into the application of enzymatic TTI in monitoring the shelf life of pasteurized milk.

A novel and facile oxygen-activated time-temperature indicator with wide temperature monitoring range and good stability based on the laccase-like nanozyme

BACKGROUND

Time-Temperature Indicator (TTI) is an indicator device for real-time monitoring of the thermal history of the product. Due to the enzymatic reactions are affected by both time and temperature, enzymatic TTIs have been extensively studied and developed in recent years. However, enzymatic TTIs contain biologically active molecules (enzymes), which require high storage and use conditions. Most of them are designed to mix the system species together and irreversible reaction is undertaken. Nanozymes are the synthetic nanomaterials with similar biocatalytic functions as natural enzymes, which have extensive applications in analytical chemistry, biosensing, and environmental protection due to their facile synthesis, low cost, high stability and durability.

RESULTS

This work proposed to replace the natural laccase to laccase-like nanozyme, designed a novel and facile O2-activated time-temperature indicator for the first time. Nanozyme had excellent thermal and storage stability, which could maintain fabulous catalytic activity in the wide temperature range of 10-80 °C and after a long-term storage. Based on the O2 was required to participate in the oxidation of laccase-catalyzed substrates, a squeeze-type O2-activated TTI was designed by controlling O2 in the TTI system. The TTI was activated through extruding the O2-coated airbag ruptured and producing an irreversible color reaction. Combined with a smartphone to extract the chromaticity for portable visual real-time monitoring. Five sets of TTIs were prepared based on the concentration of nanozyme, and the activation energies (Ea) ranging from 28.45 to 72.85 kJ mol-1, which were able to be fitted to products with Ea ranging from 3.45 to 97.8 kJ mol-1 and the monitoring-time of less than 7 days.

SIGNIFICANCE

Compared to the traditional enzymatic TTI, the TTIs designed based on nanozyme has the advantages of controlled activation, wider temperature monitor range and good stability. Providing a new approach to the development of real-time monitoring of smart devices.

A comprehensive review of intelligent packaging for fruits and vegetables: Target responders, classification, applications, and future challenges

Post-harvest fruits and vegetables are extremely susceptible to dramatic and accelerated quality deterioration deriving from their metabolism and adverse environmental influences. Given their vigorous physiological metabolism, monitoring means are lacking due to the extent that unnecessary waste and damage are caused. Numerous intelligent packaging studies have been hitherto carried out to investigate their potential for fruit and vegetable quality monitoring. This state-of-the-art overview begins with recent advances in target metabolites for intelligent packaging of fruits and vegetables. Subsequently, the mechanisms of action between metabolites and packaging materials are presented. In particular, the exact categorization and function of intelligent packaging of fruits and vegetables, are all extensively and comprehensively described. In addition, for the sake of further research in this field, the obstacles that impede the scaling up and commercialization of intelligent packaging for fruits and vegetables are also explored, to present valuable references.

Dual bacterial strains TTI for monitoring fish quality in food cold chain

Most microbial time-temperature indicators (TTIs) considered only one spoilage strain. This research compared single and dual spoilage strains-based microbial TTI for quality changes of chilled grouper fish (Epinephelus fuscoguttatus x E. lanceolatus) fillet products during distribution. The next-generation sequencing (NGS) and traditional plate count approach showed that Pseudomonas fragi and Vibrio parahaemolyticus were specific spoilage bacteria at 7 and 15°C. A dual-strain TTI response provides more accurate results than a single-strain TTI and provides an irreversible color change from yellow to reddish-brown, showing levels of fish freshness. The microbial TTI comprises fish spoilage bacteria strains with 3 log CFU/ml, a nutrient broth supplemented with 2% NaCl as a medium, and phenol red with 0.25 mg/ml as a pH indicator. Overall, this study points to the applicability of a dual-strain microbial TTI as a valuable tool for monitoring fish quality changes during cold chain break condition.