Time temperature indicators (TTIs) based on silver nanoparticles for monitoring of perishables products

Abstract

This work presents the results of the production and characterization of silver nanoparticles (AgNPs) to applications in Time Temperature Indicators (TTIs). AgNPs were synthetized by chemical processes. The suspensions (AgNPs in water) were characterized for different temperatures (4°C and 22°C) and time (0 to 5h). The AgNPs were characterized by energy dispersive X-ray spectrometry (EDS), UV–vis spectrophotometry and dynamic light scattering (DLS). AgNPs with diameters between 40 to 160nm were produced. The UV-Vis spectra reveal a characteristic absorption peak of the Ag in 420nm. This suspension shows shifts in the emission wavelength when exposed to room temperature compared to when exposed to a temperature of 4°C for different periods of time. Δλ = 20nm in the absorption spectra were found. Size distribution showed that the nanoparticles size decreases from 164 ±8 nm to 44±3 nm in the period of time studied. Suspension with nanoparticles concentration of 1,26· 10-10 M were obtained. TTIs manufactured with nanomaterials base its operation on the variations of the characteristics of nanoparticles suspended due to absorbing heat.

An Edible Humidity Indicator That Responds to Changes in Humidity Mechanically

“…Intelligent tags are designed to monitor the storage environment of perishable products in a cost-efficient manner . Macroscopic size intelligent tags such as temperature tags − and gas tags − have been widely studied and are constantly reported in recent years. In addition to macroscopic size intelligent tags, microparticles that can report changes in pH or carry encoded information and respond to external stimuli have also been reported.…”