Abstract
The present study aimed to optimize the conditions for the synthesis of gold nanoparticles (AuNP) using chitosan and to assess its effectiveness as temperature threshold indication for frozen storage conditions. Chitosan concentration of 0.25% and temperature of 90 °C for 15 min was optimum for synthesizing AuNP. The maximum absorbance (λmax) was observed at 530 and 540 nm for 0.125% and 0.25% chitosan, respectively, indicating shifting of peak toward longer wavelengths (red shift) with increasing chitosan concentration indicating larger AuNPs. A prominent absorption peak at 1367 cm−1 by Fourier transform-infrared (FTIR) spectrum corresponding to C−C stretching of the glucosamine group of chitosan indicates the chitosan capping on the AuNP. Higher peak intensity and a peak shift toward shorter wavelength were observed for AuNPs exposed to frozen temperature abused conditions. Distinctly clear visible color variation from cherry red to gray indicates its application as temperature abuse indicator in frozen products.
Highlights
Temperature is the most crucial factor affecting the quality by influencing the kinetics of physical, chemical, and microbial spoilage in perishable food commodities as well as pharmaceutical products
It consists of a simple device that can be attached to the packaging containing food or pharmaceutical products to indicate its storage temperature history and thereby quality and safety of the products
The results indicated that storage under constant frozen condition has little influence on the properties of synthesized AuNPs up to 29 days
Summary
Temperature is the most crucial factor affecting the quality by influencing the kinetics of physical, chemical, and microbial spoilage in perishable food commodities as well as pharmaceutical products. The storage temperature of the temperaturesensitive products like chilled, refrigerated and frozen stored food, pharmaceutical, and biological products is monitored strictly to ensure that the product remains within the accepted threshold range and to ensure conformance with product release specification. A visible temperature abuse indicator will be useful for maintaining the proper storage conditions at all the stages. This can be achieved by nanotechnology by developing biosensors like thermal history indicator (THI) that provides very useful information on temperature history. Biological methods for nanoparticle synthesis using microorganisms, enzymes, vitamins, sugar, and biodegradable polymers of plant or animal origin have been suggested as possible ecofriendly alternatives to chemical and physical methods.[2,3]
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