An Ascorbate Bluetooth© Analyzer for Quality Control of Fresh-Cut Parsley Supply Chain.

This work provides companies in the fresh-cut produce sector with an Ascorbate Bluetooth© Analyzer (ABA), a screen-printed sensor-based device for ascorbic acid (AA) detection, for quality control all along the supply chain. The amperometric detection of AA on fresh and fresh-cut parsley, under correct and incorrect storage temperature, allowed us to investigate the kinetics of AA decay in response to oxidative stress. The role of ascorbate oxidase (AOx) and ascorbate peroxidase (APx) was studied. ABA was used in situ by unskilled personnel. Treatments influenced AA decay kinetics, which were linear in fresh parsley, and non-linear in fresh-cut. Two hours at 28 °C immediately after chopping, the resilience of the fresh-cut parsley was reduced, even though the cold chain was restored. Two hours at -2 °C caused a rapid loss of AA until its complete decay after 72 h. Significant differences between treatments were observed in both the expression and activity of AOx and APx. ABA registered sudden changes of parsley AA following unpredicted variations of temperature during processing or transport. It was useful to remedy the effects of unexpected flaws in the cold chain, which can be proposed for quality preservation of different fresh-cut produce.

A robust, state-of-the-art amperometric microbiosensor for glutamate detection.

Scientific knowledge of glutamate (GLU) neurobiology is severely hampered by the inadequacy of the available in vivo brain sampling techniques. Due to the crucial role of GLU in central nervous system function and pathology, the development of a reliable sampling device is mandatory. GLU biosensor holds potential to address many of the known issues of in vivo GLU measurement. We report here on the development and test of a labor- and cost-effective microbiosensor, suitable to be applied for measuring brain GLU. A glycerol-based cryopreservation method was also tested. Needle type Pt biosensors were coated with a permselective Nafion-Poly(o-phenylenediamine) layer and cross-linked to l-glutamate oxidase with poly(ethylene glycol) diglycidyl ether. Tested in vitro, the device shows high sensitivity and specificity for GLU, while being poorly influenced by common interfering substances such as ascorbate, dopamine and dihydroxyphenylacetic acid. Further, the cryopreservation procedure kept sensitivity unaltered for 30 days and possibly longer. We conclude that a highly efficient GLU biosensor of minimal dimensions can be consistently and affordably constructed with relative ease. Together with the possibility of cryopreservation this shall foster diffusion and exploitation of GLU biosensors technology.