A pyruvate dehydrogenase-based amperometric biosensor for assessing pungency in onions (Allium cepa L.)
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A disposable prototype electrochemical biosensor was constructed using pyruvate dehydrogenase immobilised on mediated Meldolas Blue electrodes to determine pungency in onions (Allium cepa L.). The optimum operating potential was +50 mV vs. Ag/AgCl reference/counter electrode. The biosensor was able to differentiate between mild and pungent bulbs with pyruvate concentrations ranging between ≈4 and 8 mM in freshly extracted juices. Resolution was 0.5 mM and thus was comparable to the standard Schwimmer and Weston-based colorimetric assay currently employed by industry for determining pungency in macerated onion tissue.
KeywordsMeldolas Blue Pyruvate Quality assurance
This work formed part of a larger HortLink project (HL0164LFV; defining quality assurance for sweet onions with rapid biosensor analysis) and is financially supported by the UK Government (Department for Environment, Food and Rural Affairs; Defra) and UK industry representatives (Allium and Brassica Centre Ltd. (ABC), Applied Enzyme Technology Ltd. (AET), Gwent Electronic Materials Ltd. (GEM), F. B. Parrish and Son Ltd., Bedfordshire Growers Ltd., Rustler Produce Ltd., Moulton Bulb Co. Ltd., G’s Marketing Ltd., Sainsbury’s Supermarket Plc., Tesco Stores Ltd. and Waitrose Ltd.). Special appreciation is extended to David O’Connor (ABC) for organising plant material and Robin Pittson (GEM) for the supply of sensors. The technical support of Mr. Allen Hilton, Cranfield University is gratefully acknowledged.
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