Biosensing of rapeseed glucosinolates using amperometric enzyme electrodes based on membrane‐bound glucose oxidase or tyrosinase

Abstract

Sinigrin, the P-D-thioglucoside of the cruciferous plant species was hydrolyzed for 15 min at pH 7 and 30°C by the enzyme myrosinase to liberate glucose and mustard oil allylisothiocyanate as aglucone. A Clark-type p02 sensor overlaid with a glucose oxidase + catalase membrane served for the glucose measurements, whereas the isothiocyanate component was measured (after conversion to allylthiourea) from the inhibition degree of a tyrosinase membrane/p02 sensor. The total amounts of glucosinolates found with the glucose probe in six assorted samples of rapeseed meal and evaluated in sinigrin equivalents (13.6 -147pmol/g) agreed with those obtained using gas chromatography as the reference. Poor agreement (results: 11 1.4-1 12.3%) was achieved when a different method of fat removal was used prior to electroanalysis. The amounts of progoitrin (not convertible to thiourea) estimated indirectly from the difference of both the glucose and the aglucone biosensor analyses were found to be in the range 6.2-103pmol/g (44.3-83.8% of the total glucosinolates).

Glucosinolates, structures and analysis in food

“…Biosensing using amperometric enzyme electrodes based on glucose oxidase and tyrosinase were utilized after conversion to glucose and thiourea. 87 Biosensing with a myrosinase-immobilized eggshell membrane, with glucose oxidase activity and an oxygen-sensitive optode membrane, measuring depletion of dissolved oxygen has also been reported. 88,89 The first amperometric flow analyzer based on the biosensor concept was described in 2003, using myrosinase and glucose oxidase.…”

Identification of a New Glucosinolate-Rich Cell Type in Arabidopsis Flower Stalk

“…Estimation of total concentration of glucosinolates in single-cell samples was based on their selective hydrolysis by the enzyme thioglucosidase (myrosinase), followed by measurement of the released Glc, an approach used in commercial food/crop analysis (Tholen et al, 1993;Stancik et al, 1995).…”