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Biosensing of rapeseed glucosinolates using amperometric enzyme electrodes based on membrane‐bound glucose oxidase or tyrosinase
Author(s) -
Stančík Lubor,
Macholán Lumír,
Pluháček Ivo,
Scheller Frieder
Publication year - 1995
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/elan.1140070806
Subject(s) - sinigrin , myrosinase , chemistry , glucose oxidase , glucosinolate , chromatography , rapeseed , amperometry , allyl isothiocyanate , isothiocyanate , tyrosinase , membrane , biosensor , biochemistry , enzyme , food science , brassica , botany , biology , electrode , electrochemistry
Sinigrin, the β‐ 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 pO 2 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/pO 2 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 −147 μmol/g) agreed with those obtained using gas chromatography as the reference. Poor agreement (results: 111.4–112.3%) 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 6.2–103 μmol/g (44.3–83.8% of the total glucosinolates).