Evaluation of Hand-Held Instruments for Representative Determination of Glucose in Potatoes

In this study, the use of two modern portable blood glucose monitors (PBGMs) and a fruit juice-specific system (RQFlex) from Merck was evaluated for determination of glucose concentrations in potato juice, as a representation of the whole potato. The two PBGMs (LifeScan OneTouch Ultra Easy and Bayer Contour) both provided squared correlation coefficients (R-2, p < 0.001) of 0.92, when compared to reference analysis based on Anion Exchange Chromatography (HPAED-PAD).The LifeScan monitor gave an error estimation of 0.54 mg ml(-1) but overestimated the glucose concentration by 20%. The Bayer monitor gave an error estimation of 1.12 mg ml(-1) and underestimated the glucose concentration by 40%. The RQFlex system outperformed (R-2 = 0.96, p < 0.001), error estimation of 0.24 mg mL(-1)) both the PBGMS, but this system is slightly more labour intensive to use than the PBGMs. A squared correlation coefficient of 0.91, p < 0.001, was found when comparing the glucose concentration in potato juice and content in lyophilized potato, indicating that sampling of potato juice may be introducing uncertainties to the measurements.