The automatic determination of sugars in foodstuffs by a continuous flow technique with a redox detector

Abstract

A method is described for the automatic determination of sugars in foodstuffs at the rate of thirty samples per hour. The system that has been developed subjects the sample to a controlled hydrolysis procedure, which selectively inverts any sucrose that is present. The optimum conditions for the hydrolysis of other sugars have also been studied. The analytical system can be adapted to determine reducing sugars without subjecting the sample to hydrolysis. The proposed system, in which potassium hexacyanoferrate(III) is used as an oxidising agent, has been evaluated by comparison with the titrimetric method of Lane and Eynon involving copper reduction. In general, good agreement between the two methods has been observed, and when anomalies have occurred, they can be explained. The system described will hydrolyse and measure reducing sugars in solutions that contain up to 0·5 per cent. of reducing sugars expressed as dextrose. A few simple modifications to the system permit the determination of low concentrations of reducing sugars, without hydrolysis, with a detection limit of 0·0025 per cent. of dextrose.