APPLICATION AND ADVANTAGES OF THE ENZYMATIC METHOD FOR THE ASSAY OF ASCORBIC AND DEHYDROASCORBIC ACIDS AND REDUCTONES Determination in Fresh and Canned Spinach

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Abstract
A new enzymatic method based on the reaction ascorbic acid +½O2→ dehydroascorbic acid + H2O permits assaying for ascorbic and dehydroascorbic acids in vegetable extracts. The method is carried out using a Clark's electrode which determines the oxygen uptake during the above reaction. The method applied to both fresh and canned spinach is specific and reproducible. Some interfering substances may reduce the specificity and precision of the method, but the addition of chelating agents or acetaldehyde eliminates these interferences. On adding boric acid, only the interfering reductic acid is assayed. The ascorbic and dehydroascorbic acid values for fresh spinach range between 528–919 mg/100g for ascorbic acid and from 21–81 mg/100g for dehydroascorbic acid. For canned spinach the ascorbic acid values ranged from 119–202 mg/100g and the dehydroascorbic acid values from 25–110 mg/100g. The method is easy and rapid and can be utilized advantageously for routine analyses.