Reactivity of vegetables towards sulphur dioxide

When Brussels sprouts, cabbage, carrot, peas and potato are dried in air at 80°C in the presence of sulphur(IV) oxospecies, S(IV), 51 ± 6% of the additive is lost, irrespective of the vegetable or the amount of S(IV) in the final product when present in the following amounts: Brussels sprouts, 800–2000mg SO₂/kg; cabbage, 260–1900 mg SO₂/kg; carrot, 270–1300 mg SO₂/kg; peas, 250 mg SO₂/kg; potato, 32–220 mg SO₂/kg.The reactivity, towards S(IV), of aqueous extracts of different vegetables is compared and assessed in relation to the total solids, glucose, fructose, amino-nitrogen and Kjeldahl-nitrogen contents of the extracts. It is suggested that the rate-limiting process in the loss of S(IV) during vegetable dehydration is not the reaction of reducing sugars with amines but is possibly some physical process.