Examination of 1,5-Anhydro-d-fructose and the Enolone Ascopyrone P, Metabolites of the Anhydrofructose Pathway of Glycogen and Starch Degradation, for Their Possible Application in Fruits, Vegetables, and Beverages as Antibrowning Agents^†

The anhydrofructose pathway describes the degradation of glycogen and starch to 1,5-anhydro-d-fructose (1,5AnFru) and its further conversion to the enolone ascopyrone P (APP) via the transit intermediate ascopyrone M. The two products, 1,5AnFru and APP, were examined in this study for their effects in controlling the browning of selected fruits, vegetables, and beverages. The results showed that 1,5AnFru had an antibrowning effect in green tea and was able to slow turbidity development in black currant wine. APP proved to be an antibrowning agent comparable to kojic acid. It showed an antibrowning effect in a range of agricultural products, such as various cultivars of apple, pear, potato, lettuce, and varieties of green tea in an efficacy concentration range from 300 to 500 ppm. Mechanism studies indicated that, like kojic acid, APP showed inhibition toward plant polyphenol oxidase and was able to decolor quinones.

Keywords: Anhydrofructose pathway; 1,5-anhydro-d-fructose; antibrowning; ascopyrone P; beverage; fruit juice; green tea; kojic acid; turbidity; vegetable