4-hydroxy-2,5-dimethyl-furan-3(2H)-one + NAD(+) => 4-hydroxy-5-methyl-2-methylenefuran-3(2H)-one + NADH + H(+)
4-hydroxy-2,5-dimethyl-furan-3(2h)-one + nad(+) => 4-hydroxy-5-methyl-2-methylenefuran-3(2h)-one + nadh + h(+)