If you're foraging for wild chestnuts, don't confuse edible sweet chestnuts with unrelated (and inedible) horse chestnuts - also known as conkers. Wild British sweet chestnuts are not fully ripe until they fall in large numbers in late October. Look for the glint of shiny dark brown nuts; paler nuts are unripe and will quickly shrivel.
Most of the chestnuts available in supermarkets during the chestnut season (late September to December) are from Europe rather than home-grown. If you buy your chestnuts fresh, choose plump smooth, shiny nuts. Avoid any wrinkled nuts and discard any bad ones, which will have an acrid smell and bitter taste. Chestnut flour, dried chestnuts, chestnut purée and vacuum-packed chestnuts are sold throughout the year, although they're more readily available in autumn and before Christmas. Dried chestnuts and chestnut flour are available from Italian delicatessens; chestnut flour is also available online. Both sweetened and unsweetened chesnut purées are sold in cans (read the label carefully to make sure you're buying the right one). The best quality vacuum-packed chestnuts are usually sold whole and unbroken, also in cans. They tend to be more expensive than the plastic vacuum-sealed packets of smaller nuts and nut pieces.
