Rye

Rye is an annual or biennial grass growing up to about two metres, with narrow blue-green leaves and long, bristly spikes. Each spikelet bears grains that are slender, grey-brown to olive and more elongated than wheat kernels. The grain is sold whole as rye berries, cracked, flaked or milled into light, medium, dark or pumpernickel flours. The taste is earthy, sour and slightly sweet. Rye flour has less gluten-forming potential than wheat, so rye doughs are dense and are often leavened with sourdough starter.

Rye probably originated in south-western Asia, in the area of present-day Turkey and Iran, where it grew as a weed within wheat and barley fields. Over time farmers in colder or poorer-soil regions found that rye outperformed those crops and gradually selected it as a crop in its own right, in the Bronze and Iron Ages. It spread across central, northern and eastern Europe and today Russia, Poland, Germany, Belarus and Ukraine are among the leading growers. Rye also grows well as a winter cover crop in many countries, protecting soil and suppressing weeds.

Rye was a minor crop in antiquity but became a staple bread grain in northern and eastern Europe by the early Middle Ages, because it tolerates cold, acidic and sandy soils and ripens reliably where wheat struggles. Dark rye breads, such as German Roggenbrot and pumpernickel, Scandinavian knäckebröd and Russian black bread, became defining foods of those regions.

Rye is also known for ergot, a fungal disease that infects the grain and in the Middle Ages caused outbreaks of ergotism, called St Anthony's fire, when contaminated flour was eaten. Improved grain cleaning and farming practices largely ended these outbreaks. Rye migrated to North America with settlers, where it also became the base of rye whiskey. Today it is used in specialty breads, crispbreads, whisky, vodka and kvass.

Rye flour makes sourdough loaves, crispbreads, pumpernickel, bagels and pancakes. Rye berries are simmered as a chewy salad grain or porridge, and flaked rye is eaten like oats. Rye is fermented to make kvass, a mildly alcoholic Slavic drink, and distilled into rye whiskey and some vodkas and gins. The straw has been used for thatching, weaving and paper, and the plant is grown as a cover crop and green manure.

Whole rye is high in dietary fibre, including arabinoxylans and fructans, and provides manganese, phosphorus, magnesium, copper and B vitamins. Studies of rye bread suggest it may lead to a slower rise in blood sugar and greater fullness than refined wheat bread, though results vary and depend on the type of rye product. Dark rye breads and whole grain products contribute to the whole grain intake recommended in most dietary guidelines. Light rye breads made largely with refined flour offer less fibre.