Barley and their hybrids and derivatives, barley contains gluten, which makes it an unsuitable grain for consumption by people with gluten-related disorders, such as celiac disease, non-celiac gluten sensitivity and wheat allergy sufferers, among others. Nevertheless, some wheat allergy patients can tolerate barley or rye. Barley is a key ingredient in beer and whisky production. Two-row barley is traditionally used in German and English beers. Six-row barley was traditionally used in US beers, but both varieties are in common usage now. Distilled from green beer, whiskey has been made primarily from barley in Ireland and Scotland, while other countries have used
Rye bread "Lactobacillus" "sourdough" cultures lowers bread pH, facilitating growth of an acid-tolerant yeast strain, and helping gelatinize starches in the dough matrix. The byproduct of this approach is lighter breads. In areas where high-gluten hard wheat is readily available the need for a complex polyculture of bacteria and yeast can often be reduced or removed by adding a large proportion of hard wheat flour to the rye flour. Its added gluten compensates for amylase activity on the starch in the dough, allowing the bread to retain its structure as it bakes. The "deli rye" tradition in the United States is based