Rye ( Secale cereale )
Rye ( Secale cereale ) is a type of grain from the sweet grass family (Poaceae) that is widespread in the temperate regions . It still delivers good yields on lighter or sandy soils and in cooler or damp locations. In Europe, winter rye is often grown, while summer rye is of secondary importance. The grain of rye is used for food, feed and luxury goods or as a renewable raw material . Sometimes the plants that are still green ( green rye ) or the straw left over from the grain harvest are also used. Here, the rye is mostly used as feed in the form of meal or silage.
The rye has 65 to 200 centimeters long stalks and 5 to 20 centimeters long, four-edged, slightly overhanging the heyday ears of individual, mostly zweiblütigen spikelets with narrow Glumes and langbegrannten lemmas . The thousand grain mass (mass of 1000 grains) is 28 to 50 grams for rye.
Rye is annual, usually hardy (winter rye), less often summer annual (summer rye) and a long-day plant . It is an intensive rooter , its roots reach up to 1 meter deep. In a free-standing plant, the roots can reach a length of 80 m and the root hairs a surface of 400 square meters. Depressed stalks can quickly straighten up again through one-sided growth of a knot.
In terms of flower biology, it is a wind- flowering "long-dust type". The pollen is relatively large and heavy. The flowers are opened by an increase in the turgor in the erectile tissue and then closed again within half an hour by a decrease in the turgor. Often many flowers open at the same time, ie in “pulses”. By very rapid growth pushing up before the stamens and after opening of the dust bag then the feathery scars from the flower out. The flowers are self-sterile , but neighbor pollination is possible. The flowering period is between May and July.
Rye is an allergy plant : rye pollen is considered to be the strongest allergy trigger among domestic grasses.
The fruits are caryopses , seeds and fruit peel are fused together. The rye grain is not tightly enclosed by the husks, with old varieties there is a great risk that the grains will fall out of the ears when they ripen when they are lightly touched. Fruit ripening is from July to August. The time from seed germination to fruit ripening is around 280 to 320 days for winter rye.
Of the cereals, rye is most affected by the highly poisonous ergot fungus Claviceps purpurea . After infection of the flowers, a long, brown, hard grain develops at the place of the fruit, which is also used medicinally.
In the Orient, rye was a wild grass. Its seeds were brought into the wheat and barley fields (wind, animals) and spread there. Because winter frosts, diseases, drought and lack of nutrients are less likely to affect it than the demanding wheat, rye has prevailed in the harsh climate of Central and Northern Europe and has become the only bread grain of the Slavs, Celts and Teutons. For more than 1,200 years rye was the most important breadfruit in Germany, often referred to by people as “the grain”.
In the 1970s, rye grains and spindles were found in two places in Stone Age layers (approx. 6600 BC) in northern Syria ( Tell Abu Hureyra ). Otherwise there is almost no evidence of the use of rye until it is found in archaeological finds in Europe dating from around 1800–1500 BC. Originate, appears again. It is possible that it was brought into Europe as a contamination in wheat seeds and only specifically cultivated here (see also secondary grain ). In Germany, grains of rye appear in archaeological excavations only in the 6th – 5th centuries. Century BC BC (i.e. in the Hallstatt period ) and thus only 3000–3500 years after the beginning of the agricultural culture ( band ceramics ). The Romans knew rye, but Pliny the Elder describes it in his Naturalis historia (Book 18, keyword 40) , written around 79 AD, as inferior and harmful to the stomach, only suitable for warding off starvation in times of need.
Forest rye is one of the older rye varieties.
Since the 1980s, in addition to the classic open-pollinated varieties, hybrid varieties have also been bred, which have better disease resistance, higher yields ( heterosis effect ) and a lower tendency to outgrow. Early hybrid varieties were consistently more susceptible to ergot because of their lower pollen release . In the meantime this property is very dependent on the variety, and the breeders have greatly improved the pollen release of hybrid varieties, so that it can no longer be said that hybrid varieties are more susceptible to ergot than open-pollinated varieties.
A modern cross between wheat and rye, triticale , combines several positive properties of both species.
There are summer and winter rye, with winter rye being grown almost exclusively in Central Europe. Winter rye is the hardest type of cereal that can withstand winter temperatures down to −25 ° C, it can make better use of winter moisture, it can withstand a spring drought more easily and is therefore far superior to the summer form in terms of grain yield. The summer form is only grown in locations with a risk of late frost and on exposed mountain locations.
Winter rye is sown in Germany between mid-September and mid-October; like all winter cereals , it needs vernalization to overcome the lock-in . In order to get from the vegetative growth phase to the generative phase, a cold stimulus is necessary. At temperatures from 0 to +5 ° C, successful vernalization is achieved after 30 to 50 days. Rye needs a total heat of around 1800 ° C until it is ripe. (Heat sum = number of growing days × daily temperature mean). After maturing on the stalk , the rye only has a very short dormancy . The harvest takes place in Germany from mid-July to the end of August. In a rainy harvest season, there is a risk that the grains will germinate in the ear and the harvest can only be used as feed grain.
Rye is better adapted to cool and dry climates than high-yielding wheat and is therefore the grain of regions with widespread sandy soils . Rye is a light germ and therefore places special demands on the seed , the seed bed and the time of sowing. Male pollen and female flowers become active at different times, which is why rye is usually a cross- pollinator , unlike the self-fertilizing cereals wheat and barley .
Hybrid varieties and population varieties are bred , with hybrid rye having a cultivation share of 70–75%. Marker-based selection, cell culture techniques and genomic selection are used and expanded as modern breeding methods. Genetic markers make it possible, for example, to read characteristics of the variety from the DNA. On the one hand, this analytical method is independent of external influences, such as the weather, and on the other hand, the breeding value of a variety can be determined at an early stage. Breeding advances focus on diseases, stress tolerance and, above all, quality and yield. Particular attention is paid to the breeding of hybrid varieties, as these allow a better expression of the desired characteristics, for example high yields, due to the heterosis effect. Corn, rye and sugar beet are strongly represented as cross-pollinators in hybrid breeding.
Winter rye can also be used as green manure .
The largest rye producers
According to the Food and Agriculture Organization (FAO), around 11.3 million t of rye were harvested from around 4.5 million hectares of land worldwide in 2018 . The following table gives an overview of the 10 largest producers of rye worldwide, which together harvested 85.6% of the total. The values for Austria and Switzerland are given for comparison.
(in t )
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- List of the largest grain producers
- The largest wheat producers
- The largest barley producers
- The largest rice producers
- The largest corn producers
- The largest oat producers
At the beginning of the 20th century, trading in rye played a role on the world's stock exchanges, as is the case today with wheat, cocoa and soybeans. The rye loans had their peak with the establishment of a rye pension bank in 1922 and at the time of hyperinflation in 1923 . The Roggenrentenbank served to finance agricultural land by taking out rye and fine gold mortgages . Under the National Socialists , the rye bonds were converted into Reichsmark bonds in 1934 .
In Germany, rye was grown on 523,300 hectares in 2018 . This is far below the previous level of over 1 million hectares in 1990. In Germany, around 4 million tons of rye were harvested in 1990. The average yield per hectare in 2018 was 42 dt / ha (1990 just under 38 dt / ha).
Today rye only plays a minor role in Switzerland. In the mountain regions of Valais , Ticino and Graubünden , it was often grown up to high altitudes. In the canton of Valais, rye cultivation is recognized as an intangible cultural heritage. The rye bread here has AOC approval and has been sold increasingly since then.
Rye is used as a bread grain for rye bread or mixed breads , especially in Central and Eastern Europe . Pasta can also be made from rye semolina. In addition, this type of grain is hardly widespread, so that its share in world grain production is only one percent.
Ingredients of rye
The composition of rye naturally fluctuates, both depending on the environmental conditions (soil, climate) and the cultivation technique (fertilization, plant protection).
Details per 100 g of edible portion:
The baking properties of rye flour are fundamentally different from those of wheat flour. This is mainly due to the fact that the gluten (sticky protein) in the rye dough cannot build up a sticky structure to hold gas due to the presence of pentosans (mucilage). These mucilages have about the same function in rye as the gluten in wheat. They are important for the water retention and water retention capacity of the flours during the dough production and the baking process. Rye biscuits, in contrast to wheat biscuits, are characterized by a darker, firm and aromatic dough. A rye bread consists mainly of gelatinized starch; its crumb is denser and contains smaller pores, so it is less loose than wheat bread. This is why mixed breads and whole grain breads are often made from rye flour . In order to produce salable products, pure rye flour doughs must definitely be leavened, which means they must be subjected to a sourdough process . In wet harvest years , outgrowth can cause problems in rye bread production due to the strong amylase activity. Pure rye bread, for example, is the Westphalian type of bread pumpernickel (black bread), which is made from rye meal and is more steamed than baked.
Because of the comparatively high content of the amino acid lysine , rye can be an important part of a balanced diet. In terms of nutritional physiology and baking technology, rye is of particular interest in human nutrition because of the pentosans (see hemicellulose ). Various, e.g. According to partly contradicting studies, the longer retention time of the food pulp in the digestive system due to the pentosan content is said to have an anti-carcinogenic effect.
The pentosans (e.g. arabinoxylates) pose a problem in pig feeding. In addition to them, rye contains other, relatively high proportions of such "non-starch polysaccharides (NSP)", such as cellulose , beta-glucan , pectins , etc. The pentosans swell and disrupt the transport of food. It is only in the large intestine that these "NSP substances" are broken down by resident microbes , which, however, no longer contributes to the pig's energy supply , but leads to increased gas emissions .
Rye has long been used to make alcohol . For example, the better types of vodka are made from it. The grain , which is often drunk in northern Germany , is also mostly made from rye. Which is from the grain for initially mash prepared according to the fermentation process in distilleries distilled ( burned is). In the past, rye was widely used to make beer , but this was then banned in order to save the valuable rye for baking bread. Commercially produced rye beer has only been available again in Germany since the early 1990s . Until the time of Prohibition, whiskey made from rye, rye whiskey , was the predominant whiskey in the USA and Canada and was only replaced by bourbon whiskey made from corn after Prohibition .
Both the grain and the whole green rye plant ( green rye ) can be used fresh or ensiled ( whole plant silage ) as animal feed . Green rye is the first green fodder on cattle farms in spring. The feed value of rye grain is usually between wheat / triticale and barley. A high proportion of non-starch polysaccharides which are difficult to digest is limiting for its suitability as animal feed . In addition, rye has a very low digestibility in the small intestine of the essential amino acids threonine , tryptophan , lysine and methionine . Rations should therefore be supplemented with amino acids.
Renewable raw material
Rye grain and plants are renewable raw materials that are used in various areas such as the production of bioethanol , biogas , insulation and other materials, as well as other areas. Rye is similar in its properties to other types of grain, so that the lower price for rye is often an important criterion for use.
Since 2004/05 rye has also been grown as an energy source. In the 2006/07 grain year, around 500,000 t were processed into bioethanol in Germany . Another area that is booming is its use as a biogas substrate . Rye is mainly used here as a whole plant in ensiled form ( whole plant silage (GPS)). But it is also used as crushed grains in the fermenters of the biogas plants . The main advantages are the cost-effective cultivation, the high dry matter yields per hectare and the high yield security. The methane yield when using rye grains as a biogas substrate is between 1,400 and almost 2,200 m³ per hectare, depending on the yield.
The material use of rye is diverse. It is mainly used as a raw material for the materials and building materials sector or as a basic material for various preliminary products, for example in the chemical industry. Relatively new is the development of an insulating fill made from rye, which also meets all building regulations (building approval as insulating material by the German Institute for Building Technology (DIBT)) and the requirements for a natural building material ( natureplus test). So far, however, this building material has not been produced.
Dry extracts from, among other things, rye pollen ( Secale cereale ) are used in the treatment of urination problems ( micturition problems ) with benign prostate enlargement and in the treatment of chronic non-bacterial prostate inflammation . Like other herbal prostate medicines, rye pollen only relieves the discomfort without curing the enlargement of the prostate itself.
In an acetone dry extract of grass pollen from rye, maize and timothy grass , anti- proliferative and anti- inflammatory effects were measured in vitro , and anti- congestive and anticonvulsant ( spasmolytic ) effects were also found.
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