Barley Flashcards
Pros for 2 row barley (Hordeum distichon)
Its higher in extract and has uniform sized grains
Pros for 6 row barley (Hordeum Vulgare)
Has naturally elevated protein content and enzyme level
Assists in the conversion process
What does Vernalization mean?
The cooling of seed during germination in order to accelerate flowering when its planted
What is Photoperiod Sensitivity?
Developmental responses of plants to relative lengths of light and dark periods (Day lengths)
(Developmental stages - flowering, budding and tubernisation)
What are the 4 types of proteins in barley?
Albumin
Globulin
Glutelin
Hordein
What are the the stages endosperm development?
Milk stage
Dough stage
Mature stage
Husk
This is the dry outer-seed covering
Made up of two halves: the palea and lemma
Regulates water and nutrient uptake during the malting process
Husk contains pigmentation.
It is rough in texture.
It is used in varietal identification.
It accounts for 10% of the dry grain weight.
Cereals that have no husk, such as wheat, will have 10% more starch than barley.
It predominantly consists of cellulose and silica
Pericarp and testa
These forrm the layers directly underneath the husk
The pericarp is a very thin layer: ~ 0.5mm.
It accounts for 1% of total grain weight.
The pericarp is semi-permeable to water.
It restricts water absorption to protect the grain.
The testa covers the whole grain including the embryo.
It is composed of two waxy layers; most barley varieties have polyphenols between the layers.
It forms the main barrier to water entry.
It makes up ~ 1-3% of the grain’s weight.
Aleurone layer
This consists of cells that form part of the endosperm. They are in the outermost layer of the endosperm. This layer of living cells is also referred to as the peripheral endosperm. It plays a critical role in producing enzymes that will convert some of the starch to sugars for the growing embryo
The hyaline layer and the aleurone layer together make up 8-15% of the dry grain weight.
One side of the aleurone layer is fused to the hyaline layer; the bottom is fused to the starchy endosperm.
Aleurone cells have dense cytoplasm and prominent nuclei.
Starch is absent in these cells.
This layer is a major reserve of phosphate and other mineral ions.
The aleurone layer is the site of enzyme synthesis during germination that helps in the modification of the starchy endosperm.
Endosperm
This is the developing embryo’s food store. It usually contains starches, which will be broken down into sugars as the seed grows. It also contains protein and other nutrients.
The starchy endosperm makes up to 75-80% of the grain’s dry weight.
Endosperm cells next to the aleurone layer are smaller and more cuboidal.
The cells are packed with starch and embedded in a protein matrix.
Starch granules in the grain have different sizes which vary between varieties:
Small granules are typically 1-5 straight mum in diameter.
Large granules are typically 20-25 straight mum in diameter (10% of the total number of starch granules, but representing 90% of the total starch by weight).
Barley kernels can also be differentiated into mealy and steely kernels.
Scutellum
This is known as the modified seed leaf in grains like barley and rice. Its name comes from Latin and means ‘small shield’. During germination it transfers nutrients to the embryo.
Embryo (germ)
This is the reproductive part of the kernel; it germinates and grows into a plant
What is Mealy grains?
Mealy grains allow rapid water penetration and uniform hydration of the endosperm. This results in quicker and more uniform modification, producing superior quality malt.
What is Steely (glassy) grains?
Steely grains hinder endosperm hydration and enzyme distribution, giving uneven modification and poor quality malt.
Requirements for Winter barley
Requires vernalisation before the plant produces a fertile head
Needs to be able to withstand the cold winter weather
Sown in Autum
