Food Proteins - Wheat, Flour, Gluten Flashcards
What is the bran of a grain and what does it contain?
The outer layer
Fibre-rich
B vitamins
What is the endosperm of a grain and what does it contain?
The middle layer
Carbohydrate
Protein
What is the germ of a grain and what does it contain?
The core
Nutrient rich
Antioxidants
What parts of the grain do wholemeal products contain?
The bran, endosperm and germ
What parts of the grain do white grain products contain?
Just the endosperm enrichedwith vitamin B1, iron and calcium
What is the biological definition of gluten?
A protein complex derived from cereals
- Wheat
- Rye
- Barley
- Oats
What is the food science definition of gluten?
A viscoelastic byproduct derived from the isolation of starch from wheat flour
- Dough forming protein
What is vital wheat gluten?
Gluten sold in dry state
How is vital wheat gluten produced?
From wheat flour by wet separation and controlled drying
What does vital wheat gluten retain when rehydrated?
Gluten properties = a cohesive viscoelastic mass
What is vital wheat gluten traded as?
An additive for bread manufacture and an ingredient for other food and non-food uses
What properties does vital wheat gluten have?
Forms a viscoelastic cohesive mass when rehydrated
High water holding capacity
Thermosetting properties
How is vital wheat gluten sold?
As a cream coloured powder
What are the challenges involved with trading vital wheat gluten?
- Modest price when compared to alike products
- Not high in biological value when completely isolated
- There is no research into the nutritional advantages
- Disadvantaged due to the link with coeliac disease
How is the world production of vital wheat gluten changing over time?
Increasing
How is gluten extracted from flour?
- Mix flour and water to produce a dough/batter
- Leave dough to rest and fully hydrate = produces gluten protein agglomerates
- Agglomerates are separated from starch by centrifugation
- Drying, grinding and sieving obtains vital when gluten powder
How are lipids obtained in vital wheat gluten?
Flour lipid content binds to hydrophobic areas on gluten proteins during washing
What percentage of protein must vital wheat gluten contain?
80%
What are the main gluten proteins?
Glutenin and Gliadin
What are the properties of glutenin?
Polymeric
Strands
High molecular weight glutenin contains a high percentage of sulphur which allows formation of disulphide bonds
What property of gluten is glutenin responsible for?
Elasticity = the ability to return to its original shape once stretched
What are the properties of gliadins?
Monomeric
Globular
Act as a fillar between glutenin strands
What are the four types of gliadin?
Alpha
Beta
Gamma = high percentage of sulphur which allows the formation of disulphide bonds
Omega
What property of gluten is gliadin responsible for?
Extensibility = the ability to stretch
What process can be used to determine the proportions of glutenins and gliadins?
Electrophoresis
How are glutenins and gliadins associated?
Disulphide bonds
Hydrogen bonds
Hydrophobic interactions
What are glutens unique physical properties and how are they achieved?
Viscosity
Extensibility
Elasticity
Achieved by the balance of glutenins and gliadins
What amino acids are found in gluten?
High levels of essential amino acids except lysine
High levels of glutamine = non-essential amino acid
What are the functional properties of gluten?
- Solubility and water holding capacity
- Viscoelasticity
- Flavour
- Thermosetting
Is gluten soluble or insoluble in water and why?
Insoluble because the components of gluten are held together by strong covalent and non-covalent bonds
Is glutens water holding capacity high or low and how is this advantageous?
High
- Improves yield
- Lengthens shelf life
What does the elasticity of gluten allow for and why is this?
Controlled expansion whilst maintaining strength because there are only a few charged amino acids present meaning protein molecules can associate very close together and resist dispersion
What is the flavour of gluten and how can it be improved?
Bland - can taste rancid due to lipid oxidation
- Blending with other proteins
- Blending with soy improves nutritional quality
What do the thermosetting qualities of gluten provide?
Structural rigidity
How can gluten be modified?
By increasing solubility for emulsions and foaming
Physical treatments
How is gluten modified to increase solubility for emulsions and foams?
- Deamidation with acid or alkali treatment = meat and milk replacements
- Enzymatic hydrolysis of peptide bonds = dough
What physical treatments can be used to modify gluten?
- Texturisation by extrusion = stimulates meat fibres
- High pressure = makes gluten more liquid like
- Low pressure increased = makes gluten more solid
What are the uses of wheat gluten?
Flour fortification in bakery Breakfast cereals Pasta and noodles Processed meat, poultry and fish Veggie meat and cheese replacements Asian food Pet food Agriculture feed
What are the non-food uses of wheat gluten?
Edible films
Skincare and haircare
How is gluten used in fortifying flour for baking?
Increases protein content
Improves nutritional quality
How is gluten used in breakfast cereals?
Improves nutritional quality
Helps binds minerals and vitamins
Contributes to textural strength of flakes
How is gluten used in pasta and noodles?
Reduces stickiness
Increases resistance to breakage
How is gluten used in processed meat, poultry and fish?
Converting less desirable cuts into more palatable products
Binds mince which can improve slicing
How is gluten used in veggie meat and cheese substitutes?
Binding of meat replacements
Texture of synthetic cheese
How is gluten used in asian food?
Soybean meat substitutes
Soy sauce
Deep fried gluten balls
What does vital wheat gluten need to be approved for?
Certain uses
- Dough strengtheners
- Stabilisers
- Thickeners
What is coeliac disease?
The inflammation of the small intestine due to an inappropriate immune response to wheat gluten
What is the current treatment for coeliac disease?
Strict diet
What is a potential treatment for coeliac disease?
Oral enzyme supplements designed to accelerate gastrointestinal degradation of gluten
