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Chemical properties of flour, Functional properties of flour - Coggle…
Chemical properties of flour
STARCH COMPOSITION
Starch is the primary carbohydrate in flour and is the majority of flour's chemical makeup, with two key parts:
amylose
and
amylopectin
Amylose is a linear polysaccharide, while amylopectin is a branched polysaccharide. The ratio of amylose to amylopectin affects the texture and firmness of pasta. When cooled, amylose forms crystals again, helping the pasta keep its shape and prevent it from getting too soft. This is particularly important for maintaining the pasta's shape and bite after cooling. Amylopectin is much more soluble, which contributes to the viscosity of the dough and helps in giving a smooth texture to the pasta.
During the cooking process, starch gelatinises - the granules swell as they absorb water. In high quality flour, this is controlled so the pasta won't absorb excess water- which would result in it being soggy. The balance between amylose and amylopectin makes sure that the pasta has the right texture - firm and tender - with minimal cooking loss.
For example, Durum Wheat Flour has a higher amylose content compared to Soft Wheat Flours - which is why it is preferred for pasta as its less sticky and soft when cooked.
LIPIDS AND LIPID-PROTEIN INTERACTION
Even though there are only small amounts of fats/lipids in flour, they still have a big impact on how the dough behaves and the overall quality of the pasta. Lipids can interact with proteins and starch to improve the flexibility of the gluten structure in the dough.
The interactions between lipids and proteins/starch improve the dough's ability to stretch and retain water - meaning that it would have a smoother texture and not become overly sticky.
Furthermore, lipids can affect the quality of the pasta by reducing the amount of starch loss during cooking - improving the pasta's firmness and won't overcook as easily.
ENZYMATIC ACTIVITY
Enzymes in flours such as amylase and protease, can influence the doughs properties and its final quality. Amylase breaks down starch, into simple sugars which could affect the dough's stickiness and consistency. However a small amount of amylase activity can benefit the dough during fermentation.
Protease breaks down proteins which could potentially weaken the gluten network if the flour is not stored or processed correctly. This could lead to a less elastic dough, and one that can break easily.
In well-processed pasta flour, enzymatic activity is controlled so that the starch and protein structures remain intact, which therefore allows a firm pasta to form.
Functional properties of flour
WATER ABSORPTION + HYDRATION
Water absorption is a vital functional property that affects the dough's formation process. As the flour hydrates, the protein and starch granules within the flour start to and absorb water.
During hydration, the proteins start to swell and bond - forming a network that supports the doughs structure. Additionally, starches hydrate and gelatinise - allowing the dough to have a smoother texture and bite when cooked.High-quality pasta flour will hold its water during cooking, reducing the starch pasta emits into the boiling water - creating a cloudy liquid and softer, stickier pasta.
Semolina flour absorbs water slowly - due to its coarse particle size - allowing gradual hydration and gluten development, producing a non-sticky dough that can be manipulated and shaped easily.
GLUTEN DEVELOPMENT
Durum wheat, commonly used to make pasta (usually in the form of semolina flour), has a high protein content of approximately 12-14%, which is perfect for a strong gluten network.
Moreover gluten allows a proper extensibility, allowing the dough to be rolled into a thin sheet or sculpted into various shapes.
This gluten structure traps starch and water forming a form and elastic texture. This firmness is crucial for the pasta’s ability to hold its shape during processing, drying, and especially cooking - preventing the pasta from becoming mushy or breaking apart.
Flour’s most important functional property in pasta is its ability to form gluten, which is created through the hydration and mechanical kneading of the flour’s proteins, primarily
glutenin
and
gliadin
.
These proteins, when mixed with water, form a network that gives pasta its structure. Gluten development is essential because it provides both elasticity and strength, allowing pasta dough to be stretched and shaped without breaking.
VISCOELASTICITY
Viscoelasticity refers to the viscosity and elasticity of (in this case) the pasta dough. This balance is essential if the right texture is wanting to be achieved - meaning it can return to its original shape after being stretched but also need to be be viscous enough to be able to mould the dough into various shapes. Viscoelasticity ensure that the pasta dough can be processed without any tearing or breakage.
The elasticity comes from the gluten network while the viscosity is influenced by the starch content and how well it reacts with water. If the flour is too elastic, the dough will be too stiff - therefore too hard to shape. If it's too viscous, the dough will be too soft and won't hold its shape well when molded.
Semolina flour has a high protein content - making it ideal for producing pasta with structural durability and a smooth, pliable texture, further ensuring that will retain its shape and will not collapse or become too sticky.