@Ian Fisk In Extrusion

Mostly, flour is attributed by gluten which develops three dimensional structure in dough form followed by baking.

The functional properties to determine the types of flours include water absorption capacity, bulk density, oil absorption capacity, swelling capacity of the particles as these will also effect the gluten formation in the flours. These functional properties help in deciding the blends of different flours for various products. Below is the link for 1 such eg:-

www.academicjournals.org/ajfs/pdf/pdf2010/.../Ikpeme%20et%20al.pdf

The functional properties of flour are essentially the physical (e.g. particle size, water absorption capacity, hot pasting attributes, etc.) and chemical (e.g. amylose-amylopectin ratio, etc.) properties of such flour that can have direct influence on its 'useability'' and the quality of derivable products from it.

Please check following paper:

Effect of Different Sprouting Conditions on Alpha Amylase Activity, Functional Properties of Wheat Flour and on Shelf-Life of Bread Supplemented with Sprouted …

Check the pdf file in link

https://atrium.lib.uoguelph.ca/xmlui/bitstream/handle/10214/6672/Shafqat_Saba_201305_Msc.pdf?sequence=1

Functional properties of flour include: Bulk density, Water absorption capacity, oil absorption capacity, Emulsion Activity, emulsion stability, nitrogen solubility index Foaming capacity, foam stability, least gelation concentration.

Read the following article

Article Nutritional Potential and Functional Properties of Heat-trea...

Rheological Properties of dough were measured by Mixolab, Alveograph and Farinograph.

The following parameters were measured by Mixolab: water absorption, development time, stability at mixing, C1 (used to determine absorption), C2 (measures the weakening of the protein based on the mechanical work and the temperature), C3 (measures starch gelatinization), C4 (measures the stability of the hot-formed gel), C5 (measures starch retrogradation during the cooling period), water absorption index, mixing index, gluten index, viscosity index, amylolysis index and retrogradation index.

The following parameters were measured by Alveograph: the maximum over pressure (P) needed to blow the dough bubble, which is an index of resistance to extension (elasticity); the average abscissa (L) at bubble rupture, an index of dough extensibility, P/L indicating the ratio of elasticity to extensibility of the dough and the deformation energy (W) an index of dough strength.

The following parameters were measured by Farinograph: water absorption, arrival time, dough stability, dough tolerance index, dough weakening and degree of softening.

Read also the following article:

Article Improving dough rheology and cookie quality by protease enzyme

There are numerous functional properties, Important are: Moisture holding capacity, fat holding capacity, color of dough, Starch gelatinization temperature, elasticity of dough, swelling capacity, bulk density, Farinograph water absorption, arrival time, dough stability, dough tolerance index, dough weakening and degree of softening.

As earlier state by previous contributors, there are many functional properties and their applications are endless.  The url of  pasted , article though on starch, but relevant functionalities were discussed. 

http://www.hiast.edu.vn/dbt/attachments/article/172/Starch%20in%20Food%20Structure_%20Function_%20and%20Applications.pdf.

Thank you 

Soaking and Drying Effect on the Functional Properties of Ogi Produce from Some Selected Maize Varieties

https://www.researchgate.net/publication/280761356_Soaking_and_Drying_Effect_on_the_Functional_Properties_of_Ogi_Produce_from_Some_Selected_Maize_Varieties

Article Soaking and Drying Effect on the Functional Properties of Og...

Please go through the following journals;

1. Phillips RD, Chinnan MS, Branch AL, Miller J, Mcwatters KH (1988) Effects of pre-treatment on functional and nutritional properties of cowpea meal. J Food Sci 53(3):805–809.

2. Coffman CW, Garcia W (1977) Functional properties and amino acid content of protein isolate from mung bean flour. J Food Technol 12:473–484

Kawabata A, Sawayama S, Nagashima N, Del Rosario RR, Nakamura M (1984) Some physico-chemical properties of starches from cassava, arrow root and sago. J Jpn Soc Starch Sci 31:224–232

Flour or flour is a powder usually made from grains such as wheat, barley, corn, etc., and sometimes made from potatoes, rice or any starch-rich crop. The flour is the main raw material in the industry of basic foods such as bread, cakes, capillaries and other foods. Flour, especially wheat flour, is a staple food that must be provided to the public even in emergencies to prevent famine. The most flour used in the world today is wheat flour because it contains high protein in addition to the high percentage of gluten which helps in the manufacture of bread and pastries. Wheat and its derivatives, especially wheat flour, are among the most important natural materials that humans have fed since ancient times (6000 BC). The flour is mainly used in bread and pastries, especially in baked dough, because it is characterized by its important nutritional contents of the human body of proteins and starch, which gives the mixture of flour and water a rubber texture and allows easy formation and manufacture while keeping the gas bubbles within the product structure to give the sponge texture, which is desired by the human with bread, cakes and other baked products Since the birth of the flour industry and so far, man has developed and improved the industry of wheat and its derivatives from the primitive form of the old, which was manufactured in small quantities and in a manual way to become a key industry.

Some functional properties to determine include water absorption capacity, oil absorption capacity, bulk density, swelling capacity, least gelation concentration, foam capacity, foam stability, nitrogen solubility.