Straight grade flour, or SGF, is the wheat flour produced by a wheat milling run which consists of a gradual milling, sifting and purifying process. In essence, this type of flour is a blend of all flour streams produced at the mill after most of the bran and germ have been removed.1,2
One characteristic of straight grade wheat flour is its kernel content ranges typically from 72% to 76%, expressed as extraction rates of 72 to 76%.
Given its convenience and low cost, straight grade flours have gradually replaced true patent flours in the production of regular products.
Straight grade flour is the starting material for all kinds of premium / refined (long and short patent) and lower grade flours, e.g. clear flour. All these flours, sourced either from soft or hard wheat classes, are used by bakers in the production of both yeast- and chemically-leavened products.
It is a blend of all flour streams obtained at the mill
Straight grade flour = patent flour (highly refined flour) + clear flour (lower grade flour with more ash, bran and aleurone)
Contains a minimum amount of bran but still more than patent or more refined flours
Has a 72–76% extraction rate (US)
Generally yields Agtron color values of 80–85 (patent flours yield higher values, and high-ash flours yield lower values)
This type of flour follows the usual procedure for making wheat milling:
Kernel tempering or conditioning
Sifting and purification
Straight grade flour represents the maximum amount of endosperm that can be separated from the outer coating (bran) and germ in a normal milling run. Despite containing the purest amount of starchy and “white” endosperm, this grade of flour still contains a minimum amount of bran and germ which determines its quality, i.e. ash content, enzymatic activity, baking performance and color.
Composition of wheat and its derivatives (% dry matter)
Given their high purity, patent flours from hard wheats are more expensive than straight grade flours. Patent flours are much whiter and purer than straight grade flours. This is why most high-speed bakers make use of straight grade flour in the production of bread, buns and many other baked goods.
Some bakers use patent flour for premium-type baked goods and artisan breads. Straight grade flours, on the other hand, are more versatile yet produce high volume finished products. In practice, patent flours require less DATEM and ascorbic acid thanks to their high quality and quantity of glutenins. However, such highly refined flours usually need higher amylase dosages to give equal volume impression as their straight grade counterparts.
Hoseney, R. Carl., and Jan A. Delcour. “Chapter 8: Dry Milling.” Principles of Cereal Science and Technology. St. Paul, MN, USA: American Association of Cereal Chemists, 2010, pp. 129–30.
Posner, E.S. “Wheat Flour Milling.” Wheat Chemistry and Technology, 4th edition, AACC International, Inc., 2009, pp. 119–152.