Wheat flour, whole-grain
Nutritional value per 100 g (3.5 oz)
Energy1,418 kJ (339 kcal)
72.57 g
Sugars0.41 g
Dietary fiber12.2 g
1.87 g
13.70 g
VitaminsQuantity
%DV
Thiamine (B1)
39%
0.447 mg
Riboflavin (B2)
18%
0.215 mg
Niacin (B3)
42%
6.365 mg
Pantothenic acid (B5)
20%
1.008 mg
Vitamin B6
26%
0.341 mg
Folate (B9)
11%
44 μg
MineralsQuantity
%DV
Calcium
3%
34 mg
Iron
30%
3.88 mg
Magnesium
39%
138 mg
Manganese
181%
3.8 mg
Phosphorus
49%
346 mg
Potassium
9%
405 mg
Sodium
0%
5 mg
Zinc
31%
2.93 mg
Percentages are roughly approximated using US recommendations for adults.
Source: USDA FoodData Central

Wheat flour is a powder made from the grinding of wheat used for human consumption. Wheat varieties are called "soft" or "weak" if gluten content is low, and are called "hard" or "strong" if they have high gluten content. Hard flour, or bread flour, is high in gluten, with 12% to 14% gluten content, and its dough has elastic toughness that holds its shape well once baked. Soft flour is comparatively low in gluten and thus results in a loaf with a finer, crumbly texture.[1] Soft flour is usually divided into cake flour, which is the lowest in gluten, and pastry flour, which has slightly more gluten than cake flour.

In terms of the parts of the grain (the grass fruit) used in flour—the endosperm or protein/starchy part, the germ or protein/fat/vitamin-rich part, and the bran or fiber part—there are three general types of flour. White flour is made from the endosperm only. Brown flour includes some of the grain's germ and bran, while whole grain or wholemeal flour is made from the entire grain, including the bran, endosperm, and germ. Germ flour is made from the endosperm and germ, excluding the bran.

Milling

To produce refined (white) wheat flour,[2] grain is usually tempered, i.e. moisture added to the grain, before milling, to optimize milling efficiency. This softens the starchy "endosperm" portion of the wheat kernel, which will be separated out in the milling process to produce what is known to consumers as white flour. The addition of moisture also stiffens the bran and ultimately reduces the energy input required to shatter the kernel, while at the same time avoiding the shattering of bran and germ particles to be separated out in this milling process by sieving or sifting.

The endosperm portion of the kernel makes up about 80% of the volume and is desirable because the products made from this white flour are often considered to have milder flavor, smoother texture, and, in the case of bread, greater volume. The balance of the kernel is composed of the bran and the germ which tend to be coarser. With the invention of the roller milling system in the late 19th century, the bran and the germ were able to be removed, dramatically improving the appeal of baked products to the public.

The moistened grain is first passed through the series of break rollers, then sieved to separate out the fine particles that make up white flour. The balance are intermediate particles of endosperm (otherwise known as product middling or farina) and coarse particles of bran and germ. The middling then makes multiple passes through the reduction rolls, and is again sieved after each pass to maximize extraction of white flour from the endosperm, while removing coarser bran and germ particles.

To produce whole wheat flour, 100% of the bran and germ must be reintroduced to the white flour that the roller milling system was originally designed to separate it from. Therefore, these elements are first ground on another mill (usually a pin mill). These finer bran and germ fractions are then reintroduced to the endosperm (white flour) to produce whole wheat flour made of 100% of the kernel of wheat.

Types

Wheat flour
Wheat flour

Wheat flour is available in many varieties; the categorization is regional, and the same name may have several different regional meanings.

Canada

Fiji

Indian wheat flours

Indian flours are generally categorized by how much of the grain is stripped away.

Southeast Asia

United States

American flours are categorized by gluten/protein content, processing, and use.

Other

Baking characteristics

W index

The W index is an indicator of a flour's strength which is commonly used by professional bakers. It is measured using a Chopin Alveograph, and it takes into account both the toughness and elasticity of the flour's gluten. The W index is often not listed on commercial flour packaging, but it can be approximated based the flour's protein content.[7]

Name W Index Protein Content (by Weight) Example Usage
Weak flour 90 - 160 9% - 10%[7] Biscuits, cakes.
Medium strength flour 160 - 250 10% - 12.5%[7] Pizza, focaccia, baguettes, pugliese bread.
Strong flour above 300 above 13%[7] Sourdough bread.

In general, a higher W index flour will require a longer rising time for leavened bread products. Higher W index flour better retains the CO2 produced during the fermentation process, because the gluten traps the produced gas.[8]

Zeleny sedimentation value

The Zeleny sedimentation value is a measurement of how much of the flour sedimentises during a set period of time in a lactic acid solution.[9][10] It is used to predict the baking characteristics of a particular cultivar.[9][10] Since this test has costs associated with it, the Zeleny value may itself be estimated by EM irradiation and spectral analysis of the dry material.[9][10] Where present, damage by insect pests[11] and fungal diseases[12] are the primary determinants of the sedimentation value, overwhelming the underlying genetic characteristics.

National Flour

United Kingdom

During World War II, the British government promoted National Flour; it was adopted in 1942 as a healthy and economic alternative to importing wheat.[13] The flour is described as being of 85% extraction, i.e. containing more of the whole wheat grain than refined flour, generally described as 70% extraction at the time. Parliamentary questions on the exact constitution of National Flour in 1943 reveal that it was "milled from a grist consisting of 90 per cent wheat and 10 per cent diluent grains. Authorised additions are calcium at the rate of 7 oz (200 g) per 280 lb (130 kg) of flour and dried milk at the rate of 2 lb (910 g) per 280 lb (130 kg) of flour and customary improvers in normal proportions." The diluent grains were barley, oats and rye and customary improvers were "certain oxidising agents which improve the quality of the bread baked from the flour, and their nature depends on the kind of grain used, whether hard or soft".[14] A survey of the composition of National Flour was conducted for the period 1946–1950.[15] National Flour was discontinued in 1956 against the recommendations of the Medical Research Council[13] as the government considered that the addition of nutritional supplements to refined flour removed the necessity for using National Flour on health grounds.

Kenya

National Flour was also a term for a flour introduced in Kenya by the colonial government which contained 70% wheat flour and 30% maize flour.[16]

See also

References

  1. ^ a b c d e Chu, Michael (2004-10-20). "Wheat Flour". Cooking for Engineers. Retrieved 2009-08-14.
  2. ^ Bass, E.J. (1988). Y. Pomeranz (ed.). Wheat Chemistry and Technology Vol. II Chapter 1: Wheat flour milling. American Association of Cereal Chemists. pp. 1–69. ISBN 978-0-913250-73-0.
  3. ^ "What's a Whole Grain? A Refined Grain? | the Whole Grains Council".
  4. ^ Prakash, Sheela (2016-10-22). "What's the Difference Between Whole-Wheat and White Whole-Wheat Flour?". The kitchn. Retrieved 2019-11-23.
  5. ^ "Frequently Asked Questions - Is flour still bleached?". Flour Advisory Board. Retrieved 2011-09-12.
  6. ^ "IARC--Summaries & Evaluations: Potassium Bromate (Group 2B)". International Agency for Research on Cancer. 1999.
  7. ^ a b c d "La forza della farina" (in Italian). 28 January 2009. Archived from the original on 18 April 2019.
  8. ^ "Flours for Pizza and Focaccia, the flour strength". Archived from the original on 5 March 2015.CS1 maint: unfit URL (link)
  9. ^ a b c Hrušková, Marie; Faměra, Oldřich (2011-11-18). "Prediction of wheat and flour Zeleny sedimentation value using NIR technique". Czech Journal of Food Sciences. Czech Academy of Agricultural Sciences. 21 (3): 91–96. doi:10.17221/3482-cjfs. ISSN 1212-1800. S2CID 54766897.
  10. ^ a b c ISO 5529:2007 Wheat — Determination of the sedimentation index — Zeleny test
  11. ^ Kınacı, Engin; Kınacı, Gülcan (2004). "Quality and yield losses due to sunn pest (Hemiptera: Scutelleridae) in different wheat types in Turkey". Field Crops Research. Elsevier BV. 89 (2–3): 187–195. doi:10.1016/j.fcr.2004.02.008. ISSN 0378-4290.
  12. ^ Wang, Jinhua; Wieser, Herbert; Pawelzik, Elke; Weinert, Joachim; Keutgen, Anna J.; Wolf, Gerhard A. (2005-02-17). "Impact of the fungal protease produced by Fusarium culmorum on the protein quality and breadmaking properties of winter wheat". European Food Research and Technology. Springer Science and Business Media LLC. 220 (5–6): 552–559. doi:10.1007/s00217-004-1112-1. ISSN 1438-2377.
  13. ^ a b "End of National Flour". British Medical Journal. 1 (4979): 1347–1348. 1956. doi:10.1136/bmj.1.4979.1347.
  14. ^ "Commons Sitting: Food Supplies: National Flour". Hansard. House of Commons of the United Kingdom. 27 October 1943. Retrieved 6 May 2020.
  15. ^ Fraser, J. R (1951). "National flour survey 1946–1950". Journal of the Science of Food and Agriculture. 2 (5): 193–198. doi:10.1002/jsfa.2740020502.
  16. ^ Madatally Manji (1995). Memoirs of a biscuit baron. East African Publishers. pp. 49–51. ISBN 9789966465023.