CEREAL TECHNOLOGY: WHEAT CLASSES
Diagram
High protein wheat for bread, low protein wheat for cakes
Hard wheat
Wheat with a hard kernel and high protein. Its flour gives a strong gluten network, suited to bread.
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Soft wheat
Wheat with a soft kernel and low protein. Its flour gives a weak gluten network, suited to cakes and biscuits.
Figure 1: Hard wheat is high in protein and makes bread, while soft wheat is low in protein and makes cakes and biscuits. Drawn in our own style from the wheat discussion in Greene, Whole Grain Baking, and in Cornell and Hoveling, Wheat: Chemistry and Utilization.
Introduction
Hard wheat and soft wheat are both wheat, but they differ in the kernel and in the protein of the flour. Hard wheat has a hard, glassy kernel and its flour is high in protein, so it forms a strong, elastic gluten network that traps gas and gives bread its volume and chew. Soft wheat has a soft, starchy kernel and its flour is low in protein, so it forms a weak gluten network that gives cakes and biscuits a tender, crumbly texture. A baker who swaps one for the other gets the wrong texture: bread from soft wheat stays flat, and cake from hard wheat turns tough.
Quick comparison
Table 1: Hard Wheat compared with Soft Wheat
| Aspect | Hard Wheat | Soft Wheat |
|---|---|---|
| Kernel | Hard and glassy | Soft and starchy |
| Protein | High | Low |
| Gluten | Strong and elastic | Weak and tender |
| Flour | Bread flour, coarse and granular | Cake and pastry flour, fine and soft |
| Water absorption | High, because protein absorbs water | Low |
| Bread volume | Large, because the strong gluten traps gas | Small, because the weak gluten cannot hold gas |
| Texture | Chewy and firm | Tender and crumbly |
| Used for | Bread, rolls and pasta wheat products | Cakes, biscuits, pastries and crackers |
| Milling | Needs more power to mill, gives coarse flour | Mills easily, gives fine flour |
| Grain examples | Hard red winter and hard red spring wheat | Soft red winter and soft white wheat |
Scientific explanation
Definition
Hard wheat is wheat with a hard kernel whose flour is high in protein and forms a strong gluten network, suited to bread. Soft wheat is wheat with a soft kernel whose flour is low in protein and forms a weak gluten network, suited to cakes and biscuits.
Working principle
The hardness of the kernel comes from how tightly the starch and protein are bound together. In hard wheat the bond is tight, so the kernel breaks along the cell walls and the flour is coarse, and the high protein forms long gluten strands when water is added and the dough is mixed. Those strands stretch and trap the carbon dioxide from yeast, so the loaf rises high and stays chewy. In soft wheat the bond is loose, so the kernel breaks easily into fine flour, and the low protein forms only short, weak gluten strands, so the batter cannot hold much gas and the crumb stays tender and crumbly, which is what a cake needs.
Apparatus
The books used here name no laboratory apparatus for measuring or comparing either term, so no apparatus list is given.
Measurement procedure
The books used here give no standard laboratory procedure with volumes and steps for either term, so no procedure is invented here.
Factors affecting readings
For both wheats, the variety and the growing conditions decide the protein: the same variety grown with more nitrogen gives more protein. For bread, the protein quality matters as well as the amount: only strong gluten gives volume. For cakes, the fineness of the flour matters: soft wheat mills into a fine flour that gives a smooth batter. The books used here give no protein values with numbers, so none are stated.
Formulas and calculations
The books used here give no formula for either term, so no formula is given here.
Industrial applications
- Hard wheat: bread, rolls and buns, where a strong gluten network gives volume and chew.
- Hard wheat: pizza dough and bagels, where a firm, elastic dough is wanted.
- Soft wheat: cakes and sponges, where a tender crumb is wanted.
- Soft wheat: biscuits, crackers and pastries, where a weak gluten gives a crumbly texture.
- Both: all-purpose flour, made by blending hard and soft wheat to suit general baking.
Advantages and limitations
- Hard wheat, advantage: its strong gluten gives bread a large volume and a chewy texture.
- Hard wheat, limitation: it makes cakes and biscuits tough, because the strong gluten will not stay tender.
- Soft wheat, advantage: its weak gluten gives cakes and biscuits a tender, crumbly texture.
- Soft wheat, limitation: it cannot make a high loaf of bread, because the weak gluten cannot hold the gas.
FAQ
What is the difference between hard wheat and soft wheat?
Hard wheat has a hard kernel and high protein, giving a strong gluten for bread, while soft wheat has a soft kernel and low protein, giving a weak gluten for cakes and biscuits.
Can I use soft wheat flour for bread?
The loaf will stay flat, because the weak gluten cannot trap the gas from the yeast.
Can I use hard wheat flour for cake?
The cake will turn tough, because the strong gluten makes the crumb firm instead of tender.
What is all-purpose flour?
A blend of hard and soft wheat flour, made to suit general baking.
Does hard wheat absorb more water?
Yes. Its higher protein absorbs more water than soft wheat flour.
References and further reading
- FTN books on disk: Cereal Technology.
- Greene, Diana Scesny. Whole Grain Baking.
- Cornell, Hugh and Albert W. Hoveling. Wheat: Chemistry and Utilization. CRC Press, 1998 (Google Books page read)
- Google Books pages read for this article:
- Cornell, Hugh and Albert W. Hoveling. Wheat: Chemistry and Utilization. CRC Press, 1998 (Google Books page read)
