Advantages and Disadvantages of Damaged Starch in Flour and its impact on Bread Products
Properties of damaged starch and its advantages and disadvantages
During the process of wheat being processed into flour, the internal structure and external shape of the starch in the flour will inevitably be damaged due to the mechanical forces such as shearing and extrusion of the mill rollers, resulting in cracks and fragments. The damaged starch granules are called damaged starch.
Properties of damaged starch
- The water absorption rate of damaged starch is about 2.5 times higher than that of undamaged starch;
- Damaged starch is more sensitive to α-amylase and β-amylase.
Advantages of damaged starch
During the fermentation process of fermented foods such as bread and steamed buns, yeast absorbs sugar in flour, performs physiological activities, produces carbon dioxide and lipid metabolites, expands the dough volume, and adds flavor to the finished bread.
Since α-amylase and β-amylase can decompose damaged starch into sugars, they can fully provide the nutrients needed for yeast activity. At the same time, damaged starch increases the water absorption rate of flour, so that flour can absorb more water, get more dough, and produce more products. This is the positive effect of damaged starch.
Disadvantages of damaged starch
If there is too much damaged starch, the flour will absorb too much water, exceeding the normal value of dough moisture content, and the dough will be sticky (what we call "false water absorption"). In this way, the internal structure of steamed bread and bread that exceeds the normal moisture value will become soft, and the supporting force will decrease, which will cause other quality problems such as collapse and shrinkage. This is the negative effect of damaged starch.
The main components of flour are protein and starch, among which protein mainly plays the role of skeleton, while starch mainly plays the role of filling. If the content of damaged starch is relatively high, then the filler will be relatively less, so it will cause the internal structure of bread to become soft, the supporting force will decrease, and collapse will occur.
The damaged starch in flour is easily hydrolyzed by α-amylase and β-amylase to produce sugars, and most of the produced sugars are the substrates of yeast in the dough fermentation stage. Therefore, the damaged starch content in flour will inevitably have a series of effects on the making of bread.
Studies have found that in the long fermentation process of traditional bread making, the sugars in the flour are first fermented by yeast, and then the yeast acts on the damaged starch to hydrolyze it, and the produced maltose continues to ferment.
In the case of insufficient damaged starch, the water absorption rate of the flour is low, and there is not enough gas production. The bread ferments slowly, and the bread produced is small in volume, dry and hard, and has a poor structure.
Too high a damaged starch content will cause a large amount of maltose and dextrin to be produced during dough fermentation, making the dough too soft to support a large volume, resulting in quality problems such as collapse and shrinkage.
An appropriate damaged starch content is conducive to the internal moisture distribution of the flour, so that the flour absorbs water quickly and is easy to form dough; the bread produced is large in volume, high in height, darker in color, and has a good shape.
When other conditions remain unchanged, too high or too low a damaged starch content will have an adverse effect on bread making.
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Lydia
Arkera Inc.
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