The nature of broken starch and its advantages and disadvantages

Wheat in the process of processing into flour, due to the milling machine rollers shear, extrusion and other mechanical forces, it is inevitable that the internal structure and external shape of the starch in the flour will be damaged, cracks and fragments, damaged starch grains are called broken starch.

1.Properties of damaged starch

(1) The water absorption rate of damaged starch is about 2.5 times higher than that of undamaged starch;
(2) Broken starch has higher sensitivity to α-amylase and β-amylase.

2. Advantages of broken starch

During the fermentation process of bread, steamed bread and other fermented foods, yeast has to absorb the sugar in the flour, carry out physiological activities, produce carbon dioxide and lipid metabolites, make the dough volume expand, and add flavor to the finished bread.

As α-amylase and β-amylase will make the broken starch decompose into sugar, fully provide the nutrients needed for yeast activities, and at the same time, as the broken starch increases the water absorption rate of the flour, so that the flour can absorb more water, get more dough, and make more products, which is the positive effect of the broken starch.

3. Disadvantages of broken starch
If the broken starch is too much, the flour has to absorb too much water, which is more than the normal value of the water content of the dough, and the dough is easy to be sticky (what we call “false water absorption”).

So more than the normal water value of the steamed bread, bread internal organization softens, the support decreases, there will be a collapse, shrinkage and other quality problems, this is the negative effect of broken starch.

The main ingredients in flour are protein and starch, in which protein mainly plays the role of skeleton and starch mainly plays the role of filler, if the content of broken starch is relatively high, then the filler will be relatively less, so it will cause the internal tissue of the bread to become softer, and the support will be reduced, and the collapse will occur.

Effects of broken starch on different foods

1.Bread
The broken starch in flour is susceptible to hydrolysis by α-amylase and β-amylase to produce sugar, and most of the sugar produced is the substrate for yeast in the fermentation stage of dough, so the content of broken starch in flour will inevitably have a series of influences on the production of bread.

Overseas research has found that in the traditional long fermentation process of bread making, the sugars present in the flour are first fermented by the yeast, and then the yeast acts on the broken starch to hydrolyze it, while the resulting maltose continues to ferment.

In the case of insufficient broken starch, the flour has a low water absorption and cannot produce enough gas, the bread is slow to ferment and the resulting bread is smaller, dry, hard and has a poor structure.

Too high a level of breaking st arch will result in the production of large amounts of maltose and dextrin during dough fermentation, making the inner texture of the dough too soft to support a larger volume and causing quality problems such as collapse and shrinkage.

An appropriate content of broken starch is conducive to the internal distribution of water in the flour, which makes the flour absorb water quickly and is easy to form a dough; the resulting bread is large in volume, high in height, darker in color, and has a good loaf shape.

In other conditions remain unchanged, broken starch content is too high or too low, will produce unfavorable factors for the production of bread.

2.Buns
Other conditions remain unchanged, the broken starch content is too high or too low in the flour are not easy to produce high quality steamed bread.

The broken starch content is too high in the dough fermentation to produce a large amount of maltose and dextrin, so that the inner texture of the dough is too soft to support a larger volume, resulting in the production of flat buns and small head, at the same time will make the center of the buns appear too sticky phenomenon.

Too low broken starch content will make the dough water absorption is low, the dough fermentation can not provide enough maltose for yeast food and make the fermentation is not sufficient, gas production is not enough, bun volume is too small.

3. Frozen food

For frozen food, broken starch should be lower for good, with low content of broken starch flour made of dough with low water content, in the freezing process can prevent the generation of a large number of ice crystals, to avoid freezing cracking (in the mixing of water and flour to form the dough, part of the water is in the way of combined water in the dough, a part of the water is in the way of free water in the dough, if the dough in the free water content is too high, there will be a large number of freezing in the process of freezing. If the content of free water in the dough is too high, a large number of ice crystals will appear in the freezing process, which will lead to the frozen products cracking), to ensure the quality of frozen food.

When making frozen food, users reflect that the UCDc value of flour with good effect is concentrated at 25~29, but the broken starch should not be too low, too low will affect the yield.