What Is Damaged Starch in Flour

Damaged starch refers to starch granules that have been physically broken during the milling process. This damage alters the starch’s properties, making it more reactive to enzymes, and capable of absorbing more water. Damaged starch plays a crucial role in starch breakdown, fermentation, and overall dough behavior.

Alpha-amylase, the enzymes that break down starch into simple sugars during fermentation, primarily targets damaged starch in flour, as it is more accessible for enzymatic breakdown. Therefore, the higher the damaged starch content, the more efficiently alpha-amylase functions.

Excessive damaged starch can lead to effects similar to an overabundance of alpha-amylase, resulting in sticky dough and a gummy crumb. Conversely, if the flour contains too little damaged starch, yeast may lack sufficient food due to limited starch breakdown into sugars, leading to poor fermentation.

Beyond its enzymatic role, damaged starch absorbs significantly more water than intact starch granules: Damaged starch can absorb 2-4 times more water than intact starch.

Since the endosperm of hard wheat is tougher and more ‘fragile’ than that of soft wheat, milling hard wheat typically results in a higher damaged starch content. A standard damaged starch content in flour falls within the 4–12% range.