High-Pressure Treatment of Non-Hydrated Flour Affects Structural Characteristics and Hydration.

In recent years, high-pressure treatment (HPT) has become an established process concerning the preservation of food. However, studies dealing with the structural, and consequently functional modification of non-hydrated starchy matrices (moisture content ≤ 15%) by HPT are missing. To close this knowledge gap, pressure (0⁻600 MPa, 10 min) and pressurization time depending (0⁻20 min, 450 MPa) alterations of wheat flour were investigated. Pressure rise from 0 to 600 MPa or pressurization time rise from 0 to 20 min resulted in a decline of amylopectin content from 68.3 ± 2.0% to 59.7 ± 1.5% (linearly, ² = 0.83) and 59.6 ± 0.7% (sigmoidal), respectively. Thereby, detectable total amount of starch decreased from 77.7 ± 0.8% linearly to 67.6 ± 1.7%, and sigmoidal, to 69.4 ± 0.4%, respectively. Increase in pressure caused a linear decrease in gelatinization enthalpy of 33.2 ± 5.6%, and linear increase in hydration properties by 11.0 ± 0.6%. The study revealed structural and technological relevant alterations of starch-based food matrices with low moisture content by HPT, which must be taken into consideration during processing and preservation of food.