Dough microstructure: Novel analysis by quantification using confocal laser scanning microscopy

Abstract

The effect and the correlation of water addition to flour on the microstructure and viscoelastic properties of wheat flour dough were investigated using confocal laser scanning microscopy and a spectrum of rheological methods. Dough with water addition in the range of 52.5–70.0 g water 100 g −1 flour was investigated using a stickiness test, uniaxial elongation test, and fundamental rheology like small amplitude oscillatory shear measurement and a creep recovery test. A method for quantifying the microstructure of dough protein gained by CLSM was established with image processing and analysis. The complex shear modulus decreased rapidly with water addition due to the plasticization effect of water molecules and increased mobility in the continuous phases. Elastic behavior, determined as loss factor tan δ and relative elastic part J el decreased. Rheological tests showed high linear correlations with each other (r of |0.66|–|0.98|). Image analysis measurements (average size, area fraction, perimeter, circularity, and fractal dimension) showed high linear correlations (r of |0.66|–|0.85|) with water addition and rheological attributes like the complex shear modulus (r = 0.85) and J el (r = 0.86). CLSM in combination with image processing and analyzing has proven to be an applicable and powerful tool for examining and quantifying dough protein microstructure. Hence, it was possible to prove the dependency of rheology on the microstructure of dough.