Effect of particle size of Eucommia ulmoides leaf micro-powder on dough characteristics and biscuit quality of shortbread biscuits

This study systematically investigated the effects of particle sizes of <i>Eucommia ulmoides</i> leaf micro-powder (EULM) on shortbread biscuit quality. Results showed that as particle size decreased, dough ΔE value increased, biscuit browning degree reduced, and dough viscosity, G' and G″ values rose, being most prominent at 150 mesh. As the mesh number increased from 100 to 300, the dough hardness increased from 173.37 g to 318.29 g, while elasticity decreased, the free sulfhydryl content increased from 1.16 μmol/g to 1.67 μmol/g, and the disulfide bonding content decreased from 2.67 μmol/g to 1.33 μmol/g. coincidentally, the content of β-folding in the secondary structure of the proteins increased, and the porosity of the biscuits increased from 45.52 % to 46.64 %. Sensory evaluation and volatile flavour component analysis indicated that 200 mesh EULM yielded biscuits with the highest overall sensory scores and richest flavour variety. This study provides a scientific basis for the application of EULM in the food industry.