Effect and Action Mechanism of Magnetic Field Treatment on the Fermentation Characteristics of Dough

Magnetic fields can improve the quality of foods by influencing the arrangement of water molecules, thus altering the distribution of water in foods. In this study, dough was fermented at magnetic field strengths of 0, 0.5, 1.0, 1.5, and 2.0 mT for 1 h. The effect of magnetic field treatment on the fermentation characteristics, moisture distribution, and protein molecular structure of dough was investigated by low-field nuclear magnetic resonance (NMR) and in situ Raman spectroscopy, with a view to providing a theoretical basis for the development of high-quality Chinese dough-based foods. The results showed that the fermentability of dough tended to increase first and then decrease as the magnetic field strength increased, and the most significant effect on the fermentability was observed at a magnetic field strength of 1.5 mT. The specific volume of steamed bread initially increased and then decreased. When the magnetic field strength was 1.0 mT, the specific volume was 2.24 mL/g. The hardness, stickiness, and chewiness showed a trend of initially decreasing and then increasing, but there was no obvious change in the elasticity, cohesiveness or resilience. The contents of strongly bound water and free water initially decreased and then increased, whereas the opposite trend was observed for weakly bound water. The effect of 1.0 mT magnetic field strength on the water distribution was most significant. The relative content of α-helix increased first and then declined, while the reverse trend was observed for random coil. At a magnetic field strength of 0.5 mT, the relative content of α-helix was the highest (54%) and the relative content of random coil was lowest (21%). Proper magnetic field treatment could increase the fermentability of dough, the specific volume and textural properties of steamed bread, accelerate the water distribution in dough and improve the stability of the gluten network. In conclusion, magnetic field treatment could improve the fermentability of dough and the textural properties of steamed bread by improving the distribution of water, increasing the moisture uniformity, and changing the molecular structure of gluten proteins in dough.