The combined effect of acid and mild heat treatment on the shelf-life and quality of fresh wet noodles

In this research, changes in microbial shelf-life and quality characteristics of fresh wet noodles (FWNs) were analyzed under acid and different mild heat treatment conditions. Acid combined with heat treatment at 50 degrees C for 30 min extended the shelf-life of FWNs by 30 - 40 d and effectively delayed the color deterioration of FWNs. The water absorption of FWNs was reduced by the mild heat treatment. Meanwhile, the cooking loss of the noodles and hardness significantly ( p < 0.05) increased. Differential scanning calorimetry (DSC) analysis showed that the gelatinization enthalpy of the starch in FWNs decreased and the gelatinization temperature increased. The X-ray diffraction (XRD) results showed that the crystallinity of the starch decreased from 27.51% to 24.2% after mild heat treatment. In addition, it was observed by confocal laser scanning microscope that the mild heat treatment made the gluten networks more continuous. The free sulfhydryl content of noodles showed a decreasing trend, while the sodium dodecyl sulfate-extractable protein (SDS-EP) value was also significantly ( p < 0.05) reduced. Overall, the combination of mild heat treatment with acid extended the shelf-life of FWNs and had less impact on their quality.