Use of a compound modifier to retard the quality deterioration of frozen dough and its steamed bread.

To retard the quality deterioration of the dough during frozen storage, the effects of a compound modifier (CM) comprised of sodium stearoyl lactate, VC, and ß-glucanase on the properties of the frozen dough, as well as the quality of the frozen dough steamed bread were investigated. The results revealed that CM restricted the migration of water in the dough and improved its rheological properties. Furthermore, CM minimized the deterioration of specific volume and textural properties, and prevented starch retrogradation in the frozen dough steamed bread. Moreover, the addition of CM strengthened the secondary structure of gluten protein and formed a more resilient gluten network. The microstructure of the frozen dough steamed bread showed that CM reduced the damage caused by ice crystals on the gluten network. Overall, the use of CM strengthened the gluten network and effectively delayed the quality deterioration of the frozen dough, thus is potential as an improver for frozen dough.

Conformational alteration and the glycated sites in ovalbumin during vacuum freeze-drying induced glycation: A study using conventional spectrometry and liquid chromatography-high resolution mass spectrometry.

Ovalbumin (Oval)-ribose glycation induced by vacuum freeze-drying (VFD) was studied. The protein conformational changes based on fluorescence, ultraviolet and circular dichroism spectra were evident with the increase in VFD time. The glycated sites and the average degree of substitution per peptide molecule (DSP) were determined using LC-HRMS. Lysine was shown to be the sole glycated site. Two glycated sites and the minimum DSP values were found during the first 6 h of VFD and increased to nine and the maximum DSP values after 48 h of VFD. The glycated sites located on the protein surface were mostly more active than those in the folded or helical regions, and the hydrophilic/hydrophobic environment could also influence DSP values. This study gave relationships between VFD time and the conformational structure and glycated sites of VFD-treated Oval-ribose system, providing a theoretical basis for VFD technique-based protein food and drug industries.