Effect of Glutathione and Storage Time on Rheological Properties of Per-proofed Frozen Dough

摘要

The effect of reduced glutathione (GSH) on fresh and pre-proofed frozen dough rheological properties wereinvestigated using dynamic stress rheometry and small scale extensibility with the addition of three levels (80 × 10-6, 160 ×10-6 and 240 × 10-6 GSH) and six storage times (0 and 1 day, 2, 4, 6 and 8 weeks). Three relaxation times (1, 13 and 26min)after loading the dough in the rheometer were used to determine storage (G') and loss (G") moduli. Correlations for G' (r=0.678and 0.622 at 0.05, and 10Hz, respectively) and G" (r=0.699, and 0.690 at 0.05, and 10Hz, respectively) were observed withthe area under the extension curve at 26 min relaxation time. The addition of GSH to fresh dough reduced G' (16.4% to 55.9%)and G" (13.7% to 52.2%). Freezing and frozen storage caused increase in G' and G". The addition of GSH reduced doughstrength indicated by the reduction in maximum resistance to extension (Rmax) and the ratio of maximum resistance to extensibility(Rmax/E). The reduction in Rmax across all relaxation times ranged from 16.2% to 59.4%. An increase in dough extension (E) wasobserved with 240 × 10-6 GSH at all frozen storage and rest period times. Addition of GSH caused an increase of liquid phase(30.6% to 35.3%) in fresh dough and frozen dough (10.3% to 20.7%) after one day frozen storage. Negative correlations of watercontent in the solid phase with dough extensibility and area under the extensibility curve were found (r= - 0.594 and - 0.563,respectively, p ＜ 0.001). This suggests a loss of dough extensibility and strength as the water holding capacity of the doughcomponents changes during frozen storage.