EFFECT OF THE THERMOSTABLE XYLANASE B FROM THERMOTOGA MARITIMA ON THE QUALITY OF FROZEN PARTIALLY BAKED BREAD

摘要

The effect of the recombinantly produced xylanase B (XynB) from Thermotoga maritima MSB8 on the quality of frozen partially baked bread (FPBB) was investigated. Addition of XynB to wheat flour dough resulted in a significant increase in dough extensibility (L), swelling (G), and a decrease in dough resistance to deformation (P), configuration. Bread crumb characteristics were studied by DSC (differential scanning calorimeter) and DMA (dynamic-mechanical analysis). Results show that addition of XynB leads to improvements in the bread quality of FPBB and retards bread staling compared to the control. The greatest improvements were obtained in specific volume (+35.2%) and crumb firmness (-40.0%). The control FPBB was significantly firmer in texture and higher in amylopectin recrystallization than the bread with XynB. During frozen storage of FPBB with and without XynB for 8 weeks, the crumb firmness increased gradually and the specific volume slightly decreased with the frozen storage time. The ΔH values of freezable water (FW) endothermic transitions increased with frozen storage time for all samples. However, addition of XynB lowered the ΔH values indicating a decrease in FW. Therefore, XynB is useful in improving the quality of FPBB.