Use of enzymes to minimize dough freezing damage

ME STEFFOLANI; PD RIBOTTA; GT PEREZ; AE LEON

Madrid, España

Congreso; 13th ICC Cereal and Bread Congress Cereals in the 21st century: present and future; 2008

ICC

Freezing technology is largely used to reduce the economical losses due to bread staling. It also allows consumers to directly produce  a fresh product. However, long periods of frozen storage decreases the quality of end product. The loss of baking quality has been ascribed to dough weakening and a reduction of both yeast viability and activity. The ice crystals may affect gluten structure and cause disruption of gluten network. These phenomena may cause a loss in the gas retention capacity during fermentation, reflected by lower bread volume and an increase in the fermentation time (Abd El-Hady et al 1999, Ribotta et al 2003). The aim of this work was to study the effect of pentosanase (Pn), glucose oxidase (Gox) and transglutaminase (TG) on frozen dough in order to minimize the damage caused by frozen storage.  The basic formulation included Pn (0.006%, 0.012% and 0.018%), Gox (0.001%, 0.005% and 0.01%), and TG (0.01%, 0.1% and 0.5%). Mixed doughs were frozen and stored at -18ºC. After 65 days, frozen dough was thawed, proofed and baked. CO2 retention capacity of frozen dough samples was determined. Specific bread volume, crust and crumb color of breads and texture profile analysis of the crumb were determined. Frozen dough with high levels of Gox developed greater bread volume compared with the control dough (without enzyme). The reduction of bread volume as consequence of frozen storage was lower than the reduction observed in control samples indicating that Gox increased the dough strength and counteracted the depolymerization effect of gluten as consequence of ice crystal formation. Samples with Pn developed high bread volume after 65 days of frozen storage; however, the reduction of bread volume, as consequence of frozen storage, was much higher than the reduction reached in the control bread. Pn decreased pentosan size which in turn reduced their water retention capacity. It is possible that more water was available to form ice, increasing damage to the gluten network. Samples with 0.1% of TG presented higher bread volume than the control, minimizing the effect of frozen dough. The CO2 retention capacity of frozen dough decreased when increased the storage time. Freezing and frozen storage of dough caused a significant increment of proofing time, which was attributed to the losses in the number of viable yeast cells, and the tested enzymes could not overcome this problem. The L value for crust color decreased with frozen storage time. The highest levels of Gox and TG had higher value of L than control, which was described as more desirable. In general, the bread crumb firmness increased when the frozen storage time increased. The use of Pn and Gox produced breads from frozen dough with lower firmness than bread control. The enzymes tested minimized the negative aspect of dough freezing as it was shown by the increase in the CO2 retention capacity and the bread volume, by the decrease in the crumb firmness and by the changes in the crust color.