Effects of freezing and temperature fluctuations during frozen storage on frozen dough and bread quality

摘要

The effects of freezing and temperature fluctuations during frozen storage on frozen dough and bread quality were investigated. Storage regimes were selected and designed to mimic either good or poor practice likely to be experienced in the cold chain (±0.1℃, ±1℃, ±3℃ or ±5℃). Quality changes and dough weight loss were measured for both constant and fluctuating frozen storage conditions. Quality was assessed as CO_2 production rate, yeast viability, bread specific volume and bread crumb firmness relative to fresh dough. Both the freezing process and subsequent frozen storage had a significant effect on all quality parameters. Dough weight loss and bread crumb firmness increased with increasing storage time. CO_2 production rate reduced with increased storage period, however, constant storage conditions (-18 ± 0.1℃) and good temperature control (-18 ± 1℃) gave no significant difference in CO_2 production rate for up to 112 days after freezing. Large temperature fluctuations during frozen storage ( - 18 ± 5℃) and storage at higher temperatures (a combination of -18℃, -13 ℃ and -8℃) resulted in significantly more rapid loss of dough and bread quality than storage at constant and/or colder temperatures.