36G-5 |
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S. D. MILLER, Institute of Food, Nutrition and Human Health, Massey Univ., Private Bag 11 222, Palmerston North, 5301, New Zealand, R. J. Winger, IFNHH, Massey Univ., Private Bag 102 904, North Shore Mail Centre, Auckland, New Zealand, and E. Shannon. The shelf life of frozen dough is limited by the decline in proofing power of the thawed dough after frozen storage. Fermentation above 20º C prior to freezing causes a significant reduction in shelf life. It is not known whether this reduction is affected by damage to yeast, loss of substrate, metabolite accumulation, or some other reason. This investigation sought to determine the dependence of shelf life on fermentation and storage time and to examine the involvement of a key fermentation metabolite, ethanol. Fermentation substrates and ethanol were determined by aqueous extraction, followed by enzymatic analysis. Proofing power was measured with a Risograph. Frozen dough shelf life was deleteriously affected by 90 min' fermentation at 20º C prior to the freezing process. This effect required a significant period of frozen storage, but occurred too fast for many frozen storage changes (such as ice recrystallization). Changes in substrates and ethanol during prefermentation were assessed and a model defined dough characteristics at the point of freezing. Ethanol had little impact on substrate consumption or gas production prior to freezing when added at levels comparable to those found in fermented dough. Mixing ethanol into fresh dough caused a small reduction in proofing power after frozen storage. Combining fresh dough and fermented doughs resulted in proofing power that was directly proportional to the composition of the mixture. Mixing fresh yeast into fermented dough substantially reversed the loss of proofing power. Published hypotheses related to frozen dough shelf life have been challenged and this study suggests that different explanations are required.
Session 36G, Refrigerated & Frozen Foods: General
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |