Cereal Chem 54:216 - 224. | VIEW
Bread Staling Studies. II. Effect of Protein Content and Storage Temperature on the Role of Starch.
S. K. Kim and B. L. D'Appolonia. Copyright 1977 by the American Association of Cereal Chemists, Inc.
The effect of flour protein content (11.0, 13.9, and 21.6% on a 14% mb) and storage temperature (21, 30, and 35 C) on the role of starch during bread staling was investigated. The recovery of soluble starch extracted from bread crumb was inversely and positively related to the protein content of the flour and storage temperature, respectively. The soluble starch from fresh crumb was predominantly amylopectin, which progressively decreased as bread aged. Although the amount of amylose in the soluble starch was small, it sharply decreased during the first day of storage and thereafter the changes were minor. This implies that the amylose contributes to staling primarliy during the first day of storage. The amylose was essentially absent in the soluble starch leached from the bread produced from the flour with the highest protein content, suggesting that the role of amylose in staling diminishes as the flour protein content increases. The amylose content in the soluble starch leached from the crumb after 10-min removal of the bread from the oven was small, indicating that the majority of the amylose retrograded during baking and subsequent cooling. Firmness data on refreshened bread showed that the staling of bread at 21 C was due primarily to starch crystallization. At 30 and 35 C, some other factor in addition to the starch played an important role in firming. It was calculated that starch crystallization in the crumb was about two and four times slower at 30 and 35 C, respectively, compared to the time at 21 C. Kinetic studies indicated that bread staling at 35 C was still basically characterized by the crystallization of the starch fraction in the crumb.