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Cereal Chem. 71:118-121   |  VIEW ARTICLE

Studies on Frozen Doughs. III. Some Factors Involved in Dough Weakening During Frozen Storage and Thaw-Freeze Cycles.

Y. Inoue, H. D. Sapirstein, S. Takayanagi, and W. Bushuk. Copyright 1994 by the American Association of Cereal Chemists, Inc.

The mechanism of dough weakening during thaw-freeze cycles and storage in frozen condition was investigated by extensigraphy, protein solubility fractionation, and electrophoresis. Molded doughs were frozen and stored for one, seven, or 70 days or subjected to three thaw-freeze (3T-F) cycles during seven days of frozen storage. Extensigraph measurements showed that maximum resistance (Rmax) decreased significantly after one day, after 3T-F cycles, and after 70 days, whereas dough extensibility increased significantly only after 70 days of frozen storage. Extensigraph results for nonfrozen doughs formulated with different yeast levels indicated that the decrease in Rmax during frozen storage does not appear to be related to the concomitant drop in gassing power. In contrast, a very strong relationship was found between extensibility and gassing power (r greater than or equal to -0.95). Therefore, the substantial decrease in gassing power of the frozen dough stored for 70 days appears to be the probable cause of the significant increase of extensibility observed for this dough. Reducing sugar content of the doughs after 3T-F cycles was considerably lower than that of doughs subjected to other storage treatments, indicating that some fermentation occurred during the thaw part of the thaw-freeze cycle. Small but significant (P less than 0.05) increases in the proportion of water- and acetic-acid-soluble protein fractions were observed for doughs subjected to 3T-F cycles. For the dough subjected to 70 days of frozen storage, the proportion of 70% ethanol-soluble protein was significantly higher than for other doughs. Sodium dodecyl sulfate- polyacrylamide gel electrophoresis performed under nonreducing conditions clearly showed changes in the high molecular weight region (glutenin oligomers) of the electrophoretic pattern of the doughs subjected to the 3T-F cycles. Factors responsible for dough weakening after prolonged frozen storage and for dough subjected to repeated thawing and refreezing appear to be different.  

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