|
R. J. Stenberg and W. F. Geddes. Copyright 1960 by the American Association of Cereal Chemists, Inc. The rate of browning of canned bread, as determined at 600 millimicrons with a Beckman Model DU spectrophotometer equipped with a reflectance attachment, increased with the temperature of storage. At 25 C. there was only very slight browning after 120 days, but at 35 C. appreciable browning had occurred at 100 days' storage. At 50 and 75 C. browning was progressively much more rapid. No appreciable biochemical changes were noted in bread stored at -15 and 25 C. At 35 C., however, the pH decreased, whereas the total soluble nitrogen, titratable acidity, and amino nitrogen increased in the samples stored for 100 days. These biochemical changes were much more marked at 50 and 75 C. Lysine nitrogen decreased with an increase in storage time at 50 and 75 C. Total reducing substances remained essentially constant. Bacteriological tests indicated that these chemical changes were not likely to be due to bacterial action. The brown pigment could not be extracted with water or with a number of organic solvents. Acetylation gave a brown reaction mixture with both white and brown crumb; water then extracted the brown pigments from both samples, yielding solutions of similar absorbance and amino nitrogen content. |
|
