Effect of Storage Temperature and Flour Water Content on Lipids, Lipoxygenase Activity, and Oxygen Uptake During Dough Mixing

Flours differing in water content of 10% (F10), 12% (F12), and 14% (F14) were stored for 16 weeks at 22, 32, and 45 degrees C. The major changes in lipids concerned the free fatty acids (increase) and the triglycerides (decrease). In all cases, the changes increased with increasing storage temperature and water content. After 16 weeks of storage, the losses in lipoxygenase (LOX) activity increased with increasing flour moisture and storage temperature from 10% for F10 at 22 degrees C to 100% for F14 at 45 degrees C. At the end of storage at 22 and 32 degrees C, the bread volumes decreased by 10 and 25%, respectively, with no statistical differences (P < 0.05) between the samples. At 45 degrees C, the volume losses were equal to 35, 46, and 61% for the F10, F12, and F14 samples, respectively. In the same time, the flour oxidative ability (oxygen uptake during dough mixing) increased for the F10 and F12 samples with increasing storage temperature, whereas it decreased for the F14 samples stored at 45 degrees C. Therefore, provided the residual LOX activity is sufficient (omission of the F14 samples stored at 45 degrees C), the flour oxidative ability increased during storage and is positively correlated to its oxidable PUFA content.