Abstract
Purpose: Vitamin D, a fat-soluble secosteroid, has
a significant role in bone metabolism and helps calcium absorption in the body.
Since vitamin D concentration is altered in fortified foods and dietary
supplements, the actual amount of vitamin D may differ from the label value.
Methods: In this study, the concentrations of vitamin D2
and D3 of fortified bread sample were analytically determined. For
this purpose, dough or homogenized bread sample was saponified using potassium
hydroxide solution (30%, w/v) at 80°C, and the saponified analytes were
extracted into n-heptane followed by liquid-liquid extraction. Then n-heptane
fraction was evaporated to dryness and the sample was reconstituted in
methanol. The effect of different parameters was evaluated by one variable at
one-time strategy.
Results: The analytes
concentrations were evaluated in dough fermentation, baking and storage steps.
The effect of temperature in dough fermentation and baking was evaluated at the
range of 5-30 and 200-250°C, respectively. Also, the fermentation time was
studied in the range of 0-120 min. The analytes concentrations were followed
for 1 to 5 days after baking. The results indicated that dough fermentation
temperature has no significant effect on the concentration of the analytes. On
the other hand, when the dough fermentation time and baking temperature are
increased, the analytes concentrations are decreased. Also, the storage
duration of the spiked bread samples decreased the analytes concentrations
after one day.
Conclusion: Based on the obtained
results, baking the dough at high temperatures lead to decrease in vitamin
levels.