Impact of UV‑C Light Treatment on the Vitamin D Content and Quality of Bread.

Vitamin D deficiency is a global health concern linked to various chronic diseases. Although food fortification is a promising solution, its implementation remains limited by processing losses, matrix inconsistency, and clean-label trends. Certain foods, including mushrooms and yeast-containing bakery products, naturally contain provitamin D2 (ergosterol), which can be photoconverted into vitamin D2 by ultraviolet (UV) light. While UV-based vitamin D2 enrichment has been extensively studied in mushrooms, its application in bread remains largely unexplored. This study investigated UV-C irradiation as a biofortification strategy for white and whole wheat bread, evaluating the effects of UV-C dose (0.50 and 2.00 kJ/m2) and dose rate (0.03 and 0.13 kJ/m2·min) on vitamin D2 content and bread quality attributes. Optimized UV-C parameters enabled a novel strategy to increase vitamin D2 content in bread without compromising the quality. UV-C treatments resulted in varying vitamin D2 levels in bread, depending on the dose and dose rate, whereas control bread did not contain any detectable vitamin D2. The highest vitamin D2 content was obtained when the 2.00 kJ/m2 dose was applied at 0.03 kJ/m2·min dose rate, although this treatment altered odor and taste. However, other treatments increased vitamin D2 without compromising the quality. The optimal treatment of 2.00 kJ/m2 dose at 0.13 kJ/m2·min dose rate achieved the best balance between vitamin D2 enrichment and sensory acceptability. Under the optimal conditions, a 14 g serving of UV-C treated white bread and a 15.5 g serving of whole wheat bread provided 27 and 37% of the recommended dietary allowance (RDA) for vitamin D, respectively. Thus, UV-treated bread represents a valuable and practical source of plant-based vitamin D for consumers, particularly for vegetarians or vegans.