## 3 Results and Discussion
### Effect of Blue Light on Carotenoid Content in Maize Kernels  
The illumination of maize kernels was conducted at 130.3 J\(\cdot\)cm\({}^{-2}\) (i.e., 36.2 mW\(\cdot\)cm\({}^{-2}\), 30 min), the most extreme studied conditions for _A. flavus_ photoinactivation. The white variety presented the lowest content of total carotenoids among the three varieties studied, with an initial content of 1.74 \(\upmu\)g\(\cdot\)g\({}^{-1}\) dry weight (DW), followed by the yellow variety with the medium content of 12.90 \(\upmu\)g\(\cdot\)g\({}^{-1}\) DW. The initial content of carotenoids in popcorn maize was about 19-fold and 2.6-fold of that of white and yellow maize, respectively, with a total content of 33.44 \(\upmu\)g\(\cdot\)g\({}^{-1}\) DW (Table 2). Zeaxanthin was the predominant carotenoid compound in all varieties, and its highest concentration was found in the popcorn accession of up to 24.04 \(\upmu\)g\(\cdot\)g\({}^{-1}\) DW. The use of LED light did not affect (\(p>0.05\)) the content of carotenoids in the investigated maize varieties. Light exposure might cause carotenoid degradation resulting in the formation of carotenoid radical cations [57]. However, the wavelengths mostly responsible for carotenoid degradation are within the UV range [58]. The light used in this study was within the visible range, and the average illuminance for a light dose of 130.3 J\(\cdot\)cm\({}^{-2}\) was \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Treatment**} & \multirow{2}{*}{
\begin{tabular}{c} **Individual** \\ **Carotenoids** \\ \end{tabular} } & \multicolumn{3}{c}{**Carotenoid Content (\(\upmu\)g\(\cdot\)g\({}^{-1}\) DW)**} \\ \cline{3-5}  & & **White** & **Yellow** & **Popcorn** \\ \hline \multirow{5}{*}{Control} & Lutein & 0.22 \(\pm\) 0.02 a & 5.69 \(\pm\) 0.19 b & 5.67 \(\pm\) 0.07 b \\  & Zexanthin & 1.54 \(\pm\) 0.01 a & 7.20 \(\pm\) 0.14 b & 24.04 \(\pm\) 0.26 c \\  & \(\upbeta\)-cryptoxanthin & n.d. & n.d. & 1.86 \(\pm\) 0.07 b \\  & \(\upbeta\)-carotene & n.d. & n.d. & 1.84 \(\pm\) 0.09 b \\  & Total & 1.74 \(\pm\) 0.00 Aa & 12.90 \(\pm\) 0.32 ab & 33.44 \(\pm\) 0.48 Ac \\ \hline \multirow{5}{*}{Illumination} & Lutein & 0.17 \(\pm\) 0.01 a & 6.07 \(\pm\) 0.48 b & 5.76 \(\pm\) 0.24 b \\  & Zexanthin & 1.45 \(\pm\) 0.02 a & 7.29 \(\pm\) 0.42 b & 24.67 \(\pm\) 0.70 c \\ \cline{1-1}  & \(\upbeta\)-cryptoxanthin & n.d. & n.d. & 2.29 \(\pm\) 0.07 a \\ \cline{1-1}  & \(\upbeta\)-carotene & n.d. & n.d. & 3.30 \(\pm\) 0.076 b \\ \cline{1-1}  & Total & 1.62 \(\pm\) 0.01 Aa & 13.36 \(\pm\) 0.91 ab & 36.01 \(\pm\) 1.05 Ac \\ \hline \hline \end{tabular} Data are means \(\pm\) SE (\(n=3\)); data with different letters in the same row are significantly different (\(p<0.05\)); n.d.: not detectable.  
\end{table} 
Table 2: Carotenoid content in the studied maize varieties (white, yellow and popcorn) before and after illumination using LED blue light at 130.3 J\(\cdot\)cm\({}^{-2}\). Figure 7: Maize extract absorption spectra after soaking in curcumin solution and illumination with blue light at 104.2 J\(\cdot\)cm\({}^{-2}\). Control maize kernels dipped in the solvent before illumination (propylene glycol); out of solution maize kernels dipped in 1000 \(\upmu\)M of curcumin in propylene glycol before illumination. 2843 \(\pm\) 16.15 lux. Therefore, although effective on reducing the viability of _A. flavus_ spores, the irradiance and illumination time used were not able to cause a significant degradation or isomerization of carotenoids in the three maize varieties. Similarly, previous studies in fruits have also reported a non-significant effect of LED illumination on the nutritional content, although an increase in some compounds was observed. [PERSON] et al. [59] evaluated the effect of LED illumination on antioxidant capacity and the content of beta-carotene, flavonoids, lycopene, and ascorbic acid in fresh-cut mango.