## 4 Discussion  
The studied bell peppers showed ~27% more water losses than those under the FL+D photoperiod. This fact can be related to previous results obtained by [PERSON] et al. [30], who recently showed similar losses in fresh-cut red chard (26.8%-38.2%) and rocket leaves (22% and 31%) after 10 d at 5 \({}^{\circ}\)C in response to monochromatic red and blue LEDs (35 mol m\({}^{-2}\) s\({}^{-1}\)), respectively. Such low weight losses are in agreement to previous results reported by [PERSON] and [PERSON] [31], who reported 1% dehydration after 6 d at 7 \({}^{\circ}\)C, whose data were not affected after UV-B treatments of 4.46 and 8.93 kJ m\({}^{-2}\). Similar results were obtained by [PERSON] et al. [4], who showed weight losses higher than 50% in serrano chilli peppers after 33 d at 25 \({}^{\circ}\)C.  
Regarding colour variations (\(\Delta\)E), this effect is similar to results reported by [PERSON] and [PERSON], [31], who showed that low UV-B doses (4.46 kJ m\({}^{-2}\)) did not affect the colour development during 6 d at 7 \({}^{\circ}\)C. As observed, TSS has been related to MI and, particularly in red peppers, these two parameters have also been associated with colour development [32], which can also be contrasted with our present results. Moreover, sensory quality values can be related to the overall marketability, which has been previously reported to be increased after applying blue and red LEDs [33] or UV low doses [31; 34]. As total phenolic and flavonoid contents have been directly related to the antioxidant capacity of these fruit [5], the TAC was positively affected by FL + FL and FL + BR LED photoperiods regarding FL + D, which was also highly remarkable after 6 d at 7 \({}^{\circ}\)C + 4 d 20 \({}^{\circ}\)C. Values obtained can be comparable to previous studies in which UV-B increased the TAC according to DPPH values [31], and this effect has also been shown in UV-C-treated red peppers [35]. Moreover, an increase of the TAC measured by FRAP in fresh-cut red peppers for 11 d at 7 \({}^{\circ}\)C has also been reported for the application of 8 h blue and red LEDs separately [33]. Nevertheless, there are no previous studies combining both UV-B and LED photoperiod to study their synergistic effect. Indeed, this behaviour can be explained by the biosynthesis of nutraceuticals as carotenoids, which were potentiated by both postharvest strategies as it is subsequently detailed. The carotenoid profile of the studied red peppers is in agreement with previous studies in different varieties of red peppers reported by [PERSON] et al. [3]. Our hypothesis to explain the basis of this positive effect on the carotenogenesis of carotenes and xanthophylls in red bell peppers, which especially occurs during fruit ripening, is that it is controlled by transcript genes which are mainly regulated by light incidence and high temperatures [36]. As the initial precursor of lycopene in the top of the carotenoid chain, phytoene synthase (PSY) plays an essential role in the conversion of geranylgeranyl diphosphate to phytoene, whose stimulation directly depends on light stimuli [37]. For instance, UVR8 as the main UV-B receptors, and cryptochromes, as receptors of blue light, are in charge to activate several transcription factors (COP1 protein, constitutive photomorphogenesis 1), which link with HY5 (elongated hypocotyl5) as the main PSY stimulator [37]. Furthermore, red and far-red wavelengths are absorbed by phytochromes, which also regulate the photomorphogenesis of carotenoids through the control of phytochrome interacting factors (PIF) [37; 38]. Regarding to this behaviour, [PERSON] et al. [39] have recently shown that the exposure to continuous red LEDs is more effective at inducing the accumulation of carotenoids than blue LEDs in mature green chilli peppers exposed to 946 kJ m\({}^{-2}\) for 3 d at 30 \({}^{\circ}\)and 75% RH.