Effects of postharvest light spectra on quality and health-related parameters in green Asparagus officinalis L.

Abstract The monitoring of quality parameters in horticultural crops under artificial light during postharvest storage is important for controlling the shelf-life of the crops. In this work, white light, red light, blue light and dark conditions were used at various durations to evaluate the effects of different spectral properties of light on parameters related to physiological and biochemical processes in green asparagus, and on compounds related to human health. For this aim, the level of glucose, fructose and sucrose, as well as that of vitamin C and the levels of lignin, chlorophyll a and b, carotenoids and anthocyanins, were determined in apical and basal segments of the edible portion of green asparagus spears before and after light treatments. A dark control was stored at 4 °C. The irradiance levels of the light treatments were 100, 117 and 116 μmol m −2  s −1 , respectively for white, blue and red light. Before treatments, in the apical segments, the content of analysed components were higher than in the basal segments, except for soluble sugars and starch, of which the basal segment exhibited higher levels; these results exhibited different nutritional value of the two segments. After the light treatments, the analysed quality-related parameters were differently influenced in the apical and basal segments during postharvest storage. The increase in dry matter content in the apical segment after both white light and red light treatments was most likely attributable to the presence of physiological postharvest activity, rather than to increased transpiration. The results indicated that light with different spectral properties vs. dark-stored controls had small or no effects on the measured parameters. Both light and dark caused the starch levels to increase in both segments. A decrease in the sugar content in the basal part might be explained by translocation of hexoses from basal towards apical regions of the spear. White light primarily determined the lignin deposition in the apical part most likely due to the synergistic effect of red and blue light on lignin biosynthesis. The vitamin C, chlorophyll a and b and carotenoids decreased in light and dark treatments in both segments. Anthocyanins were induced by light in the basal part only, most so by blue light.