Post-harvest UV-B radiation modulates metabolite profile in peach fruit

Abstract

The possibility to modify plant metabolic profile of plants and fruit to improve their healthy properties using eco-friendly tools, rather than transgenic approaches, gained interest in the last decades. Ultraviolet-B (UV-B) radiation, at low levels, thanks to its ability to influence plant secondary metabolism, could be successfully used to achieve this goal. However, few studies have been conducted so far on the effects of post-harvest UV-B treatments on fruit metabolomics. The present research, aimed to evaluate the impact of UV-B on peach metabolites profile through nontargeted metabolomics (UHPLC-ESI/QTOF-MS) coupled with multivariate chemometrics, provided evidence that 10 and 60 min of post-harvest UV-B irradiation influenced several classes of metabolites. Most phenolics were downaccumulated 24 h after both UV-B treatments, though, after 36 h, anthocyanins, flavones and dihydroflavonols increased (2.06-, 1.92-, 1.68-fold with 10 min UV-B; 6.65-, 2.53-, 2.05-fold with 60 min UV-B, respectively). UV-B reduced carotenoids and most lipids and increased some biosynthetic intermediates and degradation products, some of them known for their positive role in human health. Among alkaloids, some pteridines accumulated, likely derived from folates degradation, while indole alkaloids decreased. Despite the decrease of some bioprotective metabolites as carotenoids, the UV-B-induced up-accumulation of many antioxidant phenolics after 36 h from the exposure suggests an improvement of the healthy properties of peach fruit and reinforces the potential of UV-B controlled irradiation as a nutraceuticals-increasing tool in fruit.

The effect of postharvest ultraviolet irradiation on the content of antioxidant compounds and the activity of antioxidant enzymes in tomato

“…The studies [25,27,45,46,47,48,49,50,51,52] of UV-B and UV-C irradiation of tomatoes during storage (up to 30 days) did not show visible physical damage to the samples. In our work, we used safer UV-A irradiation, therefore, the study of this aspect with long-term storage looks inexpedient.…”

“…It was established [25,45,46,47] that immediately after the irradiation, there was no effect on the accumulation of total phenolic compounds. Moreover, in the first hours after the irradiation, even a decrease could be observed both for antioxidant activity and the content of individual antioxidant substances.…”

“…Moreover, in the first hours after the irradiation, even a decrease could be observed both for antioxidant activity and the content of individual antioxidant substances. Santin et al [47] assumed that in the first hours after the UV-B treatment, phenolic compounds already present in the tissues of tomato peel began to break down, a decrease in the amount of total phenolic compounds occurred 24 h after the treatment. However, their number increased 36 h after the irradiation, explained by the expression of genes responsible for the production of metabolites.…”

Light signaling and UV‐B‐mediated plant growth regulation

“…In the first 36 h of UV-B treatment, there is upregulation of flavonoids, anthocyanins, and polyphenols and the downregulation of phenolic precursors and steroids was seen after 12 h of UV-B exposure (Kaling et al 2015). When fruits are exposed to UV-B, phenolics were decreased after 24 h of exposure, whereas phenolics, anthocyanins, flavones, and dihydro flavonols accumulation increased after 36 h of irradiation (Kusano et al 2011;Santin et al 2018). In Eucalyptus globulus, the volatile organic compounds showed an increased level, especially that of benzaldehyde and some terpenic compounds like eucalyptol upon UV-B exposure (Machado et al 2017).…”

Effects of Ultraviolet-C Pretreatment on Sugar Metabolism in Yellow Peaches during Shelf Life

“…This is in contrast to results reported by Manzocco et al (2011), who found a higher flavor score for UVC-treated cut melons than for control cut melons. Santin et al (2018) demonstrated that UVB reduced concentrations of carotenoids and most lipids and increased some biosynthetic intermediates and degradation products, some of which are known for their positive effects on human health.…”