Plants as Biofactories: Postharvest Stress-Induced Accumulation of Phenolic Compounds and Glucosinolates in Broccoli Subjected to Wounding Stress and Exogenous Phytohormones

Abstract

Broccoli contains high levels of bioactive molecules and is considered a functional food. In this study, postharvest treatments to enhance the concentration of glucosinolates and phenolic compounds were evaluated. Broccoli whole heads were wounded to obtain florets and wounded florets (florets cut into four even pieces) and stored for 24 h at 20 °C with or without exogenous ethylene (ET, 1000 ppm) or methyl jasmonate (MeJA, 250 ppm). Whole heads were used as a control for wounding treatments. Regarding glucosinolate accumulation, ET selectively induced the 4-hydroxylation of glucobrassicin in whole heads, resulting in ∼223% higher 4-hydroxyglucobrassicin than time 0 h samples. Additionally, glucoraphanin was increased by ∼53% in whole heads treated with ET, while neoglucobrassicin was greatly accumulated in wounded florets treated with ET or MeJA, showing increases of ∼193 and ∼286%, respectively. On the other hand, although only whole heads stored without phytohormones showed higher concentrations of phenolic compounds, which was reflected in ∼33, ∼30, and ∼46% higher levels of 1,2,2-trisinapoylgentiobose, 1,2-diferulolylgentiobiose, and 1,2-disinapoyl-2-ferulolylgentiobiose, respectively; broccoli florets stored under air control conditions showed enhanced concentrations of 3-O-caffeoylquinic acid, 1,2-disinapoylgentiobiose, and 1,2-disinapoyl-2-ferulolylgentiobiose (∼22, ∼185, and ∼65% more, respectively). Furthermore, exogenous ET and MeJA impeded individual phenolics accumulation. Results allowed the elucidation of simple and effective postharvest treatment to enhance the content of individual glucosinolates and phenolic compounds in broccoli. The stressed-broccoli tissue could be subjected to downstream processing in order to extract and purify bioactive molecules with applications in the dietary supplements, agrochemical and cosmetics markets.

The time of the day to harvest affects the degreening, antioxidant compounds, and protein content during postharvest storage of broccoli

“…Studies about the variation in the concentration of phenols and flavonoids through postharvest of broccoli have rendered dissimilar results. In some studies, an increase in the level of these compounds has been detected along with postharvest storage (Costa, Civello, Chaves, & Martínez, ; Xu et al, ), while in other cases a decrement in the level of these compounds was detected (Serrano et al, ; Villarreal‐García, Nair, Cisneros‐Zevallos, & Jacobo‐Velázquez, ).…”

Postharvest storage and cooking techniques affect the stability of glucosinolates and myrosinase activity of Andean mashua tubers (Tropaeolum tuberosum)

“…Recently, Villarreal‐García et al . () pointed out that stress causing factors (e.g. storage temperature) trigger the activation of the secondary metabolism of broccoli increasing it Gls content.…”

ABA signalling manipulation suppresses senescence of a leafy vegetable stored at room temperature

“…GSLs contents are usually maximum at harvest but dependent on preharvest biotic and abiotic stressors (Velasco et al, 2007). GSLs content not only depends on preharvest contents and enzymatic activity, but de novo biosynthesis of GSLs is more likely to occur during postharvest storage (Villarreal-Garc ıa et al, 2016), and the manipulation of the environment including abiotic stressors and exogenous hormones has proven to modify GSLs content in fresh produce (Cisneros-Zevallos, 2003;Jones et al, 2006). There are previous reports of effects of ABA treatment on young leafy Brassica, including increased GSLs content in 5-day-old cabbage sprouts (Wang et al, 2015), and in pak choi shoots (Hu and Zhu, 2013).…”

“…However, cold postharvest storage can have a negative impact on the organoleptic and nutraceutical traits of leafy vegetables (Cantwell and Suslow, 2001;Kramchote et al, 2012;Liu et al, 2015), and not in all markets the cold chain can be properly maintained (Thongsavath et al, 2012). Environmental factors can be leveraged to increase nutritional value, antioxidant content, organoleptic characteristics and eventually commercial longevity, but storage at ambient conditions can hinder produce quality and value (Adams et al, 2016;Toivonen and Hodges, 2011;Villarreal-Garc ıa et al, 2016). Therefore, methods to ensure the postharvest quality of vegetables at room temperature should be improved.…”