Sneak-peek into the chlorophyll content, antioxidant activity, targeted and non-targeted UHPLC-QTOF LC/MS metabolomic fingerprints of pulse microgreens grown under different photoperiod regimes

Abstract

Pulse microgreens (mung bean, chickpea and lentil) were evaluated for compositional changes as a function of photoperiod. The pulse microgreens were cultivated under photoperiod of 16 and 22 h, with an optimum growing temperature of 22 °C in light and 17 °C in dark in polypropylene trays containing moist cotton bed. The photoperiodic response of pulse microgreens in terms of plant height, chlorophyll content, antioxidant activity, phenolic profile, sugar profile and secondary metabolites were undertaken as the experimental factors. The targeted phenolic and sugar profile varied significantly with photoperiod. The various phenolic acids, especially chlorogenic acid and p-coumaric acid increased amongst different microgreens on extending photoperiod. The increase in sugar and their derivatives reflected the upregulation of carbohydrate metabolism under longer photoperiod. Also, the plant height, total chlorophyll content and antioxidant activity of pulse microgreen increased significantly on prolonging the photoperiod. The non-targeted analysis by UHPLC-QTOF LC/MS revealed the presence of secondary metabolites of five major classes, which were known to have beneficial effects in biological system. DIMBOA-glucoside, an organic compound was exclusively present in mung bean microgreens which further increased in longer photoperiod. The extraordinary supply of secondary metabolites makes the pulse microgreens excellent ingredient for therapeutic functional foods.