Phenolic Content and Antioxidant Activity in Raw and Denatured Aqueous Extracts from Sprouts and Wheatgrass of Einkorn and Emmer Obtained under Salinity

Abstract

Total phenolic content (TPC), reducing power (RP), superoxide radical scavenging (RS), and thiobarbituric acid reactive substances (TBARS) production inhibition were measured in raw and denatured aqueous extracts from sprouts and wheatgrass of einkorn and emmer obtained at increasing salinity. Grains were incubated and kept at 0, 25, 50, and 100 mM NaCl until either sprout or wheatgrass stage. Additionally, a recovery treatment was included, in which sprouts obtained at 100 mM NaCl were then transferred at 0 mM NaCl until wheatgrass stage. All parameters (TPC, RP, RS, and TBARS production inhibition) increased with sprouting and were highest in wheatgrass. Salinity increased all parameters, but the effect varied with NaCl concentration, genotype, developmental stage, and plant material processing (raw or denatured). Overall, given the delay and limitation of growth at high NaCl concentration, the best compromise appears to be the application of a moderate salinity (25 to 50 mM NaCl). In denatured extracts, TPC, RP, and RS slightly decreased, and TBARS was not affected, which means that antioxidant activity was mainly related to compounds other than enzymes and peptides, and thus it can be assumed to remain after digestion. Thus, supplementing the human diet with einkorn or emmer sprouts and wheatgrass can actually benefit health.

Keywords: TBARS; radical scavenging; reducing power; salinity; sprouting.

Figure 1

Total phenolic content (TPC; mg gallic acid equivalents g⁻¹ fresh weight) in raw and denatured extracts from seeds (black), sprouts (grey), and wheatgrass (zebra-striped) of Triticum monococcum cv Monlis (TMoM) and Triticum dicoccum cv Zefiro (TDiZ) sprouted and grown with salt (NaCl) concentration 0, 25, 50, 100 mM (S0, S25, S50, S100) or sprouted with 100 mM and then grown with distilled water as recovery treatment (S100-R). Values are normalized for a dry matter content of 150 mg g⁻¹. Average values of triplicate determinations for n = 2 independent replicates ± standard error are depicted. Different letters indicate statistically significant differences at p < 0.05 (Fisher’s LSD).

Figure 2

Total reducing power (RP) in raw and denatured extracts from seeds (black), sprouts (grey), and wheatgrass (zebra-striped) of Triticum monococcum cv Monlis (TMoM) and Triticum dicoccum cv Zefiro (TDiZ) sprouted and grown with salt (NaCl) concentration 0, 25, 50, 100 mM (S0, S25, S50, S100) or sprouted with 100 mM and then grown with distilled water as recovery treatment (S100-R). All values are referred to a concentration of 143 mg/mL. Average values of triplicate determinations for n = 2 independent replicates ± standard error are depicted. Different letters indicate statistically significant differences at p = 0.05 (Fisher’s LSD).

Figure 3

Radical scavenging (RS) activity (%) in raw and denatured extracts from seeds (black), sprouts (grey), and wheatgrass (zebra-striped) of Triticum monococcum cv Monlis (TMoM) and Triticum dicoccum cv Zefiro (TDiZ) sprouted and grown with salt (NaCl) concentration 0, 25, 50, 100 mM (S0, S25, S50, S100) or sprouted with 100 mM and then grown with distilled water as recovery treatment (S100-R). All values are referred to a concentration of 143 mg/mL. Average values of triplicate determinations for n = 2 independent replicates ± standard error are depicted. Different letters indicate statistically significant differences at p = 0.05 (Fisher’s LSD).

Figure 4

Thiobarbituric acid reactive substances (TBARS) production (lipid peroxidation) inhibition (%) in raw and denatured extracts from seeds (black), sprouts (grey), and wheatgrass (zebra-striped) of Triticum monococcum cv Monlis (TMoM) and Triticum dicoccum cv Zefiro (TDiZ) sprouted and grown with salt (NaCl) concentration 0, 25, 50, 100 mM (S0, S25, S50, S100) or sprouted with 100 mM and then grown with distilled water as recovery treatment (S100-R). All values are referred to a concentration of 143 mg/mL. Average values of triplicate determinations for n = 2 independent replicates ± standard error are depicted. Different letters indicate statistically significant differences at p = 0.05 (Fisher’s LSD).