Total phenolic contents, antioxidant and antibacterial activities of chia seeds (Salvia hispanica L.) having different coat color

Abstract

Due to its high nutritional value and health-promoting effects, there is an increasing interest in utilizing chia seed in the human diet. The aim of this study was to compare the compositional and functional characteristics of white and black chia seeds that are commercially available in Turkey. Compositional comparisons were done by quantifying protein, oil, ash and moisture contents. The total phenolic content and antioxidant activity were measured using defatted ground chia seeds. Our results revealed that black chia seeds had significantly higher protein, ash and moisture contents, compared to white chia seeds, but no difference was found in terms of oil content (P > 0.05). Conversely, the total phenolic content of white chia seeds (3.52 ± 0.08 mg GAE [gallic acid equivalent]/g sample) was significantly higher than those in black seeds (3.42 ± 0.06 mg GAE/g sample) (P < 0.05). Consequently, a significant difference (P < 0.05) was observed between DPPH free radical scavenging activities of white and black chia seeds, with the former exhibiting 231.5 ± 6.3 mmol Trolox equivalent (TE)/g, and the latter having 197.5 ± 7.4 mmol TE/g. The higher antioxidant activity of white chia seed was further confirmed by calculating IC50 values (IC50 of black chia seed = 2.001 mg/ml vs that of white chia seed = 1.735 mg/ml). Finally, we assessed antibacterial activities of chia seed extract and chia seed oil against human pathogens using agar disc-diffusion and agar well-diffusion assays. However, neither of the assays had shown antimicrobial activity against the tested bacteria. Considering the previously published reports, chia seed and chia seed oil seem to possess species-, and even strain-, specific antimicrobial activities. Overall, the results of this study suggest that white chia seed has better functional properties than black seeds.