Bioactive Compounds, Antioxidant Potential and Color Properties of Dried Red Pepper (Capsicum annuum L.)

Abstract

This experiment was carried out in order to study the effects of drying on physical quality, color development, bioactive compounds and antioxidant potential of red peppers (Capsicum annuum L.). Dry matter, surface color values (L*, a*, b*, h*, ∆E*, C*), extractable color (ASTA), non-enzymatic browning, total-carotenoids, total phenolic content (TPC), total flavonoid content (TFC) and antioxidant potentials were measured for fresh and dried samples. Besides, rehydration rate was determined for dried samples. The L*, a*, b* values were used to calculate hue angle (h), chroma (C*) and color differences (∆E*). Total phenolic content (TPC), total flavonoid content (TFC) and antioxidant potentials were extracted by different solvents that were water, methanol and ethanol. TPC had differences for each solvent (p<0.05) and water extracts had the highest value (178.1 mg GAE/ 100g dw), followed by ethanol and methanol. Otherwise, TFC and antioxidant potentials had no significant differences according to solvents (p >0.05). Antioxidant potentials were evaluated with DPPH free radical scavenging assay and ferric reducing power assay. DPPH free radical scavenging activity showed significant moderately strong negative correlations with TPC (r=-0.958) and TFC (r=-0.821). A decreasing of color values is an expected value for dried samples and the results showed loss for all color measurements. L*, a* and b* values decreased because red pepper color became darker may be related to the carotenoids and the formation of browning compounds. As ASTA values decreased, hue angles increased, indicating color change slightly from red to orange hues. Physical examination of the rehydrated pepper samples resulted with displaying improved rehydration rate (5.95).