Different drying techniques effect on the bioactive properties of rose petals

Abstract

This study explored the effect of different drying methods (sun, shade, oven) on the total polyphenol content (TPC) using the Folin–Ciocalteu (FC) procedure, total flavonoid content (TFC) using the AlCl3 colorimetric method, volatile organic compounds using GC/MS and the antioxidant properties of the rose petals using the protocol of DPPH assy. The results demonstrated that the drying methods had a significant impact and the highest TPC (34.24 mg gallic acid equivalent (GAE)/ g fresh weight (FW)) and TFC (5.56 mg catechin equivalent (CE)/g FW) were obtained for the oven-dried sample. While, the fresh sample exhibited the lowest TPC (15.6 mg GAE/g FW) and TFC (3.83 mg CE/g FW), respectively. Similarly, the oven-dried sample showed the highest DPPH scavenging activity (60.30 %) and reducing power (absorbance 1.138) among all the samples. Fresh rose sample GC–MS analysis revealed that the there are two major compounds heptacosane 64.56 % and citronellyl propionate 28.35 %. Pentadecyl 2-phenylethyl ester oxalic acid was the second dominant compound in sun and oven-dried rose samples, 18.5 % and 14.79 % respectively.