Influence of β-Cyclodextrin on the Overall Antioxidant Activity and DPPH· Reaction Kinetics of Fresh Raspberry (Rubus idaeus L.) and Dehydrated Strawberry (Fragaria × ananassa Duch.) Extracts

The influence of natural β-cyclodextrin (β-CD) on the overall antioxidant activity of berry extracts is presented in this study. Raw raspberry (Rubus idaeus L.) and β-CD-assisted dehydrated strawberry (Fragaria × ananassa Duch.) ethanolic extracts (RB and SB, respectively) were spectrophotometrically monitored in the presence of 1 mM 2,2-diphenyl-1-picrylhydrazyl (DPPH·) solution in the absence or presence of β-CD. Cyanidin 3-O-glucoside (Cy3G) was used as standard compound, being identified by RP-HPLC in both RB and SB at 14.62 and only 0.15 mg/100 g fresh weight (fw). Pelargonidin 3-O-glucoside (Plg3G) was the most concentrated anthocyanin in SB (estimated at 2.46 mg/100 g fw). Higher antioxidant activities (expressed as the radical scavenging activity, RSA, %) were obtained for SB dehydrated in the presence of β-CD. The RSA values increased by 35% in comparison with the SB dehydrated by the classical method. On the other hand, the DPPH· reaction kinetic parameters significantly differed for RB extracts evaluated in the presence of 1 mM β-CD (in water). The DPPH· reaction rate in the 3–15 min time range was 25% higher for the RB extracts obtained from the β-CD-assisted dehydrated samples. This study demonstrates for the first time the protection capacity of β-CD against the degradation of antioxidants during the classical dehydration process of berries. This technology can be extended to other fruits and scaled up for obtaining high-quality fruit-based products.