Effects of drying method on the phenolics content and antioxidant activities of cherry laurel (Prunus laurocerasus L.)

Cherry laurel fruit is a good source of phenolics together with considerable antioxidant activity. However, it is only available for a short period of time during the year. Drying could offer long-time preservation however it harms the bioactive compounds due to the high temperatures applied during the process. The aim of this study is to determine the most proper drying method for cherry laurel in terms of preserving its bioactive compounds. The phenolics contents, antioxidant and antibacterial activities, and color properties of cherry laurel dried via lyophilization, vacuum drying, and fan oven-drying were compared. Lyophilized cherry laurel had the highest phenolics content (315.51 Gallic acid equivalent mg/100 g dried cherry laurel) and color intensity (C*). The antioxidant activity was determined using both DPPH and ABTS assays. The highest antioxidant activity (6.16 mM TE/g in DPPH and 28.83 mM TE/g in ABTS) thus, the lowest half-maximal inhibitory concentration (IC50) was detected for lyophilized samples in both DPPH and ABTS assays in methanolic (1.59 mg dried cherry laurel) and aqueous (0.30 mg dried cherry laurel) extracts, respectively. In general, vacuum- and fan oven-dried cherry laurel presented similar phenolics contents and antioxidant activities. None of the dried cherry laurel extracts showed antibacterial activity against the selected bacteria. Although lyophilization is a high-cost technology, it could be applied as an alternative method in the drying of cherry laurel since it provides high-quality products while maintaining its bioactivity.