Extraction of Bioactive Compounds from Cistus creticus Leaves and Their Use in the Preparation of Yogurt Desserts

The objective of this study was to determine the optimal conditions for the recovery of bioactive and antioxidant compounds in aqueous solutions of Cistus creticus leaves and then employ the optimal extract for the enrichment of yogurt samples. The optimal conditions were established by a response surface methodology and were determined to be a liquid-to-solid ratio of 48 mL/g at 76 °C for 41 min. The optimum extract yielded TPC 157.17 mg GAE/g dw and TFC 2.38 mg QE/g dw, while FRAP and DPPH values were 1258.52 and 933.67 μmol AAE/g dw, respectively. HPLC‒DAD was utilized to identify and quantify specific polyphenols, like myricetin rhamnoside, in the extract. The optimal extract was then added to yogurt desserts during their preparation at three different concentrations to study how the physicochemical characteristics of the yogurt, as well as the antioxidant capacity added during enrichment, were affected. Statistical analysis of the results was carried out in order to obtain more valid data. It seems that the most suitable concentration for yogurt fortification was 0.1% w/v of the extract as, at this concentration, the yogurts exhibited higher antioxidant capacity, and their physicochemical characteristics were improved.