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Green extraction approach for the recovery of polyphenols from Croatian olive leaves (Olea europea)

Putnik, Predrag, Barba, Francisco J., Španić, Ivana, Zorić, Zoran, Dragović-Uzelac, Verica, Bursać Kovačević, Danijela
Food and bioproducts processing 2017 v.106 pp. 19-28
Olea europaea, byproducts, coumaric acids, drugs, flavonols, functional foods, leaves, liquids, olives, phytopharmaceuticals, polyphenols, response surface methodology, sustainable technology, temperature
Pressurized liquid extraction (PLE) is shown as an innovative green technology for the effective extraction of the various phytochemicals from food by-products, therefore the aims of this study were to evaluate the application of PLE to engineer green extracts of Croatian olive leaves (Olea europaea, cv. Oblica) for potential industrial production (functional foods/pharmaceuticals). PLE was conducted under various cycle numbers (1, 2), temperature (60, 80, 100°C) and static times (5, 10, 15min). Obtained extracts were characterized in terms of: (i) total polyphenols (TP); (ii) total flavonoids (TF); hydroxycinnamic acids (HCA); and (iv) flavonols (FLA). Response surface methodology revealed optimal PLE parameters for polyphenols recovery, observing differences in the extraction conditions (number of cycles, temperature and time) according to the specific polyphenol groups. TP optimal extraction conditions (53.15mg GAE/g) were achieved after PLE (2 cycles, 80°C/5min,) while 1 cycle with 100°C/15min were selected as the optimal PLE conditions for TF recovery (16.51mg QE/g). For HCA, 2 cycle, 91°C/15-min were the conditions with highest yields (1.66mg CA/g); and for FLA extraction under 1 cycle, 87°C/5-min revealed the highest recovery (8.66mg QE/g). Results indicated PLE as a good choice for green recovering polyphenols from the olive leaves.