Recovery and antioxidant activity of phenolic compounds extracted from walnut press-cake using various methods and conditions

Walnut (Juglans regia L.) press-cake is a residue of oil processing from which the phenolic compounds were extracted using ethanol 60 % by batch and semi-continuous operations, or ultrasound-assisted maceration in case de-oiled cake, with particular attention to variables time solid-solvent ratio. For extraction, conditions maximizing total yield (TPC) radical scavenging activity evaluated 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay °C without addition phospholipids, provided however for yield, that an extraction min ratio 25 mL solvent per g cake applied. Values up 14.8 mg gallic acid equivalent (GAE)/gcake 136.9 μmol Trolox equivalent/gcake obtained. The variant gave TPC 19.8 GAE/gcake overall extract containing 8% 46 oil. After de-oiling, was subjected extraction. DPPH varied slightly applied conditions, between 10.4 13.3 83–107 Equiv./gcake respectively, unless solid/solvent increased 1/200 (TPC 29 GAE/gcake). It also shown oxidative stability Camelina sativa L. Crantz 24 72 h enrichment walnut extract.