Extraction, Purification and In Vitro Antioxidant Activity Evaluation of Phenolic Compounds in California Olive Pomace

Abstract

Olive pomace (OP) is a valuable food byproduct that contains natural phenolic compounds with health benefits related to their antioxidant activities. Few investigations have been conducted on OP from the United States while many studies on European OP have been reported. OP of Arbequina, the most common cultivar from California, was collected and extracted by water, 70% methanol and 70% ethanol, followed by purification using macroporous absorbing resin. Results showed that the extractable total phenolic content (TPC) was 36–43 mg gallic acid equivalents (GAE)/g in pitted, drum-dried defatted olive pomace (DOP), with major contributions from hydroxytyrosol, oleuropein, rutin, verbascoside, 4-hydroxyphenyl acetic acid, hydroxytyrosol-glucoside and tyrosol-glucoside. Macroporous resin purification increased TPC by 4.6 times the ethanol crude extracts of DOP, while removing 37.33% total sugar. The antioxidant activities increased 3.7 times Trolox equivalents (TrE) by DPPH and 4.7 times TrE by ferric reducing antioxidant power (FRAP) in the resin purified extracts compared to the ethanol crude extracts. This study provided a new understanding of the extraction of the bioactive compounds from OP which could lead to practical applications as natural antioxidants, preservatives and antimicrobials in clean-label foods in the US.

The Influence of Pulsed Electric Field and Air Temperature on the Course of Hot-Air Drying and the Bioactive Compounds of Apple Tissue

“…The antioxidant capacity was determined using a spectrophotometric method to determine the degree of quenching of the synthetic 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical [ 57 ]. In order to prepare the initial DPPH solution, 0.025 g of 2,2-diphenyl-1-picrylhydrazyl was diluted to 100 mL with 99% methanol.…”

Ultrasound-assisted extraction of hydroxytyrosol and tyrosol from olive pomace treated by gamma radiation: process optimization and bioactivity assessment

“…The antioxidant activity of olive pomace extracts has usually been measured by chemical-based assays, namely for their DPPH and ABTS radical scavenging activity and ferric (FRAP) and cupric (CUPRAC) reducing power, 10,11,[33][34][35][36] always obtaining the good correlation with the phenolic contents of olive pomace extracts.…”

Biological effects of the olive tree and its derivatives on the skin

“…OP is a biomass by-product of EVOO production with a high content of pulp, skin, pits and water. 18 It is a rich source of phenolic compounds, sterols, pentacyclic triterpenes, carotenoids and mono-and polyunsaturated fatty acids 19 that confer it anti-inflammatory, antioxidant, hepatoprotective, gastroprotective, anti-diabetic and lipid-lowering properties. [20][21][22][23] OMW is a liquid waste fraction with a high polluting power.…”