Exploitation of virgin olive oil by‐products (Olea europaeaL.): phenolic and volatile compounds transformations phenomena in fresh two‐phase olive pomace (‘alperujo’) under different storage conditions

Abstract

BACKGROUND Much effort has recently been spent for re‐using virgin olive oil by‐products as nutraceutical ingredients for human diet thanks to their richness in bioactive phenols, but their management is not easy for producers. We aimed to provide useful information for a better management of fresh olive pomace before drying, by studying the phenolic and volatile compounds transformations phenomena of fresh olive pomace stored under different conditions planned to simulate controlled and uncontrolled temperature conditions in olive oil mills. RESULTS The evolution of the phenolic and volatile compounds was studied by high‐performance liquid chromatography‐diode array detector mass spectrometry (HPLC‐DAD‐MS) and headspace solid‐phase microextraction gas chromatography‐mass spectrometry (HS‐SPME‐GC‐MS). The phenolic profile varied rapidly during storage: the verbascoside content decreased about 70% after 17 days even at 4 °C, while the content of simple phenols such as hydroxytyrosol and caffeic acid increased over time. The low temperature was able to slow down these phenomena. A total of 94 volatile organic compounds (VOCs) were detected in the fresh olive pomace, with a prevalence of lipoxygenase (LOX) VOCs (78%), mainly aldehydes (19 490.9 μg kg−1) despite the higher number of alcohols. A decrease in LOX volatiles and a quick development of the ones linked to off‐flavors (carboxylic acids, alcohols, acetates) were observed, in particular after 4 days of storage at room temperature. Only storage at 4 °C allowed these phenomena to be slowed down. CONCLUSION To preserve the natural phenolic phytocomplex of fresh olive pomace before drying and to avoid off‐flavors development, storage in open containers must be avoided and a short storage in cold rooms (7–10 days) is to be preferred. © 2021 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Olive Pomace Extract Contains Low Molecular Weight Peptides and Possesses ACE Inhibitory Activity

“…Fraction 20 (<290 Da) contained small phenolic compounds, dipeptides, tripeptides, free amino acids, and other small molecules. The total content of polyphenols measured in the LMW extract was 8.2 mg/mL, which is in agreement with previously reported values detected in olive pomace (ranging from 1-23 mg/g of fresh olive pomace) [23,[30][31][32]. Polyphenols were undetectable in fractions 16 and 17, but were mostly present in fractions 19 and 20.…”

Virgin Olive Oil By-Products: Biological Activity of Phenolic Extract of Pâté on AGS Gastric Cells

“…One aspect to underline is that the great majority of phenolic compounds are lost during the olive milling process, and no more than 0.5% of the phenols contained in the intact fruit is transferred to the virgin olive oil [4]. Olive pomace, the main by-product 2 of 15 recovered during virgin olive oil production by two-phase decanters [5], can be seen as a pollutant for the environment, but at the same time it is a valuable source of phenolic compounds [6]. Pâté is a destoned olive pomace that is recovered during, and not after, the separation of oil into the two-phase decanter and a Leopard ® system (Pieralisi Group S.p.A., Jesi, Italy) that protects phenolic compounds from oxidation.…”

Characteristics of Some Wild Olive Phenotypes (Oleaster) Selected from the Western Mountains of Syria

“…Olive oil is composed of triglycerides (98-99%) [21], and minor components such as sterols [22], waxes [23], tocopherols [24], carotenes and chlorophylls [25], phenolic compounds [26], and volatiles [27]. A balanced fatty acid composition contributes to the biological virtues of olive oil [28].…”