Long-Term Preservation of Total Phenolic Content and Antioxidant Activity in Extra Virgin Olive Oil: A Physico-biochemical Approach

Abstract

Objectives: This work, on low-cost controlled freeze methodology for stabilizing the phenolic content in Extra Virgin Olive Oil (EVOO), is evaluated by studying four Quality Indexes (QIs): free acidity, as % of oleic acid (1 st-QI); UV-absorption values; K 272 , K 232 and ΔK (2 nd-QI); total phenolic content (TPC), as Gallic acid equivalence (3 rd-QI); and lipid peroxidation products, as free malondialdehyde (MDA) (4 th-QI). Methods: The study of QIs for EVOO under storage, absence of light, at 25, 4,-20 and-80°C, with or without N 2-purge showed that the phenolic charge is stabilized for > 12 months, at refrigeration conditions storage (~ 4°C) in the absence of oxygen, whilst the peroxidation of lipids is being kept at a low level. Results: The results showed that the high concentration of natural hydroxylphenols in the EVOO in combination with its degassing (via N 2-purge) and storage at ~ 4°C, constitute the optimum conditions for preservation of olive oil as a long-lasting EVOO (LL [legal limit]-EVOO) with high added value. Conclusion: The main scientific contribution of this study is: (i) development and evaluation of a methodology (freeze controlled treatment) for the long-term preservation of EVOO quality, (ii) understanding the physicochemical mechanism and factors determining EVOO quality and (iii) ready-to-use technology for the local and international market.

Long-Term Preservation Evaluation of Extra Virgin Olive Oil by Lipid Hydroperoxides and Malondialdehyde Toxicological Concern Levels

“…(iv) Additionally, at production and irrespective of the ±N 2 purge and temperature, it attains a minimum PV LOOH value of ∼6 mEql/kg, which is ∼3-fold lower than the allowable EE minimum value of 20 mEql/kg. These data are also in agreement with a previous study that found that oxidation delay of EVOO from the same Koroneiki monovariety can be achieved by minimally storing it in a cool and dark place . It should also be noted that EVOO oxidation of the same variety has been studied in other areas in Greece and measured by the traditional PV IT test (ranging from 6.20 to 74 mEql O 2 /kg). − …”

“…These data are also in agreement with a previous study that found that oxidation delay of EVOO from the same Koroneiki monovariety can be achieved by minimally storing it in a cool and dark place. 20 It should also be noted that EVOO oxidation of the same variety has been studied in other areas in Greece and measured by the traditional PV IT test (ranging from 6.20 to 74 mEql O 2 /kg). 21−24 3.1.3.…”

Use of transcriptomic profiling to identify candidate genes involved in Polyporus umbellatus sclerotial formation affected by oxalic acid

“…Unsaturated fatty acids are the intrinsic reason for lipid oxidation 26 . c9511_g1 and c9756_g1 , encoding fatty acid synthase were downregulated in the High OA group compared to that of the control group, which suggests that lipid oxidation is lower in the High OA group.…”

Evolution of Extra Virgin Olive Oil Quality under Different Storage Conditions

“…This trend is probably due to the hydrolytic and oxidative degradation processes of main secoiridois (oleuropein, oleacin, oleocanthal, 3,4-DHPEA-EA, and p-HPEA-EA) [40,41], which in fact decreased significantly under all conditions. It is widely recognized that tyrosol and hydroxytyrosol typically increase in aged EVOOs [6,9,15,16,42] and, considering that hydroxytyrosol represents an important bioactive compound for human health, with a strong antioxidant activity [43,44], a low concentration of this molecule, when balanced by a high concentration of complex phenols, may represent a good compromise for EVOOs from a quality standpoint. The relationship between complex and simple phenolic compounds also depends on the initial content and processing conditions [5,45,46].…”