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.
Objectives: In the present work, five aromatic plants: Origanum vulgare L., Rosmarinus officinalis L., Ocimum basilicum L., Salvia officinalis L. and Achillea millefolium L., are examined in order to determine Gallic Acid (GA) radical generation in them by UV-Vis and EPR spectroscopy. Methods: The phenol content of plant extracts was estimated at 280 nm by deconvolution of UV-Vis spectra using a GA calibration curve whilst the radical activity was quantitated by EPR Spectroscopy at 77 Kelvin using the stable free radical DPPH • as a reference. Results: The radical activity ranged from 7 × 10 12 spins in O. vulgare L. to 2.2 × 10 13 spins in O. basilicum L. of DPPH • /g sample whilst the phenol content as GA ranged from 28.1 mg of GA/g sample in O. vulgare L. to 65.2 mg of GA/g sample in A. millefolium L. Moreover, EPR spectra showed that all samples contain stable radical signals with g-values 2.0046-49 and a line width of 3-5 Gauss. These are characteristic for π-type semiquinone radicals of GA compounds with the unpaired electron partially on the oxygen atom of the phenolic ring radicals. Conclusion: These significant differences between the UV-Vis and EPR measurements reveal that the stabilization of the radical fraction, type GA • in aromatic plants is a combined result of aromatic species and local effects; namely, phenolic groups and aromatic environment.
According to the Greek Ministry of Environment, there are 2,000 contaminated sites in Greece. The agricultural production in these sites should be evaluated to provide an assessment and recommendations on the necessary actions required for crop sustainability. This study investigated the effects of heavy metals on White clover (Trifolium repens L.) growth in an above-referenced multi-metal contaminated site in the absence/presence of zeolite as an agent empowering the rehabilitation of pollution and immobilization of heavy metals. The addition of 1% zeolite to the polluted soils significantly contributed to plant growth by limiting the availability of Cd, Pb and Zn. However, the dry biomass of plants grown in the presence of zeolite was evaluated to be unsuitable as a raw material (feed) in livestock production, due to the high Cd toxicity. In the context of sustainable production, this study aims to holistically approach and evaluate mechanisms of phytoremediation, bioaccumulation and the disposal of the bioaccumulator as a high value-added product (feed).
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