No abstract

New electroanalytical methods have been proposed for the estimation of the total content of phenolic compounds of low oxidation potential in cork boiling water, expressed as gallic acid equivalent/g dry cork, by using screen‐printed electrode modified with graphene. The results obtained have been compared with spectrophotometric method (Folin‐Ciocalteau) and a good correlation has been found between them. The detection limits obtained by Winefordner‐Long and Clayton methods were 0.04 and 0.06 ppm for ellagic acid (EA), and 0.05 and 0.09 ppm for gallic acid (GA), respectively. The sensitivity, simplicity, selectivity, fast and low cost of the developed methodologies is also demonstrated.

The chemical composition of extra virgin olive oils (EVOOs) from six new progenies, obtained through controlled crossings between the main Tunisian variety Chemlali and autochthonous (Chemcheli) and foreign cultivars (Sigoise, Coratina, Koroneiki, and Arbequina) used as pollen acceptor or pollinator, were compared with the EVOO of Chemlali cultivar known to be the main one cultivated in Tunisia as it is the most adapted to the arid climate. Several analytical determinations of major and minor components of EVOO were employed, especially triacylglycerol and sterol fractions. All the studied hybrid EVOOs showed an improvement in their chemical composition and stability by comparison with Chemlali EVOO. The main triacylglycerols were 1,2,3-trioleylglycerol (OOO), 2,3-dioleyl-1-palmitoylglycerol (POO), 2,3-dioleyl-1-linoleylglycerol (LOO) and 2,3-dioleyl-1-stearoylglycerol (SOO). β-sitosterol, Δ5-avenasterol and campesterol were the principal sterols in all samples. Cholesterol, stigmasterol, clerosterol and Δ7-stigmastenol were also found in all samples. Oil samples examined showed inter-variability between the studied cultivars. Results of discriminant and principal component analyses appear to prove that genetic origin of the raw materials has a great influence on the final composition of the oil; especially triacylglycerol and sterol compositions.

Quercus suber L. cork contains a diversity of phenolic compounds, mostly low molecular weight phenols. A rising number of reports support with convergent findings that polyphenols evoke pro-apoptotic events in cancerous cells. However, the literature related to the anti-cancer bioactivity of Q. suber L. cork extractives (QSE) is still limited. Herein, we aim to describe the antitumor potential displayed by cork extractives obtained by different extraction methods in the human promyelocytic leukaemia cells. In order to quantify the effects of QSE on cancer cells viability, phosphatidylserine exposure, caspase-3 activity, mitochondrial membrane potential and cell cycle were evaluated. The results indicated that the QSE present a time-dependent and dose-dependent cytotoxicity in the human promyelocytic leukaemia cells. Such a noxious effect leads these leukaemia cells to their death through apoptotic processes by altering the mitochondrial outer membrane potential, activating caspase-3 and externalizing phosphatidylserine. However, cells cycle progression was not affected by the treatments. This study contributes to open a new way to use this natural resource by exploiting its anti-cancer properties. Moreover, it opens new possibilities of application of cork by-products, being more efficient in the sector of cork-based agriculture. Copyright © 2015 John Wiley & Sons, Ltd.

Organic production has increasing importance in the food industry. However, its effect on the olive oil characteristics remains unclear. The purpose of this study was to research into the effect of organic production without irrigation, the traditional harvesting methods (tree vs. ground picked fruits), and the harvesting time (over a six-week period) on the oil characteristics. Free acidity, peroxide value, K232, K270, ΔK, total phenols, oxidative stability and the volatile compound profile (by SPME extraction, gas chromatography and mass detection) of olive oils from the Verdial de Badajoz cultivar were analysed. The organic production affected the peroxide value, total phenols, oxidative stability and 34 out of 145 volatile compounds. Its effect was much less strong than that of the harvesting method, which affected severely all the chemical and physical-chemical parameters and 105 out of 145 volatile compounds. Conversely, the harvesting time was revealed as a factor with little repercussion, on the chemical and physical-chemical parameters (only peroxide value was influenced), although it affected 83 out of 145 volatile compounds. The larger content in total phenols in the organic oils than in the conventional ones could explain the increase in oil stability and the differences in the volatile compounds.