Giovanni Lercker

Study of Chemical Changes Produced in Virgin Olive Oils with Different Phenolic Contents during an Accelerated Storage Treatment

Chemical changes produced in an extra virgin olive oil sample in the presence (EVOO) and absence (EVOOP) of its phenolic fraction during an accelerated storage treatment at 60 degrees C up to 7 weeks were studied. Modifications in phenol content, as well as changes in several quality parameters (free acidity, peroxide value, UV absorbance, fatty acid composition, oxidative stability index, and tocopherol content) were also evaluated under the same storage conditions and compared to those of the same sample deprived of phenolic compounds. When the phenolic extract of the EVOO was studied, a decrease of the antioxidants first present in the sample and an increase of the oxidized products were observed. In addition, oxidation seemed to produce the transformation of such phenolic compounds as secoiridoids and the appearance of oxidized forms of them. These latter compounds could be used as molecular markers of the lack of extra virgin olive oil freshness.

Effects of Different Rearing and Feeding Systems on Lipid Oxidation and Antioxidant Capacity of Freeze-Dried Egg Yolks

Lipid oxidation and antioxidant capacity of freeze-dried egg yolks produced with two rearing systems (battery cages and free-range) and two types of feedings (conventional and organic) were studied. Nine fresh egg yolks of each crossed treatment were pooled, frozen for a month, freeze-dried, vacuum-packed, and kept at -18 degrees C until analysis. No significant differences were observed in the lipid (58.0-62.1%) and total sterol contents (33.0-35.5 g/kg of lipids) of the freeze-dried egg yolks. Free rearing and conventional feeding systems resulted in significantly higher total tocopherol, alpha-tocopherol, and lutein contents, as compared to the battery cage and the organic feed, respectively. However, no significant differences were found in lipid oxidation (peroxide value = 0.7-0.9 mequiv of O(2)/kg of fat; thiobarbituric reactive substances = 1.0-1.3 mg of malonylaldehyde/kg of sample) and cholesterol oxidation (28.8-43.5 mg of cholesterol oxidation products/kg of lipids; 0.08-0.12% oxidized cholesterol) of freeze-dried egg yolks except for 7alpha-hydroxycholesterol, which was significantly lower in samples obtained with organic feed.

Biochemical and histopathological effects of dietary oxidized cholesterol in rats

Cholesterol oxidation products (COPs) have been associated with the genesis of chronic degenerative diseases, such as atherosclerosis. The purpose of this work was to study the histological changes by toxic effects of dietary COPs in liver and kidney. Five‐week‐old male Wistar albino rats were randomly divided into three groups of 10 rats each. Standard rat chow was supplemented with either 1% (w/w) pure cholesterol or 1% oxidized cholesterol and fed to the rats for 8 weeks. Control animals were fed standard rat chow. At the end of the treatment period, the serum lipid profile was determined. The aorta, liver and kidneys were excised immediately, frozen with liquid nitrogen, and held at −70u2009°C. The histological study was carried out using conventional hematoxylin‐eosin staining, and histochemical red oil ‘O’ was applied. COPs were analyzed by gas chromatography. Intake of dietary COPs altered biochemical parameters involved in lipid metabolism associated with atherogenesis in rats: total cholesterol, triacylglycerols and low density lipoproteins in serum. COPs detected in the liver and kidneys modified the organ original structure, caused an inflammatory process and promoted atherogenesis and atrophy of the tissue. Copyright

Evaluation of the oxidative status of virgin olive oils with different phenolic content by direct infusion atmospheric pressure chemical ionization mass spectrometry

Atmospheric pressure chemical ionization mass spectrometry was used to predict the oxidative status of virgin olive oils (VOO) during their storage. VOO samples, with and without phenolic compounds, were stored in the dark at 60xa0°C up to 7xa0weeks. The VOO samples were diluted in an alkaline propanol/methanol mixture and directly infused into an ion-trap mass spectrometer. The abundances of the [M−H]− peaks of free fatty acids, oxidized fatty acids, tocopherols and phenolic compounds, jointly with their oxidized forms, were measured and used as predictors. Two linear discriminant analysis (LDA) models were constructed in order to classify samples according to their oxidative levels. The first model was constructed using both VOO samples (with and without phenols), considering as predictors only fatty acids and their oxidized products. The second LDA model was constructed with the VOO sample with phenolic compounds considering as predictors all the peaks measured. In both models, the samples divided in the eight different storage times were correctly classified (100%) by leave-one-out cross-validation with an excellent resolution among all the category pairs (for the first model Wilks’ lambda, λwu2009=u20090.229 and for the second λwu2009=u20090.928). This method is a very fast tool for on-line monitoring of VOO oxidation status.