Anastasia Mylona

Oxidative Stability of Edible Vegetable Oils Enriched in Polyphenols with Olive Leaf Extract

Commercially available oils (olive oil, sunflower oil, palm oil, and a vegetable shortening) were enriched in polyphenols, by adding olive leaf extract. Addition of the extract was performed in such way that the oils were enriched with 200 mg/kg polyphenols. Total polyphenols of both enriched and commercial oils were estimated by the Folin—Ciocalteau assay, while identification and quantification of individual simple phenolic compounds was performed by GC/MS and of oleuropein by HPLC analysis. The enrichment resulted in the supplementation of the commercial oils mainly with oleuropein, hydroxytyrosol, and quercetin. Antioxidant capacity and oxidative stability of the enriched oils and the commercial ones were assessed by the 1,1-diphenyl-2-picrylhydrazyl radical (DPPH•) scavenging assay and the Rancimat method, respectively. Both antioxidant capacity and oxidative stability were substantially improved for all the oils studied after supplementation. By the procedure adopted, oils rich in polyphenols, mainly in oleuropein, can be produced with olive leaf extract supplementation.

Detection and Identification of Simple Phenolics in Pistacia lentiscus Resin

Abstract Identification and quantification of a series of phenolic compounds in Pistacia lentiscus resin, commonly known as Chios mastic gum, has been achieved based on high performance liquid chromatography (HPLC) fractionation of polar extract of the resin prior to dual‐column gas chromatography‐mass spectrometry (GC‐MS) analysis. Polyphenols were extracted from the resin with methanol/water and the extract was fractionated by HPLC. Identification of tyrosol, p‐hydroxy‐benzoic, p‐hydroxy‐phenylacetic, vanillic, gallic, and trans‐cinnamic acids was performed on both HP‐5 and Innowax columns using GC‐MS at SIM mode. Also, the triterpenoids dihydroabietic acid, oleanolic and its isomer ursolic acid and hydroxy‐ursenal were detected in the same HPLC run with polyphenols, as a result of GC‐MS at full scan mode.

Triacylglycerol Species of Less Common Edible Vegetable Oils

Abstract Chromatographic and spectroscopic methods used for the detection and quantification of triacylglycerol (TAG) species present in less common edible vegetable oils (almond, hazelnut, pumpkin seed, safflower, sesame, walnut, and wheatgerm oils) are reviewed. For these oils, as well as for thistle oil and high-oleic sunflower oil, for which no data exist on their TAG composition, both high-performance liquid chromatography (HPLC) and gas chromatography (GC) chromatographic plus spectrometric techniques have also been performed. Triacylglycerol comparison of the data found in the literature is also presented. Five fatty acyl moieties (palmitoyl-, stearoyl-, oleoyl-, linoleoyl-, and linolenoyl-) are found to mainly contribute to the formation of TAG species of the aforementioned edible vegetable oils, whereas six more (palmitoleoyl-, arachidoyl-, gadoleoyl-, heptadecenoyl-, margaroyl-, and erucoyl-) are reported as minors. Only 19 to 33 TAG make up the mass of these oils. These TAG are also found in most common edible oils, thus indicating a “uniformity” in the minor and main TAG composition of edible vegetable oils. Trioleoyl-glycerol predominates in almond (13.3–48.6%), hazelnut (35.3–57.9%), and high oleic sunflower (44.2% and 52.9%) oils, trilinoleoyl-glycerol in safflower (40.1–49.7%), thistle (36.9% and 46.0%), walnut (25.9–38.1%), and wheatgerm (15.7–33.0%) oils. Sesame and pumpkin seed oils are rich in dioleoyl-linoleoyl-glycerol (5.9–17.5%, 9.5% and 18.6%, respectively) and oleoyl-dilinoleoyl-glycerol (8.0–18.7% and 12.8–21.1%, respectively).

Dietary Evaluation of Vegetables Pan-Fried in Virgin Olive Oil Following the Greek Traditional Culinary Practice

The aim of this work was the nutritional evaluation of fresh vegetables, pan-fried in virgin olive oil according to the traditional Greek culinary practices. The vegetables studied (potatoes, green peppers, zucchini, and eggplant) are traditionally consumed after pan-frying in virgin olive oil in Greece and other Mediterranean countries. The fried samples contained less moisture, more fat, and more energy when compared to the raw ones, while they were significantly enriched in squalene, β-sitosterol, campesterol, and stigmasterol. Their fatty acid composition reflected that of the olive oil they absorbed. The results obtained indicate that among other nutritional benefits of their consumption, vegetables fried in virgin olive oil appear to represent a healthy lipid profile in regard to fatty acid classes and their atherogenic and thrombogenic indices, while they furthermore provide an additional intake of monounsaturated fat, squalene, and phytosterols for Mediterranean peoples. The authors would like to thank Mrs. Margarita Christea for her technical assistance.

Compositional Changes and Enrichment of Mediterranean Finfish During Pan Frying With Virgin Olive Oil

Eight species of small Mediterranean finfish were prepared and pan-fried in virgin olive oil, according to traditional Greek culinary practices. The changes in their proximate composition, energy content, fatty acids, squalene, cholesterol, β-sitosterol, campesterol, and stigmasterol were investigated. Pan-fried fish contained more protein, total fat, monounsaturated fatty acids, energy, and cholesterol and were enriched in squalene and phytosterols than the raw samples. The results suggest that fish pan-fried in olive oil can be classified as highly nutritive in regard to its protein, major fatty acid classes, n-6/n-3 ratios, and total fat content. It provides an additional intake of squalene and phytosterols for Mediterranean people.