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OLIVE AND AVOCADO OILS AND THEIR BLEND: EVALUATION AND UTILIZATION IN SOME FOODS
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A staple food for thousands of years for the inhabitants of the Mediterranean region, olive oil is now becoming popular among consumers all over the world. Olive oil differs from other vegetable oils because it is used in its natural form and has unique flavor and other characteristics. More and more research suggests its healthful benefits including reduced risk of coronary heart disease. Olive Oil is a compact and readable text on the most important aspects of chemistry, technology, quality, analysis and biological importance of olive oil. The topics selected have been developing rapidly in recent years, and will provide the reader with a background to address more specific problems that may arise in the future. Readers can expect more contributors and chapters in the 2nd edition, as well as a glossary.
The total polar fraction and individual phenols present in virgin olive oil were tested for their antioxidant effect in refined
olive oil. Hydroxytyrosol and caffeic acid showed protection factors greater than BHT. Protocatechuic and syringic acid were
also found to have antioxidant activity. Tyrosol, p-hydroxyphenylacetic acid, o-coumaric acid, p-coumaric acid, p-hydroxybenzoic
acid and vanillic acid had very little or no effect, and their contribution to the stability of the oil is negligible.
Reports on the methylsterol fractions of hazelnut oils are scarce. The objectives of this study were to characterize methylsterols
in hazelnut and virgin olive oils and to study the possibility of detection of adulteration of virgin olive oils. In hazelnut
oils, 4-desmethylsterols were present in higher proportions (86 to 91%) than in virgin olive oils where this fraction was
ca. 50% of the total sterol. In the 4-monomethylsterol fraction, citrostadienol was the major component in both kinds of oils
followed by cycloeucalenol and obtusifoliol in virgin olive oils, and obtusifoliol in hazelnut oils. 24-Methylenecycloartanol
was predominant in both kinds of oils in the 4,4′-dimethylsterols. For the first time, δ-amyrin was tentatively identified
by comparing published mass spectral data in the analyzed samples of both kinds of oils. An unknown compound X (containing
a lupane skeleton) and lupeol were detected only in the 4,4′-dimethylsterols fraction of hazelnut oils at a level of 2–8 and
6–10%, respectively. GC-MS analysis showed that adulteration of virgin olive oil by hazelnut oil could be detected at a level
less than 4% by using these two compounds as possible potential markers.
Effect of methanol extracts of rosemary and olive vegetable water on the stability of olive oil and sunflower oil. Methanol phenolic extracts of dry rosemary leaves and olive vegetable water filtrate, in combination with BHA, were added to olive oil (blend of refined and virgin olive oil, 3 to 1) and to sunflower oil and their antioxidant effects under accelerated conditions were evaluated. Accelerated conditions included the oven test (at 63 °C) and the conductivity method (Rancimat at 120 °C). Frying process at 180 °C was also applied. The methanol phenolic extracts and the BHA were added to each oil at the following concentrations: 200 ppm rosemary extract; 200 ppm olive vegetable water extract; 100 ppm rosemary extract + 100 ppm BHA; 100 ppm vegetable water extract + 100 ppm BHA and 200 ppm BHA. In general, antioxidant effect of phenolic additives of rosemary and of BHA was in the following order: 200 ppm rosemary extract > 100 ppm rosemary extract + 100 ppm BHA > and 200 ppm BHA. The addition of 200 ppm vegetable water extract and 100 ppm vegetable water extract + 100 ppm BHA exhibited similar antioxidant effect to that of 200 ppm BHA.
Hydroxytyrosol acetate was synthesized, and the antioxidant activity of this olive oil component was assessed in comparison with that of other olive oil components, namely hydroxytyrosol, oleuropein, 3,4-DHPEA-EA, and alpha-tocopherol in bulk oil and oil-in-water emulsions. The activity of the compounds was also assessed by scavenging of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals. Hydroxytyrosol acetate had a weaker DPPH radical scavenging activity than hydroxytyrosol, oleuropein, or 3,4-DHPEA-EA but it had a radical scavenging activity similar to that of alpha-tocopherol. In oil, the antioxidant activity of hydroxytyrosol acetate was much higher than that of alpha-tocopherol or oleuropein, but in an emulsion 3,4-DHPEA-EA and alpha-tocopherol were more effective as antioxidants than hydroxytyrosol acetate. The antioxidant activity of hydroxytyrosol acetate was rather similar to that of hydroxytyrosol in oil and emulsions despite the difference in DPPH radical scavenging activity.
To study the differences in cognitive status with respect to food habits and energy and nutrient intake in a group of non institutionalised, elderly people.
Prospective study.
The study subjects were independently living, elderly people who spent some of their time at day centres in the Comunidad de Madrid (the Madrid region). The study centres were selected by the Madrid City Hall.
The study included 168 elderly people aged 65-90 y. All accepted the invitation to participate, met all inclusion criteria, and were free of significant cognitive impairment.
Dietary intake was monitored using a 'food record' for 7 consecutive days including a Sunday. In addition, the 'precise individual weighing' method was used for 5 days in order to monitor the meals taken by the subjects at the centres' canteens. Cognitive capacity was measured using Folstein's mini-mental state examination (MMSE), validated for the Spanish population.
Subjects with an adequate cognitive capacity (MMSE>/=28) showed a greater intake of total foods, fish, and alcoholic drinks, but took less foods from the 'various' group (chocolates, cakes, etc). These subjects had a more adequate intake of fatty acids and cholesterol, and a greater intake of vitamins implicated in correct brain function (thiamine, folic acid, vitamin C).
Subjects with satisfactory intellectual function generally had a better diet. This shows the importance of correct nutrition in its maintenance.
Plant sterols are naturally occurring molecules that humanity has evolved with. Herein, we have critically evaluated recent literature pertaining to the myriad of factors affecting efficacy and safety of plant sterols in free and esterified forms. We conclude that properly solubilized 4-desmetyl plant sterols, in ester or free form, in reasonable doses (0.8-1.0 g of equivalents per day) and in various vehicles including natural sources, and as part of a healthy diet and lifestyle, are important dietary components for lowering low density lipoprotein (LDL) cholesterol and maintaining good heart health. In addition to their cholesterol lowering properties, plant sterols possess anti-cancer, anti-inflammatory, anti-atherogenicity, and anti-oxidation activities, and should thus be of clinical importance, even for those individuals without elevated LDL cholesterol. The carotenoid lowering effect of plant sterols should be corrected by increasing intake of food that is rich in carotenoids. In pregnant and lactating women and children, further study is needed to verify the dose required to decrease blood cholesterol without affecting fat-soluble vitamins and carotenoid status.
The relationship between the intake of olive oil, the richest dietary source of the monounsaturated fatty acid oleic acid (OA; 18:1n-9), and breast cancer risk and progression has become a controversial issue. Moreover, it has been suggested that the protective effects of olive oil against breast cancer may be due to some other components of the oil rather than to a direct effect of OA.
Using flow cytometry, western blotting, immunofluorescence microscopy, metabolic status (MTT), soft-agar colony formation, enzymatic in situ labeling of apoptosis-induced DNA double-strand breaks (TUNEL assay analyses), and caspase-3-dependent poly-ADP ribose polymerase (PARP) cleavage assays, we characterized the effects of exogenous supplementation with OA on the expression of Her-2/neu oncogene, which plays an active role in breast cancer etiology and progression. In addition, we investigated the effects of OA on the efficacy of trastuzumab (Herceptin), a humanized monoclonal antibody binding with high affinity to the ectodomain of the Her-2/neu-coded p185(Her-2/neu) oncoprotein. To study these issues we used BT-474 and SKBr-3 breast cancer cells, which naturally exhibit amplification of the Her-2/neu oncogene.
Flow cytometric analyses demonstrated a dramatic (up to 46%) reduction of cell surface-associated p185(Her-2/neu) following treatment of the Her-2/neu-overexpressors BT-474 and SK-Br3 with OA. Indeed, this effect was comparable to that found following exposure to optimal concentrations of trastuzumab (up to 48% reduction with 20 microg/ml trastuzumab). Remarkably, the concurrent exposure to OA and suboptimal concentrations of trastuzumab (5 microg/ml) synergistically down-regulated Her-2/neu expression, as determined by flow cytometry (up to 70% reduction), immunoblotting, and immunofluorescence microscopy studies. The nature of the cytotoxic interaction between OA and trastuzumab revealed a strong synergism, as assessed by MTT-based cell viability and anchorage-independent soft-agar colony formation assays. Moreover, OA co-exposure synergistically enhanced trastuzumab efficacy towards Her-2/neu overexpressors by promoting DNA fragmentation associated with apoptotic cell death, as confirmed by TUNEL and caspase-3-dependent PARP cleavage. In addition, treatment with OA and trastuzumab dramatically increased both the expression and the nuclear accumulation of p27(Kip1), a cyclin-dependent kinase inhibitor playing a key role in the onset and progression of Her-2/neu-related breast cancer. Finally, OA co-exposure significantly enhanced the ability of trastuzumab to inhibit signaling pathways downstream of Her-2/neu, including phosphoproteins such as AKT and MAPK.
These findings demonstrate that OA, the main monounsaturated fatty acid of olive oil, suppresses Her-2/neu overexpression, which, in turn, interacts synergistically with anti-Her-2/neu immunotherapy by promoting apoptotic cell death of breast cancer cells with Her-2/neu oncogene amplification. This previously unrecognized property of OA offers a novel molecular mechanism by which individual fatty acids may regulate the malignant behavior of breast cancer cells and therefore be helpful in the design of future epidemiological studies and, eventually, dietary counseling.
The present communication describes a new system for the complete separation of lipid classes in natural mixtures by two-dimensional
chromatography on thin layers of silica gel impregnated with ammonium sulfate to improve separations. For quantitative analysis
an amount of 1 mg of total lipids is chromatographed, and the lipid classes resolved are then determined by gas chromatography
of their constituent fatty acids with added internal standard. The patterns of the constituent fatty acids of the individual
lipid classes are obtained simultaneously.
A novel method for measuring the antioxidant activity using N,N-dimethyl-p-phenylenediamine (DMPD) was developed. The radical cation of this compound gives a stable colored solution and a linear inhibition of color formation can be observed in the presence of 0.2−11 μg of TROLOX. The experimental protocol, which is rapid and inexpensive, ensures sensitivity and reproducibility in the measure of antioxidant activity of hydrophilic compounds. The effectiveness of the DMPD method on real foods was verified by evaluating the antioxidant ability of wine samples coming from different areas of Campania, Italy. Antioxidant capacity of wines is strictly related to the amount of phenolic compounds. The results obtained by the DMPD method are very similar to those obtained on the same samples when the radical cation of 2,2‘-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) (Miller et al., 1996) was used. Keywords: Antioxidant activity; DMPD; radical cation; ABTS; wine
The effects of chlorophyll and pheophytin on the autoxidation of oils in the dark were investigated by oven tests. The results
indicated that both chlorophyll and pheophytin show antioxidant activity when methyl linoleate is used as substrate. Furthermore,
chlorophyll retarded the oxidative deterioration of triglycerides in rapeseed and soybean oils at 30 C. Among the four chlorophyll
derivatives (chlorophylls a and b and pheophytins a and b), chlorophyll a showed the strongest antioxidant activity. The antioxidant
effects of chlorophyll and pheophytin depended on the storage temperature and the kinds of oil used as substrate.
Adsorption chromatography on thin layers of silicic acid or alumina provides a new and highly efficient analytical tool for
the rapid separation of lipids according to classes of compounds.
The oxidative stability and minor constituents of three cold-pressed low erucic acid rapeseed oils and three virgin olive oils were compared. The rapeseed oils were more easily oxidized, in part due to their higher contents of polyunsaturated fatty acids. The rapeseed oils were rich in %-tocopherol and had low initial peroxide values (PVs), but their hydrophilic phenol content was low, only 3-4 ppm. Olive oils contained !-tocopherol and 40-100 times more hydrophilic phenols compared to the rapeseed oils. The initial PVs of fresh olive oils were much higher than those of rapeseed oils. Lutein and #-carotene were present in all oils but chlorophylls (pheophytin a) only in the olive oils. The phenolic extract from the olive oils protected both bulk and emulsified methyl linoleate (MeLo) from oxidation at the 100 ppm level. The extracts obtained from the rapeseed oils had either moderate or no antioxidative effect in MeLo. Testing of the extracts for their 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity yielded similar results. We conclude that phenolic compounds contribute significantly to the oxidative stability of cold-pressed oils.
The antioxidant effects of hydrophilic phenols and tocopherols on the oxidative stability in virgin olive oils and in purified
olive oil have been evaluated. Total hydrophilic phenols and the oleosidic forms of 3,4-dihydroxyphenolethanol (3,4-DHPEA)
were correlated (r=0.97) with the oxidative stability of virgin olive oil. On the contrary, tocopherols showed low correlation (r=0.05). Purified olive oil with the dialdehydic form of elenolic acid linked to 3,4-DHPEA, an isomer of oleuropeine aglycon,
and 3,4-DHPEA had good oxidative stability. A synergistic effect was observed in the mixture of 3,4-DHPEA and its oleosidic
forms with α-tocopherol in purified olive oil by the Rancimat method at 120°C.
Polyphenols were extracted from the rape of Israeli olive oil using hexane, acetone and ethanol in a simple sequential procedure
yielding three fractions (A,B,C). Fraction A (extracted with hexane) contained few polyphenols (0.05%), while Fraction B (extracted
with acetone) and Fraction C (extracted with ethanol) contained about 5% polyphenols each. Fractions B and C were also found
to contain the highest ortho-di-phenol concentration (about 3%). The addition of purified Fraction B at a level of 100 ppm
to refined olive or soybean oils partially inhibited the oxidative deterioration when the oils were stored in the dark at
100 C.
The impact of the environment on human physiology and pathology has been recognized for decades. In this respect, the diet certainly plays a major role, as indicated by the wellknown observation that the incidence of certain diseases is quite different in geographical areas where populations have traditionally been exposed to somewhat unique diets. "Niches" characterized by distinct dietary conditions maintained throughout the centuries can be recognized throughout the world, such as those of populations in the Far East, or living on sea coasts, where fish is a major component of the diet, and those in the Mediterranean area. In the Mediterranean basin, several components of the diet are derived from plants and fruits and, among them, olives and grapes have been, at least originally, rather unique to this area. Due to the particular climate, plants in the Mediterranean basin are subjected to prolonged exposure to sunlight. Thus, many fruits, including olives and grapes, have developed an array of protective compounds that limit the effects of ultraviolet light and the subsequent oxidative damage. Accordingly, the levels; dependent upon the rates of synthesis, of anthocyanins, flavonoids, and phenols in dark-colored fruits are enhanced by sunlight. Wine and olive oil, which originate from the Mediterranean area, are obtained by pressure techniques from ripe fruits; the compounds, responsible for the organoleptic and other properties of the fruits are thus transferred to the fluids. The observation of a lower incidence of coronary heart disease (CHD) (1,2) and of certain types of cancers (3,4) in the Mediterranean area lead to the hypothesis that a diet rich in grain, legumes, fresh fruits and vegetables, wine in moderate amounts, and olive oil had beneficial effects on human health. To date, this effect has been mainly attributed to the low saturated-fat intake of the Mediterranean diet and to its high monounsaturates proportion, which indeed may favorably affect the plasma lipid/lipoprotein profiles. Nevertheless, other components of the diet, such as fiber, vitamins, flavonoids and phe
Fifty-one virgin olive oils of good quality, extracted with a laboratory mill in the same operative conditions from different unripe Italian, Greek and Spanish cultivars, were submitted to sensory evaluation, and to the determination of both polyphenols and the composition of volatile compounds produced through lipoxygenase (LOX) pathways. Univariate analysis was applied to the mentioned variables and some correlations were observed among them. Moreover, a Linear Regression Analysis (LRA) was carried out assuming, as dependent variable, each sensory attribute perceived by tasters and, as independent variables, all compounds derived, derived LOX pathways and polyphenols. The results obtained demonstrate the essential role played by hexanal in the formation of most attributes considered. The most relevant contributors among C6 compounds from linolenic acid were trans-2-hexenal, trans-2-hexen-1-ol and cis-3-hexenyl acetate. Polyphenols contributed to the characterization of walnut husk, bitter and pungent characters, whereas C5 compounds, especially 1-penten-3-one, strongly affected most attributes.
Phenolics antioxidant phytochemicals have been recently implicated for the lower rates of cardiac disease mortality among people consuming a Mediterranean diet. Essential oils are natural products extracted from vegetable materials, which can be used as antibacterial, antifungal, antioxidants, and anti-carcinogenic agents or to preserve and give specific flavors to foods. The activities of 23 selected essential oils in inhibiting the copper-catalyzed oxidation of human-low-density lipoproteins (LDL) were determined in vitro. LDL oxidation was inhibited between 6, 2, and 83% by 2 microM (GAE) total phenolics. The relative inhibition of LDL oxidation was used to categorize the essential oils into four groups below 2% when they contained methylchavicol, anethol, p-cymen, apiole, cinnamic ether; 6-10% if they possessed a majority of carvacrol, thymol, p-cymene, or vanillin; 10-50% for moderate amounts of thymol, carvacrol, cuminol, or eugenol; and 50-100% when eugenol is the major component. Total phenol content of essential oils gave a correlation with LDL antioxidant activity of r = 0.75. The Activity of each phenolics compound could play a role in protecting LDL against oxidation if the substance is absorbed by the body.
To determine the types and proportions of vegetable oils to recommend for a healthy diet.
Optimal vegetable oil combinations were designed, using linear programming and, as decision variables, nine single oils and 29 basic food items. 'Oil models' were run to determine whether reasonable amounts of individuals oils or oil mixtures satisfied a set of constraints on essential fatty acids and vitamin E. 'Meal models' were run to test whether selected mixtures could be used as the sole source of added fat in a meal that met micronutrient and macronutrient recommendations.
The cheapest mixture (0.97 euro L(-1)) that solved the oil models contained 81% rapeseed and 19% sunflower oils. About 10-15 g of this mixture, alone or with olive, soya bean, wheat germ or walnut oils, also solved the meal models. Mixtures that contained a high proportion (>or=50%) of the tasty olive and walnut oils also solved the models but were more expensive (4.9 euro L(-1) and 8.5 euro L(-1), respectively).
The consumption of a mixture composed of rapeseed and sunflower oils in a 4 : 1 proportion is an inexpensive and simple way to meet current dietary recommendations for essential fatty acids and vitamin E, favouring overall dietary nutrient adequacy.
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