Ramón Aparicio

Authentication of vegetable oils by chromatographic techniques

Food authentication has been evolving continually to situations that were basically governed by a global market trend. Analytical techniques have been developed or modified to give plausible solutions to the devious adulterations at each moment. Classical tests have largely been replaced with newer technical procedures, most of which are based on gas chromatography, with some being based on high-performance liquid chromatography. Determination of trans-fatty acid and sterolic composition, together with sterol-dehydration products, have been used most frequently used to detect contamination and adulteration. Sophisticated new adulterations, e.g., olive oil with hazelnut oil, represent a new challenge for the next millennium, although suggestive proposals for detecting these kinds of adulterations are emerging with the contribution of databases and mathematical algorithms.

Characterisation of monovarietal virgin olive oils

This review analyses, how pedoclimatic aspects together with olive ripeness, harvest of olives, and the olive extraction system determine the chemical composition and sensory descriptors which assess the quality of virgin olive oils. Thus for monovarietal virgin olive oil, sensory descriptors evaluated by different European panels, volatile compounds produced through the lipoxygenase pathway, and series of compounds from unsaponifiable matter have been quantified.

Oil and Fat Classification by Selected Bands of Near-Infrared Spectroscopy

One hundred and four edible oil and fat samples from 18 different sources, either vegetable (Brazil nut, coconut, corn, sunflower, walnut, virgin olive, peanut, palm, canola, soybean, sunflower) or animal (tallow and hydrogenated fish), have been analyzed by high-performance gas chromatography (HPGC) and near-infrared spectroscopy (NIRS). Fatty acids were quantified by HPGC. The near-infrared spectral features of the most noteworthy bands were studied and discussed to design a filter-type NIR instrument. An arborescent structure, based on stepwise linear discriminant analysis (SLDA), was built to classify the samples according to their sources. Seven discriminant functions permitted a successive discrimination of saturated fats, corn, soybean, sunflower, canola, peanut, high oleic sunflower, and virgin olive oils. The discriminant functions were based on the absorbance values, between three and five, from the 1700–1800 and 2100–2400 nm regions. Chemical explanations are given in support of the selected wavelengths. The arborescent structure was then checked with a test set, and 90% of the samples were correctly classified.

Relationship between volatile compounds and sensory attributes of olive oils by the sensory wheel

Sixty-five volatile compounds and 103 sensory attributes were evaluated in 32 virgin olive oil samples from three different Mediterranean countries. Volatile compounds were analyzed with a dynamic headspace gas-chromatographic technique by using a thermal desorption cold-trap injector. The sensory analysis was conducted by six panels composed of assessors from the United Kingdom, Spain, the Netherlands, Greece and Italy. Principal-components analysis of sensory attributes was used to construct a statistical sensory wheel that represents the whole virgin olive oil flavor matrix. This wheel is composed of seven sectors that show the basic perceptions produced by the oil: green, bitter-pungent, undesirable, ripe olives, ripe fruit, fruity and sweet. The boundaries of each sector were calculated from the circular standard deviation of its sensory attributes. The relationship between sensory and instrumental analysis was determined by projecting volatiles onto the sensory wheel. Correlations of each volatile with the first two components of the principal-components analysis were taken as its coordinates (x, y) in the sensory wheel. Volatiles took up the most appropriate place within the sector that corresponded with their perception, and often close to the sensory attributes that explained their sensory properties. A gas-chromatographic/sniffing method was applied to virgin olive oil samples to assess the aroma notes that corresponded to olive oil volatile compounds and to verify the relationships found by the sensory wheel procedure. Most (89%) of the volatiles were well classified. Use of the statistical sensory wheel as an appropriate method to relate volatile and sensory data was clearly demonstrated.

Dynamic headspace gas chromatographic method for determining volatiles in virgin olive oil

Abstract Dynamic headspace sampling methods prior to capillary gas chromatography are especially suitable in the determination of volatile compounds at a wide range of concentrations, and numerous methods have been developed and applied to very different kinds of samples. In this work, a simple and rapid dynamic headspace technique was developed to determine volatiles present in virgin olive oil samples. Headspace components were swept from 0.5 g of sample at low temperature (40°C) and concentrated on Tenax TA, thermally desorbed and subsequently trapped in a fused-silica cold trap previously cooled to −110°C. They then passed to the capillary column. This system was connected to a mass spectrometer to identify the most important compounds and a comparative study of the main volatiles identified in virgin olive oil samples using other methods was carried out. Sniffing of the components eluted from the chromatographic column was also performed. Different virgin olive oil samples showing different chromatographic profiles were analysed. The differences were mainly quantitative because most compounds were present in all oils analysed, and only the proportions in which these compounds are present varied. Discriminant analysis of these compounds allowed the origin of each sample to be determined with a probability of greater than 90%.

Handbook of olive oil

Handbook of olive oil : , Handbook of olive oil : , کتابخانه مرکزی دانشگاه علوم پزشکی ایران

Research in Olive Oil: Challenges for the Near Future

Olive oil, a traditional food product with thousands of years of history, is continually evolving toward a more competitive global market. Being one of the most studied foods across different disciplines, olive oil still needs intensive research activity to face some vulnerabilities and challenges. This perspective describes some of them and shows a vision of research on olive oil for the near future, bringing together those aspects that are more relevant for better understanding and protection of this edible oil. To accomplish the most urgent challenges, some possible strategies are outlined, taking advantage of the latest analytical advances, considering six areas: (i) olive growing; (ii) processing, byproduct, and environmental issues; (iii) virgin olive oil sensory quality; (iv) purity, authentication, and traceability; (v) health and nutrition; (vi) consumers. The coming research, besides achieving those challenges, would increase the understanding of some aspects that are still the subject of debate and controversy among scientists focused on olive oil.

Influence of Olive Ripeness on the Concentration of Green Aroma Compounds in Virgin Olive Oil

Changes have been demonstrated in the concentration of those volatile compounds responsible for green sensory notes in virgin olive oils obtained from four different varieties at three stages of ripeness. The information corresponding to each volatile compound for each stage of ripeness, after fuzzy filtering of the quantitative data, has been established and the relationship between volatile compounds and green sensory attributes has also been demonstrated by means of principal components analysis, correlation and stepwise linear regression analysis.

Characterization of French and Spanish dry-cured hams: influence of the volatiles from the muscles and the subcutaneous fat quantified by SPME-GC.

The influence of the volatile compounds on the characterization of Spanish and French dry-cured hams was studied. Thirty volatiles were quantified in each one of four locations (biceps femoris, semimembranosus and semitendinosus muscles and subcutaneous fat) of 29 dry-cured hams by solid-phase microextraction gas-chromatography (SPME-GC). The Brown-Forsythe univariate test allowed determination of the volatiles that individually could characterize (p<0.05) the samples by their geographical origin (France, Spain) and breed type (Iberian, white). Stepwise linear discriminant procedure, under very strict conditions (F-to-Enter for a F-distribution>0.95), then selected the most remarkable volatile compounds. Four compounds from the subcutaneous fat (methyl benzene and octanol) and the semitendinosus muscle (2-butanone and 2-octanone) allowed 100% correct classifications by geographic origin. On the other hand, only two compounds from the subcutaneous fat (octanol) and the biceps femoris muscle (3-methyl 1-butanol) correctly classified all the samples by the breed type. The ability of these variables to classify the samples was checked by the unsupervised procedure of principal components.

1H NMR-based protocol for the detection of adulterations of refined olive oil with refined hazelnut oil.

A (1)H NMR analytical protocol for the detection of refined hazelnut oils in admixtures with refined olive oils is reported according to ISO format. The main purpose of this research activity is to suggest a novel analytical methodology easily usable by operators with a basic knowledge of NMR spectroscopy. The protocol, developed on 92 oil samples of different origins within the European MEDEO project, is based on (1)H NMR measurements combined with a suitable statistical analysis. It was developed using a 600 MHz instrument and was tested by two independent laboratories on 600 MHz spectrometers, allowing detection down to 10% adulteration of olive oils with refined hazelnut oils. Finally, the potential and limitations of the protocol applied on spectrometers operating at different magnetic fields, that is, at the proton frequencies of 500 and 400 MHz, were investigated.