Characterization Of Virgin Olive Oils Research Articles

Análisis mediante HPLC de la fracción fenólica del aceite de oliva virgen de la variedad Arbequina. Relación con la medida del amargor K225 y la estabilidad

Phenolic compounds have a high importance because of their effect on shelf life and sensorial characteristics of virgin olive oil. In this paper, the phenolic fraction of Arbequina virgin olive oils has been characterized by HPLC. Bitterness index K225, total phenols and autoxidation stability have been evaluated for olive oil samples. From the phenolic compounds separated using HPLC method, one of then (tr: 34,49 min) was close correlated both with bitterness K225 and oil stability Rancimat at 98oC. The regression coefficients, with high significance p<0,001, were r: 0.974 and r: 0.918 respectively. Phenolic compound responsible of bitterness K225 and oil stability has been found for the Arbequina virgin olive oils.

Estudio de la calidad del aceite de oliva virgen de la Denominación de Origen «Les Garrigues» (Lleida) durante la campaña 1995/96

The Garrigues territorial quality label (Les Garrigues D.O.) is located in the southern part of Lleida (Catalonian. Spain). The most oil produced in this D.O. corresponds to extra virgin classification and it has a distinctive sensorial quality, as a consecuence of olive cultivar («Arbequina» cv) and the careful elaboration of oil. The new cultural technologies applied to the olive tree cultivar and.the new technologies of olive oil extraction have made necessary the study of oil composition and quality during consecutive harvests, to know if the quality could be afected. The objective of this work is the characterization of virgin olive oils (67 samples from 13 olive mills) during the 1995/96 harvest. Analytical controls show that the mean acidity index is 0.17% in oleic acid, the mean peroxide value is 6.9 meq oxygene active/kg of oil and the mean K 270 of 0.21; these quality parameters fulfill the policy values of «Les Garrigues» D.O. The mean polyphenol content is 152 ppm expressed as cafeic acid, with a great variability among olive mills. As harvesting time progresses, the concentration of pigments in olive oil decreases. The concentration of chlorophyl and that of carotenoid pigments at the begin of the harvest is 15 and 12.6 mg/kg of oil respectively and at the end of the period they are 6 and 4.6 mg/kg of oil respectively. The oil color, expressed as visual ABT index and the chromatic ordinates CIELAB, lies within the yellow zone and does not vary along the harvest season.

Sensory profiling: a method for describing the sensory characteristics of virgin olive oil

Sensory profiling is an objective, descriptive technique which uses a panel of trained assessors. It was used at Campden to differentiate olive oil which differed in terms of the country of origin, variety, ripeness and extraction techniques. The data were related to similar results from the Netherlands and Italy. The results indicated that all three sensory panels perceived the samples in the same way, however, the differed in the way the oils were described. The new European legislation on olive oil is partially concerned with the sensory aspects of the oil. The sensory grading takes into account the 'positive' and 'negative' attributes in the oil before giving an overall quality grade. These attributes do not reflect the consumer requirements, therefore, the grading should be restricted to the assessment of the presence or absence of sensory defects.

Simple and hydrolyzable phenolic compounds in virgin olive oil. 1. Their extraction, separation, and quantitative and semiquantitative evaluation by HPLC

Phenolic compounds have a fundamental importance in the nutritional and sensory characteristics of virgin olive oil. Problems regarding their qualitative and quantitative evaluation have not been completely solved; hence, in this paper the extractive and HPLC methods of analysis are examined and some modifications are presented. By means of these techniques, elenolic acid and four unknown compounds having phenolic behavior were separated from virgin olive oil. Four of them were correlated with total phenols evaluated by means of the Folin-Ciocalteu reagent, and two of them were correlated with olive oil autoxidation stability

Caracterización de alimentos combinando reglas de decisión relaciónales y lineales. Una aplicación al aceite de oliva virgen de Málaga

The chemical compounds of a food, quantified by GC, can be used to build relational and lineal decision rules, which merged by mathematical algorithms, could allow its characterization. The paper describes the methods applied to design and evaluate those rules, which are kept in the knowledge base of a deductive expert system, and the procedure applied to know the similarity between an unidentified sample and the food defined by the rules. The characterization of virgin olive oil of Malaga province has been used to explain the methodology. Thus, 54 chemical compounds belonging to five different series, fatty acids, methylsterols, sterols, aliphatic and triterpernic alcohols, and aliphatic and terpenic hydrocarbons, besides a group composed by a hydroxi-aldehid-triterpenic, phytol, and erytrodiol, were identified and quantified in each of the 172 samples collected over Andalusia. Their chromatograms, which were redrawn by computers, allowed to build seventeen rules among lineal and relational ones. These relational rules (10) show linguistic interrelations, such less, great, equal, etc., among two or more chemical compounds of the same or different series. On the other hand, statistical programs of discriminant analysis allowed to get the lineal rules (7) whose coefficients were taken from each one of the series, plus a rule where they were reached in the whole set of chemical compounds. Finally, twenty-six samples collected in different zones, provinces or countries, or in the same area but from different crops, were used to measure the performance of the methodology.

Authentication of virgin olive oils using principal component analysis of triglyceride and fatty acid profiles: Part 2—Detection of adulteration with other vegetable oils

Principal Component Analysis of triglyceride and fatty acid profiles has been reported as a method for the characterisation of virgin olive oils, and this approach is now extended to study adulteration of the same oils. The effect of incorporating 10 or 20% w/w of maize, cottonseed, sunflower, soyabean or rapeseed oil in olive oil on both the triglyceride and fatty acid compositions is studied. At the 20% level of incorporation PCA was able to show clearly the presence of a foreign oil, the distinction being less marked at the 10% level. The triglyceride profiles proved to be more discriminating than those of the fatty acids.