Influence of agroclimatic parameters on phenolic and volatile compounds of Chilean virgin olive oils and characterization based on geographical origin, cultivar and ripening stage.

BACKGROUND: This study involved two commercial orchards located in Limarí Valley and Molina from two important Chilean production zones of extra virgin olive oil (EVOO). The investigation evaluated the effects of climate, soil composition, agricultural practices (fertilization and irrigation) and variety (considering two harvests) on the compounds responsible for the flavor of EVOO (volatiles and phenols) and how these compounds can explain the differences in chemical profiles by geographical origin, cultivar and fruit ripeness stage. RESULTS: Varieties from the Limarí Valley presented the highest content of phenolic compounds. A significant relationship (P < 0.05) between volatile compounds and climate indicated that the compounds produced via the lipoxygenase cascade were affected by the maximum temperature and, to a lesser extent, by evapo-transpiration and irrigation. The selection of different individual phenolic and volatile compounds independently allowed the significant differentiation of EVOOs, principally by geographical origin, crop season, fruit ripeness stage and, in a few cases, by cultivar. CONCLUSION: Soil and climate of the Chilean regions have much more influence than cultivars on the concentration of sensory quality compounds. Difference in latitude between orchards increases the importance of the geographical origin on the virgin olive oil chemical composition while full irrigation decreases the impact of the cultivar.

Volatile and amino acid profiling of dry cured hams from different swine breeds and processing methods.

The flavor of dry cured ham explains the high appreciation of this product and it determines consumer acceptance. Volatile compounds provide valuable information about the odor and sensory quality of dry cured hams. Since amino acids are the origin of some volatile compounds of dry cured ham, the volatile and amino acid compositions of forty-one dry cured hams from Spain and France were determined to establish associations between them. The samples included different pig breeds (non Iberian vs. Iberian), which were additionally affected by different maturation times and feeding types (acorn vs. fodder). Results showed that 20 volatile compounds were able to distinguish Iberian and non Iberian hams, and 16 of those had relevant sensory impact according to their odor activity values. 3-Methylbutanol, 2-heptanol and hexanal were among the most concentrated volatile compounds. In the case of non-volatile compounds, the concentrations of amino acids were generally higher in Iberian hams, and all the amino acids were able to distinguish Iberian from non Iberian hams with the exception of tryptophan and asparagine. A strong correlation of some amino acids with volatile compounds was found in the particular case of alcohols and aldehydes when only Iberian hams were considered. The high correlation values found in some cases proved that proteolysis plays an important role in aroma generation.

Implementing Dynamic Headspace With SPME Sampling of Virgin Olive Oil Volatiles: Optimization, Quality Analytical Study, and Performance Testing.

Competition and interaction phenomena among volatiles during their adsorption process by solid phase microextraction (SPME) fibers in static headspace sampling procedure (SHS) cast doubt on its ability to quantify virgin olive oil volatiles. SPME fibers being excellent traps, their use was analyzed with a new device allowing the concentration of volatiles in a dynamic headspace sampling procedure (DHS). A central composite experimental design optimized the main variables of the device (4 g sample weight, 40 °C temperature, 150 mL/min flow rate, 50 min adsorption time), while values of the analytical quality control parameters of the method (repeatability, limits of detection and quantification, working range, sensitivity, and resolution) were compared with those ones from static headspace. DHS shows better precision results for aldehydes and alcohols than SHS and allowed analyzing higher concentrations with no problem of saturation. In 19 of 28 compounds analyzed in 50 samples the chromatographic areas were higher when running DHS. The concentration values of volatile compounds in these samples after applying SHS and DHS are discussed together with the ability of the new method for distinguishing virgin olive oil by their categories (extra virgin, virgin, and lampante) by the volatiles quantified in commercial oils.

PhotooxidationEffect in Liquid Lipid Matrices: Answers from an Innovative FTIR Spectroscopy Strategy with "Mesh Cell" Incubation.

Developing new approaches to evaluate the stability of edible oils under moderate conditions is highly demanded today to avoid accelerated experiments that are not well correlated with actual shelf life. In particular, low intensity of visible light (photooxidation) needs to be integrated in stability studies, together with mild temperature. Thus, in this work, a strategy based on a "mesh cell"-FTIR to monitor chemical changes in lipid matrices using a combination of light and mild heating was applied. The results were compared with those obtained for the stability of triolein used as a molecular model. The study showed that the moderate light intensity (400 lx) at a low temperature (23 °C) has an early effect on the degradation of lipid matrices that is not observed when they are stored at 35 °C in the absence of light. Thus, the results proved that the exposure to light (400 lx) was more relevant than mild heating (35 °C) in monounsaturated lipid matrices, while polyunsaturated lipid matrices were more sensitive to mild heating.

Validation of a method based on triglycerides for the detection of low percentages of hazelnut oil in olive oil by column liquid chromatography.

The difference between theoretical and empirical triglyceride content is a powerful tool to detect the presence of any vegetable oil in olive oil. The current drawback of the method is the separation between equivalent carbon number ECN42 compounds, which affects the reliability of the method and, hence, its cutoff limit. The determination of the triglyceride profile by liquid chromatography using propionitrile as the mobile phase has recently been proposed to improve their quantification, together with a mathematical algorithm whose binary response determines the presence or absence of hazelnut oil. Twenty-one laboratories from 9 countries participated in an interlaboratory study to evaluate the performance characteristics of the whole analytical method. Participants analyzed 12 samples in duplicate, split into 3 intercomparison studies. Statistically significant differences due to the experimental conditions were found in some laboratories, which were detected as outliers by use of Cochran's and Grubbs' tests. The relative standard deviations (RSD) for repeatability and reproducibility were determined following the AOAC Guidelines for Collaborative Studies. The analytical properties of the method were determined by means of the sensitivity (0.86), selectivity (0.94), and reliability (72%) for a cutoff limit of 8% (probability 94%).

Virgin olive oil stability study by mesh cell-FTIR spectroscopy.

Mesh cell is a rapid tool designed to monitor chemical changes that occurs as a consequence of oxidation at moderate conditions. In this study this accessory has been proposed for assessing virgin olive oil (VOO) stability by Fourier transform infrared (FTIR) spectroscopy. Monocultivar VOOs have been stored in mesh cells under different temperatures (at 23, 35, 65°C) simulating the real conditions during storage and transport (<60°C). In addition to temperature, the samples have been also stored in mesh cells at different light intensities (400, 1000, 7000lx) to evaluate the resistance of the samples to photooxidation. The oil stability of the samples determined by using this accessory has been compared with the oil stability determined with the common methods used for this purpose (e.g. Rancimat). Despite the moderate conditions applied, mesh cell-FTIR spectra have revealed the formation of hydroperoxides and the subsequent formation of alcohols and aldehydes. Unlike other methods that require high temperature to accelerate the oxidation rate, mesh cell-FTIR has allowed differentiate the oil stability of the samples from a multi-factor perspective that includes several properties (temperature and light) and chemical species (primary and secondary oxidation products). The information obtained with this method can be relevant for optimizing handling (e.g. packaging and storage temperature) of VOO samples during their shelf life.

Soft-deodorization of virgin olive oil: Study of the changes of quality and chemical composition.

The potential adulteration of extra virgin olive oil (EVOO) with soft-deodorized virgin olive oil (VOO) has raised the interest of researchers in investigating this fraud in recent years. The objective of this study was to determine chemical changes occurring after a soft-deodorization process in terms of volatiles, fatty acid ethyl esters (FAEEs) and pyropheophytins (PPPs) concentrations in VOOs. After testing several conditions (80, 100 and 130°C, for 30 and 60min), the parameters of 100°C and 60min were considered as the optima. These conditions allowed removing volatiles responsible for sensory defects with low losses of total phenols (14%-32%), and values of PPPs (11.83%) and FAEEs (34.53mg/kg) lower than the limits of standard regulations. The experiments show that soft-deodorized VOOs could be added up to 50% to EVOOs and current standard methods would not detect this kind of adulteration.

Volatile compound biosynthesis by green leaves from an Arabidopsis thaliana hydroperoxide lyase knockout mutant.

The degradation of polyunsaturated fatty acids through the lipoxygenase pathway is responsible for the production of volatile compounds that confer green sensory notes to the aroma of fruits and vegetables. The peroxidation of free linoleic or linolenic acid by action of lipoxygenase and then the lysis of the resulting hydroperoxides, through a reaction catalyzed by the hydroperoxide lyase, are the most determinant steps of this pathway. This work analyzes the impact of the hydroperoxide lyase depletion on the volatile composition of leaves from Arabidopsis thaliana that is used as model system. The work involves the characterization of the volatile profiles of the Arabidopsis plants followed by a study of the metabolism of radio-labeled linoleic acid and determinations of lipoxygenase activity. Hydroperoxide lyase-knockout plants show similar levels of C6 compounds, but the total amount of C5 compounds is 4-fold higher in mutant plants. The perspectives of production of vegetable products with a modified aroma by genetically engineering the lipoxygenase pathway were discussed with respect to the statistical results.

Interlaboratory evaluation of dry-cured hams (from France and Spain) by assessors from two different nationalities.

Two panels of assessors from France and Spain assessed 41 dry-cured hams from diverse geographical origins, pig breedings and feedings. Univariate (Kolmogorov-Smirnov test and t-test) and multivariate (canonical correlation and principal component analysis) statistical procedures have been used to explain the agreement and disagreement between panels evaluating similar and dissimilar sensory attributes quantified with a 9-points structure scale. The results pointed out that there were basic agreements between panels, although some disagreements were detected in mould, acorn and crust attributes. The classification of Iberian and white dry-cured hams and the sensory attributes that characterise them are also displayed.

Characterization of Virgin Olive Oils with Two Kinds of 'Frostbitten Olives' Sensory Defect.

The frost of olives on the tree due to drops of temperature can produce sensory defects in virgin olive oil (VOO). Temperature changes can be abrupt with freeze-thaw cycles or gradual, and they produce sensory and chemical variations in the oil. This study has analyzed the quality parameters (free fatty acids, peroxide value, UV absorption, and fatty acid ethyl esters) and phenols of VOOs described with the 'frostbitten olives' sensory defect. The phenol profiles allowed grouping these VOOs into two types. One of them, characterized with "soapy" and "strawberry-like" aroma descriptors, had higher values of 1-acetoxypinoresinol, pinoresinol, and aldehydic form of the ligstroside aglycon. The other one, characterized with "wood" and "humidity" descriptors, had higher concentrations of luteolin and apigenin. Most VOOs (75%) from the first group, associated with abrupt drops of temperature, have concentration of phenols higher than the value established by the health claim on olive oil polyphenols approved by the European Commission.

Impact of the suppression of lipoxygenase and hydroperoxide lyase on the quality of the green odor in green leaves.

Most of the volatile compounds responsible for the "green" notes to the aroma of fruits and vegetables are produced by the degradation of polyunsaturated fatty acids through the lipoxygenase pathway. The most determinant steps of this pathway are the peroxidation of free linoleic or linolenic acid by the action of lipoxygenase and then the lysis of the resulting hydroperoxides through a reaction catalyzed by the hydroperoxide lyase. This work analyzes the impact of the depletion of these enzymes on the volatile composition of leaves from potato plants. A characterization of the volatile profiles of the different potato mutants, a study of the metabolism of radiolabeled linoleic acid, and a determination of lipoxygenase activity have been carried out. The depletion of hydroperoxide lyase induced an increase in the lipoxygenase activity and the content of C5 volatiles, whereas the lipoxygenase silencing caused a severe decrease in the amount of volatiles produced by the leaves and always in the intensity of their aroma. The changes in the sensory evaluation of leaf aroma, as correlated to depletion of the two enzymes, have been investigated. The perspectives of producing vegetable products with a modified aroma by genetic engineering are discussed in light of the statistical results.

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.

Geographical traceability of virgin olive oils from south-western Spain by their multi-elemental composition.

The geographical traceability of virgin olive oil can be controlled by chemical species that are linked to the production area. Trace elements are among these species. The hypothesis is that the transfer of elements from the soil to the oil is subjected to minor variations and therefore this chemical information can be used for geographical traceability. In order to confirm this hypothesis, the trace elements of virgin olive oils from south-western Spain were analysed, and the same elements were determined in the corresponding olive-pomaces and soils. The differences in the concentration were studied according to cultivars and locations. Results show some coincidences in the selection of elements in soils (W, Fe, Na), olive-pomace (W, Fe, Na, Mg, Mn, Ca, Ba, Li) and olive oils (W, Fe, Mg, Mn, Ca, Ba, Li, Bi), which supports their utility in traceability. In the case of olive oils, 93% of the samples were correctly classified in their geographical origins (96% for Beas, 77% for Gibraleón, 91% for Niebla, and 100% for Sanlúcar de Guadiana).

In-depth assessment of analytical methods for olive oil purity, safety, and quality characterization.

This paper evaluates the performance of the current analytical methods (standard and widely used otherwise) that are used in olive oil for determining fatty acids, triacylglycerols, mono- and diacylglycerols, waxes, sterols, alkyl esters, erythrodiol and uvaol, tocopherols, pigments, volatiles, and phenols. Other indices that are commonly used, such as free acidity and peroxide value, are also discussed in relation to their actual utility in assessing quality and safety and their possible alternatives. The methods have been grouped on the basis of their applications: (i) purity and authenticity; (ii) sensory quality control; and (iii) unifying methods for different applications. The speed of the analysis, advantages and disadvantages, and multiple quality parameters are assessed. Sample pretreatment, physicochemical and data analysis, and evaluation of the results have been taken into consideration. Solutions based on new chromatographic methods or spectroscopic analysis and their analytical characteristics are also presented.

Subjective annoyance caused by environmental noise.

We developed an acoustic study implemented throughout a neighborhood of Valencia (Spain). Acoustic recordings were made during the months of November and December 1989, on workdays between 9 a.m. and 1 p.m., and between 5 p.m. and 8 p.m. We also directly interviewed individuals living in this city area to determine their perception of noise and to evaluate the discomfort caused by it in daily life. A personal interview in the form of a questionnaire was employed to poll the neighborhood inhabitants on the magnitude of environmental noise and the distress it caused. The results showed that 40% of those interviewed considered environmental noise to cause considerable distress. On a 1 to 10 scale, over half of those interviewed rated noise in the neighborhood of 5 or higher. Traffic was considered the major source of noise, followed by noise from neighbors and factories. Of those interviewed, 9% changed the location of their bedroom as a result of noise, whereas 11% were forced to sleep with the windows closed for the same reason.

Acute mountain sickness: Is there a lag period before symptoms?

The present study was designed to determine if symptoms of acute mountain sickness are presented within six hours after arrival at high altitude. Seventeen male subjects, 23-30 years, were studied. The subjects were professional soccer players, life-long residents at low altitudes except one player who was playing soccer in a team at 3400 m (512 mm Hg of Barometric Pressure) during an entire year in 1995. The players were transported by a commercial airline from Lima (150 m) to Cusco (3400 m). The trip lasted 1 hour. Heart rate and arterial oxygen saturation were measured at rest in Lima (150 m), at the time of arrival at Cusco, and at 4 and 6 hours after arrival at 3400 m. On day 6 at high altitude, the physical performance during a soccer game was assessed. The symptoms of acute mountain sickness (AMS) were assessed 6 hours after arrival at Cusco with a self-administered questionnaire, and thereafter each 24-hours up to 5 days of exposure to high altitude. The following symptoms were assessed: headache, gastrointestinal symptoms, dizziness, fatigue, and sleep abnormalities. AMS was defined by a Lake-Louise score ⩾4 (self-assessment only). Thirty five percent of the soccer players developed AMS within 6 hours after arrival by air at 3400 m altitude. Arterial oxygen saturation at arrival was higher in those player who developed AMS within 6 hours after arrival (94.3 ± 0.94% vs 90.8 ± 2.36; P < 0.001). From arrival to 6 hours of exposure to altitude, there was a significant fall in arterial oxygen saturation in those men who developed AMS than in those who did not. Results from the stepwise multiple regression (R2 = 0.59; P < 0.04) and logistic regression (R2 = 0.48; P < 0.0019) analyses showed that the difference between arterial oxygen saturation at sea level and at arrival at Cusco was a predictor for the development of AMS within 6 hours upon arrival at altitude. This suggests that the lower the difference between arterial oxygen saturation at sea level and at arrival, the higher the probability to develop AMS within 6 hours after arrival at 3400 m. The presentation of AMS, however, does not predict low performance in physical activity at high altitude. Am. J. Hum. Biol. 10:669-677, 1998. © 1998 Wiley-Liss, Inc.

Virgin olive oil quality classification combining neural network and MOS sensors.

A model based on neural networks has been designed to detect lampante virgin olive oils, a category of olive oil that cannot be consumed without a previous refining process according to the current regulation of the European Communities. The response of 7 metal oxide sensors analyzing 114 olive oil samples has been used in the design, training, and internal validation of the neural network with only 4.5% error in validation. The designed mathematical model, the equations of which are fully described, has been validated also with an external set of 13 samples of diverse varieties and geographical origins with 100% correct classification.

Detection of vinegary defect in virgin olive oils by metal oxide sensors.

An array of metal oxide sensors has been set up for detecting the vinegary defect in virgin olive oil. The optimization process was carried out evaluating the variables affecting the process by three desirability functions. Repeatability studies for 6 months and within day were done to evaluate the sensor responses and remove those with high relative standard deviation. The sensor responses were preprocessed applying five weight functions previously to build a regression model. Samples of Spanish Arbequina and Picual virgin olive oil varieties spiked with different amounts of acetic acid (15-200 mg/L) were used as a training set for the regression model. The test set was composed of samples of Italian Coratina virgin olive oil spiked with the vinegary standard at five percentages (10, 25, 40, 50, and 75). A fine-adjusted regression coefficient (R(adj)(2) = 0.98) was computed with the test set.

Analysis of virgin olive oil volatiles by a novel electronic nose based on a miniaturized SAW sensor array coupled with SPME enhanced headspace enrichment.

A novel electronic nose based on solid-phase microextraction (SPME) coupled with a surface acoustic wave (SAW) sensor array has been used to analyze different quality virgin olive oils. A mathematical model was designed with 37 samples to distinguish lampante from the other virgin olive oils categories (extra-virgin and virgin), because lampante-virgin olive oils cannot be consumed without a previous refining process. The model, successfully validated with a test set of 16 samples, was able to classify 90% of the samples correctly. Misclassifications were explained by SPME-HRGC analyses and a second sensory evaluation.

Does "best before" date embody extra-virgin olive oil freshness?

Virgin olive oil (VOO) decays in quality properties during aging, so aged VOOs may have detectable undesirable sensory descriptors in comparison with oils recently extracted. For that reason, freshness has become a parameter of paramount importance to maintain the highest standard levels within the period indicated in the "best before" date. However, it is important to note that freshness of VOOs is not necessarily related to its sensory quality. Pigments have been suggested for tracing aging of VOO, and pyropheophytin a (PPP) seems to be the most promising molecule for this task. A predictive model has been used to estimate %PPP in VOO stored at different worldwide locations characterized with different temperatures. The recorded average temperatures, on a monthly basis, were inputs of the predictive model. The results show the influence of temperature in %PPP and how this molecule could serve as a better monitor of the storage period of VOOs. The initial value of %PPP in the oil could help to carry out the storage traceability. This information would be of interest for producers, sellers, and inspection agencies.