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.
The evolution of the fluorescent compounds during the thermal deterioration of virgin olive oil is not yet well-known. Samples of heated virgin olive oils collected from a fryer every 2 h up to 94 h ...were analyzed to study their fluorescence spectra as well as the evolution of the concentrations of α-tocopherol and individual phenols by high-performance liquid chromatography (HPLC). The regions of the fluorescence spectra of the heated oils, diluted in hexane at 1%, were explained by the content of these compounds with regression coefficients higher than 0.90 (R 2 adjusted). The fluorescence intensity recorded at 350 nm and the wavelength of the spectrum maximum in the range of 390−630 nm also allowed for the explanation of the increase of the percentage of polar compounds during the experiment. On the other hand, the spectra of the undiluted heated oils indicated that the maximum of the spectrum of any undiluted oil at 490 nm or beyond is related to a percentage of the polar compounds higher than 25%, which is the maximum percentage accepted for edible oils used in frying processes.
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.
•A comprehensive methodology to characterize Spanish PDO wine vinegars is proposed.•Multidimensional fluorescence spectroscopy and chemometrics are used.•PARAFAC was applied to chemically ...characterize the different wine vinegars.•SVM models were able to differentiate the Spanish PDOs and wine vinegar categories.
This work assesses the potential of multidimensional fluorescence spectroscopy combined with chemometrics for characterization and authentication of Spanish Protected Designation of Origin (PDO) wine vinegars. Seventy-nine vinegars of different categories (aged and sweet) belonging to the Spanish PDOs “Vinagre de Jerez”, “Vinagre de Montilla-Moriles” and “Vinagre de Condado de Huelva”, were analyzed by excitation-emission fluorescence spectroscopy. A visual assessment of fluorescence landscapes pointed out different trends with vinegar categories. PARAllel FACtor analysis (PARAFAC) extracted the potential fluorophores and their values in the PDO vinegars. This information, coupled with different classification methods (Partial Least Square Discrimination Analysis “PLS-DA” and Support Vectors Machines “SVM”), was able to discriminate the wine vinegar category within each PDO, for which SVM models obtained better results (>92% of classification). In each category, SVM also allows the differentiation between PDOs. The proposed methodology could be used as an analysis method for the authentication of Spanish PDO wine vinegars.
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.
The oil overlay micro-drop system is widely used for cultures of mammalian gametes and embryos. We evaluated hereby the effects of two unaltered commercial oils- Sigma mineral oil (S-MO) and Nidoil ...paraffin oil (N-PO)-on in vitro embryo production (IVP) outcomes using a pig model. The results showed that while either oil apparently did not affect oocyte maturation and fertilization rates, S-MO negatively affected embryo cleavage rates, blastocyst formation rates, and, consequently, total blastocyst efficiency of the system. No differences in the oxidation state were found between the oils or culture media incubated under S-MO or N-PO. Although both oils slightly differed in elemental composition, there were no differences in the concentrations of elements between fresh media and media incubated under oils. By contrast, we demonstrated clear oil-type differences in both the composition of volatile organic compounds (VOC) and the transfer of some of these VOC´s (straight-chain alkanes and pentanal and 1,3-diethyl benzene) to the culture medium, which could have influenced embryonic development.
•2H/1H, 13C/12C, 18O/16O of bulk was combined with 13C/12C and 2H/1H of fatty acids.•Isotopic composition was used to distinguish EU and non EU extra virgin olive oils.•Application of Random Forest ...classification and model performance were evaluated.
European law requires a designation of origin for virgin and extra virgin olive oils (at least in terms of EU/non-EU provenance). Stable isotope ratios have been successfully applied to determine the geographical origin of olive oils, but never to distinguish EU and non-EU oils. In this study 2H/1H, 13C/12C and 18O/16O ratios were analysed in bulk olive oils using Isotope Ratio Mass Spectrometry (IRMS) as well as 13C/12C and 2H/1H in the four main fatty acids (linoleic, oleic, palmitic and stearic acids) using IRMS coupled with GC. The isotopic composition of olive oils was successfully used to distinguish samples originating in the two areas. Specifically, when bulk data were combined with fatty acid isotopic data the differentiation power of the method improved clearly. This separation is due to the specific isotopic fingerprint of the individual countries making up the EU and non-EU samples.
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.
Virgin olive oil is inevitably subject to an oxidation process during storage that can affect its stability and quality due to off-flavors that develop before the oil surpasses its 'best before' ...date. Many parameters are involved in the oxidation process at moderate conditions. Therefore, a multiparametric study is necessary to establish a link between physico-chemical changes and sensory quality degradation in a real storage experiment. In this context, a storage experiment of 27 months was performed for four monovarietal virgin olive oils, bottled in transparent 500-mL PET bottles and subjected to conditions close to a supermarket scenario. Volatile composition, quality parameters and phenolic compounds were determined monthly. Simultaneously, an accredited sensory panel assessed their sensory characteristics. The stability of the fresh samples was also studied with the oxidative stability index (OSI) and mesh cell-FTIR. (
)-2-hexenal, (
)-3-hexen-1-ol and (
)-2-hexen-1-ol were identified as markers of the fruity attribute. Hexanal and nonanal were also identified as compounds that were associated with the rise of median of defect during storage. Some disagreements were observed between the sensory assessment and the OSI analyzed by Rancimat. However, the increase of concentration of rancid markers agreed with the increase of aldehyde band measured with mesh cell-FTIR.
New cultivars with greater adaptability to modern irrigated (super-) high-density orchards and producing good sensory quality oils are highly demanded by an olive oil industry in continuous change. ...This work analyzes olive oil sensory quality, in terms of phenols and volatiles that are responsible for virgin olive oil flavor, for three cultivars: Picual, which is used for >15% of world olive oil production; Arbequina, which is cultivated worldwide; and the new progeny Sikitita, which is derived from the other two. The availability of data at three different levels of ripeness allowed quantifying the genetic and olive maturity effects on the oil composition by means of the analysis of variance (ANOVA) and principal component analysis (PCA). Phenols and volatiles varied greatly both with genotype and, to a lesser extent, with olive maturity. With regard to the phenol profile, the crossbred cultivar Sikitita showed a higher degree of similarity with the Arbequina variety. The volatile composition of var. Sikitita, however, varies significantly from that of Arbequina, in the first stages of the olive ripeness, and becomes more similar to that of Picual as the level of ripeness increases.
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