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BACKGROUND: Nowadays, olive oil extraction is basically achieved by means of two-phase decanters, which allow a reduction of water consumption and the leaching of phenolic compounds. Despite this, most of the working settings derive from studies carried out on three-phase decanters. Hence, the aim of the present study was to assess the influence of two-phase decanter feed pipe position (FP) on the extraction efficiency and chemical-sensory characteristics of virgin olive oil. Three different positions were considered: at 825 mm (FP1), 610 mm (FP2) and 520 mm (FP3) from the outlet of the oily phase. RESULTS: Position FP3 allowed the highest oil recovery (up to 10%), the lowest percentage of oil in the olive pomace and, in general, a regular trend in terms of oil extraction efficiency. However, the oily must that came out of the decanter was not completely clean in terms of residual content of solid sediment and water. The feeding position partially affected the profile of antioxidant compounds. CONCLUSION: In two-phase decanters, loading the olive paste close to the outlet of the oily phase is recommended to increase the extraction efficiency without jeopardizing the chemical-sensory characteristics of virgin olive oil. © 2018 Society of Chemical Industry.

Natural deep eutectic solvents (NADES) are a green, promising class of solvents. Phenolic compounds are among the targets of NADES’ use in foods. A health claim is admitted by European Regulations for olive oils (OOs) containing at least 250 mg kg−1 of selected polyphenols (hydroxytyrosol and its derivatives, included tyrosol, HTD), but their determination involves analytical issues that are being currently debated. A NADES based on glucose and lactic acid was here used to develop a green and rapid tool for correct labelling of OOs. 163 OOs were submitted to liquid/liquid extraction with the NADES. Regression and classification approaches were adopted to relate features of the UV spectra of extracts to HTD content. The models allowed to assess HTD content for screening purposes (R2prediction = 0.84, RMSEP = 35.5 mg kg−1). For labelling purposes, oils could be labelled according to health claim limits with an error of 0.6%.

Microgreens are gaining increasing interest as a potential functional food due to their relevant contents of micronutrients and bioactive compounds, including carotenoids. Nevertheless, the analysis of carotenoids is inherently difficult, due to their thermal and chemical susceptibility, as well as to their varying polarity. From this point of view, extraction is the most critical step, compared to chromatographic separation and detection. Thus, the reliability of data on carotenoids should be guaranteed by a constant focus on analytical issues, with appropriate adaptations to each sample matrix. In this research, a specific extraction procedure for the analysis of carotenoids in microgreens was developed. Solvent composition, extraction time, solvent/sample ratio, and repeated extractions were evaluated. The obtained protocol showed recovery of 97.2%, limits of quantitation of 5.2 &mu, g&middot, g&minus, 1 for lutein and 15.9 &mu, 1 for &beta, carotene, as well as intra-day mean repeatability of 5.7% and inter-day mean repeatability of 4.7%.

The determination of phenolic compounds in extra virgin olive oils (EVOO) by means of rapid, low-cost, environment-free methods would be a desirable achievement. A natural deep eutectic solvent (DES) based on glucose and lactic acid was considered as extraction solvent for phenolic compounds in EVOO. DESs are green solvents characterized by high availability, biodegradability, safety, and low cost. The spectrophotometric characteristics of DES extracts of 65 EVOO samples were related to the total phenolic content of the oils, assessed by methanol-water extraction coupled to the Folin-Ciocalteu assay. A regression model (ncalibration= 45, nvalidation= 20), including the absorbance at two wavelengths (257, 324 nm), was obtained, with an adjusted R2= 0.762. Therefore the DES could provide a promising and viable approach for a green screening method of phenolic compounds in EVOO, by means of simple spectrophotometric measurements of extracts, even for on-field analysis (for example in olive mills).

Background Determination of the total phenolic content (TPC) in olive oils is of great interest, as phenolic compounds affect the health benefits, sensory attributes and oxidative stability of olive oils. The aim of this study was to explore the feasibility of direct front-face fluorescence measurements coupled with chemometrics for developing multivatiate models for discrimination between virgin olive oils with low and high TPC and determination of TPC concentration. Results Parallel factor analysis and principal component analysis of fluorescence excitation-emission matrices (EEMs) of virgin olive oils revealed different fluorescent properties for samples with low and high TPC. A perfect discrimination of oils with low and high TPC was achieved using partial least squares (PLS) discriminant analysis. The best regression model for the prediction of TPC was based on the PLS analysis of the unfolded entire EEMs (R-2 = 0.951, RPD = 4.0). Conclusions The results show the potential of fluorescence spectroscopy for direct screening of virgin olive oils for TPC. This may contribute to the development of fast screening methods for TPC assessment, providing an alternative to conventional assays. The procedure is environmentally friendly and fulfils the requirements for green analytical chemistry. (c) 2018 Society of Chemical Industry info:eu-repo/semantics/publishedVersion

The aim of this study was to test the usability of fluorescence spectroscopy to evaluate the stability of cold-pressed rapeseed oil during storage. Freshly-pressed rapeseed oil was stored in colorless and green glass bottles exposed to light, and in darkness for a period of 6 months. The quality deterioration of oils was evaluated on the basis of several chemical parameters (peroxide value, acid value, K232 and K270, polar compounds, tocopherols, carotenoids, pheophytins, oxygen concentration) and fluorescence. Parallel factor analysis (PARAFAC) of oil excitation-emission matrices revealed the presence of four fluorophores that showed different evolution throughout the storage period. The fluorescence study provided direct information about tocopherol and pheophytin degradation and revealed formation of a new fluorescent product. Principal component analysis (PCA) performed on analytical and fluorescence data showed that oxidation was more advanced in samples exposed to light due to the photo-induced processes, only a very minor effect of the bottle color was observed. Multiple linear regression (MLR) and partial least squares regression (PLSR) on the PARAFAC scores revealed a quantitative relationship between fluorescence and some of the chemical parameters.

This data article refers to the paper “Towards green analysis of virgin olive oil phenolic compounds: extraction by a natural deep eutectic solvent and direct spectrophotometric detection” [1]. A deep eutectic solvent (DES) based on lactic acid and glucose was used as green solvent for phenolic compounds. Eight standard phenolic compounds were solubilized in the DES. Then, a set of extra virgin olive oil (EVOO) samples (n=65) were submitted to liquid–liquid extraction by the DES. The standard solutions and the extracts were analyzed by UV spectrophotometry. This article reports the spectral data of both the standard solutions and the 65 extracts, as well as the total phenolic content of the corresponding oils, assessed by the Folin–Ciocalteu assay. Keywords: Natural deep eutectic solvents, Extra virgin olive oil, Phenolic compounds, UV spectrophotometry

Emulsion filled gels (EFG) can help food producers to reduce fat content in foods. The present study evaluated the physical, chemical, sensorial and microbiological properties of emulsion filled gels based on inulin, a gel-forming prebiotic carbohydrate, and extra virgin olive oil (EVOO), well-known for its high nutritional value and phenolic antioxidant content. EFG based on inulin and EVOO were produced by means of both mechanical shearing and ultrasound homogenization. Three different ingredient ratios lead to high, medium and low oil content EFG (H, M, L respectively). H EFG had also lower inulin/water ratio. The resulting gels could be considered as a healthy alternative to spreads, rich in fiber, unsaturated fatty acids and phenolic antioxidants. Compared to mechanical shearing, ultrasound homogenization gave more consistent EFG, characterized by lower lightness respect to mechanical processing. Lower coarseness and fusion-like behavior and higher greasiness, perceived by panelists, confirmed the structural and textural differences conferred by ultrasound. Higher inulin content and inulin/water ratios determined consistency increase. The EFG with the best sensory profile (melting, less coarse texture, higher consistency, greasy mouthfeel) was submitted to consumer test and liked by over 70% consumers ( n = 80). The volatile pattern was characterized by compounds found in fresh oils, mainly 2-hexenal. Oxidized triacylglycerols showed a slight increase in the EFG oil fraction respect to the fresh oil, particularly when using ultrasound homogenization. The residual phenolic compounds were in the range 50–76%, with losses minimized in mechanically sheared EFG. Ultrasound improved the microbiological stability of EFG.

The aim of this work was to characterize the physico-chemical, sensory and volatile profile of functional biscuits enriched with grape marc extract. Control biscuits, without the addition of extract, were produced for comparisons. The enriched biscuits showed higher phenolic content and antioxidant activity than control. Moreover, they had higher sensory scores for color (confirmed by greater values of a* and 100-L*), fruity odor, and sour taste, coupled with lower friability. The volatile analysis pointed out higher amounts of compounds derived from Maillard reaction (with the exception of pyrazines) and from lipid oxidation. The latter, imputable to the presence of grape seeds in raw materials, were far from provoking off-flavors. The principal components analysis, carried out on the volatile compounds and color data, discriminated biscuit types on the basis of the presence of grape marc extract. PC1 explained 68% of data variability.

The aim of this work was to study the physical properties and oxidative stability of model olive oil-in-water (o/w) emulsions stabilised by β-lactoglobulin (BLG), enriched with olive phenolic compounds, namely oleuropein, tyrosol and hydroxytyrosol, and added with maltodextrins (MD 7.5–9.9) in different concentrations to modify the viscosity of the continuous water phase. Emulsions were characterized for their viscosity, droplet size distribution, microstructure and interfacial protein coverage. The oxidative stability was monitored by means of hydroperoxides, hexanal and nonanal contents as indices of primary and secondary oxidation products, respectively. At high concentrations, MD increased significantly the viscosity of the emulsions; conversely, the addition of olive phenolic compounds did not show any significant effect on it. Both MD and phenolic compounds resulted to affect both the droplet size and the bigger to smaller particles ratio, with phenolic compounds generally improving the dispersion degree. A delay in the decomposition of hydroperoxides was observed as a consequence of MD addition, which also resulted to affect the efficiency of the phenolic compounds among the different systems. However, the highest protection towards oxidations was obtained when hydroxytyrosol was added. MD effect was related not only to the higher viscosity of the emulsions but also to complex interactions that occurred among the different components of the system.

One sample of lampante olive oil, neutralised and bleached by a laboratory-scale refining plant, was deodorised at the two most frequently adopted temperatures in olive oil refining (220°C and 230°C). The samples of deodorised oil were subjected to oven test at 60°C for 25 days. Aliquots of the oils were sampled at fixed times for analytical determinations, and the oxidative stability was evaluated by measuring the time needed to reach the peroxide value of 20 meq O2/kg. The sample that showed the highest oxidative stability was the oil deodorised at the highest temperature. This oil presented a higher level of TAG oligopolymers (TAGP) and lower amounts of oxidised TAGs (ox-TAG) respect to the oil deodorised at lower temperature. These findings could be explained by the greater pro-oxidant effect of ox-TAG respect to TAGP. Practical applications: The results of this paper can help to choose the right deodorisation temperature for an oil. In fact, increasing the deodorisation temperature – other parameters being equal – leads to an increase in the oxidative stability of the refined oil. Therefore it could be an option when refining oils with potentially low stability. Nevertheless, it should be preferred submitting to refining slightly oxidized oils, with lower deodorisation temperatures, in order to obtain oils with low amounts of both ox-TAG and TAGP. Effect of different deodorisation temperatures on the oxidative stability of an olive oil.

Fatty acid ethyl esters are the newest mandatory quality parameters introduced for extra virgin olive oil classification linked to fermentative processes occurring in low-quality olives. Although it is clear the strong linkage of ethyl esters with sensory fermentative defects there is a lack of knowledge about their relationship with specific volatile compounds. Hence, a study was carried out to evaluate the correlation among extra virgin olive oil quality indices and its respective volatile profile with fatty acid ethyl esters. Thirty-five virgin olive oils were collected from local oily industry and analysed for the fatty acid ethyl esters content, the basic quality parameters, the total phenolic content and the volatile profile. The obtained results showed that the fatty acid ethyl esters were negatively correlated to total phenolic compounds (p

In this work, differential scanning calorimetry (DSC) was for the first time applied to evaluate cooling and heating curves and related thermal properties of olive oil during refining process steps starting from two series of samples at different initial peroxide values (low, 15meqO2/kg and high, 30meqO2/kg). Thermal properties were statistically correlated by means of principal component analysis (PCA) to those substance classes (products deriving from oxidation, polymerization and hydrolysis of triacylglycerols (TAG)) that could exert adverse effects on consumer health and a negative contribution to the shelf-life of the refined oil. A concomitant significant increase of K270 and polymerized TAG, as a general decrease of oxidation level was exhibited by oils during bleaching. Crystallization significantly shifted towards lower temperatures as well as onset temperature of heating, enlarging transition range, starting from bleaching and at both oxidation levels. PCA was performed to tentatively discriminate among samples according to different refining steps and/or initial level of oxidation correlating thermal properties and chemical results. The first principal component clearly clustered samples according to different refining steps and this differentiation was possible on the basis of the relation of thermal parameters with polymerized TAG conjugated dienes and trienes (K232 and K270, respectively). This preliminary goal should lead to deepen the study of DSC application in the evaluation of the quality of olive and other vegetable oils during refining. Practical applications: DSC is a thermal technique that nowadays covers a large set of applications in lipid technology due to its indisputable advantages as it does not require sample preparation and use of solvents, resulting in a reduced environmental impact. The preliminary findings of this study promote the application of the technique in the evaluation of olive oil quality during refining steps in relation with molecular species formed as polymerized TAG and conjugated trienes discriminating crude and neutralized samples to bleached and deodorized oils. DSC could be also applied on other vegetable oils where refining process is more frequently applied. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The effect of the surrounding molecular environment (β-lactoglobulin as an emulsion stabilizer and maltodextrin as a viscosity modifier) on the antioxidant activity of three olive oil phenolic compounds (PCs) in olive oil-in-water emulsions was investigated. Oxidation potential, phenolic partitioning, and radical quenching capacity were assessed in solution and in emulsion for oleuropein, hydroxytyrosol, and tyrosol; the influence of β-lactoglobulin and maltodextrin concentration was also evaluated. Finally, the observed properties were related to the oxidative stability of the emulsions containing the PCs to explain their behavior. The order hydroxytyrosol > oleuropein > tyrosol was observed among the antioxidants for both oxidation potential and radical quenching activity. Radical quenching capacity in emulsion and anodic potential were complementary indices of antioxidant effectiveness. As the intrinsic susceptibility of an antioxidant to oxidation expressed by its anodic potential decreased, the environmental conditions (molecular interactions and changes in continuous phase viscosity) played a major role in the antioxidant effectiveness in preventing hydroperoxide decomposition.

In oil-mills, olive-pomace recentrifugation is a common way to reduce pomace moisture and, at the same time, to recover the oil therein. According to current rules, the obtained oil is defined as “crude olive-pomace oil.” The aim of this work is to verify the effect of recentrifugation on specific chemical and molecular parameters of the crude olive-pomace oil, by comparing it with the corresponding virgin olive oil obtained from the same olive lots. In particular, the following were considered: (i) the polar compounds of the oils that include compounds originated from oxidative and hydrolytic degradation, analyzed by high-performance size exclusion chromatography (HPSEC), and (ii) the profile of DNA microsatellite molecular markers that was analyzed by using the High Resolution Melting (HRM) technique. The obtained results evidenced the significantly higher hydrolytic degradation of crude olive-pomace oil, compared with the corresponding virgin olive oil, but at an extent unlikely able to allow the detection of fraudulent admixtures with virgin olive oils. In addition, the findings demonstrated the feasibility of the application of the HRM analysis of DNA microsatellites to crude olive-pomace oil, able to reveal the alteration of the declared varietal profile of a virgin olive oil sample by simply checking the HRM curve profiles.

An investigation was carried out to evaluate the use of High Performance Size-Exclusion Chromatography (HPSEC) of polar compounds of refined, mild deodorized, extra virgin olive oils as well as of their blends, in attempting to reveal significant differences in the amounts of the substance classes constituting polar compounds among these oils. Two sets of blends were prepared by mixing an extra virgin olive oil with both refined and mild deodorized olive oils in increasing amounts. The obtained data highlighted that the triacylglycerol oligopolymers were absent or present in traces in the extra virgin olive oil, while their mean amount was equal to 0.04. g/100. g and 0.72. g/100. g in mild deodorized and refined olive oils, respectively. Oxidized triacylglycerols and diacylglycerols were more abundant in mild deodorized oil and refined oil than in extra virgin olive oil. The Factorial Discriminant Analysis of the data showed that the HPSEC analysis could reveal the presence of refined/mild deodorized oils in extra virgin olive oils. In particular, the classification functions obtained allowed designation of mixtures containing at least 30. g/100. g of mild deodorized oil and all those containing refined olive oil as deodorized oil, therefore as oils subjected to at least a mild refining treatment. © 2011 Elsevier Ltd.

Several studies have investigated the interaction of free fatty acids with the oxidative phenomena involving oils during processing and storage. Nevertheless, the available information is insufficient and, in some cases, contradictory.The aim of this work was to throw light upon this matter, by evaluating - by means of different analytical approaches - the effect of adding increasing amounts of free fatty acids (0.25%, 0.5%, 1%, 3%) on the oxidative processes occurring in purified olive oil during oxidation at 60°C.The results obtained showed that oxidized forms of triglycerides and polar oligopolymers of triglycerides increased during oxidation. Low amounts of added FFA caused a further increase of the levels of oxidized triglycerides and triglyceride oligopolymers - pointing out a pro-oxidant activity - while higher doses of added free fatty acids lead to lower amounts of oxidized forms of triglycerides respect to the purified oil. This could be due to an increase in peroxide decomposition exerted by free fatty acids when present in higher amounts. © 2010 Elsevier Ltd.

Second centrifugation of olive paste is often carried out to recover the residual oil of the olive paste, leading to a product that must be marketed as raw olive pomace oil. An experimental investigation was carried out to assess yield, chemical composition, and volatile compounds of oils obtained after the first and the second centrifugation of olive paste. Olives from Coratina cultivar were used in trials and were processed by adding 1 g/100 g and 2 g/100 g of technological coadjuvant micronized talc, as well as without talc addition, as control. The obtained results evidenced that the second centrifugation deter- mined a significant decrease of residual oil in pomace. The addition of talc determined a significant increase of oil yield respect to control without talc, but only after the first centrifugation. A scarce in- crease of oil yield was observed after the second centrifugation, in presence of talc, that would render economically not viable the use of a second working line. Moreover, the oil obtained after the second centrifugation showed higher extent of oxidative and hydrolytic degradation than the oil from the first centrifugation. Some volatile compounds, derived from oxidative and fermentative phenomena, were observed in specific amounts in the oil of second centrifugation.

The capability of different spectroscopic techniques in estimation of adulteration of extra virgin olive oil with mild deodorized and refined olive oils was investigated. The visible absorption and ultraviolet-visible fluorescence spectra were distinctly different for oils of different quality grades. Differences in the near- and mid-IR absorption spectra were less pronounced and could only be revealed by principal component analysis. The calibration models for estimation of adulterant oil in the blends obtained using partial least squares (PLS) and principal component regression (PCR) showed similar performance using all of the examined spectroscopic techniques. The simultaneous analysis of combined spectra using concatenated matrix did not improve the calibration results. The prediction parameters for the set of 20 samples were: R2>0.96, the relative error of prediction (REP) was in the range 5.6-12.0%. The RPD (ratio of the SD of reference values to RMSEP) were in the range of 5.1-10.9, indicating that all models were at least suitable for quality control.

The effect of drying temperatures on the profile of volatile compounds of pasta was studied. The solid phase microextraction coupled with gas chromatography/mass spectrometry allowed to identify 72 volatile compounds in the samples of not-dried, low-temperature-dried (LT-dried), high-temperature-dried (HT-dried), and wrongly very-high-temperature-dried (WVHT-dried) pastas. The samples of not-dried pasta contained alcohols, aldehydes, short-chain ketones, esters, furans, and some sulfur compounds. In the LT-dried pasta, the volatile aldehydes derived from lipid oxidation were more abundant than in HT-dried pasta. HT-dried pasta showed higher levels of furan and furan derivatives (especially 2-furanmethanol), derived from the Maillard reaction, than LT-dried pasta (p < 0.05). Pyrazines arose from WVHT treatment. Significant differences were observed also for the color indices when comparing pasta subjected to LT and HT drying (p < 0.001). Several volatile Maillard reaction products were significantly correlated (p < 0.05 and p < 0.01) to a* and 100 - L*. The ratio aldehydes/furans allowed distinguishing in a significant way the treatments, independently from the lot characteristics. © 2013 Springer Science+Business Media New York.

An experimental investigation was carried out with the aim to investigate on the isomerisation of 1,2-diacylglycerols to 1,3-diacylglycerols as a function of the storage conditions, as well as to identify indices useful to evaluate the freshness of the oils. Two oils derived from two different cultivars (Coratina and Ogliarola barese) were stored for two years as follows: in bottles at dark; in clear glass bottles at light; in green glass bottles at light; in bottles at dark, the latter subjected to repeated opening and samplings to simulate domestic use. The obtained results evinced that during the storage period a significant increase in the 1,3-isomers was observed due to an isomerisation from the 1,2 to the 1,3 isomeric form, consequently the 1,3/1,2 ratio increased in both oils. The covariance analysis of the data showed that the isomerisation of diacylglycerols, taking place during time, was affected by the type of oil, probably due to the different initial hydrolysis level, but was not affected by the storage conditions. Among the parameters considered, the total diacylglycerols/1,3-diacylglycerols ratio could be used as freshness index of extra virgin olive oil, since it is not affected by either oil or storage conditions. © 2012 Elsevier Ltd. All rights reserved.

The refining process is essential to make edible both lampante olive oils and solvent-extracted vegetable oils. The aim of this work was to evaluate the influence of the crude oil oxidation level and of the standard refining process on the amount of oxidized triacylglycerols (ox-TAG) and triacylglycerol oligopolymers (TAGP) in the corresponding refined oil. A virgin olive oil was let to progressively autoxidize at room temperature and was used at different oxidation levels in the experimental trials. Samples were submitted to the same refining process, utilizing a laboratory-scale pilot plant. The results obtained showed that the steps of the refining process caused the increase of oligomeric oxidation products in the refined oil respect to the corresponding raw oil. In this study the oxidative degradation in the crude oil resulted to be correlated to the final amounts of ox-TAG and TAGP. These findings point out that the final levels of oxidation products in refined oils depend both on the adopted standard refining steps and on the oxidative level of the crude oils. In particular, being ox-TAG highly pro-oxidant substances, the oxidative status of the crude oil can severely affect the shelf-life of the refined oil. © 2011 Elsevier Ltd.

An experimental investigation was carried out with the aim to evaluate the pro-oxidant activity of oxidized triacylglycerols and compare it with that observed for polar triacylglycerol oligopolymers. The research on these classes of substances, that form during processing and storage of fats and oils, has a great concern with the study of the effect of heat in technologic processes, such as vegetable oils refining, frying and cooking. Oxidized triacylglycerols and polar triacylglycerol oligopolymers, obtained in purity by preparative gel permeation chromatography, were added in amounts of 0.25-1 g/100 g both to a purified and an unpurified olive oil. Regarding the oxidized triacylglycerols, the accelerated oxidation tests showed that the induction times of both oils significantly decreased at increasing concentrations of these compounds, demonstrating their pro-oxidant effect. Moreover, the data showed that the pro-oxidant activity of oxidized triacylglycerols was greater than that of polar triacylglycerol oligopolymers. © 2010 Elsevier Ltd.

An experimental investigation was carried out to evaluate the influence of processing and storage time on the lipidic fraction of taralli. The data obtained pointed out that the kneading phase caused a significant increase of the oxidized triacylglycerols and triacylglycerol oligopolymers, primary and secondary oxidation compounds, respectively, accompanied by a significant decrease of the content of polyunsaturated fatty acids. The successive baking step caused the degradation of a part of the oxidized compounds to volatile substances, as confirmed by the p-Anisidine values, whereas the storage time determined a further significant increase of the level of oxidized triacylglycerols. Finally, the level of diacylglycerols, monoacylglycerols, and free fatty acids, indicative of hydrolytic degradation, did not show significant changes. The principal component analysis allowed one to clearly distinguish among samples obtained through processing conditions. © 2009 Institute of Food Technologists®.

An experimental investigation was carried out with the aim to understand the oxidative and hydrolytic phenomena involving the lipid fraction of vacuum-packed sausages during long-term storage (5 months) and to verify their influence on the sensory characteristics. The data obtained pointed out that the oxidation was more pronounced in the initial stages of storage than in the further period, while the hydrolysis of lipid fraction significantly advanced during the whole storage time, supported by the high moisture level of the product. Both these phenomena resulted to be correlated with the sensory decay of the product. In particular, in the first stage of vacuum storage overall acceptability was found to be negatively correlated (p < 0.05) with rancid taste, acid value, and oxidized triacylglycerols. In the further stage the oxidative processes slowed down and affected in a lesser extent the sensory properties, which were more distinctly characterized by the onset of pungent perception attributed to compounds arising from multiple origins such as carbohydrate fermentation. This investigation confirmed the unreliability of thiobarbituric acid reactive substances test and the usefulness of high performance size exclusion chromatography analysis of the polar compounds of the lipid fraction to correctly determine the levels of the oxidative and hydrolytic degradation of the lipid fraction of vacuum-packed ripened sausages during long-term storage. © 2009 Elsevier Ltd. All rights reserved.

The aim of the research was to evaluate the pro-oxidant action of oxidized triglyceride oliogopolymers, a class of oxidation compounds present in refined vegetable oils. Silica gel column chromatography was used to obtain the polar compounds from a thermally oxidized oil and preparative gel permeation chromatography to separate and collect the oxidized triglyceride oligopolymers. A purified oil that was practically free of oxidation and hydrolytic degradation products, pigments and anti-oxidants was prepared in the laboratory to evaluate pro-oxidant activity without interferences. Addition of percent amounts of oxidized triglyceride oligopolymers of 0.25 to 1.0% to both the purified and unpurified oils clearly evidenced the pro-oxidant activity of this class of compounds. © 2007 Springer-Verlag.