A comprehensive study on the colour of virgin olive oils and its relationship with their chlorophylls and carotenoids indexes (I): CIEXYZ non-uniform colour space

Stability, chromatic characteristics and chemical changes of sacha inchi (Plukenetia huayllabambana) oil enriched with aguaje oil (Mauritia flexuosa L.f.) rich in carotenoids

Sacha inchi (Plukenetia huayllabambana) oil is a food matrix that contains more than 80 % of polyunsaturated fatty acids, especially linoleic and α-linolenic acids. The objective of this study was to develop blends of sacha inchi oil (P. huayllabambana) enriched with aguaje oil (Mauritia flexuosa L.f.) and evaluate the induction period, total carotenoid content, nutritional quality indices and oxidative stability from the fatty acid composition. The analytical tests were conducted for oil blends that had the following proportions: sacha inchi oil enriched with aguaje oil at 5, 10 and 20 %. The results prove that the enrichment of sacha inchi oil with aguaje oil (SIO-PH-AO) leads to an improvement in oxidative stability and nutritional and physical properties. For example, the oxidative stability index (OSI) varied from 0.87 to 2.53 h. The content of total carotenoids produces an increase from 0.35 to 99.90 mg/kg, while total polyphenols from 47.45 to 126.90 mg GAE/g, and chroma from 39.91 to 69.02 units. Regarding the fatty acid profile, the oxidizability value improves with the addition of aguaje oil. Reduces levels of PUFA, PUFA/SFA, and hypo-and hypercholesterolemic ratio (h/H). Additionally, an increase in SFA and MUFA levels, while the ω6/ω3 ratio remained constant. Finally, it can be noted that the enrichment of sacha inchi oil with aguaje oil (rich in carotenoids) provides better stability and can be used for commercial applications as a mechanism to establish new vegetable oils with better properties.

Effect of the Storage Conditions and Freezing Speed on the Color and Chlorophyll Profile of Premium Extra Virgin Olive Oils

Premium extra virgin olive oils (PEVOO) are oils of exceptional quality and retail at high prices. The green color of recently extracted olive oils is lost during storage at room temperature, mainly because of the pheophytinization of chlorophylls. Since a green color is perceived as a mark of high-quality oils by consumers, it is especially important for PEVOO to maintain their initial green color. This study assessed the effect of applying low temperatures (refrigeration and freezing) and modified atmospheres on the color of four PEVOO for 24 months. Also, the effect of two freezing methods (slow freezing by placing the oil at -20 °C and fast freezing by immersing the oil in a bath of liquid nitrogen) was studied. Results showed that the green color was better preserved in oils frozen and stored at -20 °C whereas in oils frozen with liquid nitrogen the green color was lost much faster during frozen storage. An in-depth study of this unexpected phenomenon showed that this loss of green color was mainly due to a pheophytinization of chlorophylls. This phenomenon did not happen at the moment of freezing with liquid nitrogen, but over the first 100 days of storage at -20 °C. In addition, correlations between single chlorophyll and pheophytin contents and chromatic coordinates were established.

Volatile profile and quality characteristics of the Greek “Chondrolia Chalkidikis” virgin olive oils: effect of ripening stage

Among the various parameters affecting olive oil quality, ripening stage is one of the most important. Optimal harvest time ensuring target quality for the final product varies in relation to the effect of many intrinsic and extrinsic factors. Therefore, its determination necessitates thorough examination of each case. The present study explores the impact of six harvest times on volatile profile and quality attributes of olive oils from “Chondrolia Chalkidikis” Greek cultivar. All samples examined were classified “Virgin Olive Oils” (VOOs) according to findings of acidity, peroxide, and K values. The low values for the principal official quality indices, the high oleic acid percentages (76–78%), the high oxidative stabilities (up to 36 h induction period), and phenols content (606–290 mg/kg) were considered nutritionally promising. Total phenols, carotenoids and chlorophylls contents, as well as oxidative stability (induction period values) decreased with ripening. Harvest time had a strong impact on HS-SPME–GC–MS volatile fingerprint. Optimal volatile profiles were related to intermediate examined ripening stages. Fatty acid composition did not show remarkable trends. Chondrolia Chalkidikis VOOs perform as interesting candidates of high quality. Findings of the study may support existing databases with scientific records for Chondrolia Chalkidikis VOOs, boost their competitiveness in the global market, and encourage worldwide exploitation of VOOs from similar cultivars (table olives oriented).

Potential of Near-Infrared Spectroscopy for the Determination of Olive Oil Quality

The analysis of the physico-chemical parameters of quality of olive oil is still carried out in laboratories using chemicals and generating waste, which is relatively costly and time-consuming. Among the various alternatives for the online or on-site measurement of these parameters, the available literature highlights the use of near-infrared spectroscopy (NIRS). This article intends to comprehensively review the state-of-the-art research and the actual potential of NIRS for the analysis of olive oil. A description of the features of the infrared spectrum of olive oil and a quick explanation of the fundamentals of NIRS and chemometrics are also included. From the results available in the literature, it can be concluded that the four most usual physico-chemical parameters that define the quality of olive oils, namely free acidity, peroxide value, K232, and K270, can be measured by NIRS with high precision. In addition, NIRS is suitable for the nutritional labeling of olive oil because of its great performance in predicting the contents in total fat, total saturated fatty acids, monounsaturated fatty acids, and polyunsaturated fatty acids in olive oils. Other parameters of interest have the potential to be analyzed by NIRS, but the improvement of the mathematical models for their determination is required, since the errors of prediction reported so far are a bit high for practical application.

Purity of Olive Oil Commercially Available in Poland

The aim of this study was to examine olive oils purchased in Poland for their compliance with label declarations and EEC criteria. Statistical analysis was used to compare the olive oils in terms of their content and composition of essential constituents and color parameters. Fifty olive oils (extra virgin, bioextra virgin, cold-pressed, refined, and pomace) from different countries (Spain, Italy, Greece, Portugal, Germany, France, Israel, and the European Union), were purchased commercially in Poland. The contents of triacylglycerols, sterols, and tocopherols, the fatty acid composition, and the color parameters were determined using chromatographic and spectrophotometric methods. Statistical methods were used to divide the olive oils into clusters. Our results show that the composition and color parameters of olive oils available commercially in Poland, excluding pomace olive oils, are similar. It can thus be concluded that, irrespective of the type of olive oil stated on the label, their quality is the same or very similar.

Study of the Evolution of Pigments from Freshly Pressed to 'On-the-Shelf' Extra-Virgin Olive Oils by Means of Near-UV Visible Spectroscopy

Spectroscopic non-destructive methods have high potentialities as fast, cheap and easy-to-be-used approaches to address olive oil quality and authenticity. Based on previous research where near-UV Visible spectroscopy was used to investigate extra-virgin olive oils (EVOOs) and their main pigments’ content (i.e., β-carotene, lutein, pheophytin a and pheophytin b), we have implemented the spectral deconvolution method in order to follow the EVOO’s life, from ‘freshly pressed’ to ‘on-the-shelf’ EVOO samples at different storage time. In the first part of the manuscript, the new implemented deconvolution spectroscopic method aimed to quantify two additional pigments, namely chlorophyll a and chlorophyll b, is described and tested on ‘ad hoc’ samples with known concentrations of chlorophylls. The effect of light exposure and acidification was investigated to test the reliability and robustness of the spectral deconvolution. In the second part of the work, this approach was used to study the kinetic of pigments’ degradation in several monocultivar fresh EVOO samples under optimal storage’s conditions. The results here reported show that this spectroscopic deconvolution approach is a good method to study fresh EVOOs too; moreover, the proposed method revealed to be sensitive to detect eventual stresses of olive oil samples stored in not-good conditions.

Shelf-Life Evaluation of "San Marzano" Dried Tomato Slices Preserved in Extra Virgin Olive Oil

Since ancient times, vegetables have been preserved in oil, to be consumed throughout the year, and not just during the period in which they were harvested. Dried tomato slices in Extra Virgin Olive Oil (EVOO) are one of the most famous Italian preserves. This is the first study which aimed to investigate the shelf-life parameters of this preserve during the 12 months of storage in both light and dark conditions. For this purpose, quality and CIELab color parameters were analysed in EVOO alone and as preserving liquid; total phenols and carotenoids content as well as β-carotene and lycopene content, a fatty acids profile, and antioxidant activities were examined. Results showed that samples stored in the dark are protected against degradative processes. Moreover, after 6 months of storage, the EVOO used as preserving liquid is enriched by the phytochemicals contained in dried tomato slices. This enrichment of EVOO by tomato bioactive compounds is reflected in the increase in the antioxidant activity of the oil independently by the presence of light during storage.

European Database of Carotenoid Levels in Foods. Factors Affecting Carotenoid Content

Many studies indicate that diets including carotenoid-rich foods have positive effects on human health. Some of these compounds are precursors of the essential nutrient vitamin A. The present work is aimed at implementing a database of carotenoid contents of foods available in the European market. Factors affecting carotenoid content were also discussed. Analytical data available in peer-reviewed scientific literature from 1990 to 2018 and obtained by HPLC/UHPLC were considered. The database includes foods classified according to the FoodEx2 system and will benefit compilers, nutritionists and other professionals in areas related to food and human health. The results show the importance of food characterization to ensure its intercomparability, as large variations in carotenoid levels are observed between species and among varieties/cultivars/landraces. This highlights the significance of integrating nutritional criteria into agricultural choices and of promoting biodiversity. The uncertainty quantification associated with the measurements of the carotenoid content was very rarely evaluated in the literature consulted. According to the EuroFIR data quality evaluation system for food composition tables, the total data quality index mean was 24 in 35, reflecting efforts by researchers in the analytical methods, and less resources in the sampling plan documentation.

Bioactive Compounds and Quality of Extra Virgin Olive Oil

(1) Background: Extra virgin olive oil (EVOO) is responsible for a large part of many health benefits associated to Mediterranean diet as it is a fundamental ingredient of this diet. The peculiarities of this golden, highly valued product are in part due to the requirements that must be met to achieve this title, namely, it has to be obtained using exclusively mechanical procedures, its free acidity cannot be greater than 0.8%, it must not show sensory defects, and it has to possess a fruity taste. (2) Methods: All these characteristics are key factors to EVOO quality, thus the chemical composition of these many health-promoting compounds, such as unsaturated fatty acids (which are also the major compounds, especially oleic acid), as well as minor components such as tocopherols or phenolic compounds (which behave as natural antioxidants) must be preserved. (3) Results: Due to the presence of all these compounds, the daily consumption of EVOO entails health benefits such as cardioprotective, antioxidant, anti-inflammatory, anti-tumor properties or acting as regulator of the intestinal microbiota, among others. (4) Conclusions: Taking all together, conserving EVOO chemical composition is essential to preserve its properties, so it is worth to control certain factors during storage like exposure to light, temperature, oxygen presence or the chosen packaging material, to maintain its quality and extend its shelf-life until its consumption.

An Artificial Intelligence Approach for Italian EVOO Origin Traceability through an Open Source IoT Spectrometer

Extra virgin olive oil (EVOO) represents a crucial ingredient of the Mediterranean diet. Being a first-choice product, consumers should be guaranteed its quality and geographical origin, justifying the high purchasing cost. For this reason, it is important to have new reliable tools able to classify products according to their geographical origin. The aim of this work was to demonstrate the efficiency of an open source visible and near infra-red (VIS-NIR) spectrophotometer, relying on a specific app, in assessing olive oil geographical origin. Thus, 67 Italian and 25 foreign EVOO samples were analyzed and their spectral data were processed through an artificial intelligence algorithm. The multivariate analysis of variance (MANOVA) results reported significant differences (p < 0.001) between the Italian and foreign EVOO VIS-NIR matrices. The artificial neural network (ANN) model with an external test showed a correct classification percentage equal to 94.6%. Both the MANOVA and ANN tested methods showed the most important spectral wavelengths ranges for origin determination to be 308–373 nm and 594–605 nm. These are related to the absorption of phenolic components, carotenoids, chlorophylls, and anthocyanins. The proposed tool allows the assessment of EVOO samples’ origin and thus could help to preserve the “Made in Italy” from fraud and sophistication related to its commerce.

Quality, stability, carotenoids and chromatic parameters of commercial Sacha inchi oil originating from Peruvian cultivars

Sacha inchi oil is a high-quality product with market potential and a wealth of bioactive compounds beneficial for food and health. The main objective of this work was to evaluate three quality parameters, stability, chromatic parameters and total carotenoids of commercial oils obtained from Sacha inchi seeds. The free acidity and peroxide value of all samples studied were in ranges of 0.16-1.86 (% α-linolenic acid) and 1.87-17.47 (meq O₂/kg), respectively. While K₂₃₂ value for the samples ranged from 1.96 to 2.29, the K₂₇₀ value was between 0.08 to 0.20 and ∆K in the range of - 0.005 to 0.005. Regarding color, Sacha inchi oils showed high h _ab and low C ab ∗ values, and the L ^* values were from 91 to near 100 units. Samples were located in the second quadrant of the CIELAB a ^* b ^*-color diagram. These characteristics corresponds to low-vivid light-yellow colors. Carotenoid content of Sacha inchi oils was 0.31-9.10 mg/kg. The oxidative stability using Rancimat (100 °C, 20 L/h air flow rate) of these oils presented an average value of 5.6 h. Pearson's coefficients indicate a very high correlation coefficient between the values of Car (carotenoid) versus b ^* (yellow area) (r = 0.991). The results of this study provide better understanding of the quality, stability, chromatic intensities and carotenoid contents of Sacha inchi oil that is marketed in Peru.

Determination of Pigments in Virgin and Extra-Virgin Olive Oils: A Comparison between Two Near UV-Vis Spectroscopic Techniques

The colour of olive oil is due to the presence of natural pigments belonging to the class of carotenoids, chlorophylls, and their derivatives. These substances, other than being responsible for the colour, an important qualitative feature of the oil, have antioxidant and, more generally, nutraceutical properties and their quantification can be related to the product’s quality and authenticity. In this work, we have quantified the total amount of carotenoids and chlorophylls’ derivatives in several virgin and extra-virgin olive oils produced in Italy, by using two different methods that are based on near-ultraviolet-visible absorption spectroscopy. The first method defines two indexes, K670 and K470, related to absorbance values of oil at wavelengths of 670 and 470 nm, respectively. The second method is based on the mathematical deconvolution of the whole absorption spectrum of the oil to obtain the concentrations of four main pigments present in olive oils: β-carotene, lutein, pheophytin A, and pheophytin B. The concentrations of the total carotenoids and total chlorophylls’ derivatives, as obtained by the two spectroscopic methods, are compared and the results are discussed in view of the practical usefulness of spectroscopic techniques for a fast determination of pigments in olive oil.

Novel Noninvasive Brain Disease Detection System Using a Facial Image Sensor

Brain disease including any conditions or disabilities that affect the brain is fast becoming a leading cause of death. The traditional diagnostic methods of brain disease are time-consuming, inconvenient and non-patient friendly. As more and more individuals undergo examinations to determine if they suffer from any form of brain disease, developing noninvasive, efficient, and patient friendly detection systems will be beneficial. Therefore, in this paper, we propose a novel noninvasive brain disease detection system based on the analysis of facial colors. The system consists of four components. A facial image is first captured through a specialized sensor, where four facial key blocks are next located automatically from the various facial regions. Color features are extracted from each block to form a feature vector for classification via the Probabilistic Collaborative based Classifier. To thoroughly test the system and its performance, seven facial key block combinations were experimented. The best result was achieved using the second facial key block, where it showed that the Probabilistic Collaborative based Classifier is the most suitable. The overall performance of the proposed system achieves an accuracy −95%, a sensitivity −94.33%, a specificity −95.67%, and an average processing time (for one sample) of <1 min at brain disease detection.

Rapid NIR determination of alkyl esters in virgin olive oil

The regulation of The European Union for olive oil and olive pomace established the limit of 35 mg·kg-1 for fatty acids ethyl ester contents in extra virgin olive oils, from grinding seasons after 2016. In this work, predictive models have been established for measuring fatty acid ethyl and methyl esters and to measure the total fatty acid alkyl esters based on near infrared spectroscopy (NIRS), and used successfully for this purpose. The correlation coefficients from the external validation exercises carried out with these predictive models ranged from 0.84 to 0.91. Different classification tests using the same models for the thresholds 35 mg·kg-1 for fatty acid ethyl esters and 75 mg·kg-1 for fatty acid alkyl esters provided success percentages from 75.0% to 95.2%.

The Effect of Soil Management on Olive Yield and VOO Quality in a Rainfed Olive Grove of Central Spain

Rainfed olive groves have been traditionally tilled in order to reduce the competition for water and nutrients. In sloping Mediterranean olive groves, this practice leads to high erosion rates, resulting in a reduction in soil fertility. Cover crops have been employed as a sustainable olive grove management strategy, but previous studies found differences in their effect on fruit load and there is scarce information on their influence on the virgin olive oil (VOO) quality. The aim of this study is to evaluate the effect of different soil management strategies on olive and oil yield and VOO physicochemical and sensory characteristics in a rainfed olive grove (238 trees·ha−1) of Cornicabra cultivar, the main in Central Spain. No effect of soil management was found in olive or oil yield along three cropping seasons. VOO quality was mainly influenced by the year, but slight differences were found in the driest year between the studied treatments. Small differences in fruit ripening, pigments, and several fatty acids as well as in sensory parameters were found.

On-field monitoring of fruit ripening evolution and quality parameters in olive mutants using a portable NIR-AOTF device

This study optimizes the application of portable Near Infrared-Acousto Optically Tunable Filter (NIR) device to meet the increasing demand for cost-effective, non-invasive and easy-to-use methods for measuring physical and chemical properties during olive fruit development. Fruits from different phenotypically cultivars were sampled for firmness, total and specific phenols detection by HPLC, total anthocyanins, chlorophyll and carotenoids detection by spectrophotometry. On the same fruits, a portable NIR device in diffuse reflectance mode was employed for spectral detections. Predictive models for firmness, chlorophyll, anthocyanins, carotenoids and rutin were developed by Partial Least Square analysis. Oleuropein, verbascoside, 3,4-DHPEA-EDA, and total phenols were used to develop a validation model. Internal cross-validation was applied for calibration and predictive models. The standard errors for calibration, cross-validation, prediction, and RPD ratios (SD/SECV) were calculated as references for the model effectiveness. The determination of the optimal harvesting time facilitates the production of high quality extra virgin olive oil and table olives.

Rapid determination of olive oil oxidative stability and its major quality parameters using vis/NIR transmittance spectroscopy

This paper reports the determination of the olive oil stability index (OSI) by multivariate models from the visible and near-infrared spectrum. The technique proposed is rapid and nondestructive and can be used as a multiparametric method. Moreover, it does not require specific instrumentation, and it is environmentally friendly. The determination of the OSI using the Rancimat instrument was used as a reference method. Predictive visible and near-infrared (vis/NIRS) models were obtained from partial least squares (PLS) for the OSI, showing satisfactory performance in independent tests as proven by the R(2) values of 0.93 and 0.94 from the calibration and the residual predictive deviation (RPD) of the external validations of 3.30 and 3.00, respectively. Predictive models for the determination of free fatty acids, peroxide value, and conjugated dienes were also developed, and their satisfactory performances were demonstrated by RPDs of 3.14, 2.84, and 2.56; hence, its multiparametric determination together with OSI would be possible.

Characterization of the Olive Oil from Three Potentially Interesting Varieties from Aragon (Spain)

The commercial potential of olive oils from three autochthonous olive varieties Bodocal, Racimilla and Negral from Aragón (Spain) has been examined. Physicochemical characteristics, sensory analysis, nutritional composition, color and pigments were considered. The three varieties are generally used for producing table olives or olive oil in coupages but not for the production of monovarietal virgin olive oil. The values of the physicochemical and sensory analysis for the three olive oils corresponded to extra virgin category, however important differences among the three oils were observed in relation to pigment content, color measurements and fatty acid and phenol and tocopherol composition. Several characteristics such as oil yield, fatty acid and phenol and tocopherol content and sensory profiles suggested that some of these oils are of a promising composition. The olive yield of the Bodocal variety was the lowest (17%) and its corresponding oil had the smallest oleic acid (69%), phenols (272 mg gallic acid/kg) and tocopherol (96 mg/kg) contents and not equilibrated sensory parameters. The main characteristics of the Racimilla variety were a very high oil yield (28%) with very high contents in oleic acid (79 %) and phenols (831 mg gallic acid/kg). The oil of the Negral variety had very equilibrated sensory properties and its oleic acid content (76%) was similar to that of Racimilla. Its phenol content (456 mg gallic acid/kg) was between that of the other two varieties and its tocopherol content (190 mg/kg) was the highest. Therefore, the two last varieties could be of great interest for producing monovarietal olive oils.