Importance of some minor compounds in olive oil authenticity and quality

Enhanced quantification of chlorophyll a and its degradation products in olive oil using time-resolved laser-induced fluorescence fingerprint analysis

Potential errors in the fluorescence analysis of chlorophylls and their degradation products, primarily due to spectral overlap and inner filter, are widely acknowledged. This study aimed to devise a sensitivity-enhanced technique for the concurrent quantification of chlorophyll a and its degradation products while minimizing effects from type-B chlorophylls. Initially, a time-resolved laser-induced fluorescence spectroscopic system was designed and tested on stardard chlorophyll samples. The origins, implications, and mitigation strategies of spectral overlap and the inner filter effect on the measured fluorescence intensity were thoroughly examined. Then, this methodology was proved to be efficacious within complex liquid matrices derived from olive oil. The experimental outcomes not only shed additional light on the mechanisms of chlorophyll fluorescence overlap and the inner filter effect, but also establish a general framework for developing spectrally and timely resolved fluorescence fingerprint analysis for the simultaneous quantification of chlorophylls and their degradation products at high concentrations.

CsPbBr3 NCs Confined and In Situ Grown in ZIF-8: A Stable, Sensitive, Reliable Fluorescent Sensor for Evaluating the Acid Value of Edible Oils

Rapidly and sensitively evaluating the acid value (AV) of edible oils is significant to ensuring food quality and safety. Cesium lead bromide perovskite nanocrystals (CsPbBr3 NCs) are an effective candidate for AV detection; however, their instability restricts wide applications. Herein, CsPbBr3@ZIF-8 was prepared by confining and growing CsPbBr3 NCs in situ into zeolitic imidazolate framework-8 (ZIF-8) to improve the stability, and a fluorescence sensor was established to evaluate the AV of edible oils. The results present that CsPbBr3 NCs (below 5 nm) with excellent optical properties were confined and grown in situ in micropores and mesopores of ZIF-8. Meanwhile, CsPbBr3@ZIF-8 had better long-term storage, ultraviolet-irradiation, and water-exposure stabilities, compared with CsPbBr3 NCs. Given the fact that free fatty acids (the major contributor of AV) decrease the fluorescence of CsPbBr3 NCs, the fluorescence intensities of CsPbBr3@ZIF-8 were negative-linearly related to oil AV (R2 = 0.9902) in 0.04-6.00 mg of KOH/g with a 0.06 mg of KOH/g limit of detection. Besides, the practical AV recovery was 92-101% with an average relative standard deviation of 2%. Furthermore, the detection time was 20 min. The response mechanism revealed that free fatty acids could remove surface ligands and increase surface defects to prompt the aggregation of CsPbBr3 NCs and the formation of lattice fringe dislocations, inducing a decrease in the fluorescence. Thus, a stable, sensitive, reliable sensor was established to evaluate the AV of edible oils.

Trends in authentication of edible oils using vibrational spectroscopic techniques

The authentication of edible oils has become increasingly important for ensuring product quality, safety, and compliance with regulatory standards. Some prevalent authenticity issues found in edible oils include blending expensive oils with cheaper substitutes or lower-grade oils, incorrect labeling regarding the oil's source or type, and falsely stating the oil's origin. Vibrational spectroscopy techniques, such as infrared (IR) and Raman spectroscopy, have emerged as effective tools for rapidly and non-destructively analyzing edible oils. This review paper offers a comprehensive overview of recent advancements in using vibrational spectroscopy for authenticating edible oils. The fundamental principles underlying vibrational spectroscopy are introduced and chemometric approaches that enhance the accuracy and reliability of edible oil authentication are summarized. Recent research trends highlighted in the review include authenticating newly introduced oils, identifying oils based on their specific origins, adopting handheld/portable spectrometers and hyperspectral imaging, and integrating modern data handling techniques into the use of vibrational spectroscopic techniques for edible oil authentication. Overall, this review provides insights into the current state-of-the-art techniques and prospects for utilizing vibrational spectroscopy in the authentication of edible oils, thereby facilitating quality control and consumer protection in the food industry.

Investigation of the influence of minor components and fatty acid profile of oil on properties of beeswax and stearic acid-based oleogels

Understanding the impact of minor components and the fatty acid profile of oil on oleogel properties is essential for optimizing their characteristics. Considering the scarcity of literature addressing this aspect, this study aimed to explore the correlation between these factors and the properties of beeswax and stearic acid-based oleogels derived from rice bran oil and sesame oil. Minor oil components were modified by stripping the oil, heating the oil with water, and adding β-sitosterol. Oleogels were then prepared using a mixture of beeswax and stearic acid (3:1, w/w) at a concentration of 11.74 % (w/w). The properties of oils and oleogels were evaluated. The findings indicated that minor components and fatty acid composition of the oils substantially influence the oleogel properties. Removing minor components by stripping resulted in smaller and less uniformly distributed crystals and less oil binding capacity compared to the oleogels prepared from untreated oils. A moderate amount of minor components exhibited a significant influence on oleogel properties. The addition of β-sitosterol did not show any influence on oleogel properties except for the oleogel made from untreated oil blend added with β-sitosterol which had more uniform crystals in the microstructure and demonstrated better rheological stability when stored at 5 °C for two months. The oil composition did not show any influence on the thermal and molecular properties of oleogels. Consequently, the oleogel formulation derived from the untreated oil blend enriched with β-sitosterol was identified as the optimal formula for subsequent development. The findings of this study suggest that the physical and mechanical properties as well as the oxidative stability of beeswax and stearic acid-based oleogels are significantly affected by the minor constituents and fatty acid composition of the oil. Moreover, it demonstrates that the properties of oleogels can be tailored by modifying oil composition by blending different oils.

A Review of Recent Progresses on Olive Oil Chemical Profiling, Extraction Technology, Shelf-life, and Quality Control

Olive oil (OO) is widely recognized as a main component in the Mediterranean diet owing to its unique chemical composition and associated health-promoting properties. This review aimed at providing readers with recent results on OO physicochemical profiling, extraction technology, and quality parameters specified by regulations to ensure authentic products for consumers. Recent research progress on OO adulteration were outlined through a bibliometric analysis mapping using Vosviewer software. As revealed by bibliometric analysis, richness in terms of fatty acids, pigments, polar phenolic compounds, tocopherols, squalene, sterols, and triterpenic compounds justify OO health-promoting properties and increasing demand on its global consumption. OO storage is a critical post-processing operation that must be optimized to avoid oxidation. Owing to its great commercial value on markets, OO is a target to adulteration with other vegetable oils. In this context, different chemometric tools were developed to deal with this problem. To conclude, increasing demand and consumption of OO on the global market is justified by its unique composition. Challenges such as oxidation and adulteration stand out as the main issues affecting the OO market.

In Situ Rapid Analysis of Squalene, Tocopherols, and Sterols in Walnut Oils Based on Supercritical Fluid Chromatography-Quadrupole Time-of-Flight Mass Spectrometry

Quantification of liposoluble micronutrients in large-scale vegetable oil samples is urgently needed, because their health benefits are increasingly emphasized. However, current analytical methods are limited to either labor-intensive preparation processes or time-consuming chromatography separation. In this work, an online oil matrix separation strategy for direct, rapid, and simultaneous determination of squalene, tocopherols, and phytosterols in walnut oil (WO) was developed on the basis of the lipid class separation mode of supercritical fluid chromatography. A single run was completed in 13 min containing 6 min of column cleaning and balancing. Satisfactory limit of detections (0.05-0.20 ng/mL), limit of quantifications (0.15-0.45 ng/mL), recoveries (70.61-101.44%), and matrix effects (78.43-91.62%) were achieved, indicating the reliability of this method. In addition, eight sterol esters were identified in WO, which have not previously been reported. The proposed method was applied to characterize the liposoluble micronutrient profile of WO samples obtained from different walnut cultivars, geographical origins, and processes.

A classification and identification model of extra virgin olive oil adulterated with other edible oils based on pigment compositions and support vector machine

Adulteration identification of extra virgin olive oil (EVOO) is a vital issue in the olive oil industry. In this study, chromatographic fingerprint data of pigments combined with machine learning methodologies were successfully identified and classified EVOO, refined-pomace olive oil (R-POO), rapeseed oil (RO), soybean oil (SO), peanut oil (PO), sunflower oil (SFO), flaxseed oil (FO), corn oil (CO), extra virgin olive oil adulterated with rapeseed oil (EVOO-RO) and extra virgin olive oil adulterated with corn oil (EVOO-CO). Support vector machine (SVM) classification of EVOO, other edible oils, and EVOO adulteration identification achieved 100% accuracy for the training set sample and 94.44% accuracy for the test set sample. As a result, this SVM model could identify effectively the adulteration EVOO with the limit of 1% RO and 1% CO. Therefore, the excellent classification and predictive power of this model indicated pigments could be used as potential markers for identifying EVOO adulteration.

Multiomics Approach To Decipher the Origin of Chlorophyll Content in Virgin Olive Oil

The color of virgin olive oils, ranging from intense green to brown-yellow, is one of the main selection factors for consumers and a quality criterion in specific legislations. Such coloration is due to their chlorophyll content and depends on the composition of the olive fruit. Through analytical chemistry (HPLC-hrMSⁿ), biochemistry (enzymatic activity), and molecular biology (qRT-PCR) approaches, we have analyzed the origin of the differences in the chlorophyll content among several varieties of olive fruit throughout their ripening process. The higher chlorophyll biosynthetic capacity in olive fruits is due to the enzyme protochlorophyllide reductase, whereas chlorophyll degradation is accomplished through the stay-green and pheophytinase pathways. For the first time, the implication of chlorophyll dephytylase during the turnover of chlorophylls in fruit is shown to be responsible for the exclusive accumulation of dephytylated chlorophyll in Arbequina fruit. The multiomics results excluded the in vivo participation of chlorophyllase in chlorophyll degradation in olive fruits.

A comprehensive review on different classes of polyphenolic compounds present in edible oils

Edible oils are used as a frying medium and in the preparation of several food products. They are mainly constituting triacylglycerols as major components, while other compounds are classified as minor constituents, which include polyphenols. This class of compounds plays an important role in the thermal stability and quality attributes of the finished industrial food products. In addition to other antioxidants, the desired thermal stability of edible is achieved by either fortification or mixing of edible oils. This comprehensive review was therefore aimed to review the different classes of polyphenolic compounds present in commonly consumed edible oils. The edible oils reviewed include soybean, olive, rapeseed, canola, sunflower, flaxseed, sesame, cottonseed, palm, almond, peanut, chestnut, coconut, and hazelnut oils. The identified classes of polyphenolic compounds such as simple phenols, hydroxybenzoic acids, phenylethanoids, hydroxycinnamic acid, esters of hydroxycinnamic acids, coumarins & chromans, stilbenes, flavonoids, anthocyanins, and lignans were discussed. It was observed that a single edible from different origins showed the varied composition of the different classes of phenolic compounds. Among the oils, soybean, sunflower, olive, and brassica oils received higher attention in terms of polyphenol composition. Some classes of phenolic compounds were either not reported or absent in one edible oil, while present in others. Among the different classes of phenolics, hydroxybenzoic acids, hydroxycinnamic acid and flavonoids were the most widely present compounds. Phenolic compounds in edible oils possess several health benefits such as antioxidant, antibacterial, anti-viral, anti-inflammatory, anti-tumour, antioxidants, cardioprotective, neuroprotective, anti-diabetic properties and anti-obesity.

Chemical and volatile characteristics of olive oils extracted from four varieties grown in southwest of China

The present study was conducted to determine the quality parameters, fatty acid profile, minor compounds (pigments, tocopherols, phenolic compounds, squalene and total sterols) and volatile compounds of olive oils from four common olive cultivars (cv. 'Koroneiki', 'Coratina', 'Frantoio' and 'Arbequina') planted in China. The effect of maturation stage on the characteristics of the oils was also evaluated. All samples were classified as extra virgin according to the standards established by IOC. Statistically significant differences (p < 0.05) were observed in the most analytical indicators of the oils among the cultivar and ripening. Coratina oils contained the highest contents of carotenoids, chlorophylls, tocopherols, phenolic compounds and high level of volatiles, demonstrating their excellent nutritional qualities and pleasant flavors. Whereas, Koroneiki oils contained the highest contents of oleic acid and squalene. Further, high levels of total sterols were found in Frantoio and Arbequina oils. Phenolic compounds and volatiles decreased with increase of ripe degree, which indicated the oils from green olive fruits possess better quality and flavor.

Evolution of Flavors in Extra Virgin Olive Oil Shelf-Life

Extra virgin olive oil (EVOO) is one of the most distinctive ingredients of the Mediterranean diet. There are many properties related to this golden ingredient, from supreme organoleptic characteristics to benefits for human health. EVOO contains in its composition molecules capable of exerting bioactivities such as cardio protection, antioxidant, anti-inflammatory, antidiabetic, and anticancer activity, among others, mainly caused by unsaturated fatty acids and certain minor compounds such as tocopherols or phenolic compounds. EVOO is considered the highest quality vegetable oil, which also implies a high sensory quality. The organoleptic properties related to the flavor of this valued product are also due to the presence of a series of compounds in its composition, mainly some carbonyl compounds found in the volatile fraction, although some minor compounds such as phenolic compounds also contribute. However, these properties are greatly affected by the incidence of certain factors, both intrinsic, such as the olive variety, and extrinsic, such as the growing conditions, so that each EVOO has a particular flavor. Furthermore, these flavors are susceptible to change under the influence of other factors throughout the oil's shelf-life, such as oxidation or temperature. This work offers a description of some of the most remarkable compounds responsible for EVOO's unique flavor and aroma, the factors affecting them, the mechanism that lead to the degradation of EVOO, and how flavors can be altered during the shelf-life of the oil, as well as several strategies suggested for the preservation of this flavor, on which the quality of the product also depends.

Degradation of the polar lipid and fatty acid molecular species in extra virgin olive oil during storage based on shotgun lipidomics

Among the bioactive compounds present in extra-virgin olive oil, polar lipids and free fatty acids are minor compounds with well-known nutritional values and have been studied for traceability and adulteration investigations as well. In the present paper, the simultaneous characterization of polar lipids and free fatty acids in a pool of fifteen EVOO samples was achieved by means of reversed phase C18 analysis coupled to negative polarity high-resolution mass spectrometry. A total of 24 polar lipids, comprising 19 phospholipids and 5 sulfolipids, and 27 free fatty acids were tentatively identified, including several odd-chain and very long-chain fatty acids at trace levels. Moreover, a one-month study of lipid degradation on simulated storage conditions was carried out thanks to the set-up of a dedicated approach for degradation product analysis which was implemented of Compound Discoverer software. By virtue of the customized data processing workflow, more than forty compounds were tentatively identified, including compounds deriving from hydrolysis and oxidation reactions. Finally, by analysis of peak area trends, phosphoester hydrolyses of polar heads of phospholipids emerged as the fastest reactions, followed by glycerol ester hydrolyses and oxidative processes.

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.