Search Results (103)

The transition to bio-based fuels requires a thorough understanding of how molecular structure governs key physicochemical properties such as oxidation stability and viscosity. In this study, the combined influence of fatty acid composition and alcohol structure on biodiesel and biolubricant performance is investigated using a multivariate statistical approach. A dataset comprising 108 samples was analyzed, including 17 experimental samples produced in this work and 91 samples collected from peer-reviewed literature. Each sample was characterized by its fatty acid composition and at least one physicochemical property, namely oxidation stability (Rancimat induction time) and/or kinematic viscosity. Principal Component Analysis (PCA) was applied to identify dominant compositional patterns, followed by clustering (k-means) to define homogeneous compositional regions. Within these regions, a variance decomposition approach was used to quantify the relative contribution of alcohol type to property variability. The results show that fatty acid composition defines the primary structural framework governing oxidative stability, largely driven by the degree of unsaturation. In contrast, viscosity is more strongly influenced by the type of alcohol used, particularly in systems involving higher alcohols or polyols. The proposed approach provides a structured multivariate framework focused on analyzing oxidation stability and viscosity, enabling the systematic interpretation of the relative influence of fatty acid composition and alcohol structure on these key physicochemical properties. This study demonstrates that integrating PCA, clustering, and variance decomposition offers a robust strategy for analyzing complex bio-based systems, supporting the rational selection of feedstocks and processing conditions for the optimization of biodiesel and biolubricant formulations. Full article

Fava bean (Vicia faba L.) is a nutritionally valuable and sustainable legume with strong potential for plant-based food applications. However, similar to other lipid-containing food systems, fava bean-based spreads are susceptible to lipid oxidation during storage, leading to quality deterioration and reduced shelf life. This study evaluated the effect of basil (Ocimum basilicum L.), winter savory (Satureja montana L.), and cumin (Cuminum cyminum L.) essential oils (EOs) (0.1 μL/g) on the physicochemical properties and oxidative stability of fava bean-based spreads during 90 days of storage at 4 °C. Four treatments were prepared: control spread without essential oil (B-CO), basil essential oil-enriched spread (B-BA), winter savory essential oil-enriched spread (B-WS), and cumin essential oil-enriched spread (B-CU). Water activity and pH remained stable in all samples throughout storage. Color changes were most pronounced in the control, while B-WS exhibited the highest color stability (ΔE = 1.81 vs. 6.07 in B-CO). Winter savory and cumin significantly reduced peroxide value and thiobarbituric acid reactive substance (TBARS) formation and improved oxidative stability (Rancimat: 9.11 and 9.10 h vs. 7.73 h in B-CO), whereas basil showed no protective effect. Cumin was characterized by the highest flavonoid and phenolic acid contents, while winter savory exhibited the highest total polyphenols. Sensory evaluation revealed that EOs significantly influenced consumer acceptance, particularly taste and aroma. Although the control sample achieved the highest overall scores, cumin-containing formulations provided the most favorable balance between oxidative stability and sensory quality, whereas winter savory negatively affected overall acceptability. Taken together, winter savory and cumin EOs effectively enhanced oxidative stability, highlighting their potential as natural antioxidants in the development of plant-based spreads. Full article

Lipid oxidation affects the quality and functionality of vegetable oils, and its progression depends largely on fatty acid composition and antioxidant content. Oxidation kinetics provide essential information about oxidative resistance in oils. The determination of activation parameters allows for the evaluation of oxidation susceptibility under thermal stress. Oxidative stability and oxidation kinetics at different temperatures of rosehip, sunflower, olive and jojoba oils were studied using both Rancimat and BQC-Redox System methods, enabling the calculation of kinetic constants and thermodynamic activation parameters for the process. BRS measurements showed an increase in total antioxidant capacity (TAC) with temperature in all samples, with olive oil presenting the highest TAC and jojoba the lowest at 298 K, while rosehip oil showed the lowest TAC at 373 K. Kinetic analysis revealed negative ΔS^# values, indicating the formation of ordered transition states, and similar activation energies (ΔG^# ≈ 56–58 kJ/mol), although jojoba displayed the highest ΔH^# and ΔG^#. Rancimat analysis at 373 K showed clear differences in oxidative stability: jojoba oil had the longest induction period, followed by olive, sunflower, and rosehip. These results correlated with PUFA levels. Principal component analysis (PCA) confirmed strong associations between induction period, fatty-acid composition, and kinetic parameters, demonstrating good agreement between the two analytical methods. Full article

Olive pomace (OP) has been widely reported as a rich source of phenolic compounds with potential application as food additives with health-promoting properties. The aim of this work was to evaluate pressurized liquid extraction (PLE) as a strategy to obtain antioxidant and antimicrobial extracts from OP. Extractions were carried out in laboratory-scale equipment following a combined static/dynamic procedure. The extraction temperature (100, 120 and 140 °C) and the composition of solvent (50, 75 and 100% ethanol in water) were studied as independent variables of the process using a Face Centered Central Composite Design (α = 1). According to the fitted quadratic model (p < 0.05), the maximum Total Phenol Content (TPC) and Trolox Equivalent Antioxidant Capacity (TEAC) values were obtained at 120 °C using ethanol concentrations between 60 and 80%. Chemical characterization by RP/HPLC-Q-TOF MS/MS allowed the tentative identification of 37 compounds, with quinic acid being the most abundant compound under all extraction conditions, followed by elenolic acid, dimethyl-hydroxy-verbascoside, maslinic acid, hydroxy-verbascoside and oleuropein aglycone. Other secoiridoids, secoridoid derivatives, flavonoids, simple phenols and triterpenic acids were also identified. The extract obtained at 120 °C with 75% ethanol was able to protect purified sunflower oil in an accelerated oxidative stability test (Rancimat), increasing its induction period by 2.4-fold when added at 1000 mg/kg. This extract also exhibited antimicrobial activity against S. aureus, B. cereus, S. enterica and S. sonnei with a Minimum Inhibitory Concentration (MIC) of 3.6 mg/mL. These results highlight the potential of PLE olive pomace extracts as natural preservatives for food applications. Full article

Olive tree cultivation occupies a central place in Algerian agriculture and is of considerable economic and cultural importance. Several production factors strongly influence the quality of olive oil. Among the determinants of this quality, the vegetative growth of the olive tree plays a crucial role, as it controls photosynthetic capacity, the distribution of assimilates, and fruit filling. These physiological mechanisms directly influence oil percentage, as well as fatty acid and phenolic compound compositions, and consequently, sensory characteristics such as bitterness and pungency. This study examines the quantitative relationships between vegetative growth, chemical parameters, and sensory attribute interactions that are still poorly understood using seven representative olive cultivars: local varieties (Chemlal, Bouchouk Lafayette, Blanquette de Guelma, Sigoise, and Limli) and European varieties (Frantoio and Belgentéroise). Vegetative growth was characterized by the average shoot length; fruit oil content was expressed as a percentage on a dry basis, and fatty acids were analyzed by gas chromatography after derivatization. The total polyphenol content was determined by spectrophotometry and expressed as concentration, and oxidative stability was measured using the Rancimat method. Sensory analysis was conducted by a trained panel in accordance with international recommendations. The results indicate substantial positive correlations between vegetative growth parameters, oil concentration, olive oil composition, and those sensory attributes related to polyphenols, for all varieties studied. This functional consistency suggests that improvement in one parameter is generally associated with improvement in others. The Algerian variety Chemlal stands out for its optimal performance profile in agronomic, chemical, and sensory aspects compared to the other varieties. These preliminary results suggest that optimizing oil characteristics is directly linked to the physiological and biochemical performance of the olive tree, thus confirming the relevance of a systems approach in the selection and management of olive varieties. Full article

The growing demand for healthier lipid alternatives has driven interest in oleogels as promising substitutes for the conventional saturated and trans fats in foods systems. In this context, this study explores the formulation and characterization of oleogels based on avocado oil (Persea americana var. Lorena) and monoglycerides, as an alternative to conventional saturated fats. Hydraulic compression was used to extract the oil, and the formulation was optimized using a Box–Behnken experimental design, evaluating the effects of temperature (70–90 °C), monoglyceride concentration (4–8%), and heating time (15–45 min) on oil retention capacity (ORC) and firmness. Results showed that temperature and concentration significantly influenced ORC and firmness, while heating time had no relevant effect. The optimal formulation achieved 85.95% ORC, 1.09 N firmness, and superior oxidative stability (41.71 h vs. 10.80 h in pure oil, Rancimat test). The obtained oleogel exhibited good mechanical and thermal properties, with an elastic-dominant rheological profile and higher oxidation resistance compared to unmodified avocado oil. These findings indicate that the avocado oleogels structured with monoglycerides have potential applications in the food and cosmetic industries, although further improvements in structural stability are recommended to broaden their range of applications. Full article

Deep-fat frying remains the predominant method of food preparation; however, increasing concerns regarding health and sustainability have prompted the search for safer alternatives. Palm olein is widely used as a frying medium but its consumption has been questioned due to the presence of contaminants (e.g., 3-monochloropropane-1,2-diol, 3-MCPD) and the challenges associated with its transportation from producing countries, creating a need for healthier and more sustainable alternatives. The present study aimed to assess the oxidative stability, physicochemical properties, and sensory characteristics of various oils used for deep-fat frying, with particular emphasis on identifying suitable replacements for palm olein. Five oils were evaluated: refined sunflower oil (RSO), RSO supplemented with tert-butylhydroquinone (RSO+TBHQ), RSO supplemented with rosemary extract (RSO+RE), high-oleic sunflower oil (HOSO), and palm olein (PO). Samples were evaluated before and after deep-frying of French fries, at 175 °C for 2.5 min, over a total of 12 consecutive frying cycles. The results demonstrated that palm olein and HOSO exhibited the highest oxidative stability (induction period determined by Rancimat method at 100 °C was 27 h and 26.2 h, respectively), whereas the addition of TBHQ (induction period 23.4 h) and rosemary extract (induction period 11.5 h) provided only a modest enhancement of RSO stability (induction period 9.6 h). Hierarchical cluster analysis grouped palm olein and HOSO together, confirming their similar stability, while RSOs formed a distinct cluster. These findings suggest that high-oleic sunflower oil represents the most promising, stable, and nutritionally advantageous alternative to palm olein, simultaneously supporting local production and improved dietary quality. Full article

Hydroxytyrosol (HT), the primary phenolic compound in virgin olive oil, has notable cardiovascular benefits, particularly in preventing low-density lipoprotein (LDL) oxidation. However, its hydrophilicity limits its solubility and integration into lipid-based formulations. This study aimed to enhance its lipophilicity by synthesizing hydroxytyrosyl eicosapentaenoate (HT-EPA), a derivative of HT and eicosapentaenoic acid (EPA), using a one-step enzymatic catalysis with lipase B from Candida antarctica (CALB). The reaction, performed as a suspension of HT in ethyl eicosapentaenoate (Et-EPA) (1:9 molar ratio) under vacuum, achieved higher yields and shorter reaction times than previously reported, with a purity exceeding 98%, confirmed by ¹H-NMR. For the first time, the antioxidant capacity of HT-EPA in comparison with other natural antioxidants was assessed using the FRAP assay, while its oxidative stability in an omega-3-rich oil matrix was evaluated via the Rancimat method. HT-EPA and hydroxytyrosyl acetate (HT-Ac) displayed antioxidant activity comparable to HT but significantly higher than α-tocopherol, a common food antioxidant. Given the scarcity of effective lipid-soluble antioxidants, HT-EPA represents a promising candidate for omega-3 nutraceuticals, offering enhanced stability and potential health benefits. This study provides a simple, efficient, and scalable strategy for developing functional lipid-based formulations with cardioprotective potential by improving HT solubility while preserving its antioxidant properties. Full article

This study investigated the phenolic profile and biological activities (antioxidant, antimicrobial, anti-hyperglycemic and antiproliferative) of aqueous infusions prepared from the following medicinal and edible plants: Geranium macrorrhizum L., Verbascum thapsus L., Ononis spinosa L., Achillea millefolium L., and Polygonum aviculare L. Despite their long-term usage and numerous scientific results on various solvent extracts of selected plants, they are still un-explored in terms of certain aspects of in vitro biological activities, especially in the form of aqueous infusions, which are a very common form of consumption of medicinal plants. The phenolic analysis of the selected infusions was carried out using the HPLC-DAD method and showed the highest content of total phenols in G. macrorrhizum and P. aviculare, the highest total flavonoid content in P. aviculare, and a high content of procyanidins in G. macrorrhizum. The highest antioxidant activity according to the three methods (DPPH, FRAP and Rancimat) was achieved by G. macrorrhizum and A. millefolium. The aqueous infusions of the selected plants showed no antimicrobial activity against Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 25923. The highest anti-hyperglycemic activity by inhibition of the enzymes α-glucosidase and α-amylase and the highest antiproliferative activity against MD-MBA-231, A549 and T24 cells was obtained from G. macrorrhizum. Full article

Caffeic, syringic, and protocatechuic acids are phenolic acids with important antioxidant activity. In this work we studied how the oxidative stability of rosehip, hemp, and passion fruit oils improves with the addition of these antioxidant acids. We used the BQC-Redox System method to measure the antioxidant activity of oils and phenolic acids, and compared these results with other methods described in the literature. In addition, principal components analysis was used to show the relationship between oxidant activity and fatty acids in the oils studied. The results show, in most cases, the improvement of oxidative stability of oils by addition of phenolic acids, and that oxidative stability is determined by the molecular structure of phenolic acids, solubility of oils, the composition of oils in fatty acids, and the influence of temperature in stabilizing phenolic acids and oils. In addition, we support that the BQC-Redox System (BRS) is a suitable method to measure antioxidant activity. Full article

This study assessed the potential of dried Cayenne pepper (CP; Capsicum annuum L.) as a natural additive to rice bran oil (RBO), grape seed oil (GSO), and virgin olive oil (OO). Key analyses included peroxide and acid values, oxidative stability (Rancimat method), the composition of fatty acids (FAs) (GC-FID method), antioxidant activity (AA; DPPH method), and antimicrobial properties (disc diffusion method). Capsaicin and the dihydrocapsaicin contents in CP were quantified (HPLC-DAD method) as 1499.37 ± 3.64 and 1449.04 ± 5.14 mg/kg DW, respectively. Oleic acid (C18:1cis n9) dominated in OO (69.70%), OO-CP (69.73%), and RBO-CP (38.97%), while linoleic acid (C18:2cis n6) prevailed in RBO (41.34%), GSO (57.93%), and GSO-CP (58.03%). The addition of CP influenced the FA profile, particularly linoleic acid in OO and RBO, and all FAs in GSO. Peroxide and acid values increased significantly in RBO and GSO upon CP addition, but induction times remained unaffected. The strongest AA (77.00 ± 0.13%) was observed in OO-CP. Cayenne pepper significantly enhanced the antioxidant profiles of all oils compared to the counterparts. However, the antimicrobial activity was weak (≤5.0 mm inhibition zones) against tested microorganisms. These findings support CP as a functional additive for enhancing the nutritional and functional properties of gourmet oils, while highlighting the need for further optimization to improve stability and bioactivity. Full article

The Oxidative Stability Index (OSI) is crucial for evaluating the commercial, nutritional, and sensory properties of extra virgin olive oils (EVOO). Near-infrared spectroscopy (NIRS) offers a rapid and cost-effective alternative to evaluate OSI with respect to traditional methods like Rancimat. This study aimed to develop a robust global NIRS model for predicting OSI in EVOO and compare it with specific models for key Spanish cultivars such as ‘Picual’, ‘Arbequina’, and ‘Sikitita’ (a new, recently released cultivar for commercial hedgerow planting systems). Using NIRS spectra from 1100 to 2500 nm, we analyzed 939 samples globally and developed cultivar-specific models based on 59 ‘Picual’, 84 ‘Arbequina’, and 48 ‘Sikitita’ samples. Partial Least Squares (PLS) regression models demonstrated promising results in all sample sets tested, with the global model outperforming individual yearly models, highlighting the importance of incorporating variability to enhance predictive performance. Log-transformed OSI data improved accuracy across all models. Additionally, discriminant analysis (LDA) was performed on NIRS spectra from five cultivars (‘Arbequina,’ ‘Picual,’ ‘Koroneiki,’ ‘Sikitita,’ and ‘Arbosana’), a total of 254 samples, achieving 96% accuracy in differentiating monovarietal EVOO samples. These findings demonstrate the versatility of NIRS for OSI modeling and cultivar discrimination, making it a valuable tool for breeding programs and quality assessment. Full article

Virgin avocado oil (VAO), treasured for its nutritional and sensory properties, is susceptible to oxidation. To improve its oxidative stability, the feasibility of enrichment with antioxidants from avocado or olive-processing by-products via ultrasound-assisted maceration was explored. Dried, milled avocado (AL), olive leaves (OL), or olive pomace (OP) were ultrasound-macerated with laboratory-extracted VAO at 5, 10, and 20% w/w levels. Induction-period (IP) values, determined via Rancimat (110 °C, 20 L/h), increased by 1.1–1.6-fold. Maceration with AL and OL added pigments (β-carotene, lutein, α-chlorophyll, and α-pheophytin) but only AL significantly boosted α-tocopherol levels (up to 3.7-fold). Extraction of major polar phenols (chlorogenic acid, oleuropein, and hydroxytyrosol) was poor (<42 mg/kg oil). Oleanolic and maslinic acids, from OL and OP, reached up to 650 and 260 mg/kg. The IP values correlated (r = 0.796, p = 0.002) only with total polar phenol content. Maceration with OP resulted in superior antioxidant activity, extending the predicted shelf-life from 14 to 22.3 months, reaching that of a hydroxytyrosol-rich extra-virgin olive oil (24.9 months). GC-MS revealed the dominance of volatile acids in OL- and OP-VAOs, and estragole in AL-VAO highlighting some organoleptic and safety challenges to be considered, particularly when aiming to exploit these materials for the enhancement of the oxidative stability of VAOs to sustain its production. Full article

Biodiesel and biolubricants play strategic roles in green technologies, as they can be produced in biorefineries. The design of industrial facilities is essential to assess the industrial implementation of these processes, with few studies about this subject in the literature. The aim of this work was to produce biodiesel and a biolubricant from waste cooking oil through double transesterification with methanol and trimethylolpropane, obtaining high conversion values (>97 and 98%, respectively). The biolubricant (characterized according to the UNE-14214 standard) had a density of 951 kg·m⁻³, a viscosity of 127 cSt (at 40 °C), an acidity value of 0.43 mgKOH·g⁻¹, flash and combustion points of 225 and 232 °C, and an oxidation stability of 6 h through the Rancimat method. Also, a kinetic study was carried out (at temperatures ranging from 80 to 140 °C and with catalyst concentrations from 0.3 to 0.9% w/w and working pressures from 210 to 760 mmHg) to establish the main kinetic parameters, obtaining a second-order reaction and an activation energy of 17.8 kJ·mol⁻¹. Finally, a conceptual design was included, considering the main components of the facility. Thus, the projected plant worked in a discontinuous regime (producing 2 cubic meters per day), pointing out the feasibility of this plant at an industrial scale. Full article

The choice of antioxidant to be used in the formulation of an oleogel is crucial to determine its oxidative stability and functionality, as these factors can also affect the physical, chemical, and rheological properties of the oleogel. In this study, the effect of two antioxidants (ascorbic acid, AA, and alpha-tocopherol, AT) and their concentration (0.01, 0.02, and 0.03%) on the physical and chemical properties of beeswax and canola oil oleogels were evaluated. The results show that the type and concentration of antioxidants did not affect the thermal properties of the samples, and in FTIR analyses, no noticeable changes in spectra patterns are observed. Rheological analyses showed that the oleogels containing AA exhibited higher elasticity and resistance to deformation. Accelerated oxidative stability tests (storage at 50 °C and the Rancimat test) showed that AA effectively delayed oxidation. The induction time increased by 2.61-fold at higher concentrations, while AT did not significantly affect oxidation resistance. Overall, it was observed that AA improved oleogel firmness and OBC (up to 1.75-fold and 2.8%, respectively), whereas AT resulted in a softer and less stable gel structure. These results show the importance of antioxidant selection, indicating that hydrophilic antioxidants have promising applications in the formulation of beeswax oleogels. Full article