Fast screening of turkish olive oil by NMR spectroscopy for geographical determination and discrimination purposes

Omega-3 Fatty Acids, Lecithin, Sterols, Vitamins and Lipid Oxidation of Olein and Super Olein Fractions of Fish Oil Produced by Winterization

To concentrate omega-3 fatty acids (n-3) in fish oil (FO), olein and super olein fraction (OF) of FO were produced by winterization. For this purpose, FO was slowly cooled to -50°C (24 h), the mixture of crystallized and non-crystallized phases was separated, filtrate was coded as OF (yield 32%), 35% of OF was kept for storage study and analytical purpose, remaining 65% was further slowly cooled down to -75°C (24 h) and filtered, filtrate was coded as super olein (SF, yield 23%). GC-MS analysis showed that unsaturated fatty acids increased due to successive winterization. In OF, C18:1, C18:2, C18:3, C20:1, C20:5 (EPA), C22:1, C22:2 and C22:6 (DHA) increased to 7.85%, 19.52%, 54.16%, 17.82%, 16.31%, 41.02%, 32.43%, and 29.89% than parent FO. In SF, C18:1, C18:2, C18:3, C20:1, C20:5, C22:1, C22:2 and C22:6 increased to 9.84%, 24.35%, 61.09%, 32.10%, 39.96%, 56.81%, 39.02%, and 48.94% than parent FO. Total phenolic contents (TPC) of FO, OF, and SF were 6.59, 12.67 and 19.72 (mgGAE/mL). Lecithin content of FO, OF, and SF were 1.29%, 0.575%, and 0.19%. In SF, desmosterol, cholesterol, stigma sterol and sitosterol were 91.57, 22.51, 12.67 and 112.18 mg/100 g. Total antioxidant capacity (TAC) of FO, OF, and SF was 49.32%, 64.27%, and 85.47%. DPPH values of FO, OF, and SF were 32.14%, 39.87%, and 46.41%. Winterization significantly raised vitamin A and E in OF and SF; vitamin A content in FO, OF, and SF (0-day) were 46.28, 67.94, and 116.48 IU; vitamin E content in FO, OF, and SF (0-day) were 1238.95, 1897.65, and 2375.11 mg/100 g. At 0-day, peroxide value (POV) of FO, OF and SF was 0.22, 0.24 and 0.25 (MeqO2/Kg) with no variation in sensory characteristics. The results of this study proved that n-3 could be increased in olein and super OFs of FO with reasonable oxidative stability.

Fatty Acid Composition, Phenolic Compounds, Phytosterols, and Lipid Oxidation of Single- and Double-Fractionated Olein of Safflower Oil Produced by Low-Temperature Crystallization

By dry crystallization, concentrations of unsaturated fatty acids and bioactive compounds can be increased in olein and super-olein fractions in vegetable oils. Among all sources of vegetable oils, safflower oil (SO) possesses the maximum linoleic acid content. To boost the industrial applications of SO, two variants were produced by single- and two-stage crystallization. This study aimed to determine the fatty acid compositions, phenolic compounds, phytosterols, and oxidative stability of fractionated olein (OF) and double-fractionated olein (DFO) produced by dry crystallization. For this, SO was cooled to -45 °C and filtered, the filtrate was denoted as single-fractionated olein (OF), and 40% of this section was taken for analytical purposes, while the remaining 60% was again cooled to -70 °C and filtered, and the filtrate was denoted as double-fractionated olein (DFO). Unfractionated safflower (SO) was used as a control, filled in amber glass bottles, and stored at 20-25 °C for 90 days. Fatty acid compositions and phytosterols were determined by gas chromatography-mass spectrometry (GC-MS). Phenolic compounds and induction periods were determined by high-performance liquid chromatography (HPLC) and Rancimat. GC-MS analysis revealed that the C18:2 contents of SO, OF, and DFO were 77.63 ± 0.82, 81.57 ± 0.44, and 89.26 ± 0.48 mg/100 g (p < 0.05), respectively. The C18:1 contents of SO, OF, and DFO were 6.38 ± 0.19, 7.36 ± 0.24, and 9.74 ± 0.32 mg/100 g (p < 0.05), respectively. HPLC analysis showed that phenolic compounds were concentrated in the low-melting-point fractions. In DFO, concentrations of tyrosol, rutin, vanillin, ferulic acid, and sinapic acid were 57.36 ± 0.12, 129.45 ± 0.38, 165.11 ± 0.55, 183.61 ± 0.15, 65.94 ± 0.11, and 221.75 ± 0.29 mg/100 g, respectively. In SO, concentrations of tyrosol, rutin, vanillin, ferulic acid, and sinapic acid were 24.79 ± 0.08, 78.93 ± 0.25, 115.67 ± 0.41, 34.89 ± 0.51, and 137.26 ± 0.08 mg/100 g, respectively. In OF, concentrations of tyrosol, rutin, vanillin, ferulic acid, and sinapic acid were 35.96 ± 0.20, 98.69 ± 0.64, 149.14 ± 0.13, 57.53 ± 0.74, and 188.28 ± 0.82 mg/100 g, respectively. The highest concentrations of brassicasterol, campesterol, stigmasterol, β-sitosterol, avenasterol, stigmastenol, and avenasterol were noted in DFO followed by OF and SO. The total antioxidant capacities of SO, OF, and DFO were 54.78 ± 0.12, 71.36 ± 0.58, and 86.44 ± 0.28%, respectively. After the end of the storage time, the peroxide values (POVs) of SO, OF, and DFO stored for 3 months were 0.68, 0.85, and 1.16 mequiv O2/kg, respectively, with no difference in the free fatty acid content.

Exploring the Gas Sensing Potential of Cross-Linked Asphaltene: A Promising Application of an Affordable Material

In recent years, there has been significant research interest in carbon-based nanomaterials as promising candidates for sensing technologies. Herein, we present the first utilization of asphaltenes as an affordable, cost-efficient carbon-based material for gas sensing applications. Asphaltenes, derived from various oil sources, are subjected to facile cross-linking reactions to produce nanoporous carbon materials, where the asphaltene molecules from different layers are interconnected via covalent bonds. The characterization results of these cross-linked asphaltenes revealed substantial enhancement in their specific surface area and surface functionality. Quartz crystal microbalance sensors with sensing films derived from various asphaltene samples were prepared to detect different ethanol concentrations at room temperature. All the cross-linked asphaltene samples showed a significant enhancement in the sensing response (up to 430%) compared to that of their respective raw parent samples. Such a response of the cross-linked asphaltene samples was comparable to that obtained from graphene oxide. The sensor based on cross-linked asphaltenes demonstrated good linearity, with a response time of approximately 2.4 min, a recovery time of around 8 min, and an excellent response repeatability. After 30 days, the sensor based on cross-linked asphaltenes showed approximately 40% reduction in its response, suggesting long-term aging. This decline is partially attributed to the observed swelling. The current study opens the door to a deeper exploration of asphaltenes and highlights their potential as promising candidates for sensing applications.

Nuclear magnetic resonance spectroscopy in extra virgin olive oil authentication

Extra virgin olive oil (EVOO) is a high-quality product that has become one of the stars in the food fraud context in recent years. EVOO can encounter different types of fraud, from adulteration with cheaper oils to mislabeling, and for this reason, the assessment of its authenticity and traceability can be challenging. There are several officially recognized analytical methods for its authentication, but they are not able to unambiguously trace the geographical and botanical origin of EVOOs. The application of nuclear magnetic resonance (NMR) spectroscopy to EVOO is reviewed here as a reliable and rapid tool to verify different aspects of its adulteration, such as undeclared blends with cheaper oils and cultivar and geographical origin mislabeling. This technique makes it possible to use both targeted and untargeted approaches and to determine the olive oil metabolomic profile and the quantification of its constituents.

Assessing the concentration of conjugated fatty acids within pomegranate seed oil using quantitative nuclear magnetic resonance (qNMR)

INTRODUCTION

Pomegranate seed is rich in oil, and seed oil of pomegranate consists of conjugated fatty acids with different percentages.

OBJECTIVES

The current contribution covers how to determine percentages of different isomeric conjugated fatty acids.

METHODS

The percentages of these isomers are analysed by quantitative nuclear magnetic resonance (qNMR) using benzoic acid as an internal reference chemical with a well-defined amount. Linear mathematical equations are developed for the quantitative analysis of fatty acids found in pomegranate seed oil.

RESULTS

The developed approach is utilised for the pomegranate seed oils prepared in the laboratory and tested for commercial samples. Among the oils derived at the laboratory, the Yeni Hicaz pomegranate cultivar seeds yielded the highest fraction of punicic acid. Among the acids, punicic acid was the one with the highest fraction, while linolenic acid was the one with the lowest percentage.

CONCLUSIONS

These results are important in identifying pomegranate seed oils. Among the commercial samples tested with the current approach, only one of them showed similar content analysis as in the laboratory-derived oils.

Geographical Origin Assessment of Extra Virgin Olive Oil via NMR and MS Combined with Chemometrics as Analytical Approaches

Geographical origin assessment of extra virgin olive oil (EVOO) is recognised worldwide as raising consumers’ awareness of product authenticity and the need to protect top-quality products. The need for geographical origin assessment is also related to mandatory legislation and/or the obligations of true labelling in some countries. Nevertheless, official methods for such specific authentication of EVOOs are still missing. Among the analytical techniques useful for certification of geographical origin, nuclear magnetic resonance (NMR) and mass spectroscopy (MS), combined with chemometrics, have been widely used. This review considers published works describing the use of these analytical methods, supported by statistical protocols such as multivariate analysis (MVA), for EVOO origin assessment. The research has shown that some specific countries, generally corresponding to the main worldwide producers, are more interested than others in origin assessment and certification. Some specific producers such as Italian EVOO producers may have been focused on this area because of consumers’ interest and/or intrinsic economical value, as testified also by the national concern on the topic. Both NMR- and MS-based approaches represent a mature field where a general validation method for EVOOs geographic origin assessment could be established as a reference recognised procedure.