In this work, fatty-acid profiles, including trans fatty acids, in combination with chemometric tools, were applied as a determinant of purity (i.e., adulteration) and provenance (i.e., geographical origin) of cosmetic grade argan oil collected from different regions of Morocco in 2017. The fatty acid profiles obtained by gas chromatography (GC) showed that oleic acid (C18:1) is the most abundant fatty acid, followed by linoleic acid (C18:2) and palmitic acid (C16:0). The content of trans-oleic and trans-linoleic isomers was between 0.02% and 0.03%, while trans-linolenic isomers were between 0.06% and 0.09%. Discriminant analysis (DA) and orthogonal projection to latent structure—discriminant analysis (OPLS-DA) were performed to discriminate between argan oils from Essaouira, Taroudant, Tiznit, Chtouka-Aït Baha and Sidi Ifni. The correct classification rate was highest for argan oil from the Chtouka-Aït Baha province (90.0%) and the lowest for oils from the Sidi Ifni province (14.3%), with an overall correct classification rate of 51.6%. Pairwise comparison using OPLS-DA could predictably differentiate (≥0.92) between the geographical regions with the levels of stearic (C18:0) and arachidic (C20:0) fatty acids accounting for most of the variance. This study shows the feasibility of implementing authenticity criteria for argan oils by including limit values for trans-fatty acids and the ability to discern provenance using fatty acid profiling.

Olives affected by active and damaging infestation (olive fruit fly Bactrocera oleae (Rossi)) were assayed for their chemical composition. Biophenols were determined by HPLC, sterols, triterpenic dialcohols, and fatty acids by gas chromatography analysis. The acquired data were statistically analyzed. Oils produced from “Istrska belica” fruit affected by active infestation compared to the oils made from fruit affected by damaging infestation showed higher amounts of total oleuropein biofenols (377.3 versus (vs.) 106.6 mg/kg), total biophenols (755 vs. 377 mg/kg), lignans (85.3 vs. 32.9 mg/kg), the dialdehydic form of decarboxymethyl oleuropein aglycone (DMO-Agl-dA) (148.3 vs. 49.0 mg/kg), its oxidized form (DMO-Agl-dA)ox (35.2 vs. 8.5 mg/kg), the dialdehydic form of oleuropein aglycone (O-Agl-dA) (61.1 vs. 8.0 mg/kg), the dialdehydic form of ligstroside aglycone (L-Agl-dA) (63.5 vs. 28.0 mg/kg), the aldehydic form of oleuropein aglycone (O-Agl-A) (40.6 vs. 8.4 mg/kg), and lower amounts of tyrosol (Tyr) (6.0 vs. 13. 9 mg/kg) and the aldehydic form of ligstroside aglycone (L-Agl-A) (13.8 vs. 40.3 mg/kg). Higher values of stigmasterol (2.99%) and lower values of campesterol (2.25%) were determined in oils affected by damaging infestation; an increase in triterpenic dialcohols was also observed (3.04% for damaging and 1.62% for active infestation). Oils affected by damaging infestation, compared to active infestation, showed lower amounts of oleic acid (73.89 vs. 75.15%) and higher amounts of myristic (0.013 vs. 0.011%), linoleic (7.27 vs. 6.48%), and linolenic (0.74 vs. 0.61%) acids.

The adaptation of autochthonous olive varieties to local soil and climatic conditions can lead to a unique chemical composition and characteristics of olive oils that may differ from the generally accepted quality standards set out in the International Olive Oil Council strategy documents and EU regulations. Therefore, the fatty acid composition, biophenol, tocopherol, sterol and triterpenic dialcohol content and composition of the autochthonous Slovenian olive varieties ‘Buga’, ‘Črnica’ and ‘Drobnica’ were studied for a three-year period with the aim of valorising the characteristics of the three olive varieties. Standardised and accredited analytical methods in accordance with SIST EN ISO/IEC 17025:2017 were applied. The results of the investigation showed that the highest average amount of oleic acid (75.75%) was found in the oils of the ‘Črnica’ variety, followed by the ‘Drobnica’ (72.06%) and the ‘Buga’ (68.73%). All three varieties are a good source of total biophenols (‘Buga’ 616 mg/kg, ‘Drobnica’ 569 mg/kg and ‘Črnica’ 427 mg/kg) and α-tocopherol (‘Buga’ 378 mg/kg, ‘Drobnica’ 279 mg/kg, and ‘Črnica’ 243 mg/kg). ‘Buga’ and ‘Drobnica’ are characterised by high amounts of total sterols, 2468 mg/kg and 2391 mg/kg, respectively, while ‘Črnica’ oils, in comparison, showed a lower average value of total sterols (1351 mg/kg). Due to their exceptional chemical composition, ‘Buga’, ‘Črnica’ and ‘Drobnica’ show great potential for the further cultivation and valorisation of traditional olive oil production in the region, thus contributing to the preservation of biodiversity and local traditions. The quality parameters of olive oil from the autochthonous Slovenian olive varieties ‘Buga’, ‘Črnica’ and ‘Drobnica’ also fulfil the limits for extra virgin olive oil according to the Commission Delegated Regulation (EU) 2022/2104, despite local climatic influences. However, accelerated growth due to climatic changes affecting early harvest can lead to them falling outside these limits, which was observed in particular for the ‘Buga’ variety in terms of the linoleic acid content. This study emphasises the importance of timing the harvest to achieve optimum maturity and meet EU quality standards, taking into account the genetic makeup of the varieties and their response to the current climatic conditions.

Main text: This Supplementary Comparison, EURAMET.QM-S15 "PAHs in Protein Matrix", was organized by the Federal Institute of Metrology METAS. The target analytes were four PAHs: benz[a]anthracene (BaA); benzo[a]pyrene (BaP); benzo[b]fluoranthene (BbF); and chrysene (Chr), for which maximum limits are set in the European and Swiss food legislation. The measurands were the mass fractions (µg/kg) of these PAHs in a protein-rich matrix. Six National Metrology Institutions (NMIs) and Designated Institutes (DIs) participated in EURAMET.QM-S15. The study required solvent extraction, separation of the target analytes from interfering matrix components (clean-up), analytical/chromatographic separation and selective detection of the target analytes. Solvent extraction (ASE, PLE, HUPsSE, QuEChERS) followed by SPE cleanup was applied by the participants in the sample pretreatment and GC-IDMS/MS, GC-HR-IDMS and LC-FLD were applied for separation and detection. The results for the determination of the four PAHs in EURAMET.QM-S15 ranged from 0.5 µg/kg to 5.3 µg/kg for BaA, 0.6 µg/kg to 13.3 µg/kg for BaP, 0.6 µg/kg to 7.0 µg/kg for BbF and 0.5 µg/kg to 5.0 µg/kg for Chr. Due to poor extraction efficiencies, as a result of unfavorable choice of solvent and insufficient demonstration of metrological traceability of the calibrant, only the results of two participants were included in the evaluation of the Supplementary Comparison Reference Value (SCRV). The SCRV was assigned using the weighted mean of these two participants which agreed well with gravimetrically prepared mass fractions and evidence from an ancillary study performed with external expert laboratories. Four participant results were excluded from the SCRV for the technical reasons mentioned above. The SCRV (X ± u(X)) was 3.291 µg/kg ± 0.079 µg/kg for BaA, 4.28 µg/kg ± 0.10 µg/kg for BaP, 4.77 µg/kg ± 0.12 µg/kg for BbF and 2.967 µg/kg ± 0.070 µg/kg for Chr. The two institutes that were included in the assignment of consensus SCRV agreed within their standard uncertainties. Successful participation in EURAMET.QM-S15 demonstrates the following measurement capabilities in determining the mass fractions of organic compounds, with a molecular mass between 150 g/mol and 500 g/mol, having a low polarity (pKow < -2), in a mass fraction range from 0.1 µg/kg to 100 µg/kg in a high protein food matrix. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Monografija obsega pregled znanja na področju prilagoditve oljk na sušne razmere ter pregled tehnologij namakanja oljk. Res je, da je oljka manj zahtevna vrsta, saj lahko uspeva v izjemno skeletnih tleh in je zelo dobro prilagojena na pomanjkanje vode v njih, a kljub fiziološkim prilagoditvam, lahko sušne razmere negativno vplivajo na rast, razvoj in pridelek oljk. Sušni stres lahko pri oljkah blažimo z deficitnim namakanjem. Deficitni način namakanja je oblika nadgradnje namakanja, saj z nadzorovanim primanjkljajem vode zagotovimo kakovost pridelka, obstoj rastline ter hkrati zmanjšamo porabo vode in energije. Deficitni način namakanja, temelji na načelu, da obrok vode dodamo takrat, ko ga rastlina najbolj gospodarno uporabi. Pri tem je ključnega pomena poznavanje rastlinske vrste, njenih anatomskih in morfoloških značilnosti, fizioloških prilagoditev na sušo, biokemijski odziv na stresne dejavnike in s tem vpliv na kakovost plodov in olja. Poleg tega je potrebno tudi poznavanje dejavnikov, ki vplivajo na pridelovalne sposobnosti oljk, kot so lastnosti tal s svojimi vodno zadrževalnimi sposobnostmi ter dostopna voda v tleh. Ob skrbnem upoštevanju potreb rastline in okoljskih razmer z ustreznim delovanjem namakalnega sistema lahko dosežemo usklajeno razmerje med kakovostjo in količino pridelka o hkratnem varovanju potencialov naravnih virov.