Cultivar influence on variability in olive oil phenolic profiles determined through an extensive germplasm survey.

Despite the evident influence of the cultivar on olive oil composition, few studies have been devoted to exploring the variability of phenols in a representative number of monovarietal olive oils. In this study, oil samples from 80 cultivars selected for their impact on worldwide oil production were analyzed to compare their phenolic composition by using a method based on LC-MS/MS. Secoiridoid derivatives were the most concentrated phenols in virgin olive oil, showing high variability that was significantly due to the cultivar. Multivariate analysis allowed discrimination between four groups of cultivars through their phenolic profiles: (i) richer in aglycon isomers of oleuropein and ligstroside; (ii) richer in oleocanthal and oleacein; (iii) richer in flavonoids; and (iv) oils with balanced but reduced phenolic concentrations. Additionally, correlation analysis showed no linkage among aglycon isomers and oleocanthal/oleacein, which can be explained by the enzymatic pathways involved in the metabolism of both oleuropein and ligstroside.

Development and application of a quantitative method based on LC-QqQ MS/MS for determination of steviol glycosides in Stevia leaves.

Stevia is a currently well-known plant thanks to the presence of steviol glycosides, which are considered as sweeteners obtained from a natural source. In this research, a method based on LC-MS/MS by using a triple quadrupole detector was developed for quantitation of 8 steviol glycosides in extracts from Stevia leaves. The ionization and fragmentation parameters for selected reaction monitoring were optimized. Detection and quantitation limits ranging from 0.1 to 0.5ng/mL and from 0.5 to 1ng/mL, respectively, were achieved: the lowest attained so far. The steviol glycosides were quantified in extracts from leaves of seven varieties of Stevia cultivated in laboratory, greenhouse and field. Plants cultivated in field presented higher concentration of steviol glycosides than those cultivated in greenhouse. Thus, the way of cultivation clearly influences the concentration of these compounds. The inclusion of branches together with leaves as raw material was also evaluated, showing that this inclusion modifies, either positively or negatively, the concentration of steviol glycosides.

Characterization of refined edible oils enriched with phenolic extracts from olive leaves and pomace.

Refined edible oils (viz., oils from maize, soya, high-oleic sunflower, sunflower, olive, and rapeseed) enriched at two concentration levels (200 and 400 µg/mL total phenolic content) with phenolic extracts isolated from olive pomace and leaves have been characterized and compared with nonenriched oils and extra virgin olive oil (EVOO). Enriched oils were analyzed by LC-TOF/MS to generate representative fingerprints and compared with nonenriched oils and EVOO by unsupervised principal component analysis (PCA). The two raw materials reported enriched oils with profiles which were compared with those provided by EVOOs. Correlation analysis enabled us to establish the enriched oils with a composition more similar to EVOO. Discrimination according to the enrichment level depended on the raw material for extracts, and a global discussion about the enrichment on relevant phenolic compounds present in EVOO has reported quantitative results concerning the enrichment level for those significant compounds with known nutraceutical properties.