Evaluation of virgin olive oil bitterness by quantification of secoiridoid derivatives

Abstract

The bitterness of the main compounds identified in the phenolic extract of virgin olive (Olea europaea L.) oils has been sensory-tested. The aldehydic form of oleuropein aglycone (AOA) was responsible for this attribute. Correlations between the sensory bitterness and concentrations of secoiridoid derivatives, analyzed separately or in different combinations, were obtained for olive oils from different olive varieties. The best correlation obtained corresponds to AOA content (r = 0.96; P = 1.83 × 10 −17 ) in the concentration range of 0.03 to 0.5 mmol/kg. AOA concentrations ≥0.5 mmol/kg produce sensory saturation of this attribute. The correlation with AOA concentration was better than that with the absorbance of the phenolic extract at 225 nm. Therefore, the equation obtained allows the evaluation of the bitterness in virgin olive oils by HPLC analysis of the phenolic extract using detection at 280 nm.Paper no. J10590 in JAOCS 81, 71-75 (January 2004).

Phenolic Molecules in Virgin Olive Oils: a Survey of Their Sensory Properties, Health Effects, Antioxidant Activity and Analytical Methods. An Overview of the Last Decade Alessandra

“…It was concluded that the peaks corresponding to the 3,4-DHPEA-EDA, 3,4-DHPEA-EA and p-HPEA-EDA were those mainly responsible for the bitter taste of VOO. As previously reported, Mateos et al [135] verified the better correlation between the aldehydic form of oleuropein aglycon and bitterness.…”

“…In 1992 Gutiérrez et al [134] proposed an analytical method for measurement of bitterness, based on solid phase extraction (SPE) of phenols and their spectrophotometric detection at 225 nm; this parameter termed IB or index of bitterness, was highly correlated to the sensory intensity of bitterness and is still the most widely used for its determination. Some years later, Mateos and co-workers [135] showed that several non-bitter phenolic compounds could also absorb at 225 nm; consequently, they asserted that this index was not appropriate for comparing bitterness of VOO obtained from blend of olive varieties characterized by very different phenolic profiles (e.g. Picual and Arbequina).…”

“…As already discussed, several authors have associated some phenols with bitterness, thus obtaining models and relationships between individual phenols separated by HPLC and bitterness intensity [135,138,140]. In these reports, bitterness was measured by a panel test or calculated from K 225 values.…”

LC‐DAD/ESI‐MS/MS study of phenolic compounds in ash (Fraxinus excelsior L. and F. americana L.) heartwood. Effect of toasting intensity at cooperage

“…Isoligstroside was also identified in leaves of Fraxinus griffithii [13] and F. malacophylla. [26] Phenylethanoid glycosides Ten compounds (16,19,20,23,25,44,45, 49, 51 and 53) have been identified as phenylethanoid glycosides. Among them, peaks 19 and 23 were identified as verbascoside and isoverbascoside, respectively, by comparing them with the reference standard.…”

Oxidation of oleuropein studied by EPR and spectrophotometry

“…Among the phenolic components, the secoiridoid oleuropein glucoside is the principal biophenol commonly found in Olea europaea fruits and leaves, while it is also present in virgin olive oil, together with its respective aglycone and the decarboxylated dialdehyde derivative [3]. The aldehydic form of oleuropein seems to be responsible for the bitterness of virgin olive oil [4].…”