Dialdehydic Form Of Decarboxymethyl Elenolic Acid Research Articles

Phenolics compounds and temporal perception of bitterness and pungency in extra-virgin olive oils: Changes occurring throughout storage

A mapping of the sensory characteristics of bitterness and pungency and phenol composition of monovarietal virgin olive oils in relation to storage conditions (time and temperature), was undertaken. The two sensory qualities were evaluated by static (descriptive intensity) and dynamic (time–intensity) evaluation methods, to get information on the duration of bitter and pungent sensations and on the intensity variation over the time of duration of the two sensations. Relationships between bitter or pungent sensations and phenolic compounds were measured. Only oleopeurin and ligstroside derivatives were good predictors of two sensations of taste and mouthfeel. Particularly, 4-(acetoxyethyl)-1,2-dihydroxybenzene (3,4 DHPEA-AC) and dialdehydic form of decarboxymethylelenolic acid linked to hydroxytyrosol (3,4 DHPEA-EDA) were good predictors of bitterness and pungency (static and dynamic analysis) under the storage conditions (10 and 28 °C). For the higher of the two temperatures only, the dialdehydic form of decarboxymethylelenolic acid linked to tyrosol ( p-HPEA-EDA), for pungency, and oleuropein aglycone ( p-HPEA-EA), for bitterness and pungency, had relevant predictor power.

Compositional and Tissue Modifications Induced by the Natural Fermentation Process in Table Olives

Olive fruits contain high concentrations of phenols that include phenolic acids, phenolic alcohols, flavonoids, and secoiridoids. The final concentration of phenols is strongly affected by brine conditions. The factors involved in modification by brine are still partially unknown and can include hydrolysis of secoiridoid glucosides and the release of hydrolyzed products. In this study olives from various Italian cultivars were processed by natural fermentation (e.g., without a preliminary treatment of olives with NaOH) using a selected Lactobacillus strain. Processed olives are characterized by a low phenolic concentration of phenols, consisting mainly of phenyl alcohols, verbascoside, and the dialdehydic form of decarboxymethylelenolic acid linked to (3,4-dihydroxyphenyl)ethanol (3,4-DHPEA-EDA), whereas a high level of phenols occurs in olive brine from all the cultivars studied. Olives of the Coratina cultivar, control and with fermentation by Lactobacillus pentosus 1MO, were analyzed in a frozen hydrated state by cryo scanning electron microscopy and energy-dispersive X-ray microanalysis, on both surface and transversal freeze-fracture planes. Structural modifications, found in olives after fermentation, may explain the phenol release in brine.