Quality evaluation of olive oil by statistical analysis of multicomponent stable isotope dilution assay data of aroma active compounds

An instrumental method for the evaluation of olive oil quality was developed. Twenty-one relevant aroma active compounds were quantified in 95 olive oil samples of different quality by headspace solid phase microextraction (HS-SPME) and dynamic headspace coupled to GC-MS. On the basis of these stable isotope dilution assay results, statistical evaluation by partial least-squares discriminant analysis (PLS-DA) was performed. Important variables were the odor activity values of ethyl isobutanoate, ethyl 2-methylbutanoate, 3-methylbutanol, butyric acid, E,E-2,4-decadienal, hexanoic acid, guaiacol, 2-phenylethanol, and the sum of the odor activity values of Z-3-hexenal, E-2-hexenal, Z-3-hexenyl acetate, and Z-3-hexenol. Classification performed with these variables predicted 88% of the olive oils? quality correctly. Additionally, the aroma compounds, which are characteristic for some off-flavors, were dissolved in refined plant oil. Sensory evaluation of these models demonstrated that the off-flavors rancid, fusty, and vinegary could be successfully simulated by a limited number of odorants

SULL'UTILIZZAZIONE AGRONOMICA DELLE ACQUE DI VEGETAZIONE DEI FRANTOI: RISULTATI SPERIMENTALI SU COLTURE ARBOREE

L'utilizzazione in agricoltura di alcuni rifiuti/sottoprodotti industriali ed urbani rappresenta una forma particolare di recupero e di riciclo nella produzione e nel consumo delle merci. Per essere praticabile è necessario soddisfare due esigenze: non può in alcun modo pregiudicare l'ambiente e deve risultare di concreta utilità per l'agricoltura. Per quanto riguarda il primo punto, la normativa vigente appare molto rigida. La valutazione del secondo punto, ovvero dell'utilità in agricoltura, appare meno immediata dal momento che questa si può realizzare in più momenti dell'attività produttiva ed in termini quali-quantitativi diversi nel tempo

Influencia del tiempo de batido de la pasta de aceitunas sobre los rendimientos en aceite y sobre la calidad química y organoléptica del aceite de oliva virgen obtenido con un decanter centrifugo con ahorro de agua.

Experimental tests were carried out to ascertain the influence of malaxation time of olive paste on extraction yields and qualitative characteristics of virgin olive oils obtained by a centrifugal decanter at water saving. Results show that malaxation time has to be no less than 45 minutes to have a satisfactory oil extraction yield. Furthermore, it was ascertained that the malaxation time, protracted up to 90 minutes, does not have influence upon qualitative and organoleptic characteristics of oils. Only the total phenols content of oils changed significantly when the malaxation time of olive paste increased from 15 to 90 minutes. However, in this research has been demonstrated that in some cases the total phenols content of oils increased during the first 30-45 minutes of malaxation and after it diminished. This is due to the variation of total phenols content of vegetable water that in the first time increased and after diminished very quickly. Because of the partition equilibrium law, the total phenols content of oil changed in the same way. Finally, results show that the composition of volatile substances of head-space of oils did not change increasing the malaxation time of olive paste obtained from good quality olive fruits.Se realizaron pruebas experimentales para verificar la influencia del tiempo de batido sobre los rendimientos en aceite y sobre las características de la calidad de los aceites obtenidos con un decanter centrifugo con ahorro de agua. Los resultados conseguidos indicaron que el tiempo de batido no debe ser inferior a 45 minutos para poder obtener rendimientos en aceite satisfactorios. Además, se pudo verificar que la operación de batido, aun siendo prolongada a 90 minutos, no influencia significativamente en las características cualitativas y organolépticas de los aceites. Solo el contenido de fenoles totales en los aceites disminuyó cuando el tiempo de batido fue incrementado de 15 a 90 minutos. Sin embargo, se demostró que en algunos casos el contenido de fenoles totales en los aceites aumentó durante los primeros 15-45 minutos de batido mientras, sucesivamente, disminuyó de acuerdo con los resultados de la literatura. Esto se debe a la variación del contenido de fenoles totales en las aguas de vegetación que anteriormente aumentaron y luego disminuyeron. Debido a la ley del equilibrio de partición, también el contenido de los fenoles totales en sus correspondientes aceites varió de la misma manera. Finalmente, se hace notar que la composición de las sustancias volátiles del espacio de cabeza de los aceites no varia significativamente al variar el tiempo de batido de las pastas de aceitunas de buena calidad