Rapid Determination of Olive Oil Chlorophylls and Carotenoids by Using Visible Spectroscopy

The determination of total chlorophylls and total carotenoids in olive oil by using visible spectroscopy (VIS) is reported. The proposed technique has been compared with the determination of these pigments by near infrared spectroscopy (NIRS) and VIS together with NIRS. Several procedures for multivariate regression were tested. The reference methods used were the determination of the extinction coefficient K670 for total chlorophylls and K470 for total carotenoids. A total of 258 samples were tested. The optimization of the calibration for total chlorophylls was set by using multiple linear regression (MLR) from the wavelengths 670¿686 nm exclusively visible. Its satisfactory performance was proven from the model coefficients standard error of calibration SEC 2.63 and R2 0.97, and the residual predictive deviation (RPD) 5.76 from the external validation. For the total carotenoids the best VIS calibration was fit by using the window of 465¿475 nm and partial least squares (PLS), which provided an RPD of 3.68. However, the model built using the entire spectrum VIS-NIRS available (350¿2,500 nm) was slightly better for this last pigment, showing an RPD of 3.86. Hence, this study showed that the proposed VIS technique can be advantageous for the determination of total chlorophylls in olive oils while it is also suitable for determining total carotenoids.The authors are indebted to the Junta de Andalucía (project AGR-6456) for its financial support, and gratefully acknowledge Antonio Montero, of the Instituto de Recursos Naturales y Agrobiología (CSIC) for his technical assistance. Our thanks are also due to the group Quality and Purity of Oils, of the Instituto de la Grasa (CSIC), for the use of the chromatographic equipmentPeer Reviewe

Pacifica: Poetry International: Revolutions in Tunisian Poetry

A collection of contemporary poetry from Tunisia, including poems in translation with their French and Arabic original texts

La postcosecha de aceituna de molino

The greatest deterioration of olive oil is due to poor handling of the olives during the time between harvesting and processing. Storage of olive fruits is carried out by simple heaping in fruit piles, waiting their processing. These fruits develop all kinds of degenerative processes in a short period of time. Oils obtained from them show characteristics hydrolytic and oxidative deteriorations confirmed by their high acidity values, peroxide value or ultraviolet absorbance at 232 and 270 nm. To avoid this situation, the industry is currently reducing the interval between harvesting and processing, through an increase in milling capacity. However, the equipment necessary for preventing the accumulation of fruit in January would be unnecessary for the rest of the season. In this chapter, refrigeration of the olive fruits, or the use of physical treatments, to allow the processing of unripe fruits, are analysed as possible alternatives.El mayor deterioro del aceite de oliva es debido a la inadecuada manipulación de las aceitunas durante el tiempo que media entre su cosecha y su procesado. El almacenamiento de las aceitunas se lleva acabo mediante el simple amontonamiento del fruto, esperando su procesamiento. Estos frutos desarrollan toda clase de procesos degenerativos en un corto periodo de tiempo. Los aceites obtenidos a partir de estos frutos exhiben deterioros hidrolíticos y oxidativos característicos, confirmados por sus valores altos de acidez, de índice de peróxidos o de absorbancia en la región ultravioleta a 232 y 270 nm. Para evitar esta situación, la industria intenta reducir al máximo el intervalo entre la cosecha y el procesado del fruto, mediante un aumento de la capacidad de molturación. Sin embargo, el equipo necesario para prevenir la acumulación de fruto en Enero no se precisa para el resto de la campaña. En este capítulo, la refrigeración de las aceitunas o el uso de tratamientos físicos, que permiten el procesado de frutos poco maduros, son analizados como alternativas posibles.Peer reviewe

Reduction of virgin olive oil bitterness by fruit cold storage

8 pages, 1 figure, 6 tables.-- PMID: 18937491 [PubMed].-- Printed version published on Nov 12, 2008.Green mature olives (Olea europaea L. cv. ‘Manzanilla’, ‘Picual’, and ‘Verdial’) were stored at 5 °C, and the oil extracted from them showed a middle intensity level of sensory-evaluated bitterness. The storage times necessary for this reduction were different for the three varieties tested, requiring 4, 6, and 8 weeks, respectively, for ‘Manzanilla’, ‘Picual’, and ‘Verdial’ olives. The level of commercial quality of the extracted oil did not deteriorate as a consequence of previous fruit storage. Olives matured during refrigeration at 5 °C, as the increase of maturation index and the decrease of color index and fruit firmness indicated. Similarly, as the fruit storage period progressed, the total phenolic compound content of the extracted oils decreased. Although the use of green mature olives may require a more prolonged storage time, it allows for a better postharvest handling of the fruits, which are more resistant to physical damage or fungal infections than the riper ones.The authors are grateful to the Project Citrisaude SP5.P120/03 of the Program Interreg IIIA of the European Community for their financial support.Peer reviewe

Effect of Temperature, Modified Atmosphere and Ethylene During Olive Storage on Quality and Bitterness Level of the Oil

6 pages, 4 tables.-- Printed version published Mar 2009.Mill olives (Olea europaea L. cv. ‘Lechín’), harvested at the green mature stage of ripening, were stored for 72 h under six different storage conditions: in air, in a closed container, and in a closed container with 30 ppm ethylene either at 20 or at 40 °C. The use of 40 °C as the fruit storage temperature reduced oil bitterness, regardless of the atmosphere applied; however, it also induced a significant reduction in stability and pigment content of the oil extracted. At 20 °C, mill olives stored under air supplemented with 30 ppm ethylene engendered oils with middle bitterness intensity, whereas the oils obtained from fruit stored similarly, but without ethylene, or in an open container exhibited a strong intensity of this sensory attribute. Fruit respiration in the closed containers caused a CO2 accumulation and an O2 decrease in the storage atmosphere. This CO2 concentration was increased by the previous ethylene addition, but O2 presence did not suffer an additional reduction. The use of modified atmospheres in fruit storage induced off-flavor development in the oils extracted, producing a significant reduction in the overall grading of their sensory quality.The authors are grateful to the Project Citrisaude SP5.P120/03 of the Program Interreg IIIA of the European Community for their financial support. The authors also gratefully acknowledge M.C. Martínez for technical assistance and Sociedad Agraria de Transformacion N-1941 Santa Teresa de Osuna for supplying the olive fruit.Peer reviewe

Reduction of oil bitterness by heating of olive (Olea europaea) fruits

Olives (Olea europaea) of the Manzanilla and Verdial varieties, harvested at the green mature stage of ripening, were heated at 30, 40, 45, and 50 °C during 24 h and at 40 °C during 24, 48, and 72 h, respectively. Just after treatments, oils were physically extracted from the olives. Olive heating promotes a reduction of oil bitterness in direct relationship to the time and temperature used. Fruit heating at ≤40 °C during 24 h did not produce significant changes of acidity, UV absorption, peroxide index, panel test score, or oxidative stability of the obtained oils. Both longer treatments at 40 °C and heating at >40 °C yielded oils with less oxidative stability. Oils obtained from olives heated at ≥40 °C showed higher concentrations of chlorophylls and carotenes. For each olive variety, a good correlation between oil bitterness and content of hydroxytyrosol secoiridoid derivatives was found.This work was supported by research project OLI96-2159-C02-01 (CICYT).Peer reviewe