Thermal Stability of Chlorophyll Pigments in Virgin Olive Oil

The control of virgin olive oil (VOO) freshness requires new tools that reflect the diverse chemical changes that take place during the market period. Fluorescence spectroscopy is one of the techniques that has been suggested for controlling virgin olive oil (VOO) freshness during its shelf-life. However, a complete interpretation of fluorescence spectra requires analyzing multiple parameters (chemical, physical–chemical, and sensory) to evaluate the pace of fluorescence spectral changes under moderate conditions with respect to other changes impacting on VOO quality. In this work, four VOOs were analyzed every month with excitation–emission fluorescence spectra. The same samples were characterized with the concentration of fluorophores (phenols, tocopherols, chlorophyll pigments), physical–chemical parameters (peroxide value, K232, K270, free acidity), and sensory attributes (medians of defects and of the fruity attribute). From the six components extracted with parallel factor analysis (PARAFAC), two components were assigned to chlorophyll pigments and those assigned to tocopherols, phenols, and oxidation products were selected for their ability to discriminate between fresh and aged oils. Thus, the component assigned to oxidation products correlated with K270 in the range 0.80–0.93, while the component assigned to tocopherols–phenols correlated with the fruity attribute in the range 0.52–0.90. The sensory analysis of the samples revealed that the changes of these PARAFAC components occurred at the same time as, or even before, the changes of the sensory characteristics.

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Monitoring Carotenoid and Chlorophyll Pigments in Virgin Olive Oil by Visible-Near Infrared Transmittance Spectroscopy. On-Line Application

Journal of Near Infrared Spectroscopy ◽

10.1255/jnirs.368 ◽

2003 ◽

Vol 11 (3) ◽

pp. 219-226 ◽

Cited By ~ 24

Author(s):

A. Jiménez Márquez

Keyword(s):

Olive Oil ◽

Least Squares ◽

Partial Least Squares ◽

Near Infrared ◽

Virgin Olive Oil ◽

Reference Laboratory ◽

Least Squares Regression ◽

Chlorophyll Pigments ◽

Infrared Transmittance ◽

On Line

Visible-near infrared transmittance spectroscopy was used to determine total levels of chlorophyll and carotenoid in virgin olive oil. Calibration models were developed in the laboratory using partial least squares regression. An initial smoothing followed by a first derivative treatment was the best signal correction. The validation set gave a correlation coefficient and standard error of prediction of 0.985 and 0.66 mg kg−1 for carotene totals and 0.993 and 0.96 mg kg−1 for chlorophyll totals. These partial least squares models were used to monitor on-line levels of these compounds during virgin olive oil processing in olive oil mills. The results indicate similarity between both visible-near infrared transmittance spectroscopy and reference laboratory methods.

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Flavored olive oils: focus on their acceptability and thermal stability

Grasas y Aceites ◽

10.3989/gya.0224181 ◽

2019 ◽

Vol 70 (1) ◽

pp. 293 ◽

Cited By ~ 1

Author(s):

M. Issaouia ◽

A. Bendini ◽

S. Souid ◽

G. Flamini ◽

S. Barbieri ◽

...

Keyword(s):

Thermal Stability ◽

Volatile Compound ◽

Oxidation Process ◽

Virgin Olive Oil ◽

Control Sample ◽

Extra Virgin Olive Oil ◽

Sensory Acceptability ◽

Olive Oils ◽

Consumer Test ◽

Thermal Stability Of

The presence of flavored olive oils (FOO) on the market represents an answer to an increasing consumer demand for novel and healthy food. This work aims to compare the sensory acceptability and the thermal stability of FOO prepared by mixing different flavors (lemon, onion, garlic, paprika) to an extra virgin olive oil (EVOO) also used as the control sample. 96 Tunisian citizens were involved in a consumer test and the lemon flavored oil was the most liked whereas the least liked was the oil with onion. Samples were subjected to different heat treatments (60 °C, 100 °C, 200 °C for 1, 2, 4, 8 hours) and the flavor addition did not influence the EVOO stability when samples were heated at 60 °C, whereas at 200 °C the FOO with onion and garlic showed higher oxidative stability. The thermo-oxidation process at 60 °C and at 100 °C of the FOOs was not detrimental for the volatile compound markers but the effect was noticeable for all these markers at 200 °C.

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Pyropheophytin a in Soft Deodorized Olive Oils

Foods ◽

10.3390/foods9080978 ◽

2020 ◽

Vol 9 (8) ◽

pp. 978

Author(s):

Raquel B. Gómez-Coca ◽

Mahmoud Alassi ◽

Wenceslao Moreda ◽

María del Carmen Pérez-Camino

Keyword(s):

Low Temperature ◽

Olive Oil ◽

Virgin Olive Oil ◽

Extra Virgin Olive Oil ◽

Pheophytin A ◽

Chlorophyll Pigments ◽

Refined Olive Oil ◽

Olive Oils ◽

Refining Processes ◽

Chlorophyll Derivatives

Mild refined olive oil obtained by neutralization and/or by soft deodorization at a low temperature and its blending with extra virgin olive oil (EVOO) is not allowed and is difficult to detect. Chlorophyll derivatives, pheophytins and pyropheophytin, and their relative proportions were proposed as parameters to detect such processes. The objective of this study is to determine changes in EVOO, in terms of pheophytins and pyropheophytin, occurring after several well-controlled mild refining processes. The changes on those chlorophyll pigments due to the processes depend on the temperature, stripping gas, acidity and oil nature. The data obtained show that, at temperatures below 100 °C, the rate at which pyropheophytin a is formed (Ra) is lower than the rate at which pheophytins a+a’ disappear (Ra+a’). As a consequence, the Ra+a’ and Ra ratios are considered to be directly linked to pheophytins a+a’ decrease instead of to pyropheophytin a formation. Stripping gas very slightly affects the transformation of the chlorophyll pigments; actually both acidity and N2 enhance the increment in the Ra+a’ and Ra ratios. In relation to the oil nature, the higher the initial pheophytin a+a’ content, the higher the increase in the Ra+a’ and Ra relations.

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Influence of the Neutralization Step on the Oxidative and Thermal Stability of Acid Olive Oil

Journal of Oleo Science ◽

10.5650/jos.58.339 ◽

2009 ◽

Vol 58 (7) ◽

pp. 339-346 ◽

Cited By ~ 3

Author(s):

Kamel Essid ◽

Manef Chtourou ◽

Mahmoud Trabelsi ◽

Mohamed Hédi Frikha

Keyword(s):

Thermal Stability ◽

Olive Oil ◽

Thermal Stability Of

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The Ordered Phase Formation in Ti-Al-Ga Alloys

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100069193 ◽

1970 ◽

Vol 28 ◽

pp. 440-441

Author(s):

Shiro Fujishiro ◽

Harold L. Gegel

Keyword(s):

Thermal Stability ◽

High Temperature ◽

Titanium Alloys ◽

Growth Kinetics ◽

Stoichiometric Composition ◽

Good Potential ◽

Alpha Titanium ◽

Cold Rolled ◽

Kinetics Of ◽

Thermal Stability Of

Ordered-alpha titanium alloys having a DO19 type structure have good potential for high temperature (600°C) applications, due to the thermal stability of the ordered phase and the inherent resistance to recrystallization of these alloys. Five different Ti-Al-Ga alloys consisting of equal atomic percents of aluminum and gallium solute additions up to the stoichiometric composition, Ti3(Al, Ga), were used to study the growth kinetics of the ordered phase and the nature of its interface.The alloys were homogenized in the beta region in a vacuum of about 5×10-7 torr, furnace cooled; reheated in air to 50°C below the alpha transus for hot working. The alloys were subsequently acid cleaned, annealed in vacuo, and cold rolled to about. 050 inch prior to additional homogenization

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Microstructure studies of tungsten silicide schottky contacts on Gaas

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100126445 ◽

1987 ◽

Vol 45 ◽

pp. 328-329

Author(s):

Yih-Cheng Shih ◽

E. L. Wilkie

Keyword(s):

Thermal Stability ◽

Field Effect Transistors ◽

Schottky Contact ◽

Schottky Contacts ◽

Excellent Thermal Stability ◽

Barrier Heights ◽

Gaas Substrates ◽

Film Adhesion ◽

Threshold Voltages ◽

Thermal Stability Of

Tungsten silicides (WSix) have been successfully used as the gate materials in self-aligned GaAs metal-semiconductor-field- effect transistors (MESFET). Thermal stability of the WSix/GaAs Schottky contact is of major concern since the n+ implanted source/drain regions must be annealed at high temperatures (∼ 800°C). WSi0.6 was considered the best composition to achieve good device performance due to its low stress and excellent thermal stability of the WSix/GaAs interface. The film adhesion and the uniformity in barrier heights and ideality factors of the WSi0.6 films have been improved by depositing a thin layer of pure W as the first layer on GaAs prior to WSi0.6 deposition. Recently WSi0.1 has been used successfully as the gate material in 1x10 μm GaAs FET's on the GaAs substrates which were sputter-cleaned prior to deposition. These GaAs FET's exhibited uniform threshold voltages across a 51 mm wafer with good film adhesion after annealing at 800°C for 10 min.

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A preliminary study on the potential of front face fluorescence spectroscopy for the discrimination of Moroccan virgin olive oils and the prediction of their quality

Analytical Methods ◽

10.1039/d0ay01746a ◽

2021 ◽

Author(s):

Hicham Zaroual ◽

El Mestafa El Hadrami ◽

Romdhane Karoui

Keyword(s):

Fluorescence Spectroscopy ◽

Olive Oil ◽

Virgin Olive Oil ◽

Front Face ◽

Virgin Olive Oils ◽

Olive Oils ◽

Preliminary Study

This study examines the feasibility of using front face fluorescence spectroscopy (FFFS) to authenticate 41 virgin olive oil (VOO) samples collected from 5 regions in Morocco during 2 consecutive crop seasons.

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