The chemical parameters and oxidative resistance to heat treatment of refined and extra virgin Moroccan Picholine olive oil (original) (raw)
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How Heating Affects Extra Virgin Olive Oil Quality Indexes and Chemical Composition
Journal of Agricultural and Food Chemistry, 2007
Two monovarietal extra virgin olive oils from Arbequina and Picual cultivars were subjected to heating at 180°C for 36 h. Oxidation progress was monitored by measuring oil quality changes (peroxide value and conjugated dienes and trienes), fatty acid composition, and minor compound content. Tocopherols and polyphenols were the most affected by the thermal treatment and showed the highest degradation rate although their behavior was different for each cultivar. R-Tocopherol loss was more important in Arbequina oil whereas, total phenol content loss was greater in Picual oil. The later showed an important decrease in hydroxytyrosol (3,4-DHPEA) and its secoiridoid derivatives (3,4-DHPEA-EDA and 3,4-DHPEA-EA), while lignans decrease was lesser. For Arbequina oil these compounds remained stable, and a lowering tendency was observed for tyrosol (p-HPEA) and its derivatives (p-HPEA-EDA and p-HPEA-EA). In general, flavone content showed a decrease during heating, being higher for Arbequina oil. On the other hand, oleic acid, sterols, squalene, and triterpenic alcohols (erythrodiol and uvaol) and acids (oleanolic and maslinic) were quite constant, exhibiting a high stability against oxidation. From these results, we can conclude that despite the heating conditions, VOO maintained most of its minor compounds and, therefore, most of its nutritional properties.
Effect of Refining and Thermal Processes on Olive Oil Properties
Journal of Agricultural Science and Technology, 2016
Olive cultivars Bladi and Arbequina were collected and their oil was extracted (cold press). Oil was refined under bleaching and deodorization conditions for 30 minutes at 55-50°C and their property was compared with the virgin olive oil. Virgin and refined oils of the cultivars were processed by fryer heating at 180°C (intervals of 0, 1, 2, 4, and 8 hours) and indexes of fatty acid, free fatty acid, peroxide, thiobarbituric acid, polar compounds, conjugated dienes and trienes, Rancimat, color, total polyphenol, tocopherol, chlorophyll and carotenoid were compared. Results showed that these oils mainly contained oleic (48.69-60.18%), palmitic (18.31-27.02%), linoleic (7.54-18.58%), palmitoleic (3.9-3.08%), stearic (1.78-2.53%), and linoleic acids (1.87-0.22%). According to the results, it was recommended to refine virgin olive oil by mild bleaching and deodorization to save bioactive compounds. Due to the heating condition, the relative amounts of unsaturated fatty acids (22.37-50.6...
Effect of cooking on olive oil quality attributes
Food Research International, 2013
Virgin olive oil consumption, as final seasoning or within cooked foods, is increasing worldwide, mainly due to its recognized nutritional benefits. However, the maintenance of its quality and health attributes after thermal processing is frequently questioned. The aim of this article was to provide a careful review of published studies on the assessment of olive oil thermal processing, in order to ascertain the optimal settings for maximization of olive oil quality, while delaying the onset of oxidation products with detrimental health impacts. Through the selection of a particular olive grade, such as extra-virgin, virgin or refined olive oil, distinct starting compositions may be achieved, particularly regarding bioactive and antioxidant compounds, with a direct effect on thermal performance and nutritional value of cooked foods. Furthermore, different cooking practices, from common frying to boiling and including microwave cooking, along with operating conditions, as time, temperature and food amounts, undoubtedly modify the olive oil chemical profile. According to the compiled studies, in order to preserve virgin olive oil bioactive components heating time should be reduced to the minimum. Nevertheless, olive oil performance under prolonged thermal processing is usually equal or superior to other refined vegetable oils, due to its balanced composition regarding both major and minor components. However, as most of its bioactive components, including phenolic compounds, are gradually loss, it is economically advantageous to use lower olive oil grades and frequent replenishment under prolonged thermal processing. Future studies dealing with thermal degradation paths of minor olive oil components and their implication in human health will be of particular value to further clarify this issue.
Journal of Food Chemistry and Nutrition, 2016
Four olive oils with varying amounts of total phenols were exposed to four different heating conditions. Chemical parameters such as free fatty acid, peroxide values, UV absorbency, total phenols, individual phenols, α-tocopherol, squalene, oleocanthal, fatty acid profile and smoke point were measured before and after heating to evaluate the impact of heating conditions on the oils. We found olive oils have reasonably high smoke point that is suitable for typical home-cooking conditions and fresh olive oil with low FFA and high phenolics are important for the conservation of olive oil quality and health benefits. A larger degree of oxidation occurred as with increase of heating time and temperature, oils with high level of phenols produced less polar compounds than oils with lower levels of phenols, including refined oils. A significant amount of total phenols and individual phenols such as oleocanthal remained after heating at 121 °C for 10 and 20 minutes, most of squalene stay in...
Journal of Chemistry
The use of olive oil with cooking purposes, as final seasoning or within cooked foods is increasing worldwide due to its numerous nutritional and health benefits. These attributes are mainly determined by olive oil chemical composition, which can be altered after thermal processing, oxidation processes, or incorrect practices. For this reason, and due to the numerous factors which have influence in olive oil quality, the correct chemical characterization is highly relevant. In this study, fatty acid composition of four extra virgin olive oil (EVOO) varieties was studied. The major fatty acid (FA) determined was oleic acid (77.1% on average), followed by palmitic (11.5% on average). In addition, thermal oxidation behaviour of the four EVOO samples was studied as an indicator of their quality and stability during thermal processing. This was performed through differential scanning calorimetry (DSC) from a temperature of 40°C at six different heating rates in the range of 0.5–10°C min−...
Effects of sunlight, temperature and adulteration on the quality of the virgin olive oil
The Moroccan Picholine olive variety shows performance against climate stress and environmental constraints. The virgin olive oil is exposed to extraction conditions, storage and commercialization that could alter its quality. Among the factors involved by these conditions there are; sunlight, temperature and adulteration. The objective of the present work was to evaluate the impact of such factors on the quality of the virgin olive oil extracted from the Moroccan Picholine variety. So, we have determined characteristic parameters of the quality of the virgin olive oil (VOO) like water content (WC), peroxide index (PI), acid index (AI) and density (D) according to sunlight, temperature and adulteration effects. 25 samples of VOO from the «Moroccan Picholine» cultivar in two areas in Morocco (Demnat Virgin Olive Oil and Tagzirt Virgin Olive Oil) have been studied using chemical analytical methods and pycnometry. VOO from the two Moroccan areas (DVOO and TVOO) presents low peroxide index when it is stored 15 days in obscurity. Concerning water content (WC), peroxide index (PI), acid index (AI) and density (D) parameters, a similar behavior has been observed between the two virgin olive oils (VOOs). The evolution of oils according to temperature was also evaluated. The samples were slowly heated until the temperatures of 25, 40, 55, and 70 °C. For, each VOO sample, each one of these four temperatures was maintained 10 mn. The same analyses were carried out on VOO adulterated by Refined Olive Oil (ROO). The sunlight promotes oxidation in DVOO and TVOO so that the PI Index increased but has no significant effect on the AI and the density. The WC at 25°C in TVOO is greater than the one in DVOO. In the case of heated oil, water content in DVOO, TVOO and ROO decreases progressively with temperature. The olive oil stored in darkness is affected by temperature since it makes the PI increasing from 14.6 to 19.9 O2 meq/kg in TVOO and from 16.9 to 19.9 O 2 meq/kg in DVOO. DVOO and TVOO present a considerable decreasing of PI when they are adulterated by ROO. AI values of TVOO are higher than those of DVOO and decrease after adding ROO, especially below 10% of ROO. Heating makes AI increasing in oils and the heated oil the greatest AI is TVOO. A consistent result has been recorded in the case of the sunlight effect on the value of AI in TVOO whose acid index was 0.51% in the darkness and 0.73% at sunlight. Globally, virgin olive oil density increases according to the temperature and to the adulteration by refined olive oil.
DergiPark (Istanbul University), 2022
Objectives: Olive oil is very valuable oil with the components it contains. It is often preferred in healthy nutrition menus. The antioxidants and fatty acids it contains make this oil valuable. Methods: In this study, total antioxidant capacity was determined with spectrophotometer in eight riviera olive oils and eight extra virgin olive oils in different brands sold in the markets. Total antioxidant capacity and fatty acid compositions were determined in eight olive oil samples taken from the producers. Fatty acid compositions determined with gas chromatographymass spectrometry/flame ionization detector (GC-MS/FID). Results: As a result, when three olive oils were compared, the highest total antioxidant capacity was determined in olive oils (4.146±0.062 mM trolox equiv./L.) purchased from producers. The highest amount of oleic (72.39±0.02%) was detected in the chromatographic analyses of coldpressed pure olive oils. Conclusion: This research has proven once again that olive oil is a healthy food. In particular, the total antioxidant capacity of untreated pure olive oils is remarkable.
Changes in the Biochemical Composition of the Tataouine Virgin Olive Oils During Thermal Oxidation
沙漠研究: 日本沙漠 …, 2009
An experimental investigation was carried out to evaluate the quality of virgin olive oils from varieties (Chemlali Tataouine, Fakhari Douirat, Zarrazi Douirat, and Dhokar Douirat) grown in the harsh conditions of the arid region of Tataouine, using accelerated oxidation and deep frying studies at 180 ˚C from 0 to 10h. The experimental data showed the resistance of the studied oils to the oxidation especially Chemlali Tataouine and Zarrazi Douirat who maintained their high stability and their natural biophenol contents during 2.5 and 5h, respectively, under frying temperature. A positive correlation was observed between the induction time and the total polar phenol contents during the thermal oxidation. The capacity of the heated and unheated oils to quench the free radicals has been also studied.
Oxidative stability of olive oil during the thermal process: Effect of Pistacia khinjuk fruit oil
International Journal of Food Properties, 2017
The oxidative stability of refined olive oil with incorporated Pistacia khinjuk fruit oil (PKFO; 0.5%, 1%, 2%, 5%, and 10%) during thermal processing at 170ºC for 8 h was evaluated. The conjugated diene values, carbonyl values, acid values, oil/oxidative stability indices, and total tocopherol content were measured during thermal processing. Olive oil containing 0.5% PKFO was identified as the most oxidative stable oil followed by oils containing 100 ppm TBHQ and 1, 5, 10, and 2% PKFO. No significant difference between samples of olive oil containing 100 ppm TBHQ and 1% PKFO was observed. Thus, it was concluded that PKFO at levels lower than 1% could provide stronger antioxidation activity in comparison with TBHQ (the strongest syntactic antioxidant used in the food industry). Moreover, reduction in tocopherol compounds during thermal processing was higher in olive oil containing TBHQ as compared to those in pure olive oil.
A spectroscopic and chemometric study of virgin olive oils subjected to thermal stress
Food Chemistry, 2011
The paper describes a study of thermal stress of three different samples of virgin olive oil in terms of oxidative stability. Fatty acid composition, evaluation of oxidative stability under forced conditions (OSI), determination of UV-spectrophotometric oxidation indexes (k 232 and k 270 ) and spectral properties were explored along the thermal treatment. The samples were subjected to heating treatment at 180°C and evaluated after 0, 30, 60, 90, 120, 150 and 180 min. Middle infrared (MIR) and visible-near infrared (Vis-NIR) spectra were elaborated by partial least squares modelling to individualise regions and bands where critical variations were present. Two bands were found as principal influential ones (1245-1180 cm À1 and 1150-1030 cm À1 ) on MIR while one primary region was identified on Vis-NIR (2200-1325 cm À1 ).