Bioaccessibility of carotenes from carrots: Effect of cooking and addition of oil

Food processing and occurrence of dietary lipids are believed to be important and limiting factors for carotenoid bioavailability in humans. In the present study the isolated and combined effects of household cooking and addition of olive oil on the bioaccessibility of carotenes from carrots have been investigated. Although thermal treatment during cooking showed to have a negative impact on the carotenoid content, a positive effect on the micellarisation of carotenes and therefore on their bioaccessibility was found. Carotenes transferred to the digests were micellarised to a higher extent from cooked carrots (52%) than from crude carrots (29%). Addition of olive oil to carrot samples during cooking and before application of the in vitro digestion model had a marked positive effect on the release of carotenes, although the design of the model did not allow the correct estimation of this effect. The higher amounts of micellarised carotenes (80%) were found in the digest prepared from cooked carrots containing 10% olive oil. In general, the inclusion of olive oil during cooking increased the carotenoid extraction and micellarisation in a dose-dependent fashion. Although β-carotene and α-carotene were affected in a similar way by the cooking process, α-carotene appeared to be more efficiently incorporated into the micelles when olive oil was added to the samples. In conclusion, both processing and mainly lipid content (cooking oil in this case) significantly improve carotenoid bioaccessibility from carrots, and therefore may increase bioavailability in humans.Industrial relevanceThe consumption of carotenoid-rich foods such as fruits and vegetables has been associated with a decrease of the risk of developing certain types of degenerative and chronic diseases. Processing of food and the interaction of carotenoids with lipophilic food components or ingredients may modify the amount of the released pigment from the food matrix, and therefore potentially increase or decrease their bioavailability. For this purpose, in the present study we have investigated the effects of cooking and presence of olive oil on the release of carotenes from carrots (as a model food) and their incorporation into absorbable micelles, the bioaccessibility. From the industrial point of view, a better understanding of the factors governing the release of carotenoids and other active components from vegetable foods is of great importance with the aim of optimising the manufacturing processes.     

Pigments composition in monovarietal virgin olive oils from various sicilian olive varieties

This paper presents the first investigation of the chlorophyll and carotenoid pigments composition in sicilian monovarietal virgin olive oils from the three (Cerasuola, Nocellara, Biancolilla) main olive varieties cultivated in Sicily (Italy). In all, 19 compounds were identified and quantified in 24 olive oil samples. The application of reversed-phase liquid chromatography with photodiode array detection using a C-30 column in the simultaneous qualitative–quantitative analysis of virgin olive oils pigments, has been shown. The qualitative pigment pattern was similar among the varieties investigated, whereas quantitative differences were found among the different cultivars, which can all be considered as having an high pigment content. Pheophytin a, was the major component (19.36–25.04 ppm), followed by β-carotene (8.06–16.27 ppm). Pheophytin a′ (2.92–4.17 ppm), lutein (2.28–4.49 ppm) and neoxanthin (1.54–2.11 ppm) were also well represented. The presence of carotenoid esters was also detected. The neoxanthin and β-carotene contents were higher compared to reports present in the literature for other olive oil varieties. This may be due to genetic factors and/or geographical differences. The ratio between the two isochromic pigment fractions, namely the chlorophyll and the carotenoid fractions, was around one in all varieties, showing that they were in balance. The lutein/β-carotene ratio was less than one in all cases. These parameters, along with other analytical parameters, could be used as indicators of typicality in olive oils. The presence of a specific pigment profile in olive oils could in fact be used to guarantee the genuineness of the product, since the quality control of food requires a precise knowledge of the pigments composition of the original products.     

Chemical stability of extra-virgin olive oil added with oregano essential oil

Extra virgin olive oil is highly consumed and well known for its nutritional and health benefits. However, it is fatty food highly susceptible to lipid oxidation. The objective of this study was to evaluate the preserving effect of oregano (Origanum vulgare L. spp vulgare called "oregano compacto") essential oil on physical and chemical properties in extra virgin olive oil during storage. Oregano essential oil composition was analyzed by GC-MS. This essential oil was added into extra virgin olive oil at 0.05%. The samples were stored in 3 different conditions: darkness, light exposure, and temperature (60 °C). Chemical indicators of lipid oxidation (peroxide value, p-anisidine value, conjugated dienes, free fatty acidity, and carotenoid and chlorophyll contents) were measured. High content in carvomenthol (22.52%), terpinolene (19.77%), thymol (13.51%), and γ-terpinene (10.30%) were detected in oregano essential oil. Olive oil samples without oregano essential oil stored at 60 °C and exposure at artificial light had the highest peroxide values during storage. Higher p-anisidine and K232 values after day 7 of storage were detected in temperature, darkness, and light exposure treatments. Light treatment was the main factor that degraded chlorophyll causing loss of color. The highest chlorophyll content (3.87 mg/kg) was observed in olive oil with essential oil at the end of storage. In general, olive oil samples added with oregano essential oil had lower peroxide, conjugated dienes, and p-anisidine values and higher chlorophyll and carotenoid contents during storage. Oregano essential oil retards lipid oxidation process in olive oil prolonging its shelf life. PRACTICAL APPLICATION: Oregano essential oil was and is used with the purpose of flavoring and aromatizing food. This essential oil due to its composition has shown antioxidant activity. Synthetic antioxidants such as butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA) are thought to be promoters of carcinogenesis. Extra virgin olive oil is widely consumed because of its nutritional benefits and sensory properties which are very important to be preserved in the product. In this study, the oregano essential oil showed remarkable antioxidant activity in olive oil. Therefore, this essential oil could be considered for the industry as natural antioxidant not only to be used in olive oil but also in other fatty food products to substitute synthetic ones.     

Pigment profile and colour of monovarietal virgin olive oils from Arbequina cultivar obtained during two consecutive crop seasons

Monovarietal virgin olive oils are labelled with the olive varieties giving them their distinctive character. There are numerous studies focussed on the characterisation and quantification of the minor fractions of virgin olive oils that have generated databases on varietal olive oils. However, few studies have focussed on the components of the pigment fraction of virgin olive oils. The aim of this work was to quantify the components of the chlorophyll and carotenoid fractions of the monovarietal virgin olive oils from the Arbequina cultivar, growing in the Spanish area of Catalonia, during two consecutive crop seasons. Additionally the pigment changes occurring during 24 months of oil storage were evaluated. The results of this study showed minor qualitative differences between monovarietal virgin olive oils from two consecutive seasons. The quantitative differences could be attributed to the harvest period in each season rather than to the year’s weather conditions. Storage of the monovarietal virgin olive oils probably caused an important loss of the chlorophyll fraction, mainly chlorophyll a, during the first 6 months of storage. On the other hand, the carotenoid fraction was very stable and the retention of provitamin A was close to 80%, even after 24 months of storage.     

Chlorophyll and Carotenoid Composition in Virgin Olive Oils from Various Spanish Olive Varieties

A study of chlorophyll and carotenoid composition of nine single-variety virgin olive oils from the main Spanish producing regions has shown differences depending on variety and ripening degree of the fruits. Pheophytin a was the major pigment in all the oils studied (44–58% total pigments), followed by lutein (18–38%) and β-carotene (6–17%). The chlorophyll pigments group also included pheophytin b and in some cases chlorophylls a and b . The carotenoid fraction also included the xanthophylls neoxanthin, violaxanthin, luteoxanthin, antheraxanthin, mutatoxanthin and β-cryptoxanthin. The mean provitamin A activity of the oils was 260 μg kg⁻¹ expressed as retinol equivalent. cis -α-Carotene (tentative), mono- and di-esterified xanthophylls and pheophorbide a were pigments exclusive to Arbequina variety, a fact that could be used as a chemo-taxonomic differentiator of the oils of this variety. The ratio between the chlorophyll fraction and the carotenoid fraction was maintained in most cases around 1, demonstrating that the green and yellow fractions were in balance, notwithstanding their greater or lesser total pigment content. The considerable range in the lutein/β-carotene ratio (between 1·3 and 5·1 depending on variety) makes this ratio a differentiator of single-variety oils. Despite the different sources of the oils, some general trends have been shown which suggest what chlorophyll and carotenoid pigments should be expected in an olive oil so as to include it within the denomination ‘virgin’.     

Influence of rosemary (Rosmarinus officinalis, L.) on plant sterol oxidation in extra virgin olive oil

The objective of this study was to investigate the potential role of rosemary compounds in inhibiting the plant sterol oxidation in extra virgin olive oil during heating. The stability of plant sterols was measured by quantification of plant sterol and sterol oxide formation upon 6 h of heating in both the extra virgin olive oil and its respective oil at 10% rosemary concentration (ROE). The total sterol and sitosterol oxide contents were determined by GC-flame ionization detection (GC-FID) and GC-MS techniques, respectively. Heating experiments were carried out at 180 degrees C for 0, 1, 3 and 6 h. The total sterol content in the extra virgin olive oil was 255 mg/100 g and that in the ROE 270 mg/100 g. Sitosterol was the most abundant sterol in both samples (50% of total sterol). The ROE showed a lower content of sitosterol oxides with respect to the extra virgin olive oil during heating: after 6 h of heating only 6.1% of sitosterol oxides were formed, while up to 11.5% of sitosterol oxidized in the extra virgin olive oil. Our findings suggested that rosemary compounds were able to counteract the oxidation of plant sterols in the extra virgin olive oil during heating, preventing formation of potentially harmful compounds to human health.     

Stability of avocado oil during heating: Comparative study to olive oil

The stability of the saponifiable and unsaponifiable fractions of avocado oil, under a drastic heating treatment, was studied and compared to that of olive oil. Avocado and olive oil were characterised and compared at time 0 h and after different times of heating process (180 °C). PUFA/SFA (0.61 at t = 0) and ω-6/ω-3 (14.05 at t = 0) were higher in avocado oil than in olive oil during the whole experiment. Avocado oil was richer than olive oil in total phytosterols at time 0 h (339.64; 228.27 mg/100 g) and at 9 h (270.44; 210.30 mg/100 g) of heating. TBARs was higher in olive oil after 3 h, reaching the maximum values in both oils at 6 h of heating treatment. Vitamin E was higher in olive oil (35.52 vs. 24.5 mg/100 g) and it disappeared earlier in avocado oil (at 4 vs. 5 h). The stability of avocado oil was similar to that of olive oil.     

Composition and stability of olive oil following partial crystallization

Extra virgin olive oils were separated into two fractions, one being liquid at 4 °C and one solid. Each of the oils and their associated fractions underwent analysis for fatty acid composition, analysis of the total antioxidant activity and stability towards oxidation when heated at 150 °C. The solid fraction contained greater amounts of saturated fatty acids, although analysis of the fatty acids on position 2, obtained via a pancreatic lipase treatment, showed similar total levels of unsaturated fatty acids for all fractions. Analysis of the antioxidant components showed that there was a higher proportion associated with the liquid fractions. This trend, in combination with the results of the heating trials of the oils and associated fractions, indicated that the liquid fraction was not more susceptible to oxidation. Hence it is possible to fractionate olive oil to give fractions with onset of melting differing by some 10 °C without compromising stability towards oxidation.     

The influence of phenolic extracts obtained from the olive plant (cvs. Picual and Kronakii), on the stability of sunflower oil

Summary The phenolic compounds of olive cultivars (Picual and Kronakii) were extracted. The total phenolic content of the extracts was estimated and their ability to reduce the oxidation of sunflower oil was tested at 100 °C by using a Rancimat^®. The fruits, leaves and pomaces were extracted separately with ethanol. Portions of the fruits were crushed to produce an oil/aqueous mixture, which was separated and the two fractions further processed. The oil fraction was extracted with 60% aqueous methanol and was separated further, by the method of Dabrowski & Sosulski (1984 ), into three major fractions. These contained mainly free phenols, soluble phenolic esters or bound phenolic acids, respectively. The phenolic concentrations were measured in all the fractions and were in accordance with expected amounts. When tested at 100, 200 or 400 ppm for their ability to stabilize sunflower oil the results showed that the vast majority of the anti‐oxidant activity found in the ‘total phenols’ fraction was because of a ‘free phenolic’ group. The free phenolics, at a 400‐ppm level, exhibited remarkable anti‐oxidant activity and were superior to that of butylated hydroxy toluene (BHT) in retarding sunflower oil oxidative rancidity. The mode of action is discussed.     

Microwave heating of different commercial categories of olive oil: Part I. Effect on chemical oxidative stability indices and phenolic compounds

The effect of microwave heating of extra virgin olive oil (EVOo), olive oil (Oo) and pomace olive oil (Po) in domestic appliances, was investigated in terms of chemical oxidative indices (peroxide, p-anisidine and Totox values), free acidity, water content, total phenol content and different classes of phenolic compounds.     

Comparative study of the effect of the maturation process of the olive fruit on the chlorophyll and carotenoid fractions of drupes and virgin oils from Arbequina and Farga cultivars

Two varieties of olive fruit (Arbequina and Farga) have been characterized by their contents and types of chlorophyll and carotenoid pigments during the olive ripening. Independently of the initial content, the pigment concentrations decreased with fruit maturity. Chlorophyllides a and b, esterified xanthophylls and α-carotene were only detected in Arbequina fruits. Moreover, the synthesis of esterified xanthophylls, when the skin fruit colour changed from green to turning-colour only, was observed in this variety. The pigments transferred from fruit to the oil were also studied. All the pigments that were found in the fruit were transferred to the oils, in addition to derivative pigments associated with acidic medium in the oil extraction process. The destruction of the chlorophyll fraction was greater than of the yellow pigments during the olive oil extraction process.     

酶处理对初榨橄榄油品质及抗氧化活性的影响

将纤维素酶、果胶酶应用于橄榄油提取工艺,旨在生产具有较高总酚含量及较强抗氧化活性的高质量初榨橄榄油。随着果胶酶和纤维素酶添加量的提高,橄榄油的过氧化值及K_(232)均出现下降的趋势,油酸比例有一定程度提高,并在添加0.2%纤维素酶时油酸比例达到最高(65.85%)。结合主成分分析,确定了在油橄榄融合过程中添加0.5%纤维素酶得到的初榨橄榄油总酚含量和抗氧化活性最高。这是由于果胶酶和纤维素酶能有效降解橄榄细胞壁,减少亲水酚类物质与细胞壁多糖的络合,有助于橄榄果皮中的游离酚的释放,从而提高橄榄油中总酚含量及抗氧化活性。     

Oxidative changes in hazelnut,olive, soybean,and sunflower oils during microwave heating

The effects of microwave heating for 3, 6, and 9 min at a frequency of 2450 MHz on fatty acid composition, tocopherols, iodine value, free fatty acids (%), peroxide value, conjugated dienes and trienes, and hexanal contents of refined hazelnut, soybean, sunflower, and virgin olive oils were investigated. A significant (p < 0.05) decrease was observed in linoleic and linolenic acids contents of soybean oil during exposure to microwave heating. Tocopherol contents of oil samples significantly decreased (p < 0.05) during microwave heating. Free fatty acids of the samples slightly increased and iodine value showed reduction throughout the process. Conjugated dienes contents of samples showed an increasing trend up to the 6 min, followed by a reduction at 9 min. Conjugated triene fatty acids of all the samples significantly increased (p < 0.05) throughout the application. While peroxide value showed increasing trend up to the 3 min and sharply decreased at 9 min, hexanal contents of refined hazelnut, virgin olive, soybean, and sunflower oils increased 63, 28, 55, and 389 fold, respectively, after 9 min exposure to microwave heating. Kinetic analysis of data showed that the reaction orders for peroxide and hexanal formation were zero and first order, respectively, and in the tested oils the reaction rate followed the order: soybean oil ? sunflower oil ? hazelnut oil ? virgin olive oil for peroxide, and sunflower oil ? soybean oil ? hazelnut oil ? virgin olive oil for hexanal formation. It was concluded that hexanal could be considered as a parameter for evaluation of the quality of oils exposed to microwave heating.     

食品加工条件对于产品反式脂肪酸含量的影响

选取食用油-橄榄油、大豆油和棕榈油,模拟日常烹饪体系,采用气相色谱法分析加热和煎炸情况下食用油中反式脂肪酸的种类和含量。试验结果表明,食用油单独加热情况下,加热温度、时间和循环加热次数影响食用油中反式脂肪酸的种类和含量,高温、长时间加热、反复加热均会使反式脂肪酸的含量有所增加。煎炸情况下,在一定温度范围和加热时间内,食用油的反式脂肪酸的含量增加并不明显。因此,普通的烹饪过程中,应注意减少高温加热时间、避免食用油的反复使用。     

Pigments in Greek virgin olive oils: occurrence and levels

Fifty‐two samples of virgin olive oil from various regions of Greece were examined for the presence and levels of chlorophyll and carotenoid pigments using normal phase liquid chromatography and spectrometry. Pheophytin α (Pheo α) was the main pigment in all the oils examined (>10 mg kg^?1 in more than 70% of samples). Two pheophytin α derivatives (peaks A and B), eluted close to Pheo α, may potentially be used to examine handling conditions and length of storage of oil until analysis. Analysis of 25 Greek commercial oils obtained from retail stores verified the above observations. Chlorophyll α may be present in a virgin olive oil just after production. Its absence should not be exclusively attributed to cultivar characteristics or extraction conditions, since pheophytinisation occurs rapidly. Lutein content varied between 0.2 and 3.9 mg kg^?1 and β‐carotene content from 0.4 to 5.1 mg kg^?1. The lutein/β‐carotene ratio was characteristic (<1) for samples from Koroneiki, the major Greek cultivar for oil production. The total Pheo α (Pheo α + peak A + peak B)/total carotenoid (lutein + β‐carotene) ratio ranged between 2 and 11 owing to prevailing green hues. This ratio may be used as an indicator of oil typicality along with other analytical parameters. © 2001 Society of Chemical Industry     

Effect of microwave heating on the migration of dioctyladipate and acetyltributylcitrate plasticizers from food-grade PVC and PVDC/PVC films into olive oil and water

Migration of dioctyladipate (DOA) and acetyltributylcitrate (ATBC) plasticizers from plasticized Polyvinylchloride (PVC) and polyvinylidene chloride (PVDC/PVC (Saran) films into both olive oil and distilled water during microwave heating has been studied. The plasticizer migrating into olive oil and water was determined using an indirect GC method after saponification of the ester-type plasticizer (DOA or ATBC) and subsequent collection of the alcohol component of the ester, namely: 2-ethyl-1-hexanol and 1-butanol, respectively. Migration was dependent on heating time, microwave power setting, the nature of the food simulant and the initial concentration of the plasticizer in the film. Migration of DOA into olive oil reached equilibrium after heating for 10 min at full power (604.6 mg DOA/1). Migration into distilled water was 74.1 mg/1 after 8 min of microwave cooking at full power. The amount of ATBC migrating into olive oil reached equilibrium after heating for 10 min at full power (73.9 mg ATBC/1). Migration into distilled water was 4.1 mg/1 after heating at full power for 8 min. Control samples containing olive oil gave DOA migration values which were significantly higher than the upper limit for global migration (60 mg/1) set by the European Community. It is proposed that PVC should not be used in direct contact with food in the microwave oven, while Saran may be used with caution in microwave heating and reheating applications, avoiding its direct contact with high fat foodstuffs.     

Use crude olive leaf juice as a natural antioxidant for the stability of sunflower oil during heating

Olive leaves (Kronakii cultivar) were obtained from the annual pruning of olive trees and pressed to obtain a crude juice. Aliquots from the concentrated crude olive leaf juice, representing 400, 800, 1600 and 2400 ppm as polyphenols, were added to sunflower oil. Samples of sunflower oil mixed with olive leaf juice were heated intermittently at 180 ± 5 °C for 5 h day^?1 and the heating process was repeated for five consecutive days. A control experiment was performed where butylated hydroxyl toluene (BHT) at 200 ppm was added to sunflower oil prior to intermittent heating in order to compare the antioxidant efficiency between the natural polyphenolics of olive leaf juice and synthetic antioxidant BHT. Some physical and chemical constants for the unheated and heated sunflower oil were determined. The data indicate that the addition of olive leaf juice to sunflower oil heated at 180 °C induced remarkable antioxidant activity and at 800 ppm level was superior to that of BHT in increasing sunflower oil stability.     

Analytical evaluation of two monovarietal virgin olive oils cultivated in the south of Tunisia: Jemri‐Bouchouka and Chemlali‐Tataouin cultivars

BACKGROUND: The characterisation of virgin olive oils from two Tunisian cultivars, growing in the Tataouin zone, namely Jemri‐Bouchouka, a rare olive cultivar, and Chemlali‐Tataouin, was carried out. Several analytical parameters were evaluated; these include quality index, fatty acids, phenolic, chlorophyll, carotenoid, squalene, α‐tocopherol compositions and oxidative stability. RESULTS: Jemri‐Bouchouka olive oil had the highest value of oleic acid (74.50%) while Chemlali‐Tataouin was characterised by a high percentage of palmitic acid (14.75%), which makes this oil freeze at a low temperature. On the other hand, Jemri‐Bouchouka oil was characterised by a low phenolic and α‐tocopherol content (267.72 mg GAE kg^?1 and 278.34 mg kg^?1, respectively). Ten phenolic compounds were identified. The main phenols found in the two olive oils were oleuropein aglycon and pinoresinol. All phenolic compounds showed significant correlations with oxidative stability. CONCLUSION: The analytical parameters of virgin olive oil that were determined in this study were greatly influenced by cultivar. © 2012 Society of Chemical Industry     

Influence of fruit ripening process on the natural antioxidant content of Hojiblanca virgin olive oils

The effect of fruit ripeness on the antioxidant content of `Hojiblanca' virgin olive oils was studied. Seasonal changes were monitored at bi-weekly intervals for three consecutive crop years. Phenolic content, tocopherol composition, bitterness index, carotenoid and chlorophyllic pigments and oxidative stability were analysed. In general, the antioxidants and the related parameters decreased as olive fruit ripened. The phenolics and bitterness, closely related parameters, did not present significant differences among years. Although in general, the tocopherols decreased during olive ripening γ-tocopherol increased. Differences between crop years were found only for total tocopherols and α-tocopherol, which showed higher content in low rainfall year oils. The pigment content decreased during ripening, chlorophyll changing faster. For low rainfall years, the level of pigments was higher, reaching significant differences between yields. Significant differences among years were found for oil oxidative stability; higher values were obtained for drought years. A highly significant prediction model for oxidative stability has been obtained.     

Lipid and protein oxidation in microsomal fraction from turkeys: influence of dietary fat and vitamin E supplementation

The objectives of this study were to investigate the effects of dietary fats (6% soya oil or rapeseed oil or tallow) and α-tocopheryl acetate supplementation (30 ppm for control and 200 ppm for supplemented animals), on lipid and protein oxidation, induced by Fe(3+)/ascorbate, of microsomal fraction in turkey muscles (M. pectoralis major and M. sartorius). Supplementation of turkeys with α-tocopheryl acetate increased the vitamin E content of microsomal membranes. Vitamin E supplementation strongly decreased lipid oxidation in membranal fractions when animals were fed rapeseed oil or tallow; this effect was less pronounced in animals fed soya oil. Vitamin E supplementation induced a slight decrease in protein carbonyl content, especially in animals fed soya oil. Level of protein free thiols was considerably enhanced in diet enriched with soya oil. Vitamin E supplementation had a stabilizing effect on glucose-6-phosphatase activity of microsomes when oxidized by Fe(3+)/ascorbate. No muscle effect was detected on the level of lipid and protein oxidation in membranal fractions even if M. sartorius is known to be more oxidative than M. pectoralis major.