Composition and organoleptic characteristics of oil from Arbequina olive (Olea europaea L) trees under deficit irrigation

This study evaluated the effects of different regulated deficit irrigation (RDI) strategies applied to olive (Arbequina cultivar) trees on the qualitative and quantitative parameters of the resulting oil during the maximum evaporative demand period for three consecutive crop seasons. Quality indices, fatty acid composition, pigments, colour, α‐tocopherol and phenolic contents, bitter index, oxidative stability and organoleptic properties of the oil were determined. Irrigation did not affect those parameters used as criteria for classifying olive oil in its commercial grades. Only polyphenol and o‐diphenol contents and, consequently, the bitter index and oxidative stability were affected by the RDI strategy, with increasing values as the water applied decreased. Regulated deficit irrigation resulted in important savings in irrigation requirements without detriment to oil quality. © 2002 Society of Chemical Industry     

Changes in volatile compounds and oil quality with malaxation time of Tunisian cultivars of Olea europea

While there has been considerable work examining the effect of malaxation time on different characteristics of olive oils, there have been few that deal with all the major aspects. Here, the influence of malaxation time was evaluated using major local Tunisian (cv. Chemlali and Chetoui) cultivars. Standard characteristics were measured as well as detailed analyses of volatile compounds were conducted. Headspace solid‐phase microextraction (HS‐SPME) was applied to the analysis of volatile compounds of virgin olive oils from Chemlali and Chetoui varieties with differing malaxation time. Twenty‐seven compounds were characterised by GC‐FID and GC–MS. Compounds belonging mainly to alcohols, esters, aldehydes, ketones and hydrocarbons chemical classes characterized the volatile profile. Significant differences in the proportion of volatiles from oils of different malaxation time were detected. The results suggest that besides genetic factors, malaxation time influences volatile formation. The main variables that were affected by malaxation time were the total amount of phenols and composition of the volatile compounds. At malaxation time of 30 min, Chemlali and Chetoui olive oils presented the highest total phenol content (244.19 and 877.63 mg kg^?1, respectively), while the lowest content was observed at 60 min from regardless of cultivars. In turn, this influenced the oxidative stability and peroxide value. It was also clear that the cultivars behaved differently and this prevented general conclusions being made for all of the quality characteristics.     

应用固相微萃取气相色谱测定毛织物中的挥发性有机化合物

毛织物试样剪碎后置于饱和NaCl溶液中经40℃超声处理后,采用100μm聚二甲基硅氧烷(PDMS)作为固相微萃取技术(SPME)装置的固相涂层,通过顶空固相微萃取气相色谱(HS-SPME-GC-MSD)法测定了织物样品中的9种挥发性有机化合物(VOCs).该方法给出了相应的检测限量和适用范围,织物样品中9种VOCs的检测限量均低于0.001 mg/kg,回收率在96.8%～103.7%之间.     

Analysis of volatile compounds in L. edodes blanched by hot water and microwave

The comprehensive flavour characterisation and volatile compounds of raw L. edodes, hot water blanching (HB) sample and microwave blanching (MB) sample were comparatively analysed by electronic nose technology and headspace solid‐phase micro‐extraction combined with gas chromatography‐mass spectrometry (HS‐SPME‐GC‐MS). Results indicated that volatile components in L. edodes markedly changed after HB and MB. Volatile compounds of raw L. edodes consisted mainly ketones, sulphide and alcohols, and 3‐octanone, as well as 1‐octen‐3‐one, were the major compounds. The content of ketones and sulphides in blanched samples markedly decreased, while the relative content of aldehydes, hydrocarbons and esters increased, which became the major volatile compounds of treatment samples. In addition, the percentage contents of esters, alcohols and sulphides in MB samples were significantly (P < 0.05) higher than that in HB samples, especially 1‐octen‐3‐ol, which contributes more to mushroom flavour. Therefore, MB is a better pretreatment method of L. edodes processing and cooking according to the results of experiment.     

Pesticide residues in washing water of olive oil mills: effect on olive washing efficiency and decontamination proposal

BACKGROUND: Washing olives in the olive oil mill (a commonly used preliminary step to remove foreign materials and leaves) can help to remove pesticide residues, especially herbicides that are present in olives due to contamination either during application or as a consequence of contact with contaminated soil. The aim of the present work was the study of washing efficacy during washing cycles, i.e., from the beginning of the cycle until the water was changed. RESULTS: Four active ingredients, namely diuron, oxyfluorfen, terbuthylazine and endosulfan (α and β isomers) as well as the latter's degradation product endosulfan sulfate, were the most frequently found pesticides in raw olives after harvest. At the beginning of the washing cycle, diuron, terbuthylazine and oxyfluorfen residues were effectively removed from olives. However, progressive water contamination with pesticide residues decreased the efficiency of the washing step, specially for diuron and terbuthylazine residues. CONCLUSION: A decontamination method to enable water recycling in olive oil mills was proposed and optimized. It employed FeCl₃ as coagulant and active charcoal as adsorbent, and was effective in removing both suspended solids and pesticide residues. Copyright © 2008 Society of Chemical Industry     

Changes in volatile compounds of peanut oil during the roasting process for production of aromatic roasted peanut oil

The changes in volatile compounds composition of peanut oil during the roasting process of aromatic roasted peanut oil (ARPO) production were investigated. The analyses were performed by gas chromatography-mass spectrometry combined with headspace solid phase microextraction (HS-SPME/GC-MS). Among the volatiles identified in ARPO, the N-heterocyclic chemical class possessed the highest relative percentage area (RPA) 61.68%, followed by O-heterocyclic group with an RPA of 24.57%. Twenty pyrazines were considered to be the key contributors to the intense nutty/roasty flavor typical of ARPO. Compounds that increased significantly in concentration during the roasting process were mainly Maillard reaction products, as well as compounds derived from Strecker degradation and lipid peroxidation. The results clearly showed that the roasting process was necessary to obtain the typical nutty/roasty aroma of ARPO. PRACTICAL APPLICATION: ARPO is the traditional edible oil in China that possesses a characteristic strong nutty and roasty flavor that distinguishes it from other edible vegetable oils. During the production, the roasting process is the crucial factor for the formation of the typical roasted peanut aroma that plays an important role in sensory quality of peanut oil. In our investigation, not only the volatile changes of peanut oil pressed from relevant peanut seeds roasted at different roasting time were determined, but also the contributions of identified volatiles on the typical nutty/roasty flavor of ARPO were discussed. Our work clearly demonstrated the significant effect of roasting process on the typical flavor formation of ARPO. The results are valuable as scientific guidance for the roasting process that better satisfy demands of the peanut oil industries for better flavor.     

Influence of olive storage period on volatile compounds and oil quality of two Tunisian cultivars of Olea europea,Chemlali and Chetoui

Olives (Olea europaea cv. Chemlali and Chetoui) used for oil production were stored, in plastic containers, at 5 °C for four different periods (0–3 weeks) before oil extraction. After storage, the oils were extracted from the fruits, and the acidity, peroxide value, coefficients of specific extinction at 232 and 270 nm, stability, pigments, total phenols, fatty acids, and volatile compounds were determined. The results showed that storage of fruits produced losses in the olive oil quality. During storage, a marked decrease in total phenols content was observed. The cultivar richer in phenols (862.16 mg kg^?1 in Chétoui) had a lower loss (25%). On the contrary, in Chemlali olive oil, the starting value of 728.52 mg kg^?1 decreased to 469.25 mg kg^?1, with a loss of 35%. Chétoui and Chemlali olive oils presented the highest oxidative stability before storage (58.76 and 47.05 h, respectively), while the lowest values were recorded using olives stored for 3 weeks (54.46 and 43.43 h, respectively). The changes in the volatile bouquet were determined using headspace solid phase microextraction (HS‐SPME). Thirty compounds were characterised by GC–FID and GC–MS. Compounds belonging mainly to alcohols, esters, aldehydes, ketones and hydrocarbons chemical classes characterised the volatile profiles.     

Effect of pan-frying in extra-virgin olive oil on odour profile, volatile compounds and vitamins

Changes in odour of Arauco (ARA) and Arbequina (ARB) extra-virgin olive oil (OO) were monitored during frying by electronic nose (EN) and solid-phase microextraction–gas chromatography methodologies. Degradation of α- and γ-tocopherols was monitored by HPLC. Electronic nose data and volatile compounds were analysed at intervals of 15 min ( t ₁₅) during 60 min of frying ( t ₆₀). α- and γ-tocopherols were determined at intervals of 5 min ( t ₅) during 30 min of frying ( t ₃₀). Principal components analysis applied to EN data showed one component, PC₁ which accounted 96.6% of the total odour variation. SnO₂ sensors had a positive correlation with PC₁. ARA variety corresponding to frying t ₆₀ had the highest positive correlation with PC_1. Analysis of variance results for volatile compounds showed an increase on production for: 3-methyl butanal, n -pentanal, n -hexanal, n -heptanal and n -nonanal at 15 min of frying for ARB OO and at 30 min for ARA OO. α-tocopherol and γ-tocopherol showed an important decrease after the first 5 min of frying for ARB OO and at 15 min for ARA OO.     

Design of volatile organic compounds profiles of roasted Coffea arabica extracts produced by supercritical and conventional solvents

This work addresses the potential of supercritical fluid extraction (SFE) to design volatile organic compounds (VOCs) profiles using roasted Coffea arabica. On the whole, 57 VOCs were identified by HS-SPME/GC–MS. A full factorial design was adopted to study the effect of pressure (180 and 300 bar), temperature (40 and 80 °C) and ethanol content (0 and 5 wt.%). The total extraction yield ranged from 1.4 wt.% to 9.8 wt.%. At 180 bar and 80 °C, two extracts exhibited VOCs amount up to 3.5 times higher than the dichloromethane extract. Temperature and pressure favoured VOCs amount and total yield in conflicting ways, and ethanol had a negligible effect on VOCs amount. At 180 bar and 80 °C, the VOCs profile revealed a reinforcement of pyrroles, phenols, cyclopentenes and pyrans, at the expense of pyridines, carboxylic acids and furans. Hence, this essay evidences the potential of SFE to engineer coffee VOCs profiles.     

Characterisation and accumulation of squalene and n‐alkanes in developing Tunisian Olea europaea L. fruits

The present investigation was carried out for the analysis of hydrocarbon compounds of Tunisian Meski olives. The hydrocarbon fraction of the oils was found to contain twelve n‐alkanes (C₂₂–C₃₆) and squalene. Results from the quantitative characterisation of the oils revealed that squalene was the most abundant hydrocarbon compound, at all development stages of Meski olive, accounting for more 92% of total hydrocarbons. Pentacosane (C₂₅), heptacosane (C₂₇) and tricosane (C₂₃) represented the major compounds of n‐alkanes. The highest accumulation of n‐alkanes and squalene was observed at early stages of olive development [before 21st week after the flowering date (WAFD)]. The greatest decrease of these components occurred between 21st and 26th WAFD of the olives. At complete maturity of the fruit, the level of squalene and total n‐alkanes was 126.52 and 9.13 mg per 100 g oil, respectively. Hence, the content of n‐alkanes and squalene was remarkably influenced by the ripeness process of olive.     

The effects of a seaweed extract in addition to nitrogen and boron fertilization on productivity,fruit maturation,leaf nutritional status and oil quality of the olive (Olea europaea L.) cultivar Koroneiki

BACKGROUND: There is not adequate literature on effects of seaweed extracts (SWE) on yield and nutritional status of olive trees as well as olive oil quality. In this work, a study of the effects of a seaweed extract applied foliarly (0.5% v/v) in addition to soil application of N (500 g NH₄NO₃ per tree) and B (150 g borax per tree) on productivity, fruit parameters, nutritional status and olive oil quality of a Greek olive cultivar was performed. RESULTS: In contrast to the trees treated with N (NH₄NO₃) or N + B (NH₄NO₃ + borax), the additional application of seaweed extract (treatments N + SWE and N + B orax + SWE) increased the productivity and oil content and accelerated maturation of the olive fruits. In particular, the best results concerning productivity, oil content and earliness of maturity (colour and firmness) were observed in the trees treated with N + B + SWE. The additional application of SWE also increased K, Fe and Cu concentrations and reduced the concentrations of Mn in olive leaves compared to the corresponding treatments without SWE. Total phenol concentration in oil was minimized in all fertilization treatments but, particularly, the additional application of SWE did not affect it. The application of N + B + SWE led to a significant increase in linolenic as well as oleic acid concentrations, and to a decline in palmitoleic, stearic and linoleic acid concentrations in olive oil. CONCLUSION: The fertilizer treatments of this experiment and especially the combination of NH₄NO₃ + borax + SWE should be recommended for the studied olive orchards, in order to increase tree productivity and improve their nutrition status and various olive oil quality parameters. Copyright © 2009 Society of Chemical Industry     

Influence of free fatty acids, sterols and phospholipids on volatile compounds in olive oil headspace determined by solid phase microextraction-gas chromatography

In order to study the influence of some polar compounds, naturally present in virgin olive oils (VOOs), on the volatiles release, the volatiles-free olive oil matrix was enriched with free fatty acids (FFA) (concentration range from 0.35 to 1.40 g/100 g), sterols (1.0–2.5 g/kg) and phospholipids (1.6–6.0 g/kg). Sixteen standards of VOO aroma compounds were dissolved in thus obtained olive oil matrices. Volatile compounds were analysed by headspace solid phase microextraction with DVB/CAR/PDMS fibre and gas chromatography with flame ionization detection. Evaluation of the data by statistical analysis revealed that FFA, sterols and phospholipids, in concentration ranges considered in this study, generally did not significantly influence the determination of VOO volatiles. The most important changes occurred in the release of the three alcohols (Z-2-penten-1-ol, 1-hexanol and E-3-hexen-1-ol) and 3-methylbutyl acetate which slightly decreased upon the increase of FFA concentration.     

L‐Phenylalanine ammonia‐lyase activity and concentration of phenolics in developing olive (Olea europaea L cv Arbequina) fruit grown under different irrigation regimes

Changes in L ‐phenylalanine ammonia‐lyase (PAL, EC 4.3.1.5) activity and total phenolic, ortho‐diphenolic and fat contents of olive flesh in response to different irrigation treatments applied to olive tree cv Arbequina were studied during fruit ripening. Results indicate that the fat content of olive flesh at harvest was not affected by irrigation, although olives from the most heavily irrigated treatment reached their final fat content (dry weight) earlier than those from other irrigation treatments. PAL activity and phenolic content, expressed on a dry weight basis, decreased during fruit development and were affected by irrigation, being lowered as the water supplied increased. Good correlations were established between PAL enzymatic activity and the polyphenol and ortho‐diphenol contents of olive flesh, indicating that PAL is involved in the phenolic metabolism of olive fruit. The phenolic content of the oil depends on the PAL activity in the fruit, which varies with changes in water status. © 2002 Society of Chemical Industry     

Direct determination of phenolic compounds and phospholipids in virgin olive oil by micellar liquid chromatography

A simple HPLC method is reported for fast separation and determination of phenolic compounds (tyrosol, caffeic acid, p-coumaric acid and oleuropeina) and phospholipids (phosphatidylethanolamine and phosphatidylcholine) in virgin olive oil samples. The samples were diluted with 2-propanol and injected into the column directly without previous extraction. Samples with an olive oil content of up to 65% were injected without any problems. The analytes were separated on a C-18 column by a micellar mobile phase containing 0.07 M SDS and 2.5% 2-propanol at pH 3, and were detected at 210 nm. Linear calibration curves [r² > 0.997] were obtained with detection limits ranging from 0.052 to 0.16 μg/g and 1 to 8.6% repeatability for the phenolic compounds. Several virgin olive oil samples were analysed and the recovery values were around 110%.     

超临界提取调味香料披萨草精油及其化学成分分析

采用超临界CO2提取法提取了披萨草精油,并利用气相色谱/质谱(GC/MS)联用技术和保留指数比较法分析了该精油的化学成分.从SFE披萨草精油中鉴定了28种化合物,占精油总童的94.31%.主要成分为香芹酚(47.61%),丁香酚(16.12%)和麝香草酚(14.81%).