On-line versus off-line NIRS analysis of intact olives

Visible/near-infrared calibrations were developed for the determination of the quality parameters (fat content, moisture and free acidity) of intact olive fruits. The reflectance spectra were acquired in two different instruments (diode-array versus grating monochromator based instruments). The grating monochromator based instrument was used at the laboratory (off-line analysis), whereas the portable diode-array based device was placed on top of a conveyor belt set to simulate measurements in an olive oil mill plant (on-line analysis). Partial least squares (PLS) regression and least squares support vector machine (LS-SVM) were used for the development of the calibration models. A total of 174 samples were prepared for the calibration (N = 122) and validation (N = 52) sets. The root mean square error of prediction (RMSEP) and the residual predictive deviation (RPD) values were better using the diode-array instrument and applying the PLS regression method for the fat content parameter while for the free acidity and moisture content, the LS-SVM algorithm gave the best results. The results obtained seems to suggest the viability of the on-line system, instead of the off-line analysis, for the determination of physicochemical composition in intact olives.     

Phenolic compounds in virgin olive oils: influence of the degree of olive ripeness on organoleptic characteristics and shelf-life

 An experimental investigation was performed on virgin olive oils from Coratina and Ogliarola salentina cultivars extracted from green, partially blackened and totally blackened olives in order to evaluate changes in the organoleptic properties and in the shelf-life of the oil. The aim of the investigation was to identify the optimal stage of olive maturation for each cultivar to produce higher quality oils. Routine analyses in accordance with EC regulation no. 2568/91, the determination of phenols by HPLC and induction times were carried out. On the whole, the simple phenolic compounds increased as darker olives were used whereas the hydrolysable phenolic compounds decreased. In both the cultivars, total phenols and induction times were significantly higher in the oils obtained from green olives than in oils from totally blackened olives. Hence, it seems advisable to delay olive harvesting for cultivars usually yielding bitter to pungent oils (e.g. Coratina), but to anticipate harvesting for olives producing sweet tasting oils (e.g. O. Salentina). This would produce less bitter Coratina oils, with organoleptic features which may better fulfil consumers' expectations, and O. Salentina oils more resistant to oxidation. Received: 5 June 2000     

Pesticide residue assessment in different types of olive oil and preliminary exposure assessment of Greek consumers to the pesticide residues detected

In this study the occurrence and levels of multi-class pesticides in different types of virgin olive oil quality and origination were determined and the contribution of olive oil in the chronic risk of pesticide residues consumption in the Mediterranean diet was estimated. For this purpose, a multiresidue method for the determination of 35 pesticides in olive oil was evaluated and applied to a total number of 100 olive oil samples. Ten percent of the samples produced from fruits of conventional cultivations contained no detectable residues whereas in the rest samples were detected residues of 20 insecticides. The highest detection rates were observed for the residues of fenthion, dimethoate and endosulfan. The highest occurrence and levels of pesticides were observed in extra virgin olive oil whereas results pointed that residues in olive oil from variety of olives with high oil yield may be higher. Furthermore, olive oil from organic cultivations could be contaminated with pesticide residues and/or contain low levels of pesticide residues that are not registered for use in olive cultivations. For there were multiresidues of pesticides present in olive oil, there is no zero risk in consumption of olive oil. However, the exposure of olive oil consumers to each detected residue is far below the acceptable daily intake (ADI).     

《2015年国际橄榄油和食用橄榄协定》解析

《2015年国际橄榄油和食用橄榄协定》（International Agreement on Olive Oil and Table Olives, 2015）是国际商品协定的一种,由联合国于2015年10月9日在日内瓦万国宫谈判后通过。基于此组建的国际橄榄理事会（International Olive Council）是全球橄榄贸易领域的权威组织。该协定最早版本于1959年首签,2015年第六版有效期至2026年12月31日。本文介绍协定内容并就以下方面进行解释：国际橄榄理事会的工作目标,橄榄油和食用橄榄的有关名词术语,成员理事会的组成方式和行政机构,各成员国在理事会的参与份额计算方式。截止2020年成员国方面的变动为伊拉克退出,增加巴勒斯坦、格鲁吉亚两个国家,文中所列成员参与份额为2020更新的数据。另外2021年毛里塔尼亚有望同意签署2015年版本协定,正式加入该组织。了解和熟悉国际橄榄油和食用橄榄协定是中国橄榄油行业融入世界贸易外循环的前提条件。作为国际大宗初级产品的主要进口和出口国,本文介绍的橄榄油和食用橄榄协定的一般原则与组织方式值得借鉴,我国应当在其它初级产品贸易规则的标准制定方面掌握主动,发出更多中国声音,为完善全球治理做出中国贡献。     

Acephate and buprofezin residues in olives and olive oil

Field trials were carried out to study the persistence of acephate and buprofezin on olives. Two cultivars, pizz'e carroga and pendolino, with very large and small fruits respectively were used. After treatment, no difference was found between the two pesticide deposits on the olives. The disappearance rates, calculated as pseudo first order kinetics, were similar for both pesticides (on average 12 days). Methamidophos, the acephate metabolite, was always present on all olives, and in some pendolino samples it showed higher residues than the maximum residue limit (MRL). During washing, the first step of olive processing, the residue level of both pesticides on the olives did not decrease. After processing of the olives into oil, no residues of acephate or methamidophos were found in the olive oil, while the residues of buprofezin were on average four times higher than on olives.     

Preliminary characterisation of virgin olive oils obtained from different cultivars in Sardinia

Chemical characterisation was carried out on 12 virgin olive oil samples obtained from seven olive cultivars (Bosana, Carolea, Nocellara del Belice, Pizz'e Carroga, Semidana, Tonda and Zinzala cvs.). The olives came from different groves in Sardinia (Italy) and Corsica (France) that were processed by different types of continuous mills. Several qualitative parameters were evaluated (free acidity, peroxide value, and UV spectrophotometric indices) and analyses of major (fatty acids and triacylglycerol compositions) and minor components (chlorophylls, carotenoids, tocopherols and phenolic compounds) was also carried out. The oxidative stability index (OSI) and ABTS^•− test values were determined to evaluate the oxidative stability and antioxidant activity of the phenolic fraction, respectively. The results were subjected to a discriminative study by principal component analysis (PCA) to characterise the different oils. A first PCA using only the triglyceride compounds and a second using the minor polar compounds and their antioxidant activity was performed. The triglyceride composition was found to be particularly useful in discriminating the oil samples.     

Fatty Acids,Sterols, Polyphenols,and Chlorophylls of Olive Oils Obtained from Tunisian Wild Olive Trees (Olea europaea L. Var. Sylvestris)

Olive (Olea europaea L.) includes cultivated olive trees (var. europaea) and wild olive trees or oleaster (var. sylvestris) as two botanical varieties. These olive varieties were widely spread in the Mediterranean Region. The aim of this study was to determine fatty acid compositions, sterols, polyphenols, and chlorophylls of oils obtained from 12 wild olive trees from Northern Tunisia. Two dominated oil cultivars in Tunisia (Chétoui and Chemlali) were also used to compare results. The fatty acid methyl ester and the sterol compositions were analyzed using gas-liquid chromatography and thin layer chromatography methods, respectively. The polyphenols and chlorophylls were determined using the calorimetrical method. Results indicated that oils extracted from wild olives displayed good balanced fatty acid compositions, sterols, polyphenols, and chlorophylls. Qualitatively, for wild and cultivated olive oils, the oil has an identical composition, whereas the quantitative variation showed that some wild trees seem to be interesting oil sources as two Tunisian dominated cultivars. The highest oleic acid and polyphenol contents were 71.55% and 537.6 mg/kg of oil found in wild olives (OIch2, OIch1). The β-sitosterol was the major sterolic fraction and ranged from 84.72 to 75.70% according to the wild olives. Consequently, wild olives would be a new future edible olive oil source, as well as commonly cultivated ones.     

Proteins in Olive Fruit and Oil

This paper is a comprehensive review grouping the information on the extraction, characterization, and quantitation of olive and olive oil proteins and providing a practical guide about these proteins. Most characterized olive proteins are located in the fruit, mainly in the seed, where different oleosins and storage proteins have been found. Unlike the seed, the olive pulp contains a lower protein content having been described a polypeptide of 4.6 kDa and a thaumain-like protein. Other important proteins studied in olive fruits have been enzymes which could play important roles in olives characteristics. Part of these proteins is transferred from the fruit to the oil during the manufacturing process of olive oil. In fact, the same polypeptide of 4.6 kDa found in the pulp has been described in the olive oil and, additionally, the presence of other proteins and enzymes have also been described. Protein profiles have recently been proposed as an interesting strategy for the varietal classification of olive fruits and oils. Nevertheless, there is still a lot of knowledge without being explored requiring new studies focused on the determination and characterization of these proteins.     

The effect of irrigation level and harvest mechanization on virgin olive oil quality in a traditional rain‐fed ‘Souri’ olive orchard converted to irrigation

BACKGROUND: Olive trees are generally grown under rain‐fed conditions. Since yield response to application of water in the growing season may be considerable, irrigation is increasingly introduced to existing, mature orchards. An additional feature of modernization of olive cultivation is mechanical harvesting. To investigate the effect of irrigation level on the quality of virgin olive oil (VOO) produced from cv. Souri, six regimes, ranging from deficit to excess, were applied to trees in a mature, traditional orchard as it was converted to irrigation. Furthermore, in order to investigate the effect of damage incurred during harvest, oil quality of hand‐picked fruit was compared to that of mechanically harvested olives. RESULTS: Data were collected from two consecutive growing seasons. Increased irrigation quantity increased the free acidity level of the oil and decreased the total phenol content of VOO, while the peroxide level of the oil was not affected. Oil of hand‐picked fruits had lower free acidity, higher polyphenol content and slightly lower peroxide level compared to the oil of mechanically harvested olives. CONCLUSION: Fruits from irrigated trees demonstrated an apparent sensitivity to mechanical wounding that subsequently led to increased free acidity, increased peroxide level and decreased total phenol content in oil. Management of irrigated orchards including method and timing of harvest and oil extraction techniques should consider these results in order to optimize production of high‐quality oil. Copyright © 2008 Society of Chemical Industry     

Aroma compounds and sensory characteristics as biomarkers of quality of differently processed Tunisian virgin olive oils

The influence of the extraction system (continuous vs. discontinuous) and the degree of freshness of olives on the chemical composition and the quality of Chemlali and Chétoui virgin olive oil has been studied. Analytical data mainly concerning the volatile and sensory profiles revealed statistically significant differences in relation to the extraction system. All quality indices and sensory characteristics showed statistically significant differences associated with the degree of freshness of fruits. These results further confirm the general consensus that volatile compounds can be very useful as biomarkers of the quality of virgin olive oil and show correlations with the sensory characteristics.     

The antioxidant activity and stability of the phenolic fraction of green olives and extra virgin olive oil

The antioxidant activity of phenolic extracts from olives and olive oil has been assessed by scavenging of 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radicals and by studying the effects on the stability of stripped olive oil in the absence and presence of ferric chloride. The olive extracts contained a much higher concentration (1940–5800 mg kg^?1) of phenolic components than the olive oil extract (180 mg kg^?1). Some olive extracts were more effective than the olive oil extract in scavenging DPPH radicals, but the three varieties of olives examined showed relatively large differences in both polyphenol concentration and antioxidant activity of extracts. α‐Tocopherol and extracts from both olives and olive oil were effective antioxidants in stripped olive oil at 60 °C. Ferric chloride reduced the stability of stripped olive oil, but the olive extract studied was significantly more effective as an antioxidant in the presence of the metal salt than the olive oil extract or α‐tocopherol. Ferric ions catalysed the oxidation of caffeic acid, oleuropein and phenolic components of the olive and olive oil extracts in aqueous solution (pH 5.4). The olive extract oxidised more rapidly than the olive oil extract in aqueous solution. © 2001 Society of Chemical Industry     

Enrichment of table olives with polyphenols extracted from olive leaves

The possibility to increase the nutritional value of table olives using polyphenols extracted from olive leaves was studied. Leaves were subjected to extraction using water with proportions of 1%, 5% and 10% of leaves and various temperatures and times (room temperature/24 h, 40 °C/10 min and 70 °C/5 min). The antioxidant activity of extracts was determined using the Rancimat method and their content in oleuropein and hydroxytyrosol was determined by HPLC. The extract with the highest antioxidant activity and polyphenol content (10% ratio of olive leaves extracted at room temperature for 24 h) was used for the treatment of debittered table olives. The treated and untreated olives were subjected to determination of their α-tocopherol, oleuropein and hydroxytyrosol content. A 457% increase was observed for oleuropein and 109% for hydroxytyrosol content after treatment. Sensory evaluation of treated table olives showed an increase in bitterness. However, treated and untreated table olives showed equal overall acceptability and overall preference.     

Simultaneous Determination of Squalene, α-Tocopherol and β-Carotene in Table Olives by Solid Phase Extraction and High-Performance Liquid Chromatography with Diode Array Detection

Olives, the fruit of the Olea europaea tree, are highly appreciated in olive oil and table olives (20 % of crops) not only for their flavor but also for their nutritional properties, especially for antioxidant compounds such as squalling (SQ), α-tocopherol (TH) and β-carotene (BC). This paper presents a new analytical method for simultaneously determining SQ, TH and BC in table olives by using solid phase extraction (SPE) and high performance-liquid chromatography with diode array detection (HPLC-DAD), avoiding the classic saponification process. The correlation coefficients of calibration curves of the analyzed compounds ranged from 0.998 to 0.999, and the recoveries were in the range of 89.4–99.6 %. The validated method was used to analyze 30 table olive samples from Italy for their content of SQ (537–1,583 mg kg^?1), TH (21–90 mg kg^?1) and BC (0.4–2.6 mg kg^?1). Finally, experiments with HPLC-MS were conducted to compare this novel method with the classic saponification procedure.     

Determination of copper with 5,5-dimethylcyclohexane-1,2,3-trione 1,2-dioxime 3-thiosemicarbazone in olive oils by adsorptive stripping square wave voltammetry

In the present paper a method for the determination of Cu in olive oil samples by adsorptive stripping square wave voltammetry (Ad-SSWV) is presented. It has been proven that Cu reacts with 5,5-dimethylcyclohexane-1,2,3-trione 1,2-dioxime 3-thiosemicarbazone, DCDT, in strongly acid media giving rise to a complex. In Ad-SSWV the complex Cu–DCDT experiments an adsorptive reductive process which promotes the appearance of a peak at −0.570 V. The extraction process of Cu from olive oil is carried out with hot concentrated HCl. Calibration graph has been constructed from 0 to 35 ng mL⁻¹ and the detection limit was 0.49 ng mL⁻¹. The method has been applied to commercial olive oils samples and the amounts of Cu found are very similar to those obtained when samples are analysed by AAS.     

Soft purification of lampante olive oil by microfiltration

An efficient membrane-based process for deacidification of lampante olive oil was investigated. The neutralization of the free fatty acids with appropriate soda concentration allows the formation of submicronic particles which are subsequently removed by a microfiltration technique. A total or quasi-complete neutralisation of the acidity is necessary to achieve the complete retention of the soap molecules. Partial neutralization of the acidity leads to a lower membrane separation efficiency. The residual FFA causes permeation of soap molecules across the membrane. When filtered under suitable conditions, lampante olive oils show excellent quality characteristics, i.e., very low residual acidity as well as soap and water contents. The initial fluxes, obtained during crossflow filtration with membrane pore sizes 0.5 and 0.8 μm (147 and 212 l/h m², respectively) after neutralization with 20% NaOH are twice those obtained with 40% NaOH while there is only a slight improvement with the 0.2 μm membrane. The filtered oils show good quality (acidity and residual soaps) in the case of PS 0.2 and 0.5 μm, whereas the 0.8 μm membrane allows some soaps to pass through the membrane. The passage from the laboratory scale (1 kg) to a 50 kg unit shows the practical possibility of scaling up without meeting any particular problems or loss of efficiency.     

Partitioning of predominant lipophilic bioactives (squalene, α-tocopherol and β-sitosterol) during olive oil processing

The partitioning of predominant lipophilic olive bioactives (squalene, β-sitosterol and α-tocopherol) in olive oil processing was studied for the first time using common integrated olive milling plant. 7% of the oil and 5% of the squalene present in the olives was lost in the last pomace. β-sitosterol and α-tocopherol, which are mainly concentrated in the seed of the olive fruit, was recovered in virgin olive oil to a lesser extent (66%, 67%) while 10% were lost in last pomace. Thus, the loss of β-sitosterol and α-tocopherol was higher than that of squalene and oil, due to nonrecovered bound forms. 19% of the α-tocopherol and 21% of the β-sitosterol loss was unaccounted for, which can be attributed to degradation of α-tocopherol and incomplete recovery of sterols from the olive and pomace matrices. This study provides a basis for process development studies.     

Effects of pasteurisation and storage on quality characteristics of table olives preserved in olive oil

Two types of products obtained from the processing of Olea europaea cv ‘Taggiasca’ were monitored: pitted olives and olive paste preserved in monovarietal extra‐virgin olive oil of the same variety. The aim of this study was to follow the trends in the main physico‐chemical and sensory parameters related to the quality of these table olives and their covering oils, for simulation of the shelf‐life conditions. From all of the analyses carried out, it can be concluded that the optimum time of storage of these two products packaged in glass jars at room temperature (between 18 and 25 °C) and under artificial light and away from heat sources is approximately 9 months. After 9 months of storage, the covering oils were greatly affected by the contact with the broken fruit, which was accompanied by reductions in their antioxidant content due to the thermal treatment. The oxidative effects seen through physico‐chemical analyses are in agreement with the organoleptic analysis.     

Fatty acid methyl and ethyl esters as well as wax esters for evaluating the quality of olive oils

A promising correlation between chemical analysis and sensorial evaluation was confirmed: extra virgin olive oils with low contents of methyl and ethyl esters of fatty acids as well as straight chain wax esters were sensorially evaluated as being of high quality, whereas some with high contents were even devaluated as not being of extra virgin quality. Methanol and ethanol formed during fermentation in degrading olives are esterified, largely by transesterification with fatty acids from the triglycerides, and in this way transferred into the pressed oil. The presence of high contents of methyl and ethyl esters in degrading olives was confirmed. Wax esters from the skin of the olives are extracted at low yields, whereby the yield increases when the olives are soft and possibly degrading. High wax ester contents may, therefore, stand for mild oils, but also for deficient oils.     

Volatile compounds of virgin olive oil obtained from Italian cultivars grown in Calabria.: Effect of processing methods,cultivar, stone removal,and antracnose attack

Calabria is an important olive-growing area of the Mediterranean producing high quality virgin olive oil from a wide variety of cultivars. The present work analyses the influence of cultivars, processing methods, anthracnose attack and stone removal on volatile compounds. Solid phase microextraction (SPME) was used because is easy to use, cheap and rapid. The volatile compound content of different cultivars is influenced by the enzymes involved in the lipoxygenase pathway. The effect of anthracnose attacks increases the content of aldehydes such as heptaldehyde, octyl aldehyde and nonanal. Oil obtained from destoned olives shows a greater quantity of C5 and C6 volatile compounds compared to oil obtained from unstoned olives. Oil obtained in the laboratory has a higher volatile compound content compared to that obtained commercially. Limited scale oil production have a lower oil yields but enables greater content of compounds in the headspace in the final product and thus may be a valid alternative for small agricultural businesses.     

EFFECT OF STORAGE AND DACUS INFECTION OF OLIVE FRUITS ON THE QUALITY OF THE PRODUCED VIRGIN OLIVE OIL

Olives from three different locations ( Olea europaea cv. Koroneiki), uninfected or infected by the insect Dacus oleae, were collected and stored at 15°2C for 21 days. Samples were taken at 0, 3, 7, 10, 12, 14, 17 and 21 days following collection. Moisture and oil content of olive fruits and the quality parameters of the extracted virgin olive oil were evaluated. Analytical parameters determined were titratable acidity, peroxide value and the specific extinction coefficients at 232 nm (K₂₃₂ and 270 nm (K₂₇₀). Regression equations and best fitting curves between examined parameters and time were evaluated. Olive oil from fly infected olives had higher initial values and a higher rate of increase of the parameters measured. The only parameter affecting oil quality was K₂₇₀. Maximum storage time within legal limit for K₂₇₀ was 16 days for fly uninfected and 10 days for fly infected olives.