Oinotria table olives: Quality evaluation during ripening and processing by biomolecular components

Since ancient times, olives (Olea europaea L. cv. Cassanese) have been treated for table black olive production; the wizened Oinotria(WOTO) is still processed in the traditional way. This process and the technological treatment include three operations: blanching, salting and drying of mature black olives. In this investigation, samples were harvested at two ripening stages. The infestation conditions, firmness, oil content and quality, and biophenolic composition of the drupes were analysed before and after the processing. The results showed that fruit firmness decreased during ripening and processing, oil content increased and total biophenols (tBPs) decreased according to adopted procedures, while the fatty acid composition remained unaltered during the overall treatment. Moreover, the extracted oil parameters indicate that oil quality is maintained without lipid deterioration as the WOTO treatment progresses. The tBP content is sufficiently large to protect against autoxidation during the shelf life and to give a functional value to this traditional product of Mediterranean food culture. Received: 7 January 2000 / Revised version: 18 February 2000     

Respiratory rate of olive drupes during their ripening cycle and quality of oil extracted

During the ripening cycle of Frantoio and Leccino olive varieties, the respiration rate of drupes was measured, giving the respiratory curve of fruits. This curve, for both varieties, dropped to a minimum point towards the end of November (a few days earlier for the Leccino variety) followed by a rise up to a maximum. This phase of the ripening process of olives corresponds to the climacteric crisis of the fruits. In this period the oil extracted from drupes gave the best analytical characteristics and was rich in tocopherols, phenols and aromatic volatile substances, components closely related to the shelf-life and the organoleptic quality of the product. The climacteric phase of drupes therefore corresponds to the optimal ripening stage of fruits and the harvesting of olives should be carried out during this period, in order to obtain oils of elevated quality. The respiration rate of drupes is therefore proposed as a new ripening index for drupes. © 1998 SCI.     

油橄榄鲜果中主要化合物随成熟度的变化

为阐明油橄榄果实成熟过程中主要化合物的变化,探索最佳成熟度,本试验以不同成熟度的皮瓜尔鲜果为材料,测定其蛋白质、还原糖、粗脂肪、总多酚的含量,以及果油中主要的脂肪酸和角鲨烯的相对含量。结果表明,随着成熟度的增加,蛋白质含量无较大差异,还原糖先降低后略有升高,粗脂肪先升高后趋于平稳,总多酚先降低后趋于平稳;各种脂肪酸相对含量在整个成熟过程中变化不一致;油酸、棕榈酸、亚油酸、亚麻酸、硬脂酸是橄榄油中含量较高的脂肪酸;角鲨烯先升高后降低。利用主成分分析对油橄榄果实品质进行综合评价,第四成熟度为油橄榄果的最佳成熟度。     

Effect of olive ripeness on chemical properties and phenolic composition of chétoui virgin olive oil

BACKGROUND: The aim of the present work was to investigate the influence of fruit ripening on oil quality in an attempt to establish an optimum harvesting time for Chétoui olives, the second main olive variety cultivated in Tunisia. RESULTS: Our results showed that many analytical parameters, i.e., peroxide value, UV absorbance at 232 and 270 nm, chlorophyll pigments, carotenoids and oleic acid contents decreased during ripening, whilst oil content and linolenic acid increased. Free acidity remained practically stable with a very slight rise at the highest maturity index. The trend of oxidative stability, total phenols and o‐diphenols, showed an increase at the early stages followed by a reduction at more advanced stages of maturity. The major phenolic compounds, such as hydroxytyrosol, ligstroside aglycon, elenolic acid, acetoxy‐pinoresinol and oleuropein aglycon, seemed to have the same behaviour. In the case of tyrosol, a strong decrease was observed directly related with the ripening progress. CONLUSION: On the basis of the evolution of the analytical parameters studied, the best stage of Chétoui olive fruits for oil processing seems to be at ripeness index higher than 2.0 and lower than 3.0. Copyright © 2009 Society of Chemical Industry     

Chemical composition of virgin olive oils from Koroneiki cultivar grown in Tunisia with regard to fruit ripening and irrigation regimes

The impact of different irrigation regimes based on two ripeness index, on the quantity and quality of virgin olive oil from the introduced olive cultivar Olea europaea L. Koroneiki grown at a high‐density olive orchard in northern Tunisia, was assessed. Olive trees were subjected to three treatments (T1, T2 and T3) that received a seasonal water amount equivalent to 50%, 75% and 100% of the estimated local evaporative demand by a drip irrigation system and olives were collected in two different ripeness index. The olive oil content decreased when the water applied was increased but rose during ripening. The quality indexes and fatty acid composition were less affected by the irrigation schedule but most significantly by the maturity of olives. Moreover, phenol contents increased according to fruit ripening whereas no clear cut differences or consistent effects were observed by irrigation. α‐tocopherol decreased slightly in the oils as ripening progressed while insignificant differences between the irrigation treatments studied were obtained. Consequently, a restitution of 75% of crop evapotranspiration (ET_c.) was sufficient to achieve good minor compounds; however, higher water volumes (100% ET_c.) gave little additional α‐tocopherol and phenols increases.     

Seasonal changes in olive fruit characteristics and oil accumulation during ripening process

Olive fruits of three of the most important Spanish and Italian cultivars, ‘Picual’, ‘Hojiblanca’ and ‘Frantoio’, were harvested at bi‐weekly periods during three crop seasons to study their development and ripening process. Fresh and dry weights and ripening index were determined for fruit, while dry matter, oil and moisture contents were determined in both fruit and pulp (flesh). Fruit growth rate and oil accumulation were calculated. Each olive cultivar showed a different ripening pattern, ‘Hojiblanca’ being the last one to maturate. Fruit weight increased, decreasing its growth rate from the middle of November. Dry matter and moisture contents decreased during ripening in pulp and fruit, ‘Hojiblanca’ showing the highest values for both. Oil content, when expressed on a fresh weight basis, increased in all cultivars, although for the last time period showed variations due to climatic conditions. During ripening, oil content on a dry weight basis increased in fruit, but oil biosynthesis in flesh ceased from November. Olive fruits presented lower oil and higher dry matter contents in the year of lowest rainfall. Therefore fruit harvesting should be carried out from the middle of November in order to obtain the highest oil yield and avoid natural fruit drop. Copyright © 2004 Society of Chemical Industry     

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     

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     

Olive biophenols: novel ethnic and technological approach

Biophenols are monomeric dihydroxyaromatic moieties that are active non-nutrient components widely found in all plant-derived foodstuffs. Wizened Oinotria table olives (WOTO) and extra virgin olive oil (EVOO), both typical ethnic products of the Mediterranean food culture, are especially rich in biophenols. Table olives can be prepared by traditional methods or by technological processing involving blanching, salting and drying of mature black olives. Olive quality depends on harvesting at mature stages, infestation conditions, firmness, triacylglycerol and biophenol content. The fruit firmness and biophenol content decreases during ripening and processing whereas the triacyiglycerol content increases. Differential scanning calorimetry (DSC) was used to determine the triacylglycerol content in dried olive pulp, and to follow inoliation trends during the production of table olives and extra virgin olive oil. The DSC technique is fast, specific, reliable, uses no solvents and requires lower amounts of olive samples compared to conventional methods. After olive production, triacylglycerol quality was maintained without lipid deterioration. The total biophenol content was sufficiently large to ensure a shelf life and functional value for olive products. Biophenols in olive products demonstrate antioxidant, free-radical antagonism and anti-microbial activity, which are important for human health and well being. Technological innovation, such as EVOO from pitted olives, using ancient methods, can continue to be at the forefront of development in the olive agrifood chain. Creativity and sophisticated techniques will provide new perspectives for olive manufacturing, based on typical regional and ethnic products. The nutritional, sensory and functional enhancement of traditional olive foods, offer the potential for improving human health and well being within the context of the Mediterranean diet.     

添加新鲜橄榄叶和复合果胶酶压榨对油橄榄果出油率和初榨橄榄油品质的影响

为提高油橄榄果出油率、改善初榨橄榄油(VOO)品质,以甘肃陇南主栽的成熟度为7的莱星品种油橄榄鲜果为原料,考察压榨过程中新鲜橄榄叶(0、3%、5%)和复合果胶酶(0、0.01%、0.02%)添加量(以油橄榄果质量计)对油橄榄果出油率和VOO色泽、叶绿素含量、基本理化性质、总酚含量、脂肪酸组成及含量的影响。结果表明：添加适量的新鲜橄榄叶可提高出油率及总酚含量,降低酸值,但色泽加深,叶绿素含量和过氧化值升高;添加适量的复合果胶酶在提高出油率的同时,VOO的总酚含量上升,叶绿素含量和过氧化值降低,但酸值升高,色泽加深;压榨过程中添加新鲜橄榄叶和复合果胶酶对VOO脂肪酸组成没有影响,但对油酸、亚油酸、棕榈酸和棕榈烯酸等主要脂肪酸含量有一定影响。在压榨制取VOO时添加适量的新鲜橄榄叶与复合果胶酶可提高出油率,获得富含多酚的VOO。     

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.     

Characteristics of olive fruits and extra‐virgin olive oils obtained from olive trees growing in Appellation of Controlled Origin ‘Sierra Mágina’

Olives and olive oils from Appellation of Controlled Origin (ACO) ‘Sierra Mágina’ have been analysed during the 1997/98 harvest. The territory of this ACO has been subdivided into four zones of different characteristics. The olives were harvested on two occasions (November 1997 and January 1998). Various parameters were analysed, such as the ripening index, the average volume, the average weight of 100 olives and 100 stones, the pulp/stone ratio, the industrial yield, etc. From these olives, olive oils were extracted using an Abencor system, and the free acidity, the peroxide index, the coefficients K₂₇₀ and K₂₃₂ and the fatty acid composition were determined. The analysis of the results obtained, as well as principal component analysis, demonstrates a marked variability in the fruits, but the corresponding olive oils show fairly homogeneous compositions that are difficult to distinguish by sensory analysis. The olive oils from this ACO are extra‐virgin olive oils characterised by low acidity, a high content of oleic acid and a high ratio of unsaturated to saturated fatty acids. The most important sensory attributes are fruity, woody‐fig, green, bitter and pungent. Copyright © 2003 Society of Chemical Industry     

Influence of fruit ripening on ‘Cornicabra’ virgin olive oil quality A study of four successive crop seasons

The aim of this work was to study the influence of the stage of fruit ripening on analytical parameters which determine oil quality during four successive crop seasons, in an attempt to establish an optimum harvesting time for ‘Cornicabra’ olives. The majority of the analytical parameters, i.e. peroxide value, UV absorption at 270 nm, pigments, sensory scores, oleic acid and total sterols, diminished during ripening, whereas free acidity, linoleic acid and Δ-5-avenasterol increased. Oil extraction yield, oxidative stability, natural antioxidants and campesterol showed more complex behaviour. On the basis of the evolution of the analytical parameters studied the best stage of maturity of ‘Cornicabra’ olive fruits for processing seems to be a ripeness index higher than 3.0 and lower than 4.0–4.5. Results indicated that probably less than 25% of commercial ‘Cornicabra’ virgin olive oils were extracted from olives harvested at an optimum ripeness index. It is therefore of crucial recommendation to the industry to bring forward harvesting to further improve the quality of the virgin olive oil produced.     

Olive oil extractability index as a parameter for olive cultivar characterisation

Extractability, when applied to the olive oil extraction process is defined as the percentage of oil extracted from the total oil content of the fruit. In this work, extractability index (EI), a new parameter determined in a laboratory oil mill, has been studied for 24 olive (Olea europaea L) cultivars from the Olive Germplasm Bank Collection of Mengibar (Spain). In order to evaluate the genetic variability of this new parameter, the influence of cultivar and tree on EI variability has been analysed in olive fruits collected at the same ripening index. The results indicate that cultivar is the most important variation source. Thus olive oil extractability depends on extraction process variables and cultivar. Extractability index could be used together with pulp oil content (on a dry matter basis) as a parameter for olive cultivar characterisation and selection for breeding projects. Copyright © 2003 Society of Chemical Industry     

Reduction in pesticide residue levels in olives by ozonated and tap water treatments and their transfer into olive oil

The effects of different wash times (2 and 5 min) with tap and ozonated water on the removal of nine pesticides from olives and the transfer ratios of these pesticides during olive oil production were determined. The reliability of the analytical methods was also tested. The applied methods of analysis were found to be suitable based on linearity, trueness, repeatability, selectivity and limit of quantification all the pesticides tested. All tap and ozonated water wash cycles removed a significant quantity of the pesticides from the olives, with a few exceptions. Generally, extending the wash time increased the pesticide reduction with ozonated water, but did not make significant differences with tap water. During olive oil processing, depending on the processing technique and physicochemical properties of the pesticides, eight of nine pesticides were concentrated into olive oil (processing factor > 1) with almost no significant difference between treatments. Imidacloprid did not pass into olive oil. Ozonated water wash for 5 min reduced chlorpyrifos, β-cyfluthrin, α-cypermethrin and imidacloprid contents by 38%, 50%, 55% and 61% respectively in olives.     

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     

Kneading olive paste from unripe ‘Picual’ fruits: I. Effect on oil process yield

Olive growers start earlier to harvesting in order to obtain high quality oils, however unripe olives show different characteristics affecting technological and rheological properties. This work is aimed to study the effect of malaxation conditions on process oil yield for unripe ‘Picual’ olives. Experiments were carried out using Picual fruits harvested at early dates for three consecutive crops seasons. The malaxation conditions assayed using a factorial design were: time (60, 90 min), temperature (18, 30, 40 °C) and micronised talc addition (0, 1%). Olive paste from unripe Picual fruit are classified as difficult pastes. The main factor affecting oil yield was the crop year, while for each crop year the effect of each factor varied considerably. Results indicated as increasing time and temperature gave lower pomace oil losses although its effect varied on crop year. Micronised Natural Talc addition lowered pomace oil content on dry weight. Therefore for early harvesting dates knowing olive characteristics ‘on line’ is essential to adapt the kneading conditions.     

ANN-based method for olive Ripening Index automatic prediction

The influence of ripening degree of drupes during the harvesting period is well established in olive oil sector. A range of methods for expressing the stage of maturity of olives have been proposed in scientific literature. One of the most commonly adopted methods provides the evaluation of a Ripening Index (RI) on the basis of olive skin and pulp colour. Unfortunately, the RI evaluation technique is time-consuming, subjective (depending on expert skill) and depends on environmental conditions that may affect colour appearance of olives. This work describes a novel method for rapid, automatic and objective prediction of the Ripening Index of an olive lot. The method integrates a Machine Vision system, capable of performing a colour-based raw prediction of RI, with an Artificial Neural Network (ANN) based algorithm to refine it. Such a refinement is based on a set of chemical parameters (oil content, sugar content and phenol content) which are provided as input to the ANN and which can be obtained by historical curves for the region where the RI needs to be predicted. Experimental results demonstrate the effectiveness of the proposed approach.     

Sugar and polyol compositions of some European olive fruit varieties (Olea europaea L.) suitable for table olive purposes

An experimental investigation was carried out on olive fruits of Douro, Hojiblanca, Cassanese, Taggiasca and Thasos cultivars, to assess free sugar and polyol compositions and their changes during ripening and processing. TMS ethers of sugars from olive pulp were analysed by GC and GC–MS and identification of each sugar component was obtained by comparison of retention times and mass spectra with those of authentic compounds. Quantitation of sugars was performed on mixture whose tautomeric equilibria were stable. Glucose, fructose and galactose were the main sugars found in olive pulp. Appreciable quantities of mannitol were also present. Sucrose and inositol were present in very low concentrations. A significant correlation (r=0.941) between mannitol and oil contents was found. Sugar content decreased from green to cherry and black colour, according to the stage of ripeness of fruits. In processed olive-fruits, sugar contents varied among olive cultivars according to processing conditions.     

The Historical Development and Nutritional Importance of Olive and Olive Oil Constituted an Important Part of the Mediterranean Diet

The olive tree (Olea europaea) is widely cultivated for the production of both oil and table olives and very significant because of its economic value. Olive and olive oil, a traditional food product with thousands of years of history, are the essential components of the Mediterranean diet and are largely consumed in the world. Beside of their economical contribution to national economy, these are an important food in terms of their nutritional value. Olive and olive oil may have a role in the prevention of coronary heart disease and certain cancers because of their high levels of monosaturated fatty acids and phenolic compounds. In addition, olives (Olea europaea L.) and olive oils provide a rich source of natural antioxidants. These make them both fairly stable against auto-oxidation and suitable for human health. The aim of this paper is to define the historical development and nutritional importance of olive and olive oil constituted an important part of the Mediterranean diet.