Optimization of the Abencor system to extract olive oil from irrigated orchards

Studying the composition of olive oil requires cold‐press olive oil extraction. One of the most common laboratorial mills is the Abencor system. However, its operation protocol was formulated decades ago for Spanish olive varieties from traditionally rain‐fed orchards. We modified this protocol for use with “Barnea” and “Picual” olives from irrigated orchards that are characterized by high water content. Independent effects of malaxation time, temperature, water addition and talc addition on extraction efficiency, and major quality indices of virgin olive oil were studied. Overall, addition of talc to the fruit paste was the most significant treatment in terms of yield and quality of the oil although its effect was cultivar dependent. Improved oil yield was particularly significant for “Picual.” Extended malaxation time was also effective in improving oil extractability. Addition of talc generally improved oil‐quality parameters, while water addition had the opposite effect. Yet, quality parameters remained within the extra virgin level. Temperature increments reduced oil quality. The need to adapt a modified protocol for use with fruits from irrigated orchards that will facilitate critical comparison of results obtained from different agronomic theses and different laboratories is highlighted. It is recommended that each laboratory develops an appropriate protocol for the operation of the Abencor system in accordance to the characteristics of the olive fruit they are working with. Practical applications: Abencor system serves as the major laboratorial mill world‐wide. Those mills allow the researchers to characterize olive oil in accordance to the treatments received by the trees. This cannot be done in commercial mills. The system operation protocol was established decades ago for fruits from rain‐fed orchards. In the past decade there was a rapid increase in the use of irrigation in olive orchards and therefore it is crucial to optimize the operation protocol for fruit with relatively high water content. In the current work we have evaluated the influence of a series of technological parameters (i.e., talc and water addition, malaxation time, and temperature) on the extraction efficiency and quality indices of olive oil. This allowed us to present a modified protocol for the Abencor system operation suitable for olive fruit of irrigated orchards that will facilitate a reliable representation of the influence of different treatments on the yield and characteristics of the olive oil.     

Characterization of Turkish Virgin Olive Oils Produced from Early Harvest Olives

Olives were collected from various districts of Turkey (North and South Aegean sub-region, Bursa-Akhisar, South East Anatolia region) harvested over seven (2001–2007) seasons. The aim of this study was to characterize the chemical profiles of the oils derived from single variety Turkish olives including Ayvalik, Memecik, Gemlik, Erkence, Nizip Yaglik and Uslu. The olive oils were extracted by super press and three phase centrifugation from early harvest olives. Chosen quality indices included free fatty acid content (FFA), peroxide value (PV) and spectrophotometric characteristics in the ultraviolet (UV) region. According to the FFA results, 46% (11 out of 24 samples) were classified as extra virgin olive oils; whereas using the results of PV and UV, over 83% (over 19 of the 24 samples) had the extra virgin olive oil classification. Other measured parameters included oil stability (oxidative stability, chlorophyll pigment, pheophytin-α), cis–trans fatty acid composition and color index. Oxidative stability among oils differed whereas the cis–trans fatty acid values were within the national and international averages. Through the application of two multivariate statistical methods, Principal component and hierarchical analyses, early harvest virgin olive oil samples were classified according to the geographical locations categorized in terms of fatty acid profiles. Such statistical clustering gave rise to defined groups. These data provide evidence of the variation in virgin olive oil quality, especially early harvest and cis–trans isomers of fatty acid profiles from the diverse agronomic conditions in the olive growing regions of Turkey.     

On the quality control of ‘olive paste’, a specialty based on olives and olive oil

‘Olive paste’ is a preserved food gaining popularity as a gourmet product. Its quality depends on that of the major ingredients, table olives (green or black) and virgin olive oil, as well as on the changes occurring to the constituents of the latter during preparation and storage. In this view, our attention was focused on the characteristics of the lipid fraction (l.f.) of a great number of commercial products after a careful search in retail markets and the web. Ultraviolet absorbance values (K₂₃₂, K₂₇₀) of the l.f., a criterion set for edible and non‐edible olive oil oxidative status due to paste heat treatment during pasteurization, could not support the label information regarding the quality of the oil used. On the contrary, the content of α‐tocopherol (?250 mg/kg l.f. or ?50 mg/kg paste) was a strong indication of good‐quality major ingredients. Within each brand, consistency with labeling was checked through squalene (higher content in products containing higher amounts of olive oil) or β‐carotene determination (higher levels in preparations containing red pepper). For green olive paste samples, the values of the ratio pheophytin a/pyropheophytin a may be used to monitor the shelf life of the product. The findings support routine quality control of the new product.     

Characterisation of the geographical origin of Western Greek virgin olive oils based on instrumental and multivariate statistical analysis

In this work, measurements of free acidity, peroxide content, spectrophotometric parameters, chlorophyll content, phenol, sterol, fatty acid and triacylglycerol composition, were carried out on samples of virgin olive oils (VOOs) coming from four different Greek Ionian islands, i.e. Zakynthos, Kefalonia, Lefkada and Kerkyra. An analysis of variance (ANOVA) highlighted statistically significant differences (p < 0.01) in the values of 26 analytical parameters amongst the VOOs produced in the four different geographical regions but a post-hoc test showed that no variable was able to distinguish all four origins. Analogously, a Principal Component Analysis (PCA) showed a modest grouping of VOOs according to geographical origin except for Kerkyra samples which were more distinct from others. Applying discriminant function analysis (DFA) a good separation of the four geographical groups was achieved with classification and prediction abilities equal to 97.7% and 95.3%, respectively. Moreover, the analysis of the standardised coefficients showed that the fatty acids and triacylglycerols were the most discriminant variables. This last outcome was confirmed by comparison of the prediction performances obtained applying DFA on four subdatasets containing fatty acids (69.8%), triacylglycerols (76.7%), sterols (62.8%), and remaining parameters (65.1%) together, respectively. As the results showed, the multidisciplinary approach that combines different types of analytical determinations improved the discrimination of geographical origin for Greek virgin olive oils.     

Metal oxide semiconductor sensors for monitoring of oxidative status evolution and sensory analysis of virgin olive oils with different phenolic content

An electronic nose based on an array of six metal oxide semiconductor sensors was used to monitor the oxidative status of virgin olive oils (VOO) during storage. VOO samples, with and without phenolic compounds, were stored at 60 °C for 7 weeks. Once a week, absorbance at 232 and 270 nm, oxidized stability index, electronic nose, and sensory analysis were evaluated. Linear discriminant analysis models were constructed in order to classify samples according to oxidative levels. Based on these models, VOO samples with and without phenolic compounds at different storage times, divided in eight categories, were correctly classified also achieving a good correlation for sensory analysis. The method is a fast and economical tool for on-line monitoring of VOO oxidation status.     

Effect of Annealing on Virgin and Recycled Carbon Fiber Electrochemically Deposited with N-type Bismuth Telluride and Bismuth Sulfide

N-type thermoelectric bismuth telluride (Bi₂Te₃) and bismuth sulfide (Bi₂S₃) were deposited on virgin carbon fiber (VCF) and recycled carbon fiber (RCF) substrates by electrodeposition. The effects of annealing on the surface morphology and the Seebeck coefficient of the Bi₂Te₃ and Bi₂S₃ films were investigated. A nearly stoichiometric N-type Bi₂Te₃ was obtained from an electrolyte solution of 8 mM of Bi(NO₃)₃.5H₂O and 10 mM of TeO₂, which displayed the highest Seebeck coefficient of ?20.01 and ?13.0 µV/K for VCF and RCF, respectively. The deposition of Bi₂S₃ was slightly off-stoichiometry, but the improvement was still significant with a Seebeck coefficient of ?16.3 and ?12.4 µV/K for VCF and RCF, respectively. The effect of varying the annealing temperature (275°C and 350°C) and annealing time (2 and 3 hours) was studied on a nearly stoichiometric N-type Bi₂Te₃. The result shows an improvement in the Seebeck coefficient by 1.51–1.24 times at 350°C for 2 hours.     

Effect of location on virgin olive oils of the two main Tunisian olive cultivars

The olive oil content in phenolic compounds depends on the variety of the fruit used for its extraction as well as on the predominant climate conditions in the tree cultivation area. Here, we report on the characterization of virgin olive oil samples obtained from fruits of the main Tunisian olive cultivars Chemlali and Chétoui, grown in three different Tunisian locations, Zaghouan (North), Sousse (Center) and Sfax (South). Chétoui olive oil samples obtained from fruits of olive trees cultivated in Zaghouan and Chemlali olive oil samples obtained from fruits of olive trees cultivated in Sousse were found to have a higher mean total phenol content (1004 and 330 mg/kg, respectively). Olive oil samples obtained from fruits of both cultivars had different phenolic profiles and a higher content in 3,4‐DHPEA‐EDA when the olive trees were cultivated in Zaghouan. Both olive cultivars were found to have different responses to environmental conditions. Chétoui olive oil showed decreased oxidative stability when the fruits were obtained from olive trees cultivated in the center of Tunisia (34.8 h) and in Sfax (16.17 h). Furthermore, statistical data showed that the phenolic composition and oxidative stability of Chétoui olive oil varied more by location than those of Chemlali olive oils.     

Night Pilgrimage Chapel

Laura Moffatt describes how Gerold Wiederin's chapel in Locherboden, Austria, has been built as a focus for nocturnal Masses, giving architectural expression to a pilgrimage spot that was previously no more than a clearing in the forest. Copyright © 2007 John Wiley & Sons, Ltd.