Results 1 - 10 of 527
Results 1 - 10 of 527. Search took: 0.021 seconds
|Sort by: date | relevance|
[en] In this article, the main studies on frying performance of olive-extracted oils, namely, virgin olive oils, olive oils and olive-pomace oils, are reviewed and discussed in relation to other vegetable oils. Firstly, the most relevant compositional data of olive-extracted oils and commonly used vegetable oils are reported, including modified seed oils developed for frying uses. The influence of the degree of unsaturation and of the minor compounds with protective effect during frying are discussed, with special reference to tocopherols, other phenolic compounds, phytosterols and squalene. Results on comparative behavior of olive-extracted oils and other vegetable oils reflect that all olive-extracted oils show great stability to thermal oxidation and are highly suitable for frying, due to their high content of oleic acid, low content of polyunsaturated fatty acids and occurrence of minor components with antioxidant activity or protective effects. Among olive-extracted oils, the scarce information published on used frying pomace-olive oils is noted.
[es]En este artículo se revisan los principales estudios sobre el comportamiento en fritura de los aceites extraídos de la aceituna, es decir, aceites de oliva virgen, de oliva y de orujo de oliva. En primer lugar se describe su composición, así como la de los aceites vegetales más utilizados y los aceites de semillas modificadas, y se comenta la influencia en fritura del grado de insaturación y de los componentes menores del aceite, especialmente tocoferoles, otros compuestos fenólicos, fitoesteroles y escualeno. Los estudios realizados en comparación con otros aceites vegetales reflejan la gran resistencia de los aceites extraídos de la aceituna a la oxidación térmica y su aptitud para la fritura, debido a sus altos contenidos en ácido oleico, bajos niveles de ácidos grasos poliinsaturados y presencia de componentes menores con actividad antioxidante o protectora. Entre los aceites extraídos de la aceituna, el comportamiento del aceite de orujo de oliva es el menos estudiado en fritura.
[en] Full text: This experiment was conducted in an olive orchard containing 2,500 olive trees in Goekceada, 2002. Eco-traps (Vioryl Firm, Athens, Greece) were utilised for mass-trapping olive fly. In addition, Psyttalia concolor Szepl, which is one of the most effective parasitoids of olive fruit fly, were mass-reared on Mediterranean fruit fly, Ceratitis capitata (Wied.) larvae under laboratory conditions and were released throughout the natural population. Olive fruit fly populations in the experimental and control area were measured by means of McPhail and yellow sticky pheromone traps. A total of 2,000 Eco-traps were distributed in the experimental area before the first punctures were observed. Parasitoid releases were started by the time of the first punctures and continued in paralell to the increasing adult population. Fruit samples that were taken before each release and at harvest were counted. Wormy fruits were taken into culture to observe parasitoid emergence. As for the result of the study in the experimental area the efficiency of the combined technique was 79.32%, whereas the damage rate in control area was 87.60%. (author)
[en] The univariate generalized Waring distribution (UGWD) is presented as a new model to describe the goodness of fit, applicable in the context of agriculture. In this paper, it was used to model the number of olive groves recorded in Spain in the 8,091 municipalities recorded in the 2009 Agricultural Census, according to which the production of oil olives accounted for 94% of total output, while that of table olives represented 6% (with an average of 44.84 and 4.06 holdings per Spanish municipality, respectively). UGWD is suitable for fitting this type of discrete data, with strong left-sided asymmetry. This novel use of UGWD can provide the foundation for future research in agriculture, with the advantage over other discrete distributions that enables the analyst to split the variance. After defining the distribution, we analysed various methods for fitting the parameters associated with it, namely estimation by maximum likelihood, estimation by the method of moments and a variant of the latter, estimation by the method of frequencies and moments. For oil olives, the chi-square goodness of fit test gives p-values of 0.9992, 0.9967 and 0.9977, respectively. However, a poor fit was obtained for the table olive distribution. Finally, the variance was split, following Irwin, into three components related to random factors, external factors and internal differences. For the distribution of the number of olive grove holdings, this splitting showed that random and external factors only account about 0.22% and 0.05%. Therefore, internal differences within municipalities play an important role in determining total variability. (Author)
[en] The mineral element characterisation of olive fruits is acquiring interest to evaluate the link between their nutritional status and the olive oil quality. A method for the analysis of mineral elements in fresh olive fruits is proposed. The presence of mineral elements such as potassium, sodium, calcium, magnesium, zinc, copper, iron, and manganese in olive fruits was quantified by flame atomic absorption spectrometry. The limits of quantification were (expressed in mg kg.1 of dry weight) 1.266, 1.569, 0.272, 0.172, 0.268, 0.316, 1.017 and 0.513 for K, Na, Ca, Mg, Zn, Cu, Fe and Mn, respectively. The results showed the method is a robust, reliable, and simple analytical procedure for the mineral element characterisation of olive fruit. (Author).
[en] The frying performance of two virgin olive oils (VOO) from Cornicabra olives of different ripeness indices, 2.08 for VOO1 and 4.13 for VOO2, was evaluated. Thermal, oxidative and hydrolytic alterations were determined throughout 40 frying operations with potatoes. The initial oils showed similar fatty acid compositions and oxidative stability indices as determined by Rancimat, but VOO1 presented higher amounts of total polyphenols and tocopherols. The oils showed high and similar frying performance. No significant differences in the levels of polar compounds (PC) were found between the two oils during frying. Therefore, the frying stability of Cornicabra VOOs appears to be unconnected with olive fruit ripeness. The limit of degradation at 25% PC as established in different countries was calculated to occur at 55 frying operations in the two oils. As oil toxicity is related to the levels of compounds formed, the use of Cornicabra VOOs for frying is highly recommended.
[es]En el presente trabajo se evalúa el comportamiento de fritura de dos aceites de oliva virgen (VOO) obtenidos de aceitunas de la variedad Cornicabra con diferentes índices de maduración, 2,08 para VOO1 y 4,13 para VOO2. A lo largo de 40 operaciones de fritura con patatas se determinaron las alteraciones térmicas, oxidativas e hidrolíticas de los aceites. Los aceites iniciales presentaron composiciones de ácidos grasos e índices de estabilidad oxidativa determinados en Rancimat similares entre sí. Sin embargo, las cantidades de fenoles totales y tocoferol fueron más altas para VOO1. Los aceites mostraron una eficacia en fritura elevada y similar. No se encontraron diferencias significativas en los niveles de compuestos polares (PC) durante la fritura entre los dos aceites. Por tanto, la estabilidad en condiciones de fritura de los dos aceites Cornicabra no parece estar relacionada con el estado de maduración de las aceitunas. El límite de degradación de 25% de PC establecido en diferentes países se calculó por extrapolación de resultados, alcanzándose éste a las 55 operaciones de fritura para los dos aceites. Debido a que la toxicidad está relacionada con los niveles de compuestos formados, el uso en fritura de aceites de oliva virgen de la variedad Cornicabra es altamente recomendado.
[en] Olive (Olea europea L.) plays an important role in the Mediterranean agriculture where olive oil is the fundamental fat supply in the Mediterranean diet. Olive tree has been found within the habitats of Cyprus for a long time but, most of the olive cultivars are wild with low yield and low quality. High-density plantations are key factor for improving olive tree productivity and selection of the appropriate cultivar is crucial. The aim of current study was to test the performance and oil quality of five commercial clones cv. 'Arbequina', cv. 'Arbosana', cv. 'Sikitita', cv. Koroneiki and cv. 'Tosca' grown in high-density systems in Northern Cyprus in comparison with two local cultivars cv. 'Kato Drys' and cv. 'Klirou'. The experimental studies were conducted in Guzelyurt in Northern Cyprus during 5 sequential crop years from 2013 (2nd growing year) to 2017 (6th growing year). Seedlings of commercial clones were planted with a pattern of 4 x 2 m (1250 trees ha-1) and local cultivars with a pattern of 5 x 5 m (400 trees ha-1). Results indicated that Arbequina, Arbosana and Koroneiki are the most precocious cultivars which bore fruits in the second year after planting and had the highest cumulative olive and olive oil yield in 6 successive growing seasons. However, Arbequina cultivar was also found to have higher free fatty acid contents (% oleic acid) than the IOC limit (0.8% oleic acid) for extra virgin olive oil. (author
[en] Olive crop and olive oil industry generates several residues, i.e., olive tree pruning biomass (OTPB), extracted olive pomace (EOP) and olive leaves (OL) that could be used to produce high-added value products in an integrated biorefinery. OTPB is generated in the field as a result of pruning operation to remove old branches; EOP is the main residue of the pomace olive oil extracting industry after extraction with hexane of residual oil contained in olive pomace; and OL comes from the olive cleaning process carried out at olive mills, where small branches and leaves are separated by density. In this work, an analysis of the potential of OTPB, EOP and OL residues was addressed by estimating the production volumes at national level and the spatial distribution of these residues using geographic information system software. Information provided by public institutions and personal surveys to the industries was evaluated. Moreover, chemical analysis of the residues was undertaken and the results used to make a first assessment of valorization into biofuels such as bioethanol and bio based chemicals. Results show that close to 4.2 million tons/year of EOP, OL and OTPB derived from olive oil industry and olive tree cultivation in Spain could be available as a raw material for biorefineries in Spain. The analysis of the chemical characteristics indicates the relevant potential of these feedstocks for the production of bioethanol and other compounds such as phenols based on suitable processing and conversion routes, although techno-economic evaluations must be tackled to refine this approach.
[en] The evolution of phenolic compounds and their contribution to the quality characteristics in virgin olive oil during fruit processing was studied with the addition of a combination of various commercial enzymes containing pectinases, polygalacturonases, cellulase and β-glucanase with or without nitrogen flush. Olive fruits (Olea europaea, L.) of the cultivar Megaritiki, at the semi black pigmentation stage of maturity, were used in a 3-phase extraction system in an experiment at industrial scale. The addition of enzymes in the olive paste during processing increased the total phenol and ortho-diphenol contents, as well as some simple phenolic compounds (3,4-DHPEA, p-HPEA) and the secoiridoid derivatives (3,4-DHPEA-EDA and 3,4-DHPEAEA) in olive oil and therefore improved its oxidative stability. Furthermore, enzyme treatment ameliorated the quality parameters of the produced olive oil (acidity and peroxide value) and their sensory attributes. The use of additional N2 flush with the enzyme treatments did not improve the quality parameters of olive oil any further; however it did not affect the concentration of individual and total sterols or most of the fatty acid composition. Consequently, olive paste treatment with enzymes not only improved the quality characteristics of olive oil and enhanced the overall organoleptic quality, but also increased the olive oil yield. (Author) 33 refs.
[en] Production, distribution, taxonomy, origin, breeding objectives and systems are reviewed. The main objective should be to obtain cultivars that are reduced in size, precocious, constantly and highly productive and early ripening in order to make mechanical harvesting in different environments feasible. Processing quality (for oil and table cultivars), winter hardiness and pest and disease resistance are highly desirable traits. In addition to clonal selection, mutation breeding is a very promising method of obtaining new, useful traits. To avoid the chimeric structure, use of tissue culture is suggested. (author)
[en] Table olive processing water (TOPW) contains many complex substances, such as phenols, which could be valorized as a substrate for microalgae biomass culture. The aim of this study was to assess the capability of Nannochloropsis gaditana to grow in TOPW at different concentrations (10- 80%) in order to valorize this processing water. Within this range, the highest increment of biomass was determined at percentage of 40% of TOPW, reaching an increment of 0.36 ± 0.05 mg volatile suspended solids (VSS)/L. Components of algal biomass were similar for the experiments at 10-40% of TOPW, where proteins were the major compounds (56-74%). Total phenols were retained in the microalgae biomass (0.020 ± 0.002 g of total phenols/g VSS). Experiments for 80% of TOPW resulted in a low production of microalgae biomass. High organic matter, nitrogen, phosphorus and phenol removal were achieved in all TOPW concentrations. Although high-value products, such as proteins, were obtained and high removal efficiencies of nutrients were determined, microalgae biomass culture should be enhanced to become a suitable integral processing water treatment.
[es]El agua resultante del proceso de elaboración de la aceituna de mesa (TOPW) presenta un elevado contenido en sustancias complejas, como fenoles, que podría permitir su uso como sustrato para el cultivo de microalgas. El objetivo de este estudio se centra en evaluar la capacidad de crecimiento de annochloropsis gaditana en TOPW a distintas concentraciones (10-80%) con vistas a la valorización de estas aguas. El mayor incremento de biomasa se obtuvo para un porcentaje del 40% de TOPW, alcanzando un aumento de 0.36 ± 0.50 mg sólidos en suspensión volátiles (SSV)/L. Los componentes presentes en la biomasa han sido similares para los experimentos con 10-40% de TOPW, siendo las proteínas los compuestos mayoritarios en todos los casos (56-74%). Los fenoles totales quedaron retenidos en las microalgas, alcanzando una concentración media de 0.020 ± 0.002 g fenoles totales/g SSV. En los experimentos con 80% de TOPW se obtuvieron producciones bajas de microalgas. Las eficiencias de eliminación de materia orgánica, nitrógeno, fósforo y fenoles fueron elevadas para las diferentes concentraciones estudiadas de TOPW. Aunque se ha obtenido una elevada producción de compuestos de interés y altas eficiencias de eliminación de nutrientes, el cultivo de microalgas debería mejorarse para llegar a ser un sistema integral válido para el tratamiento de TOPW.