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Colombo S.,IFAPA Centro del Llano | Christie M.,Aberystwyth University | Hanley N.,University of Stirling
Ecological Economics | Year: 2013

This paper investigates the sensitivity of choice experiment values 3AL for ecosystem services to 'attribute non-attendance'. We consider three cases of attendance, namely that people may always, sometimes, or never pay attention to a given attribute in making their choices. This allows a series of models to be estimated which addresses the following questions: To what extent do respondents ignore attributes in choice experiments? What is the impact of alternative strategies for dealing with attribute non-attendance? Can respondents reliably self-report non-attendance? Do respondents partially attend to attributes, and what are the implications of this? Our results show that allowing for the instance of 'sometimes attending' to attributes in making choices offers advantages over methods employed thus far in the literature. © 2013 Elsevier B.V.


Guzman E.,IFAPA Centro del Llano | Baeten V.,Walloon Agricultural Research Center | Pierna J.A.F.,Walloon Agricultural Research Center | Garcia-Mesa J.A.,IFAPA Centro del Llano
Talanta | Year: 2012

In the real marketplace, providing high-quality olive oil is important from the perspective of both consumers and producers. Quality control should meet all requirements in the production process, from farm to packaging. The quality of olive oil can be affected by several factors, including agricultural techniques, seasonal conditions, farming systems, maturity, method and duration of storage, and process technology. The quality of oil produced also depends largely on the quality of the olives. In an enterprise aimed at producing high-quality oils, olives with defects ('ground'; i.e., fallen to the ground) should be separated from healthy fruit ('sound'; i.e., collected directly from the tree), because a very small portion of low-quality fruit can ruin the whole batch. The fruit falls partly because of its maturation process, but also because of pest and disease attack or weather conditions (strong wind). Fruit that has fallen to the ground can suffer a rapid deterioration in quality. Currently, the separation of fruits is based mainly on visual inspection or information provided by the farmer. These are not very reliable procedures. Methods using analytical parameters to characterize the oil, such as acidity and peroxide value, can be applied, but they require a lot of time and materials. Alternative techniques are therefore needed for the rapid and inexpensive discrimination of olives as part of a quality control strategy. The work described here aims to determine the potential of low-resolution Raman spectroscopy for the discrimination of olives before the oil processing stage in order to detect whether they have been collected directly from the tree (i.e., healthy fruit) or not. Low-resolution Raman spectroscopy was applied together with multivariate procedures to achieve this aim. PCA was used to find natural clusters in the data. Supervised classification methods were then applied: Soft Independent Modeling of Class Analogy (SIMCA), PLS Discriminate Analysis (PLS-DA) and K-nearest neighbors (KNN). The best results were obtained using the KNN method, with prediction abilities of 100% for 'sound' and 97% for 'ground' in an independent validation set. These results demonstrated the potential of a portable Raman instrument for detecting good quality olives before the oil processing stage, by developing models that could be applied before this stage, thus contributing to an overall improvement in quality control. © 2012 Elsevier B.V. All rights reserved.


Guzman E.,IFAPA Centro del Llano | Baeten V.,Walloon Agricultural Research Center | Pierna J.A.F.,Walloon Agricultural Research Center | Garcia-Mesa J.A.,IFAPA Centro del Llano
Food Chemistry | Year: 2015

The fluorescence spectra of some olive oils were examined in their natural and oxidised state, with wavelength range emissions of 300-800 nm and 300-400 nm used as excitation radiation. The fluorescence emissions were measured and an assessment was made of the relationship between them and the main quality parameters of olive oils, such as peroxide value, K232, K270 and acidity. These quality parameters (peroxide value, K232, K270 and acidity) are determined by laboratory methods, which though not too sophisticated, they are required solvents and materials as well as time consuming and sample preparation; there is a need for rapid analytical techniques and a low-cost technology for olive oil quality control. The oxidised oils studied had a strong fluorescence band at 430-450 nm. Extra virgin olive oil gave a different but interesting fluorescence spectrum, composed of three bands: one low intensity doublet at 440 and 455 nm; one strong band at 525 nm; and one of medium intensity at 681 nm. The band at 681 nm was identified as the chlorophyll band. The band at 525 nm was derived, at least partially, from vitamin E. The results presented demonstrate the ability of the fluorescence technique, combined with multivariate analysis, to characterise olive oils on the basis of all the quality parameters studied. Prediction models were obtained using various methods, such as partial least squares (PLS), N-way PLS (N-PLS) and external validation, in order to obtain an overall evaluation of oil quality. The best results were obtained for predicting K270 with a root mean square (RMS) prediction error of 0.08 and a correlation coefficient obtained with the external validation of 0.924. Fluorescence spectroscopy facilitates the detection of virgin olive oils obtained from defective or poorly maintained fruits (high acidity), fruits that are highly degraded in the early stages (with a high peroxide value) and oils in advanced stages of oxidation, with secondary oxidation compounds (high K232 and K270). The results indicate the potential of a spectrofluorimetric method combined with multivariate analysis to differentiate, and even quantify, the levels of oil quality. The proposed methodology could be used to accelerate analysis, is inexpensive and allows a comprehensive assessment to be made of olive oil quality. © 2014 Elsevier Ltd. All rights reserved.


Liazid A.,University of Cádiz | Guerrero R.F.,IFAPA Centro del Llano | Cantos E.,IFAPA Centro del Llano | Palma M.,University of Cádiz | Barroso C.G.,University of Cádiz
Food Chemistry | Year: 2011

A new method for the analysis of anthocyanins in grapes based on a systematic study of the extractability of eleven anthocyanins from grapes has been developed. Microwave assisted extraction was applied as a prior stage to the chromatographic determination of anthocyanins in the extracts. The stability of anthocyanins under the extraction conditions was checked using a standardised extract from grape skins. Temperatures from 50 °C up to 150 °C were evaluated. A fractional factorial experimental design was developed to analyse the influence on the extraction process of six different extraction variables: solvent (mixtures of methanol and water), stirring, extraction temperature, extraction time, microwave power and extraction volume. The extraction solvent was the most important variable for the recovery of most anthocyanins from grapes. Finally, the influence of the extraction time was also studied. With this new method, anthocyanins can be extracted from grapes in 5. min, using 100 °C as extraction temperature and 40% methanol in water as the extraction solvent. Repeatability and reproducibility were also checked, the resulting RSDs (. n=. 9) were lower than 7% for glucosides, the main components, and lower than 9% for the acyl derivatives, the compounds found in the lowest concentrations. © 2010 Elsevier Ltd.


Escuderos M.E.,IFAPA Centro del Llano | Sanchez S.,University of Jaén | Jimenez A.,IFAPA Centro del Llano
Sensors and Actuators, B: Chemical | Year: 2010

The potential of an artificial olfactory system, constituted by an array of five Quartz Crystal Microbalance (QCM) sensors, to discriminate virgin olive oil samples based on their aromatic profiles was researched. Five gas chromatographic stationary phases (OV-17, OV-275, PEG, Span 80 and Vaseline) were employed as sensing films of QCM sensors. The steady state sensor responses measured by a statistical measurement system were used to evaluate the discrimination properties of the system by Principal Component Analysis (PCA) method. The results of this study provide promising perspectives for the use of a low-cost, easy to use and fast system for the differentiation of edible from lampante virgin olive oils. © 2010 Elsevier B.V. All rights reserved.


Escuderos M.E.,IFAPA Centro del Llano | Sanchez S.,University of Jaén | Jimenez A.,IFAPA Centro del Llano
Food Chemistry | Year: 2011

The potential of eight Quartz Crystal Microbalance (QCM) sensor arrays to differentiate the quality of olive oil samples, based on their aromatic profiles, were investigated. Five gas chromatographic stationary phases (OV-17, OV-275, PEG, Span 80 and Vaseline) were used as sensing films of QCM sensors. The steady state sensor responses measured by a static measurement system were used to evaluate the discrimination properties of each array by Principal Component Analysis (PCA) method. The results of this study provide promising perspectives for the use of a low-cost, easy to use and rapid system for differentiation of virgin and extra virgin olive oils from lampante ones. © 2010 Elsevier Ltd.


Escuderos M.E.,IFAPA Centro del Llano
Critical Reviews in Analytical Chemistry | Year: 2011

The virgin olive oil aroma evaluation has been applied as a quality and authentication control technique. Many analytical procedures have been used to identify and quantify the volatile components that characterize olive oil flavor. Among of them, gas chromatography is the main technique applied for this purpose. This study carries out an extensive and complete review of all the works published, since 30 years ago to the present, that have used gas chromatography technology for olive oil aroma analysis. Special attention has been devoted to the olive oil volatile compounds extraction and concentration techniques and separation and identification methods applied. © Taylor and Francis Group, LLC.


Aguilar M.J.,IFAPA Centro del Llano
Journal of Water Reuse and Desalination | Year: 2011

The objective of this work was to determine how some wastewater acids could be used to prevent the decomposition of urea into ammonia during storage. The effect of storing human urine with olive oil mill wastewaters (OOMW) or water bubbled with CO2 (BW), was studied. Moreover, the application of two levels of urine dissolved in water OOMW, has been studied in relation to the properties of two soils (loam and silty-clay loam). Our data provide evidence that human urine dissolved in OOMW significantly reduced the release of ammonium-N. Moreover, OOMW and CO2 significantly lowered the pH. A dosage higher 10% OOMW dissolved in fresh urine in volume could inhibit the hydrolysis of the urea for more than 6 months. Moreover, urine-N dissolved in OOMW significantly reduced the emission of nitrates from soils for 3 months, increasing K and P values. The application of urine with BW raised the soil pH and lowered the EC, but had no effect on nutrient contents. Thus, urine dissolved in OOMW and applied to soils could act as NPK-fertilizer. However, the impact of fertilization with human urine-OOMW-CO2 requires further investigation with respect to crop production and pollution. © IWA Publishing 2011.


Lazo C.S.,IFAPA Centro del Llano | Pita I.M.,IFAPA Centro del Llano
Aquaculture Research | Year: 2012

Mussel aquaculture is widely prevalent worldwide, but generally relies on natural seed collection, which does not always meet the needs of the producers. Thus, development of mussel hatcheries is of economic interest in some parts of the world, such as Europe; it provides opportunities not only on annual reliability of seed but also on genetic improvements. To broaden knowledge on mussel larval physiology, we carried out temperature treatments (17, 20 and 24°C) on Mytilus galloprovincialis larvae under laboratory conditions. The trials ended when 30% of the larval population was in the post-larval stage. The temperature coefficient Q 10 indicated a strong relationship between temperature and increase in growth from 17 to 20°C, but not between 20 and 24°C. Exposure of M. galloprovincialis larvae to 17°C resulted in poor growth, low survival and a delayed development and was considered to be inadequate for M. galloprovincialis larval culture. Rearing the larvae at 20 or 24°C produced better growth, higher survival rates and faster metamorphosis as compared with 17°C. The temperature region within 20 and 24°C was suggested as adequate for the mussel M. galloprovincialis larval culture, and implications of these results on the development of commercial hatcheries were discussed. © 2011 Blackwell Publishing Ltd.


Aguilar M.J.,IFAPA Centro del Llano
Journal of Hazardous Materials | Year: 2012

The aim of this work was to investigate the effect of urine on the absorption of greenhouse gases such as CO 2. Human urine diluted with olive-oil-mill wastewaters (OMW) could be used to capture CO 2 from flue gas of coal-fired power plant and convert CO 2 emissions into valuable fertilizers (mainly, NH 4HCO 3) that can enhance CO 2 sequestration into soil and subsoil layers. Thus, the CO 2 emissions could be reduced between 0.1 and 1%. The proposed strategy requires further research to increase CO 2 absorption and assess the risks associated with wastewater reuse and xenobiotics in the agroecological environment. © 2012 Elsevier B.V.

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