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A Predictive Classification Model for the Management of Virgin Olive Oil Filtration at Industrial Scale
Separation Science and Technology
Abstract
Precoat-bodyfeed filtration of virgin olive oil was investigated onan industrial filter-press plant. Several chemical parameters of theunfiltered oil were measured and the relationship with filtrationperformances was investigated by Principal Component Analysis.Further, Linear Discriminant Analysis was applied to develop a predictivemodel for oil filterability. Principal Component Analysisallowed the construction of latent variables which were used to separateoil groups and to select variables for Linear DiscriminantAnalysis. The developed linear model gave an overall correct recognitionof about 88%, good enough for a convenient filterabilityprediction of oil at industrial scale.
... The current practice of virgin olive oil (VOO) industrial filtration basically involves the use of filtration aids (diatomaceous earth and/or perlite, cellulose), in the so called precoat-body-feed filtration (Sanchez, L. et al., 2010;Masella et al., 2011). The main residue of this process is the spent filtration cake, which is generally considered as a waste. ...
... Some years later, part of the data was newly processed by means of multivariate statistic allowing the development of a linear model for the oil filterability prediction at an industrial scale. The results were subsequently published (Masella et al., 2011). However, some of the original data were not included in the paper, because it was out of the scope of that work. ...
... The study was conducted at industrial scale on a horizontal filter-press (114 m2 filter area, 2.240 m 3 filter volume) for precoat body-feed filtration (Galigani Filtri Srl, Italy). This plant was located as an Italian olive oil packaging company where a detailed the company working procedure, as well as of the filtration apparatus and filtration processing can be found (Masella et al., 2011). Briefly, the ordinary factory work involves filtration of blends of different virgin olive oil mainly from Italy, Greece, and Spain. ...
The most widespread method for virgin olive oil filtration at industrial scale is the so-called precoat body-feed
filtration by means of filter aids, mainly consisting of perlite and cellulose. The residue of the process is a spent filtration cake, which has the potential for upgrading if it is understood in the context of the biorefining concept. Data about the production and composition of the spent cake were collected from an industrial case-study. The potential availability of the spent cake has been estimated both at local scale (the industrial case-study) and at larger scale based on the Spanish context, that is the world leading virgin olive oil producer. The mean percentage composition of the spent cake is 5% oil impurities, 7% cellulose, 28% perlite, 52% oil and 8% water. About 10 g of spent cake are produced per kilogram of virgin olive oil to be processed; while about 316 and 7482 Mg of spent cake could be potentially available for the local and large scale occasion, respectively. Owing to its composition entailing oil and waxes, cellulose and mineral fractions, the spent cake has the potential as feedstock for the emerging biotechnologies and biorefineries.
... Immediately after centrifugation, the VOO produced is turbid from suspended solid plant-tissue particles and vegetable water emulsified in the oil, which can deteriorate its quality by facilitating hydrolysis or oxidation of lipid matrix. Recently, filtration was included in VOO-production process as a final step before bottling in order to make VOO more brilliant and maintain its quality [1,5] and [6]. ...
... Several filtration systems are used for VOO: conventional filtration systems, cross-flow filtration, and new patented approaches based on inert gas-flow filtration and filter bags [7] and [8]. At the industrial scale, the most widespread system is the conventional one, which employs filter aids in conjunction with filtration equipment (tanks or presses) to enhance or enable suspended solids and water-oil separation [5]. Filter aids for filter cake can be produced from a wide variety of raw materials. ...
... Because of this, colloidal associations are formed which give the freshly produced oil its typical veiled appearance [23]. Regarding the effect of different filtration systems, it is important to underline that many researchers [3,9,12,18,[24][25][26][27] found significant differences both in the shelf life and physicochemical and sensory characteristics of tested olive oils. The filtration systems applied in the olive oil industry can be of different types: there are conventional filtration systems (filter tanks and filter presses), cross-flow filtration (tangential filtration), inert gas-flow filtration systems, and filter bags, as reviewed by Lozano-Sánchez et al. [25]. ...
Filtration is a process that eliminates solid sediments and moisture in olive oil to maintain its shelf life during storage. The influence of filtration on the oil characteristics is linked to many parameters such as chemical and sensory traits, cultivars and filtration systems. After assessing the literature on filtration research, we observed that there are contrasting findings and it is complicated to answer the question of whether to filter or not. An analysis of the influence of different filtration technologies used in extra-virgin olive oil production on the phenolic compounds, volatile fractions, antioxidant activity and sensory characteristics is given in this review. The information compiled could help olive oil producers to enhance extra-virgin olive oil quality and maintain it during storage.
... However, at the industrial level, a filtration process is generally applied to cloudy VOO for removing suspended solids and humidity before storage or bottling steps. Conventional filtration systems use organic or inorganic filter aids, such as diatomaceous earth and cellulose fibers, in conjunction with filtration equipment (tanks or presses) (Lozano-Sanchez et al., 2010;Masella et al., 2011). Previous studies (Lozano-Sánchez et al., 2007;Gómez-Caravaca et al., 2007) remarked that the filtration step may either positively or negatively affect the stability, phenolics, volatiles, pigments and the sensory proprieties of olive oil and discussed the possible use of different types of filtering systems. ...
In this preliminary study, two non-filtered virgin olive oils (one freshly produced VOO-N; one VOO-O stored for one year) were subjected to moisture removal with mineral clay (raw or activated) and analyses were performed to attest possible effects on the quality of the product. The results demonstrated that the treatment of oil with mineral clay at 36-38 °C had no negative effect on the basic quality parameters or on the volatile comound profile. On the other hand, a significant decrease in the water amount as well as in pigments was observed in the samples subjected to this kind of treatment, in particular with raw clay. Regarding the colour measurement, the lightness (L) as well as the consumers’ acceptability exhibited a marked increase when oils were treated with raw clay.
... Filtration systems applicable on VOO can be classified in three groups: a) conventional systems based on the use of organic or inorganic filter aids in conjunction with filtration equipment (filter tanks and filter presses), b) membrane filtration and c) new filtration systems proposed as alternative processes (the polypropylene filter bag system and filtration based on the flow of an inert gas) (Lozano-S anchez et al., 2010). At the industrial scale, the most widespread is the so-called precoat-bodyfeed conventional filtration system, which employs filtration aid and vertical leaf-filter or horizontal filter press as filtration apparatus (Masella, Parenti, Spugnoli, Baldi, & Mattei, 2011). Filter press using a cellulose filter plate as filter aid are mostly used by small companies which cannot afford to purchase other types of filters (Guerrini, Masella, Migliorini, Cherubini, & Parenti, 2015). ...
The aim of this study was to compare quality changes and compositional characteristics (fatty acids, total phenols, sensory profile) of Buža and Istarska bjelica cv. virgin olive oils clarified by filtration at an industrial scale (filter press equipped with cellulose filters) and those clarified by natural sedimentation and decantation, as well as the influence of filtration of virgin olive oils on sterols and triterpene dialcohols composition during 12 months storage. There were no significant differences in hydrolytic deterioration and sensory scores during the whole storage period between filtered and naturally sedimented oil samples. After 6 months, natural sedimentation was more favorable as regards delaying of oxidative deterioration, while filtration provided a more stable sensory profile. As regards total phenols the impact of the clarifying procedure was dependent on cultivar and fruit ripeness degree and it was more emphasized than the impact of storage. Filtration slightly affected the fatty acids composition, but natural sedimentation and decantation had no effect on it. Nevertheless, filtration did not compromise the confirmation of virgin olive oil authenticity according to the fatty acid composition, as well as according to sterols and triterpene dialcohols.
... (i) conventional systems based on use of organic or inorganic filter aids in conjunction with filtration equipment (filter tanks and filter presses); (ii) cross-flow filtration characterized by tangential flow through the polymeric and ceramic membrane; and (iii) two new filtration systems proposed as alternative processes (the polypropylene filter bag system and filtration based on the flow of an inert gas) (Lozano-Sánchez et al. 2010). At the industrial scale, the most widespread is the so-called precoatbodyfeed conventional filtration system, which employs filtration aid and vertical leaf-filter or horizontal filterpress as the filtration apparatus (Masella et al., 2011) (Figure 31.2). ...
Immediately after extraction from olive fruits, virgin olive oil is a turbid juice with suspended particles of plant tissue and vegetable water droplets, which can deteriorate their quality by facilitating hydrolysis or oxidation of oil. Recently, filtration becomes a standard virgin olive oils production step with the aim of faster product finalisation and shelf-life extension. Filtration of olive oil could influence changes in antioxidant compounds such as phenols, tocopherols, and pigments, as well as volatile substances responsible for pleasant virgin olive oil aroma. In this work the changes of these minor compounds and fatty acids in relation to different filtration systems applied to virgin olive oil are discussed. In addition, influences of several agronomic and technological factors on composition of active compounds of virgin olive oil are reviewed. Moreover, analytical techniques for determination of virgin olive oil active components are pointed out.
... Different filtration systems have been applied in the olive-oil industry: conventional filtration systems (filter tanks and filter presses) and cross-flow filtration (tangential flow filtration). 2,3 Conventional filtration systems use organic or inorganic filter aids in conjunction with filtration equipment (tanks or presses) to enhance or enable suspended solids and water−oil separations. Diatomaceous earth and cellulose fibers are commonly used as filter aids, 3−5 which are deposited on the surface of the filtration equipment by filtering specially prepared mixes. 2 On occasion, nonpower filter aids such as cotton or cellulose paper may be used instead of diatomaceous earth and cellulose fibers in filter presses. ...
The purpose of this work was to evaluate some new filtration systems in relation to the quality of extra-virgin olive oil (EVOO). Filtration processes were undertaken using a polypropylene filter bag and two different inert gas flows as filter aids (argon and nitrogen). Qualitative and quantitative variations of the glyceride composition, antioxidant and pro-oxidant compounds, and water content were correlated with the oxidative stability to establish the effect on EVOO shelf life. The influence on physicochemical and sensorial properties was also evaluated. After filtration, the oxidative stability was reduced. The behavior of the polyphenols and water content on the filtration process could explain the lowest oxidative stability of filtered EVOO. Moreover, the results of the sensorial analysis confirmed that filtration using inert gases did not decrease the intensity of the main positive sensory attributes. The results could help olive-oil producers to improve EVOO quality and establish optimal storage conditions.
The aim of this investigation was to evaluate the chemical and sensory quality of three extra virgin olive oils (EV1-3) subjected to a new patented system to clarify cloudy oils through the insertion of an inert flow gas (argon) in olive oil mass. For this purpose, several quality parameters were determined on the three clarified (EVC1-3) and untreated (EVNC1-3) samples. In particular, the system patented by the University of Bologna and Sapio (a private company that supplies gas for industrial and research sectors) was applied to a 50 L batch of each oil after its production by a low-scale mill. The EV samples were bottled and stored at room temperature and kept in darkness before analysis. Basic quality indices including free acidity, peroxide value, specific absorption in the conjugated triene region and sensory analysis, as well as the composition of the major (fatty acids) and minor (tocopherols, polar phenols, volatiles, water) compounds were determined after three months of storage. The oxidative stability under stress conditions was also assessed. The main results concern the higher overall quality of the EV samples clarified by the patented system compared to untreated ones. The quantity of water significantly decreased in all clarified samples. Above all, the non-clarified oils showed a tendency to quickly develop off-flavors over time and to decrease their oxidative stability.
THIS WORK IS A PRELIMINARY CONTRIBUTION TOWARDS UNDERSTANDING THE NATURE OFTHE MATERIAL RESPONSIBLE FOR THE PHYSICOCHEMICAL STATUS OF VEILED OLIVE OIL(DESCRIBED AS SUSPENSION–DISPERSION SYSTEM). TWENTY FOUR OLIVE OIL SAMPLESWITH DIFFERENT CLOUDY APPEARANCES WERE GROUPED INTO THREE CLASSES ACCORDING TOINCREASING TURBIDITY, BOTH BY MEANS OF A VISUAL EVALUATION AND BY SPECTROPHOTOMETRICOPTICAL DENSITY (ABSORBANCE AT 630 NM). CHEMICAL ANALYSES WERE THENPERFORMED, I.E. FREE ACIDITY (FA), PEROXIDE VALUE (PV), UV ABSORPTION (UVA), MOISTURE(MO), IMPURITY, FATTY ACID COMPOSITION (FAC), STEROLS AND WAXES CONCENTRATION.THE OIL SAMPLES WERE VERY SIMILAR, I.E. NO SIGNIFICANT OR MINIMAL DIFFERENCESIN FA, PV, UVA, FAC AND STEROLS, WHEREAS LARGE AND SIGNIFICANT DIFFERENCES WEREFOUND BOTH FOR MO AND WAXES (BOTH TOTAL AND SPECIFIC ESTERS) AMONG THE THREETURBIDITY CLASSES. IMPURITIES WERE NOT DETECTED IN ANY SAMPLES. AN ADDITIVEEFFECT OF WAXES ALONG WITH OTHER MINOR CONSTITUENTS IN THE ESTABLISHMENT OF THEPHYSICOCHEMICAL STATE OF THE VEILED VOO WAS HYPOTHESIZED.
Membrane separation is an optional technology to replace the conventional degumming step during the processing of vegetable oils. In this work, the performance of an asymmetric membrane of polyvinylidenfluoride (PVDF) during the degumming of a crude vegetable oil/hexane mixture was investigated. Samples of soybean and sunflower oil were treated and the effect of oil source on membrane fouling was evaluated.The water and hexane membrane permeability were assessed by permeation experiments and their values were used to explain the membrane behavior. The degumming tests were performed in a stirred dead-end cell, at different temperatures and pressures.Retention of phospholipids (selectivity) was greater than 95% in the whole range of studied conditions (2 bar < ΔP < 6 bar; 30 °C < T < 50 °C). The results showed that degumming of sunflower oil produced a higher membrane fouling than degumming of soybean oil.
The term "Mediterranean diet," implying that all Mediterranean people have the same diet, is a misnomer. The countries around the Mediterranean basin have different diets, religions and cultures. Their diets differ in the amount of total fat, olive oil, type of meat and wine intake; milk vs. cheese; fruits and vegetables; and the rates of coronary heart disease and cancer, with the lower death rates and longer life expectancy occurring in Greece. Extensive studies on the traditional diet of Greece (the diet before 1960) indicate that the dietary pattern of Greeks consists of a high intake of fruits, vegetables (particularly wild plants), nuts and cereals mostly in the form of sourdough bread rather than pasta; more olive oil and olives; less milk but more cheese; more fish; less meat; and moderate amounts of wine, more so than other Mediterranean countries. Analyses of the dietary pattern of the diet of Crete shows a number of protective substances, such as selenium, glutathione, a balanced ratio of (n-6):(n-3) essential fatty acids (EFA), high amounts of fiber, antioxidants (especially resveratrol from wine and polyphenols from olive oil), vitamins E and C, some of which have been shown to be associated with lower risk of cancer, including cancer of the breast. These findings should serve as a strong incentive for the initiation of intervention trials that will test the effect of specific dietary patterns in the prevention and management of patients with cancer.
Virgin olive oil quality depends on different factors such as olive cultivar, olive tree cultivation and the operations of olive picking, storage and processing. Many investigations concerning these factors were carried out and, in particular, the influence of technological operations of olive processing on oil yields and quality was examined. Leafremoval and olive washing are important operations for the mechanical safety of the olive extracting equipment which operates at high speed and for the organoleptic quality of olive oil. The leaves mixed with olives may increase, in fact, the organoleptic attributes of ‘fresh-cut’ grass or ‘green’, especially if metallic crushers are used to prepare olive paste. Olive crushing has an important influence on organoleptic and nutritional qualities of virgin olive oil. When mill stones are used, the obtained oils have a lower intensity of bitterness and pungency because this crushing method helps to produce oil with a lower content of phenolic substances. When metallic crushers are used oils have, due to the violent action, a higher content of phenolic compounds and are more bitter and pungent. Olive paste malaxation influences the oil yields and also the antioxidant content of oil. With prolonged malaxation oil yields, generally, increase while the phenol content of oils decreases. When ‘difficult’ olive pastes are processed, it is possible to increase oil yields by using technological co-adjuvants such as talc and enzymatic products during the malaxation. The separation of oil from solid and liquid phases of olive paste is performed by using either pressure, percolation or centrifugation systems. All systems may provide good-quality oil if olive fruits are sound and at the correct ripeness, but the centrifugation system helps to avoid or reduce the risk of an organoleptic contamination. The new centrifugal decanters, operating without adding water (or only a minimal amount of water) to olive paste, save heat energy and the oils obtained are more fruity and have a higher content of natural phenolic antioxidants.
In this work, the temperature-dependent rheological behavior of un-used and used vegetable cooking oils was evaluated. The un-used edible oils (soybean, sunflower, olive, rapeseed, corn, rice and the mixtures soybean + olive and sunflower + olive) presented Newtonian behavior above 10 s−1 shear rates; the values of viscosity during heating and cooling were similar, indicating that degradation of the oils did not happen at the temperature range studied (10–80 °C). After treatment at frying condition (190 °C), there was an increase of the edible oils’ viscosity, depending on frying time, perhaps due to the increase of saturation of the oil constituents. The rheological behavior of used cooking oils remained Newtonian at shear rates greater than 10 s−1.
In this work we report the measurement of the viscosity of olive oil at high pressure using a falling sinker type viscometer. The design of the viscometer relies on a close-fitting self-centring sinker enclosed within a vertical tube maintained at a controlled temperature. Based on the accurate fall times of the sinker measured electronically, the performance of the viscometer was studied to provide the relationship of viscosity with pressure for olive oil up to 150 MPa. The viscometer used in this work was shown to provide easily obtained reliable experimental data for correlation with existing relationships of viscosity and pressure.
The membrane permeability is affected by the characteristics of the membrane, chemical surroundings of the membrane and the process conditions in the filtration application. In pulp and paper mill applications the process waters contain various solutes of different chemical nature and also the process chemistry might vary. Thus, the reasons causing the changes in permeability might be very complicated. Therefore, optimisation of the membrane permeability requires a considerable number of experiments, which produces a vast amount of experimental data. Due to the multivariate nature of filtration phenomena, univariate examination cannot show effectively the correlation structure between the variables in the filtration system. Usually, only univariate monitoring and interpretation is typically used to analyse filtration data. However, in this study the experimental results from a pilot-scale pulp and paper mill filtration application were examined with multivariate methods principal component analysis (PCA), dynamic partial least squares (PLS) regression and parallel factor analysis (PARAFAC) in order to find the most significant factors affecting the membrane permeability and to extend the knowledge obtained from univariate examination. The multivariate methods applied revealed crucial information about the influence of the quality of the filtrated process water on the permeability. Moreover, the tested methods were shown to be very effective tools in the examination of membrane filtration results.
Unbiased evaluation of classification and calibration methods is important, especially as these methods are applied to increasingly complex data sets that are under-determined. Precision bounds, such as confidence intervals, are required for interpreting any experimental result. Using bootstrapped Latin partitions to evaluate classification and calibration models, bounds on the average predictions were obtained. These bounds characterize sources of variation attributed to building the model and the composition of the training set with respect to the test set. Furthermore, precision bounds on the average of the model-variable loadings allow the significance of characteristic features to be estimated. The procedure for bootstrapped Latin partitions is given and demonstrated with synthetic data sets for classification using linear discriminant analysis and fuzzy rule-building expert systems, and for calibration using partial least squares regression with one and three properties. All analyses were implemented on a personal computer with the longest evaluation requiring 6-h processing time. Analysis of variance and matched sample t-tests were also used to demonstrate the statistical power of these tests. (c) 2006 Published by Elsevier Ltd.
Cloudy olive oil, the fresh olive juice, is an intermediate form before full precipitation of freshly produced olive oil. Some consumers prefer it because they consider it as more natural and less processed. The cloudy form can persist for several months. The oil is a sort of dispersion/suspension system which can be also described as a micro-emulsion/suspension. Water micro-droplets were found to have a size ranging from 1 to 5 µm. Cloudiness is due to the low water content and the presence of natural emulsifiers in the oil. The suspension is formed by solid particles (5–60 µm) deriving from the olive fruit. They are present in small amounts (12–460 mg/kg oil). In the newly produced olive oil, containing 0.17–0.49% water, a number of microorganisms of different types (bacteria, yeasts, moulds) were found to survive, but at very low concentrations (<3 log cfu/mL oil). They originate from the exterior of the fruit (epiphytic microflora) and their presence is considered natural. Their enzyme activities do not seem to affect the quality of the final product.
The viscosities of 12 vegetable oils were experimentally determined as a function of temperature (5 to 95°C) by means of a
temperature-controlled rheometer. Viscosities of the oil samples decreased exponentially with temperature. Of the three models
[modified Williams-Landel-Ferry (WLF), power law and Arrhenius] that were used to describe the effects of temperature on viscosity,
the modified WLF model gave the best fit. The amounts of monounsaturated FA or polyunsaturated fatty acids (PUFA) highly correlated
(R
2>0.82) with the viscosities of the oil samples whereas and the amounts of saturated or unsaturated FA. An exponential equation
was therefore used to relate the viscosity of these vegetable oil samples to the amounts of monounsaturated FA or PUFA. The
models developed are valuable for designing or evaluating systems and equipment that are involved in the storage, handling,
and processing of vegetable oils.
The aim of this review is to describe different filtration systems of extra virgin olive oil (EVOO): a) to remove suspended solids, b) to eliminate humidity and making the oil brilliant, c) cross-flow filtration and d) new filtration systems based on filter bag and the flow of an inert gas. During filtering operations quantitative and qualitative changes take place, especially on minor components, which are of great value in establishing of the quality of EVOO. The present review focuses on the effect of these different filtration systems in the minor fraction of EVOO with particular emphasis on waxes, carbonyl compounds, pigments, lipophilic and hydrophilic phenols, phospholipids and proteins.
The purpose of this review has as objective to present the applications and the recent development of membrane technology in the vegetable oil processing. It approaches fundamentals aspects in the processes of separation by membranes as well as present the related works in the degumming, dewaxing, deacidification, solvent recovery, pigment removal, concentration of minor components and separation of emulsions. Its shows that oils processing with membranes, done under low temperatures, with substantial exclusion of stages, presents a promising alternative to conventional method towards the achievement of cost-effective processes that are technically advanced and less noxious to environment.
Natural treatment systems such as bank filtration (BF) and artificial recharge (via an infiltration basin) are a robust barrier for many organic micropollutants (OMPs) and may represent a low-cost alternative compared to advanced drinking water treatment systems. This study analyzes a comprehensive database of OMPs at BF and artificial recharge (AR) sites located near Lake Tegel in Berlin (Germany). The focus of the study was on the derivation of correlations between the removal efficiencies of OMPs and key factors influencing the performance of BF and AR. At the BF site, shallow monitoring wells located close to the Lake Tegel source exhibited oxic conditions followed by prolonged anoxic conditions in deep monitoring wells and a production well. At the AR site, oxic conditions prevailed from the recharge pond along monitoring wells to the production well. Long residence times of up to 4.5 months at the BF site reduced the temperature variation during soil passage between summer and winter. The temperature variations were greater at the AR site as a consequence of shorter residence times. Deep monitoring wells and the production well located at the BF site were under the influence of ambient groundwater and old bank filtrate (up to several years of age). Thus, it is important to account for mixing with native groundwater and other sources (e.g., old bank filtrate) when estimating the performance of BF with respect to removal of OMPs. Principal component analysis (PCA) was used to investigate correlations between OMP removals and hydrogeochemical conditions with spatial and temporal parameters (e.g., well distance, residence time and depth) from both sites. Principal component-1 (PC1) embodied redox conditions (oxidation-reduction potential and dissolved oxygen), and principal component-2 (PC2) embodied degradation potential (e.g., total organic carbon and dissolved organic carbon) with the calcium carbonate dissolution potential (Ca(2+) and HCO(3)(-)) for the BF site. These two PCs explained a total variance of 55% at the BF site. At the AR site, PCA revealed redox conditions (PC1) and degradation potential with temperature (PC2) as principal components, which explained a total variance of 56%.