New isobaric lignans from refined olive oils as quality markers for virgin olive oils.

Herein we describe the influence of olive oil refining processes on the lignan profile. The detection of new isobaric lignans is suggested to reveal frauds in commercial extra-Virgin Olive Oils. We analyzed five commercial olive oils by HPLC-DAD-TOF/MS to evaluate their lignan content and detected, for the first time, some isobaric forms of natural (+)-pinoresinol and (+)-1-acetoxypinoresinol. Then we analyzed partially and fully-refined oils from Italy, Tunisia and Spain. The isobaric forms occur only during the bleaching step of the refining process and remain unaltered after the final deodorizing step. Molecular dynamic simulation helped to identify the most probable chemical structures corresponding to these new isobars with data in agreement with the chromatographic findings. The total lignan amounts in commercial olive oils was close to 2 mg/L. Detection of these new lignans can be used as marker of undeclared refining procedures in commercial extra-virgin and/or Virgin Olive Oils

Steel sieves filter and stripping for the quality of extra virgin olive oil

Filtration is a widely spread procedure adopted after the olive oil extraction process to remove the suspended solids and to eliminate humidity, making the oil more brilliant and more stable. In Tuscany, the most common filtration equipment are filter-presses. Those devices are able to reach the aims of filtration but they show some disadvantages. First of all, filter-presses consume not re-generable filter sheets. These represents a direct purchasing cost as well as an indirect cost due to the trapping of a relevant oil amount. Furthermore, the use of filter sheets implies complications for their disposal. To partially overcome these issues a new filtration equipment able to reduce the filter sheets consumption has been designed. The main idea is the addition of steel sieves before the filter-press capable to retain the suspended solids. In this way, the filter sheets only have to hold the humidity of oil. The addition of the sieves increases the amount of processed olive oil up to about five times before the filter sheets has to be substituted. In addition, the opportunity of performing the stripping techniques to remove the dissolved oxygen from the olive oil is provided. The dissolved oxygen is shortly consumed by the oil in a few days and seems to act as a starter for the subsequent autoxidation reactions. This was confirmed by the faster quality decay kinetics during shelf-life of the oils with higher dissolved oxygen concentration, according to previous researches. In the presented device, the adoption of the stripping technique was able to halve the dissolved oxygen concentration in the treated extra virgin olive oils. Thus, the innovative filter should be able to considerably reduce the filter sheets consumption, and to improve the olive oil shelf-life through the reduction of the dissolved oxygen amounts. However, before the adoption of this kind of devices at the industrial scale, further investigations are necessar

The influence of crusher speed on extra virgin olive oil characteristics

Milling is an aspect of olive oil production that has received very little attention, and there have been very few studies of the relationship between crusher speed and oil quality. This work compares the effect of three blade cutter crusher speeds used in an industrial plant on the main olive oil chemical and sensory parameters, at two points in time: immediately post-production, and after eight month of storage. The ANOVA results showed that faster crushing significantly increases chlorophyll and total biophenol content. Secoiridoids are particularly affected and concentrations of 3,4-DHPEA-EDA and p-DHPEA-EDA significantly varied in oils milled at different speeds. From the lowest to the highest speed a difference of roughly 50 mg/kg (on about 400 mg/kg) for total biophenols, and about 40 mg/kg of 3,4-DHPEA-EDA is found. Panel testing found higher bitterness and astringency scores in oils produced at the higher speed. These findings suggest that crushing speed can be used to characterize olive oils. Practical applications: Crushing speed is easy to change in olive mills, and could be used to control the sensory and nutraceutical profile of extra virgin olive oil through its effect on bitterness, astringency, and phenolic content parameters. Hence, it is very useful to have a better understanding of the relationship between crushing speed and olive oil characteristics. Crushing speed can be used to characterize olive oils. Faster crushing significantly increases chlorophyll, total biophenol, 3,4-DHPEA-EDA, and p-DHPEA-EDA. Panel testing found higher bitterness and astringency scores in oils produced at the higher speed

Changes in Olive Paste Composition During Decanter Feeding and Effects on Oil Yield

In olive oil production, olive paste is fed into a decanter in order to separate the oil from solids. The decanter is usually fed by a mohno or lobe pump. In this study, we analyze the composition of olive paste and pomace at the beginning, middle, and end of decanter feeding. The results show a change in paste composition with the two types of pumps. In both cases, olive paste contains a higher percentage of water and oil at the beginning of decanter feeding than at the end. This phenomenon is probably related to the different viscosity of the three components in the system. Furthermore, as the level for the recovery of olive oil is fixed, the change in the solid/liquid ratio causes product loss. This loss is demonstrated and quantified through the measurement of pomace oil content. Practical Applications: The paper quantifies the effect of the olive paste transport from malaxers to decanter on the olive oil yield. The transport causes a change in the relative composition among oil, water, and solids. The decanter centrifuge is not able to separate efficiently paste with different compositions. This causes marked product losses. The presented data could lead to the development of a control system able to limit the losses. In this study the ratio of solids, water and oil in the olive paste at the beginning, middle, and end of decanter feeding are tested. Change in paste composition with the two types of pumps. Olive paste contains a higher percentage of water and oil at the beginning of decanter feeding than at the end. The level for the recovery of oil is fixed and the change in the ratio causes product loss that is quantified through the measurement of pomace oil conten

Whole Lyophilized Olives as Sources of Unexpectedly High Amounts of Secoiridoids: The Case of Three Tuscan Cultivars

The phenolic profiles of three typical Tuscan olive cultivars, Frantoio, Moraiolo, and Leccino, stored in different conditions (fresh, frozen, and whole lyophilized fruits), have been compared during the ripening period. Our main goals were to evaluate the phenolic content of whole freeze-dried fruits and to test the stability of the corresponding cake in oxidative-stress conditions. The comparison of fresh and whole freeze-dried fruits from the 2012 season gave unexpected results; e.g., oleuropein in lyophilized fruits was up to 20 times higher than in fresh olives with values up to 80.3 g/kg. Over time we noted that the olive pastes obtained from lyophilized olives contained highly stable phenolic compounds, even under strong oxidative stress conditions. Finally, it was also observed that the cake/powder obtained from unripe freeze-dried olives was very poor in oil content and therefore quite suitable for use in nutritional supplements rich in phenolic compounds, such as secoiridoids, which are not widely present in the human diet

An innovative cheap filtration system to improve the conservation of extra virgin olive oil

The Extra Virgin Olive is characterized by high quality both from nutraceutical and from sensory point of view. This high quality depends on various factors: the seasonal pedoclimatic conditions, the ripening stage and the health status of the olives, the storage time before crushing of the olives, the conditions of crushing, malaxation and separation of the oil. In order to provide the consumer an high quality extra virgin olive oil, this high quality should be maintained as long as possible. For this purpose, it's crucial a good and immediate filtration of the oil leaving the decanter. In this work we propose a new filtration system consisting of a steel filter and a conventional filter press. The steel filter is made from three bells containing cartridges with decreasing porosity (from 40 µm to 5 µm). The oil which leaves the last cartridge is dehydrated by final cardboards into the filter press. Furthermore, the filtration system may be provided with a device for removing dissolved oxygen using the technique of stripping at the end of the process. By the comparison of the analyses of filtered and non filtered oils, we can assess some differences: during the storage time of the oil, into the non filtered oil the acidity increases more than in the filtered one. Regarding the phenolic components, the secoiridoidic fraction of the non filtered oil undergoes a process of degradation which wasn't observed for the filtered oil. Even the volatile fraction is preserved by the filtration system, resulting more abundant for the filtered oils. From a sensory point of view, even though stored in conditions of high oxidative stress, the oils filtered with the new filtration system were free from defects for many months, while the non filtered oils were already defective after two months, mainly due to defect from fermentative origin. Another important advantage of the new filtration system is due to the possibility to drastically reduce the costs of the filtration process: the first stage of filtration in the steel filter allows to increase the lifetime of the filter in carton. As a consequence, we can reduce the number of cartons, the oil leaks and the cost of disposal of the cartons

Steel sieves filter and stripping for the quality of extra virgin olive oil

Filtration is a widely spread procedure adopted after the olive oil extraction process to remove the suspended solids and to eliminate humidity, making the oil more brilliant and more stable. In Tuscany, the most common filtration equipment are filter-presses. Those devices are able to reach the aims of filtration but they show some disadvantages. First of all, filter-presses consume not re-generable filter sheets. These represents a direct purchasing cost as well as an indirect cost due to the trapping of a relevant oil amount. Furthermore, the use of filter sheets implies complications for their disposal. To partially overcome these issues a new filtration equipment able to reduce the filter sheets consumption has been designed. The main idea is the addition of steel sieves before the filter-press capable to retain the suspended solids. In this way, the filter sheets only have to hold the humidity of oil. The addition of the sieves increases the amount of processed olive oil up to about five times before the filter sheets has to be substituted. In addition, the opportunity of performing the stripping techniques to remove the dissolved oxygen from the olive oil is provided. The dissolved oxygen is shortly consumed by the oil in a few days and seems to act as a starter for the subsequent autoxidation reactions. This was confirmed by the faster quality decay kinetics during shelf-life of the oils with higher dissolved oxygen concentration, according to previous researches. In the presented device, the adoption of the stripping technique was able to halve the dissolved oxygen concentration in the treated extra virgin olive oils. Thus, the innovative filter should be able to considerably reduce the filter sheets consumption, and to improve the olive oil shelf-life through the reduction of the dissolved oxygen amounts. However, before the adoption of this kind of devices at the industrial scale, further investigations are necessar

Shelf life and quality of olive oil filtered without vertical centrifugation

This study evaluates the effect of filter press filtration on the shelf life of extra virgin olive oil (EVOO). Olives were harvested and processed on the same day by a continuous industrial plant equipped with a hammer crusher, a vertical malaxator, and a decanter. One part of the oil obtained was bottled (cloudy oil). The other part was filtered (using a filter press) directly after decanting and manually bottled using the same procedure (filtered oil). All samples were stored in a purpose-built chamber and periodically analyzed. The results show a less degraded phenolic fraction in the filtered olive oils. In fact, compounds such as Tyrosol and Hydroxytyrosol, which are the final product of hydrolysis of secoiridoids, remain stable in filtered oils and increase in cloudy. Moreover, filtered olive oils have a better sensory profile than the cloudy along the shelf life. These data are confirmed by the GC-MS analysis. The results confirm that filtration is essential in order to maintain the nutritional characteristics of the oil, and slow the onset of the main defects