Maria Lisa Clodoveo

Working towards the development of innovative ultrasound equipment for the extraction of virgin olive oil

Malaxation has been recognized as one of the most critical points in the mechanical extraction process for virgin olive oil (VOO). It is a low and continuous kneading of olive paste at a carefully monitored temperature. Through this essential technological operation the small droplets of the oil formed during the milling merge into large drops that can be easily separated with a decanter centrifuge. During this technological phase, a complex and necessary bioprocess takes place in order to determine the quality and composition of the final product. The malaxer is a heat exchanger characterized by a low overall heat transfer coefficient because the ratio of surface area to volume is disadvantageous, so it is important to find an innovative technology to improve heat-exchange. As matter of fact, the malaxing step is the only discontinuous phase in a continuous extraction process. In the next future, the essential challenge of VOO industrial plant manufacturing sector is to design and build advanced machines in order to transform the discontinuous malaxing step in a continuous phase and improve the working capacity of the industrial plants. In order to reduce the malaxing time enhancing the quality of the product, two ultrasound-assisted virgin olive oil extraction processes were tested against the traditional method. The sonication treatment was applied on olives submerged in a water bath (before the crushing) and on olive paste (after the crushing). The ultrasound technology provides a reduction of the malaxing duration improving VOO yields and its minor compounds content. Better extractibility and higher minor compounds contents were obtained by sonicating the olives submerged in a water bath than olive paste. After experimental trials the results were employed to suggest innovative scaling up solutions of the process and new applications of ultrasounds in the VOO industry.

Influence of Different Centrifugal Extraction Systems on Antioxidant Content and Stability of Virgin Olive Oil

Publisher Summary The different centrifugal decanters employed in olive processing influence oil yields, qualitative characteristics such as total phenols and induction time values, and composition of volatile compounds such as aldehydes, alcohols, esters, hydrocarbons, ketones, furans, and other compounds that are responsible for the unique and delicate flavor of olive oil. Total phenols as well as induction time values are higher in oils obtained by the centrifugal decanter of two phases. The induction time is the length of time before the rate of lipid oxidation of an oil sample rapidly accelerates. The induction time of olive oil samples, as measured by the Rancimat instrument, showed a significant correlation to the concentration of total phenolic compounds. Dual-phase decanters work on the same principle as the three-phase decanters, except little or no water is added prior to centrifugation. This allows the retention of more polyphenols and volatiles. The “third-generation” three-phase decanters allow for the improvement of oil yields without compromising the quality of the product. This is the best solution with respect to the two-phase decanters because it is possible to extract the oil without adding water to the process, thus obtaining dry pomace, which is more easily transportable and workable.

Influence of the Crushing System: Phenol Content in Virgin Olive Oil Produced from Whole and De-stoned Pastes

Publisher Summary The mechanical processes used to extract virgin olive oil from olive fruit include the crushing of the olives, malaxation of resulting pastes and separation of the oily phase essentially by pressure or centrifugation. All these operations affect the quality of virgin olive oil. Olive paste preparation is the most important phase of the process when oil is mechanically extracted from the olives. The use of differing machines in olive oil production has inevitable repercussions on the cost-effectiveness of the oil-making process, on the amounts of oil extracted and especially on the quality of the oil obtained. In order to obtain the best virgin olive oil, quality olives must be processed as quickly as possible after harvesting from the trees. Normally they should be delivered to the mill within a day or so of picking, in order to keep down oxidation and acidity. When extracting oil from olives, it is very important to clean them properly first, in order to ensure the levels of hygiene required for a high-quality olive oil product. Once cleaned, the olives must be crushed, in order to make the olive paste that itself is the first stage in extracting the oil. How this is done is crucial for both the quantity and the quality of the olive oil product. Mechanical oil extraction from de-stoned pastes can improve the oil phenolic concentration. The quality characteristics of virgin olive oil also depend on oxidative enzyme reactions that take place in olive paste during the extraction process. Two enzymes, polyphenol oxidase (PPO) and peroxidase (POD), are highly concentrated in the olive kernel. PPO and POD can oxidize phenolic compounds resulting in a reduced phenolic concentration of oil. The de-stoning process, excluding the olive seed before malaxation, partially removes the peroxidase activity in the pastes. This results in an increase in oxidative stability and nutritional value of virgin olive oil.

Research and Innovative Approaches to Obtain Virgin Olive Oils with a Higher Level of Bioactive Constituents

Publisher Summary Phenolic compounds are important for the sensory and nutritional qualities of Virgin Olive Oil (VOO). During the extraction process, phenolic substances undergo chemical and biochemical changes that modify their structure and influence their presence in the final product. High-quality virgin olive oil can be produced only from healthy, fresh fruits at the right ripening grade. The final quality of virgin olive oil and the level of bioactive compounds arise inside the orchard. The phenolic content depends both quantitatively and qualitatively on its genetic makeup. After choosing the best harvesting time for each cultivar in each particular geographical area, the other two main factors that are crucial for establishing the final quality should be considered: the harvesting methods and the post-harvesting storage. A deeper knowledge of the working parameters is necessary to diversify the oil quality. Malaxing conditions can modify the phenol contents in virgin olive oil and, as a consequence, its nutritional and sensory properties. It is important to develop innovative solutions to increase oil yields and improve quality, reducing at the same time the environmental impact of the process. Emerging technologies, such as pulsed electric fields, microwaves and ultrasound are promising techniques suitable for plant improvement and optimization. Innovations are also being developed in the sector of pomace olive oil, aiming at obtaining a final product richer in functional minor components.

Comparison Between Different Flavored Olive Oil Production Techniques: Healthy Value and Process Efficiency.

Three different flavoring methods of olive oil were tested employing two different herbs, thyme and oregano. The traditional method consist in the infusion of herbs into the oil. A second scarcely diffused method is based on the addition of herbs to the crushed olives before the malaxation step during the extraction process. The third innovative method is the implementation of the ultrasound before the olive paste malaxation. The objective of the study is to verify the effect of the treatments on the quality of the product, assessed by means of the chemical characteristics, the phenol composition and the radical scavenging activity of the resulting oils. The less favorable method was the addition of herbs directly to the oil. A positive effect was achieved by the addition of herbs to the olive paste and other advantages were attained by the employment of ultrasound. These last two methods allow to produce oils “ready to sell”, instead the infused oils need to be filtered. Moreover, the flavoring methods applied during the extraction process determine a significant increment of phenolic content and radical scavenging activity of olive oils. The increments were higher when oregano is used instead of thyme. Ultrasound inhibited the olive polyphenoloxidase, the endogenous enzyme responsible for olive oil phenol oxidation. This treatment of olive paste mixed with herbs before malaxation was revealed as the most favorable method due to the best efficiency, reduced time consumption and minor labor, enhancing the product quality of flavored olive oil.

Chemometric analysis for discrimination of extra virgin olive oils from whole and stoned olive pastes

Chemometric discrimination of extra virgin olive oils (EVOO) from whole and stoned olive pastes was carried out by using Fourier transform infrared (FTIR) data and partial least squares-discriminant analysis (PLS1-DA) approach. Four Italian commercial EVOO brands, all in both whole and stoned version, were considered in this study. The adopted chemometric methodologies were able to describe the different chemical features in phenolic and volatile compounds contained in the two types of oil by using unspecific IR spectral information. Principal component analysis (PCA) was employed in cluster analysis to capture data patterns and to highlight differences between technological processes and EVOO brands. The PLS1-DA algorithm was used as supervised discriminant analysis to identify the different oil extraction procedures. Discriminant analysis was extended to the evaluation of possible adulteration by addition of aliquots of oil from whole paste to the most valuable oil from stoned olives. The statistical parameters from external validation of all the PLS models were very satisfactory, with low root mean square error of prediction (RMSEP) and relative error (RE%).

Bovine and soybean milk bioactive compounds: Effects on inflammatory response of human intestinal Caco-2 cells.

In this study the effects of commercial bovine and soybean milks and their bioactive compounds, namely genistein, daidzein and equol, on the inflammatory responses induced by lipopolysaccharide (LPS) treatment of human intestinal Caco-2 cells were examined, in terms of nitric oxide (NO) release and inducible nitric oxide synthetase (iNOS) expression. Both milks and their bioactive compounds significantly inhibited, dose-dependently, the expression of iNOS mRNA and protein, resulting in a decreased NO production. The NF-κB activation in LPS-stimulated intestinal cells was also examined. In all cases we observed that cell pre-treatment before LPS activation inhibited the IkB phosphorylation. Accordingly, quantification of bioactive compounds by solid phase microextraction coupled with liquid chromatography has shown that they were absorbed, metabolized and released by Caco-2 cells in culture media. In conclusion, we demonstrated that milks and compounds tested are able to reduce LPS-induced inflammatory responses from intestinal cells, interfering with NF-kB dependent molecular mechanisms.

The Malaxation Process: Influence on Olive Oil Quality and the Effect of the Control of Oxygen Concentration in Virgin Olive Oil

Publisher Summary Malaxing is an extremely important phase in olive oil extraction. During the malaxing phase the olive paste is subjected to a slow continuous kneading, aimed at breaking off the emulsions formed during the crushing process and facilitating adequate coalescence. It is necessary to heat the olive paste at a carefully monitored temperature during malaxation in order to diminish the viscosity of the product and to stimulate its enzymic activity, therefore increasing the extraction yields. This operation facilitates high extraction yields, by helping small oil droplets to coalesce. These can be separated subsequently using a decanter centrifuge. The malaxing process determines the balance between the quality and the quantity of the oil extracted, by varying a range of parameters (time, temperature, and atmosphere in contact with the olive paste), as the olive paste is gradually heated and the enzymes within are activated. All this must be done without affecting the biochemical structure of the olive paste, as this would affect the flavor, shelf-life and nutritional properties of the oil. This operation is one of the critical points in olive oil extraction. Many studies have been carried out to investigate its influence on the olive oil quality. Nowadays the olive oil consumer asks for healthy products. There has been a large increase in demand for high-quality virgin olive oil, attributed not only to its potential health benefits, but also to its particular organoleptic properties. In fact, the sensory quality plays an important role in customer preferences. The operating environment during malaxation affects the volatile and phenolic composition of virgin olive oil and, as a consequence, its sensory and healthy qualities.

Elucidation of the synergistic action of Mentha Piperita essential oil with common antimicrobials

Mentha piperita L. essential oil (EO) is employed for external use as antipruritic, astringent, rubefacient and antiseptic. Several studies demonstrated its significant antiviral, antifungal and antibacterial properties. The aim of this work is the study of the synergistic effects of M. piperita EO with antibacterials and antifungals that are widely available and currently prescribed in therapies against infections. The observed strong synergy may constitute a potential new approach to counter the increasing phenomenon of multidrug resistant bacteria and fungi. In vitro efficacy of the association M. piperita EO/drugs was evaluated against a large panel of Gram-positive and Gram-negative bacteria and yeast strains. The antimicrobial effects were studied by checkerboard microdilution method. The synergistic effect of M. piperita EO with gentamicin resulted in a strong growth inhibition for all the bacterial species under study. The synergistic effect observed for M. piperita EO and antifungals was less pronounced.

Chemical composition and antibacterial activity of seven uncommon essential oils

Abstract Seven uncommon types of essential oils obtained from Pinus nigra, Hyssopus officinalis, Sison amomum, Smyrnium olusatrum, Helosciadium nodiflorum, Pelargonium graveolens and Vepris macrophylla were tested against a panel of thirty bacterial strains that cause serious infectious diseases. Among these bacterial species, the most dangerous for human health were five documented multi-drug-resistant strains belonging to the Acinetobacter and Klebsiella genera and derived from clinical isolation. The chemical composition of essential oils was achieved by GC-MS analysis, whereas the antibacterial efficacy was evaluated by the microdilution technique according to CLSI document M7-A9. The Vepris macrophylla essential oil, which contains geranial (33.2%), neral (23.1%) and citronellol (14.5%), exhibited the strongest inhibition against the multi-resistant strains A. baumannii, K. pneumoniae and S. aureus, with MIC values of 4.1, 2.05 and 4.1 mg/ml, respectively.