Search

Extra-virgin olive oil is basically used in food, but it can also be used as a source of high added-value components, such as oleocanthal and oleacein. Oleocanthal and oleacein are bioactive compounds with proven activities in the treatment of various diseases. By applying response surface methodology, oils of the Arbequina, Arbosana, and Koroneiki cultivars of super-intensive olive trees have been elaborated, under both irrigation and rainfed conditions. 289 oils have been obtained and 13 parameters per oil determined, which have been grouped into 221 models, that determine extraction performance, quality, and minor components of oils. The maximum extractable olive oil with the current technology is 89.0 ± 3.9%, with the rest remaining in the pomace. Oleacein is the component that most influences the antioxidant capacity of oils; its activity is 5.85 ± 0.33 µmol Trolox/mg. Irrigated Arbequina produces very aromatic oils. Rainfed Arbequina produces less aromatic (18.5 mg/kg of volatile) but with a higher content of phenolic compounds (514.4 mg/kg) oils. Koroneiki produces oils with a very high content of phenolic compounds but low in volatiles. For Koroneiki, the factors that maximize phenolic compounds are: rainfed crops, mill with 4.5 mm sieve, and malaxation at 40 °C for 30 min (1307.2 mg/kg of phenolic compounds, witch 500.0 mg/kg of oleacein, and 174.3 mg/kg of oleocanthal). A method to extract oleocanthal and oleacein from olive oils is proposed, as a way to develop new strategies to improve their functional properties.

In oil milling, in order to obtain high-quality oils without reducing the industrial yield, to the use of coadjuvants with a physical action and adequate operating conditions is necessary. The aim of this study was to evaluate the influence of talc addition during the malaxation stage in an oil mill on the resulting oil. Moreover, the oil obtained by talc treatment can be classified as extra virgin olive oil as this coadjuvant has a physical action. Talc increases the extraction efficacy by up to 2.35%, but retains 26.2% of its weight in oil; therefore, it is disadvantageous to use a dose higher than 0.75%. The volatile compound contents were increased in trials using lower doses of talc. In contrast, the quantity of the phenolic compounds was increased in trials using higher talc doses. In low doses, talc does not influence the content of antioxidants and volatile compounds.

The aim of this work is to obtain a balanced commercial virgin olive oil (VOO) using response surface methodology at an industrial level under continuous working conditions. Thus, a factorial design was developed with three factors: sieve size of the hammer mill, temperature, and malaxing time. Forty different responses were modulated, including extraction efficiency, but with special attention to phenolic and volatile compounds because they are responsible for the taste and aroma of VOO. The conditions for malaxing were 22 and 32 °C for 60 and 120 min using 5 and 6 mm sieve sizes. After modeling the responses, the highest extraction efficiency was obtained at 32 °C and 120 min; similar conditions were necessary to obtain the maximum contents of chlorophyll, carotenoid, and phenolic compounds, but the maximum content of volatile compounds was obtained at 22 °C. Therefore, it has also realized a combined optimization of total phenolics and total volatiles.

This work deals with the combined effect of agronomical and technological variables on the content of virgin olive oils in phenolic compounds with special attention to flavonoids (luteolin and apigenin) and lignans (pinoresinol and 1-acetoxypinoresinol). Olives from irrigated or rainfed trees at different fruit ripening were studied using Response Surface Methodology. Relevant variables included malaxation temperature (20–60 °C); time (20–60 min); and talc dosage (5–25 g/kg g olives). According to the models, the highest concentrations were 7.83, 289.4, 38.0 and 4.70 mg/kg of hydroxytyrosol, oleocanthal, luteolin and pinoresinol, respectively. Results show that the content of phenolic compounds is mostly affected by the malaxation temperature, increasing when the temperature rises; however, the time exerts an irregular influence, while the dosage of adjuvant has little influence. The flavonoid content, both luteolin and apigenin, decreased with increasing temperature and malaxation time. The pinoresinol content increased with temperature and malaxation time. Non-irrigated olive oils have a higher content in phenolic compounds. The flavonoid contents presented a maximum around maturity index 4. Moreover, the contents usually were higher for olives coming from rainfed. Pinoresinol content decreased with the increase of the index of maturity, the oils from fruits grown in rainfed containing more pinoresinol.

Three factors for the extraction of extra virgin olive oil (EVOO) were evaluated: diameter of the grid holes of the hammer-crusher, malaxation temperature, and malaxation time. A Box&ndash, Behnken design was used to obtain a total of 289 olive oil samples. Twelve responses were analyzed and 204 mathematical models were obtained. Olives from super-intensive rainfed or irrigated crops of the Arbequina, Koroneiki, and Arbosana cultivars at different stages of ripening were used. Malaxation temperature was found to be the factor with the most influence on the total content of lipoxygenase pathway volatile compounds, as the temperature increased, the content of volatile compounds decreased. On the contrary, pigments increased when the malaxation temperature was increased. EVOO from irrigated crops and from the Arbequina cultivar had the highest content of volatile compounds. Olive samples with a lower ripening degree, from the Koroneiki cultivar and from rainfed crops, had the highest content of pigments.

Olive leaves have become a promising source of phenolic compounds and flavonoids with high added value. Phenolic compounds and flavonoids are important sources of antioxidants and bioactives, and one of the processes used to effectively produce them is extraction via solvents, using aqueous ethanol solutions. To obtain the highest extraction yield per kg of biomass, olive leaves were extracted using a conventional technique (dynamic maceration) and an emerging technology, such as pressurized liquid extraction. Studies of the factors that influence these processes were performed: temperature, leaf moisture content, solvent/solid, and aqueous ethanol concentration were optimized using the central composite and Box-Behnken experiment designs. Pressurized liquid extraction resulted in more efficient oleuropein and luteolin-7-O-glucoside extraction than dynamic maceration. The operational conditions for maximizing the recovery of phenolic compounds and flavonoids and antioxidant capacity were determined to be 190 °C, leaf moisture content of 5%, and aqueous ethanol concentration of 80%.

Centrifugation, storage, and filtration of olive oil were evaluated in an oil mill to determine their effect on the final quality of virgin olive oil. The main functions of these processes are to clarify the olive oil by removing water, solids, and other possible suspended particles. Although some changes were detected in the oil quality parameters after these processes, all the samples were extra virgin olive oil. The phenolic and volatile compound content of the olive oil was influenced by vertical centrifugation processing. Significantly, vertical centrifugation led to a 53% reduction in ethanol content. Oil storage before filtration resulted in a significant increase of around 30% in the peroxide index, while the antioxidant capacity decreased by 78%. Comparison of the results for filtered and unfiltered oil samples revealed that the most significant change was the reduction in the photosynthetic pigment content, with a decrease of around 50% in chlorophyll. Due of all this, the conditions applied in vertical centrifugation and the time of storage of the olive oils should be further controlled, enabling cleaning and decantation but avoiding the reduction of the antioxidant capacity and the content of phenolics compounds.

The malaxation conditions were studied in order to evaluate the composition of secoiridoid derivatives of Picual virgin olive oil using response surface methodology. Secoiridoid derivatives are the most abundant phenolic compounds in virgin olive oil: 3,4-DHPEA-EDA; 3,4-DHPEA-EA; p-HPEA-EDA; p-HPEA-EA. The temperature range studied was 20–60 °C, time 20–60 min, and the talc dosage 0.5–2.5 %. Also, fruit ripening and irrigation management were studied during one season in an orchard of Andalusia (Spain). The content of secoiridoid derivatives increases with increasing malaxation temperature of the olive paste. However, the content of secoiridoid derivatives from oleuropein (3,4-DHPEA-EDA and 3,4-DHPEA-EA) decreases with mixing time, while the content of secoiridoid derivatives from ligstroside (p-HPEA-EDA and p-HPEA-EA) increases. On the other hand, the secoiridoid derivatives from oleuropein increase with increasing maturity index while secoiridoid derivatives from ligstroside decrease in the range studied. Finally, the olive oils from olives cultivated without irrigation have more secoiridoid derivatives than olive oils from olives cultivated with irrigation.

A large amount of olive-derived biomass is generated yearly in Spain, which could be used as a potential source of bioactive compounds. The present work evaluates the recovery of natural antioxidants from olive tree pruning (OTP) and olive mill leaves (OML). For this purpose, the effect of different solvents on the total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity was evaluated. The solvent was found to have a significant effect (p

Three complete 23 factorial designs were developed in order to evaluate the effect of three physical acting coadjuvants on the extraction of virgin olive oil: talc, calcium carbonate and silica. Ranges of operating conditions were 0–2 % (w/w) for dosage of the coadjuvant, 20–60 °C for temperature and 20–60 min for time. Mathematical models and statistical analysis (ANOVA) were performed to evaluate the effects of these coadjuvants on oil yield, quality of virgin olive oil (acidity, peroxide index and UV absorption at 270 and 232 nm), natural pigments (chlorophylls and carotenoids) and natural antioxidants. In all cases, the oils obtained with coadjuvants were the same quality of those from non-treated olive paste. Therefore, all of them are producing a physical action. While improved oil extraction yields were achieved by using talc and calcium carbonate (1.1 and 1.0 kg oil per 100 kg olives), the use of silica resulted in an oil yield reduction (1.3 kg/100 kg olives). Concerning natural pigments and antioxidants, none of the studied coadjuvants modified the pigment content while that of the antioxidants increased slightly. All oils obtained with coadjuvants showed higher contents of polyphenols and tocopherols, which indicates increasing quality and nutraceutical level.

Olive fruit maturation depends directly on the moment of olive harvest. In addition, the composition of extra virgin olive oil changes depending on the ripening degree of the fruit harvested. Likewise, using different olive cultivars in the extraction, the olive oil obtained has different quality and composition. Superintensive crops own special characteristics such as more trees per hectare than traditional crops. This improves the production of olives by surface; being superintensive more profitable than the traditional cultivar. Three different olive cultivars: Arbequina, Koroneiki, and Arbosana, and from superintensive crops with different irrigation management are used for the extraction. Olive oils are extracted at the laboratory with the Abencor system. Monounsaturated fatty acid (MUFA) content is increased by increasing the maturity index. The highest content of phenolic compounds is obtained from rainfed Koroneiki, with approximately 1 g kg⁻¹. The maximum quantity of total lipoxygenase pathway volatile compounds is 28 mg kg⁻¹, obtained in irrigated Arbequina olives. According to the results obtained, the optimum time of harvest is with a maturity index of approximately 2, when the content of oil, phenols, and MUFA reach their maximum. In addition, higher contents of minor components are obtained for rainfed than irrigated crops. Practical Applications: Determining the optimal stage for harvest the fruit of the olive tree is the main practical application or potential use. Additionally, to predict, approximately, the composition of an olive oil that may have according to some agronomic factors, such as the cultivar used, irrigation management, or the stage of maturation of the olive fruit. Different ripening degrees of the olive fruit, with different irrigation management and with different cultivar of olive trees, from superintensive crops are used to produce an extra virgin olive oil.

Industrial scale experiments were performed in an olive oil production factory to assess the effect of different physical acting coadjuvants on oil extraction and oil quality. Up to 120,000 kg olives were processed. Talc and calcium carbonate, with different particle sizes, were assayed at concentrations ranging from 0.3% to 1% by weight. Both coadjuvant types are food grade and are recognized as food additives by EU regulations (E-170 as calcium carbonate and E-553b as talc). Industrial trials were performed at room temperature with no added water, thus avoiding volatile compound loss and hydrosoluble compound content decrease. As a consequence, the obtained oils were more aromatic and their positive attributes more intense, in comparison to other olive oils produced in different operational conditions. In addition, energy requirements were decreased (releasing a lesser amount of carbon dioxide into the atmosphere) and water uptake was kept to a minimum. Results show that the use of coadjuvants improves the oil extraction yield. The extraction efficacy, defined as the percentage of initial oil that is extracted, increased by 2% by using carbonate in comparison to experiments performed without any coadjuvant, with 91.53% of oil content in the olives being extracted. For the same particle size, calcium carbonate was found to extract a greater oil amount than talc. For a single coadjuvant, the extraction yield decreased as the particle size increased. The best results, in terms of oil extraction yield, were obtained when using 0.3% calcium carbonate. Considering oil quality, no influence by either coadjuvant was detected as oil components remained unaltered during the extraction process. The sensorial evaluation gave the same result for all olive oils, no matter if a coadjuvant was used or not, indicating that these compounds only act physically on the oil extraction process.