Virgin Olive Oil Quality Research Articles

Effect of pedoclimatic variables on analytical and organoleptic characteristics in olive fruit and virgin olive oil

Due to the expansion of olive oil cultivation around the world and the increasing effects of climate change, Olea europaea (L:) cultivation must deal with ever higher temperatures and drought conditions, with productivity and virgin olive oil (VOO) quality issues. At the same time the demand for premium quality products with high nutraceutical value, chemical and organoleptic characteristics related to specific areas of cultivation is steadily rising. Within this framework a deep knowledge of the olive variety with regards to environment interaction is necessary to achieve VOO production and qualitative standards required by the market. Rainfed adult olives (cv Bosana) cultivated in five typical areas of north and central Sardinia (Italy) were the subject of a three-year study, with the aim to investigate the influence of pedoclimatic variability on olive and olive oil characteristics. Physical and chemical attributes of fruits (morphometric features, firmness, pH, titratable acidity, sugar content, moisture, and oil yield) and VOO (fatty acid and sensory profile) were analysed at harvest and related to monthly weather data (precipitation, maximum, average, and minimum temperatures) of the whole fruit development period and soil composition. Monthly maximum temperatures were the most relevant variables. However, the role of each meteorologic variable was specific per olive and olive oil parameters and their relevance varied according to the period of the season. An emblematic example is that the maximum temperatures during summer months reduced oil yield and improved oleic acid concentration, but during the following months, the same variable exerted an opposite effect. This suggests the presence of a maximum temperature threshold in the olive fruits, for lipogenesis processes. Meteoclimatic conditions during maturation were the principal element responsible for VOO sensory profile: high precipitation and low thermal amplitude promoted an attribute’s intensities.

Properties and chemical compositions of monovarietal virgin olive oil at different ripening stages: A study on olive cultivation in Northwest China

AbstractThe olive management in China is rarely reported. This study evaluates the influence of drupes ripening on virgin olive oil (VOO) quality of four main varieties (Olea europaea L., cultivars Ezhi‐8, Koroneiki, Leccion, and Frontoio) cultivated in Northwest China. Quality indices, fatty acid profiles, polyphenols, terpenic acids, tocopherols, and squalene contents are tested at four ripening stages from September to November. The contents of linolenic acid, saturated fatty acids, triterpenic acids, and squalene in all VOO samples decreased during ripening; in contrast, the oleic acid, linoleic acid, nervonic acid (first reported in VOOs), cinnamic acid, p‐coumaric acid, apigenin, and naringenin (contents) increased. The dynamics of the major phenolic compounds, such as hydroxytyrosol, tyrosol, and secoiridoids, were cultivar‐dependent. The two‐way ANOVA and Fisher's LSD test showed that oil compositions varied depending on the ripeness stage and cultivar. Moreover, this latter had more influence than harvest dates on the VOO features. Besides, by applying the orthogonal partial least squares discriminant analysis, several key metabolites (C18:1, oleanolic acid, maslinic acid, oleacein, oleocanthal, and α‐tocopherol) differentiate the four cultivars. In contrast, squalene, oleanolic acid, maslinic acid, oleocanthal, luteolin, and α‐tocopherol could effectively differentiate the four harvesting dates.

Should extra virgin olive oil production change the approach? A systematic review of challenges and opportunities to increase sustainability, productivity, and product quality

Extra virgin olive oil is constantly gaining interest for its outstanding health and nutritional properties. However, the production process generates roughly four times more waste than the quantity of oil. For this reason, improvements in extra virgin olive oil production and in the valorisation of olive mill by-products are urgently needed, thus motivating this work. The first aim of this review is to summarise current knowledge regarding machines, plants, and processes in extra virgin olive oil production. The second aim is to suggest specific innovations and improvement strategies to increase sustainability, productivity, profitability, and quality. This review clearly highlighted the copious advantages of modern production plants, which can control oxidation processes, avoid temperature increases, and significantly improve the quality of extra virgin olive oil. However, the production chain must face the monumental environmental sustainability challenge. In this direction, this review highlighted that scientific and technological research has made great strides in managing olive mill by-products, suggesting several strategies related to the recovery of polyphenols and applications in agriculture, feed, and food. However, to succeed in this ambitious project, harmonious teamwork between European policies, states, regions, and private companies is needed.

Shelf Life Quality and Bioactive Constituents of Virgin Olive Oil Affected by Packaging Type and Storage Days

Shelf Life Quality and Bioactive Constituents of Virgin Olive Oil Affected by Packaging Type and Storage Days

Effect of region of cultivation, tree age, and harvest time on the quality of Lebanese virgin olive oil

In Lebanon, olive oil plays an essential role at both economic and social levels. However, factors influencing its quality are rarely addressed. This preliminary study is the first analysis to show a comparison between ancient and adult virgin olive oil trees in Lebanon. Analysis of pedo-climatic conditions and physicochemical parameters of virgin oil samples taken from ancient and adult trees from three Lebanese regions (Bechmizine, Kfaraaka, and Kawkaba) and at two different harvest periods showed that these parameters differed significantly among cultivation regions, while the tree age and harvest time had a lower effect. We observed that the oil obtained from adult trees of Kawkaba region during the first harvest period (green to reddish stage of fruit maturity) had the best quality, compared to all other samples. Oil produced from these trees showed the highest polyphenol content, a relatively higher composition of tocopherols, oleic acid, monounsaturated fatty acids, and trans fatty acids C18: 1–C18: 2, with relatively low acidity and peroxide values. It was concluded that the quality of virgin olive oil was associated with its chemical composition, and was the result of a complex interaction between several environmental factors associated with the area of cultivation, tree age, and harvest time.

E-Nose Quality Evaluation of Extra Virgin Olive Oil Stored in Different Containers

The degradation process of virgin olive oil (VOO) is related to storage time and the type of storage container used. The aim of this work is to explore the evolution of the VOO quality stored in different container types over a defined storage period in order to predict the organoleptic characteristics using a non-destructive technique such as the electronic-nose (E-nose). The “Picual” variety VOO was stored in different containers over a period of 21 months and monitored using sensory analysis, volatile compounds, and an E-nose. The panelists showed that oil stored in dark glass bottles and in green polyethylene bottles began to show defects after 12 and 15 weeks, respectively. However, oil stored in tin containers retained its quality throughout the 21 months studied. A total of 31 volatile compounds were identified, and the evolution of the volatile profile in the different containers during the storage period was studied. The E-nose data were able to classify oil quality by container using principal component analysis (PCA). Furthermore, the E-nose data combined with partial least squares (PLS) regression enabled the building of a predictive model to quantify sensory defect values (RCV2 = 0.92; RCV2 = 0.86), evidencing that this technique would be an appropriate screening tool to support a sensory panel.

Influence of Regulated Deficit Irrigation on Arbequina’s Crop Yield and EVOOs Quality and Sensory Profile

Regulated deficit irrigation in super-high-density (SHD) olive orchards is a well-known strategy to save water and control plant vigor, without decreasing fruit or oil yield. As there is controversial information about its influence on virgin olive oil quality, a trial was conducted in five SHD olive orchards of Arbequina cultivar in different locations of central, east, north and northeast Spain under full irrigation (FI) and regulated deficit irrigation (RDI) treatments. RDI applied during phase II of fruit growing (40% of total needs) saves more than 20% of water on average, without reductions in olive fruit or extra virgin olive oil (EVOO) yield. No threshold of 3.5 MPa of stem water potential was crossed in any case. RDI modified sterols and the fatty acid profile of EVOOs but not phenols, quality parameters, or the sensory profile. Latitude, altitude, and yearly rainfall have a big impact on some compounds such as campesterol, oleuropein, or margaroleic or linolenic acids.

Impact of traditional and innovative malaxation techniques and technologies on nutritional and sensory quality of virgin olive oil – A review

Virgin olive oil (VOO) nutritional and sensory quality depends on several aspects, including mechanical extraction technology: in this regard, malaxation conditions play a pivotal role since the major transformations linked to phenolic compounds (PC) and volatile compounds (VC) development and degradation take place during this step. Most of the reported studies state that malaxation should be carried out at temperature ranging 18–27°C for 30–40 min: this allows PC solubilization in the oil phase, the production of secoiridoid derivatives, and the development of aroma-active aldehydes, alcohols, and esters, limiting both PC losses and the generation of undesired VC. Reducing oxygen concentration in the headspace up to 5% helps to preserve the phenolic fraction, but slightly impairs VC generation. The use of pectolytic enzyme preparations and the application of innovative technologies like pulsed electric fields and ultrasound promote cell damages, and thereby the release of enzymes and micro-components. This review prioritizes the importance of further research aimed at defining specific optimization charts for each olive cultivar and maturity level, due to the relevant impact of genetics and agronomical factors. Furthermore, kneading conditions may be defined also depending on the desired quality of VOO, e.g., antioxidant power and/or bitterness level.

Combined Ultrasound and Pulsed Electric Fields in Continuous-Flow Industrial Olive-Oil Production.

The aim of the present study is to develop a new industrial process for the continuous-flow extraction of virgin olive oil (VOO) using the non-thermal ultrasound (US) and pulsed electric field (PEF) treatments. These technologies have been tested both separately and in combination, with the aim of making the malaxation step unnecessary. The ultrasound-assisted extraction (UAE) and PEF treatments are both effective technologies for VOO production and have been well documented in the literature. The present study combines a new continuous-flow set-up, with four US units and PEF treatment. The industrial-plant prototype is able to improve VOO yields, thanks to powerful non-thermal physical effects (acoustic cavitation and electroporation), from 16.3% up to 18.1%. Moreover, these technologies increased the content of nutritionally relevant minor components, which, in turn, improves VOO quality and its commercial value (overall tocopherols and tocotrienols improved from 271 mg/kg under the conventional process to 314 mg/kg under the US process). The combined UAE and US-PEF process also increased the extraction yield, while overcoming the need for kneading in the malaxation step and saving process water (up to 1512 L per working day). Continuous-flow US and PEF technologies may be a significant innovation for the VOO industry, with benefits both for oil millers and consumers. The VOO obtained via non-thermal continuous-flow production can satisfy the current trend towards healthier nutrient-enriched products.

Studies on the Detection of Oleuropein from Extra Virgin Olive Oils Using Enzymatic Biosensors.

Oleuropein (OLEU) is an important indicator of the quality and authenticity of extra virgin olive oils (EVOO). Electrochemical sensors and biosensors for the detection of oleuropein can be used to test the adulteration of extra virgin olive oils. The present study aimed at the qualitative and quantitative determination of oleuropein in commercial EVOO samples by applying electrochemical techniques, cyclic voltammetry (CV) and square wave voltammetry (SWV). The sensing devices used were two newly constructed enzyme biosensors, supported on single-layer carbon-nanotube-modified carbon screen-printed electrode (SPE/SWCNT) on whose surface tyrosinase (SPE/SWCNT/Tyr) and laccase (SPE/SWCNT/Lac) were immobilized, respectively. The active surfaces of the two biosensors were analyzed and characterized by different methods, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and Fourier transform infrared spectroscopy (FTIR) and the results confirmed the efficient immobilization of the enzymes. SPE/SWCNT/Tyr was characterized by a low detection limit (LOD = 9.53 × 10−8 M) and a very good sensitivity (0.0718 μA·μM−1·cm−2) over a wide linearity range from 0.49 to 11.22 μM. The process occurring at the biosensor surface corresponds to kinetics (h = 0.90), and tyrosinase showed a high affinity towards OLEU. The tyrosinase-based biosensor was shown to have superior sensitive properties to the laccase-based one. Quantitative determination of OLEU in EVOOs was performed using SPE/SWCNT/Tyr and the results confirmed the presence of the compound in close amounts in the EVOOs analysed, proving that they have very good sensory properties.

Effect of Combined Sulfur and Nitrogen Foliar Supply on Olive Oil Volatile Compounds and Sensory Attributes

Up to date, there are no reports on the effects of combined sulfur (S) and nitrogen (N) foliar application in olive orchards on volatile compounds and sensory characteristics of virgin olive oil (VOO). In this work, the effects of increasing the fertilizer S and N concentration on volatile compound composition and odor and taste attributes of monovarietal VOOs of Istarska bjelica and Leccino cultivars were investigated. The volatile compounds were analyzed by gas chromatography with flame ionization and mass spectrometric detection after isolation by solid-phase microextraction, while sensory attributes were assessed by a professional panel. In all the investigated VOO samples, aldehydes were the most represented group of compounds, with (E)-2-hexenal as the most abundant, followed by (Z)-3-hexenal and 1-penten-3-one. Significant differences in the volatile profiles and sensory attributes were observed between VOOs from different treatments, mainly attributable to the interactions between all the factors that were investigated: treatment, cultivar, and year. Although significant interactions were noted for sensory attributes as well, the score for overall quality was generally lower for Leccino VOOs and for VOOs from both cultivars that were obtained after the highest SN dose treatment. All the samples were graded by overall sensory scores that were higher than eight and were characterized by well-pronounced fruitiness and the absence of sensory defects. The results of this study showed that foliar application of S and N significantly affects the quality of VOO, confirming that such a practice can modulate the characteristic olive oil odor and taste attributes and thus possibly influence its acceptability and preference among consumers.

Monovarietal olive oils fortified with carotenoids: Physicochemical and sensory trends and taste sensor evaluation

AbstractThis study evaluated the effects of lutein or β‐carotene incorporation (0.1 mg/ml) on the quality, sensory attributes and stability of Arbequina, Picual or Royal monovarietal extra virgin olive oils. The fortification significantly decreased (p value < 0.05) the chemical quality of the fortified oils (peroxide values: +3% to +34%; extinction coefficients: +4% to +55%). The negative impact was higher on Arbequina oil, followed by Royal and Picual oils, especially in lutein fortified oils. Nevertheless, all fortified oils fulfilled the legal thresholds required by extra virgin category. Compared with the unfortified ones, fortified oils showed significantly lower (p value < 0.05) stability and total phenol content (−6% and −12%, respectively). The fortification changed the oils' green color into a yellowish‐orange color. Bitterness, pungency and sweetness varied significantly (p value < 0.05) with the type of monovarietal olive oil. Bitter and pungent intensities increased in Arbequina and Picual fortified oils (+29% to +191%, especially for the former) and decreased in Royal fortified oils (−42% and −62%, respectively). The fortification increased the sweetness of Picual and Royal oils (+109% and +10%), but decreased in Arbequina oils (−74%). The physicochemical‐sensory changes induced by the fortification allowed a clear differentiation of the monovarietal oils and, for each oil cultivar, by fortification agent. The use of an electronic tongue further confirmed the fortification impact at the phenolic and sensory levels, allowing the discrimination of unfortified and fortified oils and the quantification of oils' bitterness, pungency or sweetness and, in a less extent, the total phenols contents.

Experimental Investigation of a New Modular Crusher Machine Developed for Olive Oil Extraction Plants.

The crushing system is crucial in the virgin olive oil (VOO) mechanical extraction process. The use of different crusher machines can highly influence the quality of the final product, mainly due to the phenolic and volatile content responsible for VOO sensory and health properties. An experimental investigation was conducted to evaluate the effect of the geometric features of a new model of crusher machine for olives. The crusher machine consists of interchangeable rotors: a rotor with hammers and a rotor with knives. The evaluation was carried out with the same fixed grid in stainless steel with 6 mm diameter circular holes. An evaluation was carried out on the impact of the crusher tools on the pit particle size and on the distribution of energy and temperature. The performance of the plant was also assessed in terms of process efficiency and olive oil quality. The results showed that the specific energy released by the tool per unit of product, calculated through both energy conservation and comminution theory, is about 25–27% higher in the case of hammers. Since the impact energy is mainly dissipated in the product as heat, the temperature reached during milling operations with the hammer crusher was also higher by the same percentage with respect to the knife crusher. This has important consequences on the quality of the product: the new knife rotor used in the crushing phase produced an improvement in VOO quality, relating mainly to sensory attributes and the health-enhancing properties of the final product. The ability of the crusher to break cell walls and vacuoles, thus releasing the oil contained therein, is comparable for the two different rotors.

Influence of the Washing Process and the Time of Fruit Harvesting throughout the Day on Quality and Chemosensory Profile of Organic Extra Virgin Olive Oils.

In recent years, there has been a growing demand for organic extra virgin olive oils (OEVOOs) as quality products with greater added value. The aim of the present work was to determine whether the washing process and time of harvesting (morning or afternoon) plays an important role in the quality of Picual OEVOOs by studying quality parameters (degree of acidity, peroxide value, K232, K270, oxidative stability), and volatile and sensory profiles. Olive fruits were harvested at three maturity stages and within each phase at two times of the day (morning and afternoon). Then, samples were divided into two blocks (washed and unwashed). Volatile profile was obtained by headspace solid-phase microextraction (HS-SPME) coupled to gas chromatography-mass spectrometry (GC-MS). Regarding the physicochemical quality parameters, sensory and volatile profiles, there were no differences between the oils produced under the two treatments applied (washed/non-washed). However, the time of harvesting (morning or afternoon) did influence the volatile and sensory profile, with higher values in the oils obtained from fruits harvested in the morning, being statistically significant for the families of aldehydes, hydrocarbures and lactones. Besides, the olives harvested during the mornings gave rise to oils with higher values in the green and apple fruit attributes.

Irrigation of Young Olives Grown on Reclaimed Karst Soil Increases Fruit Size, Weight and Oil Yield and Balances the Sensory Oil Profile.

The influence of different irrigation regimes on olive fruit morphological parameters and on the quantity and quality (marketable indices, phenolic content, fatty acid composition, and sensory profile) of virgin olive oil (VOO) obtained from the Croatian cultivar Oblica, grown on an extremely rocky and dry reclaimed karst soil, was studied over three years. Four treatments were applied: rain-fed and three treatments calculated as 50%, 75%, and 100% of the crop’s irrigation requirement (Irr). Principal component analysis separated growing seasons (GS) that differed in precipitation. In the 2016 season, which had a low number of fruits per kilogram and provided a higher amount of balanced VOO with medium to intense bitterness and pungency (rain-fed treatment), the oil yield increased by irrigation (Irr 75 and Irr 100) up to 18%, while unchanged phenolics, bitterness, and pungency were observed for the VOOs obtained. In the drier GS (2017), which under rain-fed conditions had high fruit per kg, smallest fruit sizes, and lowest oil yield, and in which the VOOs had high phenolic content and intense sensory taste attributes, fruit weight, fruit sizes, and oil yield increased by 35% in all irrigation treatments, while phenols, bitterness, and pungency decreased, balancing the sensory profile of the VOOs. The results obtained here led us to conclude that the irrigation of young olives resulted in a positive effect, with the indication that an abundant water supply is more effective in drought conditions.

The influence of olive tree fertilization on the phenols in virgin olive oils. A review

The total phenols in virgin olive oil are highly dependent on cultivar, but also on ripening stage and other agronomic factors. The focus of most studies on agronomic factors has been irrigation, while fertilization has received less attention. Most of the fertilization works find that nitrogen over-fertilization leads to a decrease in phenol contents in virgin olive oil (VOO) and extra virgin olive oil (EVOO), under rain-fed or irrigation management. Ortho-diphenols also decrease with high doses of nitrogen, with no effect on secoiridoids. Phosphorous has a minor effect on irrigated trees; while the role of potassium is controversial, with a lack of trials with calcium and micro-nutrients. Due to the great impact of the fertilization on the phenol content and quality of VOO, new research is necessary with focus aimed at different cultivars and agronomic factors.

A statistical tool to determine the quality of extra virgin olive oil (EVOO)

A statistical tool to determine the quality of extra virgin olive oil (EVOO)

Simulation of Transport under Different Temperature Conditions: Effects on Extra Virgin Olive Oil Quality

AbstractExtra virgin olive oil (EVOO) is imported/exported globally. However, little is known about the qualitative effects of the transport conditions, and, consequently, they are not usually controlled. This study simulates temperature fluctuations in summer (18–42.5 °C, 12 h–12 h, one week) and winter (4–16.5 °C, 12 h–12 h, one week), to examine their effect on EVOO quality. The EVOO samples undergo evaluation with chemical analyses before and immediately after treatment and after 24 weeks of storage (at room temperature in the dark). The simulated summer conditions cause oil oxidation. This situation bears a connection to an increased lipid oxidation rate, peroxide value, 1.2/1.3 diacylglycerol ratio, rancid score, and rancid‐related volatile compounds. The simulated winter conditions also cause oil oxidation. In this case, the rancid score and the rancid‐related volatile compound content show similarities to the samples exposed to the simulated summer conditions. In winter conditions, the temperature fluctuations seem to play a key role in the rancid defect appearance. Eleven of the 15 (summer) and 10 of the 15 (winter) samples are downgraded from the category of “extra virgin” to “virgin” after 24 weeks of bottle storage.Practical applications: Transportation conditions constitute a critical factor in determining extra virgin olive oil quality. Transport is a critical control point in maintaining the quality of extra virgin olive oil, which can be transported without any specific controls. The obtained results improve the knowledge regarding the risks related to transport in hot and cold seasons, assessing the oxidative damages in both conditions on three different cultivars. A better understanding of the degradation phenomena during transportation helps develop specific technologies and practices (e.g., controlled‐temperature transportation, thermal insulation materials, use of digi‐sense nonreversible temperature labels, and so on) to counter the phenomena and evaluate the costs and limits of the existing protocols.

Application of Pulsed Electric Fields to Pilot and Industrial Scale Virgin Olive Oil Extraction: Impact on Organoleptic and Functional Quality.

The quality of virgin olive oil (VOO) is largely determined by the technology used in the industrial process of extracting the oil. Technological innovations within this field aim to strike a proper balance between oil yield and the optimal chemical composition of VOO. The application of pulsed electric fields (PEF) that cause the electroporation of the plant cell membranes favors a more efficient breakage of the olive fruit tissue, which in turn could facilitate the extraction of the oil and some of its key minor components. Pilot-scale and industrial extraction tests have been conducted to assess the effect of PEF technology on the oil extraction yield and on the organoleptic and functional quality of VOO. The best results were obtained by combining the PEF treatment (2 kV/cm) with short malaxation times and a low processing temperature. Under these conditions, PEF technology could decisively improve the oil yield by up to 25% under optimal conditions and enhance the incorporation of phenolic and volatile compounds into the oils. The PEF treatment neither affected the physicochemical parameters used to determine the commercial categories of olive oils, nor the tocopherol content. Similarly, the sensory evaluation of the PEF-extracted oils by means of a panel test did not detect the appearance of any defect or off-flavor. In addition, the intensity of positive attributes (fruity, bitter and pungent) was generally higher in PEF oils than in control oils.

The performance of the Tunisian olive oil exports within the new distribution of world demand

The present work aims to analyze the performance of the Tunisian olive oil exports compared to its main competitors (Spain, Italy, Greece, Turkey and Portugal) during the last fifteen years, on the European market and four potential markets: the United States, Canada, Japan and Brazil using the Shift Share Analysis, in order to identify the main sources of change. The period 2011-2015 was a boom period for Tunisia in all studied markets. The gain in Tunisian competitiveness on the new markets (Canada, Japan and Brazil) is related to the growth of their global imports and the competitiveness of Tunisian exports reinforced by the superior quality of Tunisian extra virgin olive oil and the recourse to packaged oil. The results indicate that the maintenance of a sustainable international competitiveness of Tunisia on the olive oil market depends on its domestic production and that of its European competitors, to which is added recently the Turkish competition, policies and trade agreements that must be negotiated and requires the improvement of its non-price competitiveness.