Comparative Study of Volatile Compounds and Sensory Characteristics of Dalmatian Monovarietal Virgin Olive Oils

The Composition of Volatiles and the Role of Non-Traditional LOX on Target Metabolites in Virgin Olive Oil from Autochthonous Dalmatian Cultivars

The lipoxygenase pathway has a significant influence on the composition of the volatile components of virgin olive oil (VOO). In this work, the influence of the maturity index (MI) on the activity of the lipoxygenase enzyme (LOX) in the fruits of the autochthonous Dalmatian olive cultivars Oblica, Levantinka and Lastovka was studied. The analysis of the primary oxidation products of linoleic acid in the studied cultivars showed that LOX synthesises a mixture of 9- and 13-hydroperoxides of octadecenoic acid in a ratio of about 1:2, which makes it a non-traditional plant LOX. By processing the fruits of MI~3, we obtained VOOs with the highest concentration of desirable C6 volatile compounds among the cultivars studied. We confirmed a positive correlation between MI, the enzyme activity LOX and the concentration of hexyl acetate and hexanol in cultivars Oblica and Lastovka, while no positive correlation with hexanol was observed in the cultivar Levantinka. A significant negative correlation was found between total phenolic compounds in VOO and LOX enzyme activity, followed by an increase in the MI of fruits. This article contributes to the selection of the optimal harvest time for the production of VOOs with the desired aromatic properties and to the knowledge of the varietal characteristics of VOOs.

Valorization of monovarietal Nostrana di Brisighella extra virgin olive oils: focus on bioactive compounds

A "green breakthough" at the table due to consumer demand for healthy and sustainable foods, which aligns with the typical Mediterranean diet, has recently led to an increase in the consumption of products such as extra virgin olive oil. In fact, Italian olive cultivation, which contributes an average of 15% of world production, has seen the production of extra virgin olive oil with a value of exports that have doubled in the last 20 years. In this context, the olive oil sector of the Emilia-Romagna region (Italy), and in particular the PDO Brisighella, could achieve greater success with consumers by proposing a product obtained through sustainable agriculture that enhances the content of bioactive compounds. For these reasons, in this study, different agronomic variables are investigated in order to optimize the presence of bioactive components in extra virgin olive oil made from monovarietal Nostrana di Brisighella, namely phenolic and positive volatile compounds, thus naturally enriching this product both from health and sensory points of view. The study focuses on the volatile and phenolic fractions (derivatives of hydroxytyrosol and tyrosol) of olive oil and the positive sensory attributes (fruity, bitter and pungent) that are known to be associated with these molecules. The phenolic content is of particular interest due to the potential to support health claims. Extra virgin olive oil samples were produced from olives of the Nostrana di Brisighella cultivar; fruits were obtained through integrated pest management or organic farming and picked at four increasing indices of maturity, corresponding to four successive weeks of harvesting. These agronomic variables influenced the compositional and sensory characteristics of the extra virgin olive oils assessed, highlighting differences that likely derive from the effect of the agronomic system used, i.e., integrated pest management or organic farming.

The Idesia polycarpa genome provides insights into its evolution and oil biosynthesis

The deciduous tree Idesia polycarpa can provide premium edible oil with high polyunsaturated fatty acid contents. Here, we generate its high-quality reference genome, which is ∼1.21 Gb, comprising 21 pseudochromosomes and 42,086 protein-coding genes. Phylogenetic and genomic synteny analyses show that it diverged with Populus trichocarpa about 16.28 million years ago. Notably, most fatty acid biosynthesis genes are not only increased in number in its genome but are also highly expressed in the fruits. Moreover, we identify, through genome-wide association analysis and RNA sequencing, the I. polycarpa SUGAR TRANSPORTER 5 (IpSTP5) gene as a positive regulator of high oil accumulation in the fruits. Silencing of IpSTP5 by virus-induced gene silencing causes a significant reduction of oil content in the fruits, suggesting it has the potential to be used as a molecular marker to breed the high-oil-content cultivars. Our results collectively lay the foundation for breeding the elite cultivars of I. polycarpa.

Characterization of Olive Oil Volatile Compounds after Elution through Selected Bleaching Materials-Gas Chromatography-Mass Spectrometry Analysis

Using different bleaching materials to eliminate or reduce organic volatiles in deteriorated olive oils will positively affect its characteristics. This study aims to identify the volatiles of oxidized olive oil after physical bleaching using selected immobilized adsorbents. Oxidized olive oil was eluted using open-column chromatography packed with silica gel, bentonite, resin, Arabic gum, and charcoal at a 1:5 eluent system (w/v, adsorbent: oxidized olive oil). The smoke point was determined. The collected distilled vapor was injected into GC-MS to identify the volatiles eluted after partial refining with each of these bleaching compounds. The results showed that volatile compounds were quantitatively and qualitatively affected by the type of adsorbents used for the elution of olive oil and the smoking points of eluted oils. The most prominent detected volatile compounds were limonene (14.53%), piperitone (10.35%), isopropyl-5-methyl-(2E)-hexenal (8.6%), methyl octadecenoate (6.57%), and citronellyl acetate (5.87%). Both bentonite and resin were superior in decreasing the ratio of volatile compounds compared with other bleaching materials used. Resin immobilized medium was significantly affected (p < 0.05), raising the smoke point. These results highlighted some information regarding the characteristics of volatile compounds that result after the physical elution of olive oil through selected adsorbents.

Characterization and Comparison of Extra Virgin Olive Oils of Turkish Olive Cultivars

Extra virgin olive oils (EVOOs) obtained from five Turkish olive cultivars widely produced in the Aegean and Marmara regions were investigated based on their total antioxidant capacity (TAC), total phenolic content (TPC), pigment contents, fatty acid (FA) profiles, phenolic compounds (PC), volatile compounds (VC), and sensory properties. The results showed that all properties of EVOO samples were significantly affected by the olive cultivar used. The pigment contents in Ayvalık (9.90 mg·kg^-1) and Uslu (9.00 mg·kg^-1) oils were higher than the others (p < 0.05). The greatest values for oleic acid (74.13%) and TPC (350.6 mg·kg^-1) were observed in Gemlik and Domat oils, respectively (p < 0.05). Edincik oil showed the maximum hydroxytyrosol content (48.022 mg·kg^-1) and TAC value (515.36 mg TE·kg^-1) (p < 0.05). The Edincik, Domat, and Uslu oils were significantly not different for the total content of C6 compounds derived by lipoxygenase, which are the main volatiles responsible for the typical aroma of EVOOs (p > 0.05). Domat oil also exhibited the highest scores for bitterness and pungency perceptions (p < 0.05). The fruitiness scores of the oil samples (except for Ayvalık oil) were close to each other, even if they were statistically different (p < 0.05). Principal component analysis (PCA) indicated that the Ayvalık oil was separated from the others due to its poor-quality characteristics. As a result, it can be stated that Domat olive oil has better quality than the others.

Effect of Oil Type Used in Neapolitan Pizza TSG Topping on Its Physical, Chemical, and Sensory Properties

BACKGROUND

According to the regulations of the Neapolitan Pizza TSG, extra virgin olive oil must be exclusively used as topping ingredient, together with tomato for pizza marinara-type production. As, often deliberately, other oils are replaced by pizza makers for economical and organoleptic purposes, the present study was conducted to analyze the quality of pizza depending on the oil typology used.

METHODS

Chemical and sensory analyses were performed on olive oils and on pizza topping mix samples after cooking to detect changes due to the applied cooking processing.

RESULTS

The results revealed the best quality of a monovarietal olive oil (Ottobratica cv.) for their peculiar phenolic content related to the best oxidation stability after pizza's cooking, expressed as bioactive amounts and lower presence of undesired volatile compounds.

CONCLUSIONS

The use of an extra virgin monovarietal olive oil, such as Ottobratica cv., in the topping of pizza is preferable to other oils, also EVOO, because of its higher quality, which is reflected in greater health and pleasant characteristics from a sensorial point of view.

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.

Comparison of Four Oil Extraction Methods for Sinami Fruit (Oenocarpus mapora H. Karst): Evaluating Quality, Polyphenol Content and Antioxidant Activity

The sinami palm (Oenocarpus mapora H. Karst) is a plant from the South American Amazonia that has great potential for industrial applications in the development of functional foods, nutraceuticals and cosmeceuticals. In this manuscript, the physicochemical properties, total polyphenol content and antioxidant activity of sinami oil that was obtained using four extraction systems, namely expeller press extraction (EPE), cold press extraction (CPE), ultrasound-assisted extraction (UAE) and supercritical fluid extraction (SFE), were studied and compared. The oxidative stability (OSI) was statistically non-significant in EPE and SFE. The chromatic properties (CIELab) were influenced by the extraction methods and SFE presented high values of L* and a lower content of plant pigments. Ultrasound-assisted extraction showed a higher content of polyphenols and higher antioxidant activity. Different analyses for the evaluation of the physicochemical properties, the content of total polyphenols and antioxidant activity were used to classify sinami oil according to chemometrics using principal component analysis (PCA). For example, the sinami oil that was obtained using each extraction method was in a different part of the plot. In summary, sinami oil is an excellent resource for plant pigments. Additionally, the information that was obtained on the quality parameters in this study provided a good foundation for further studies on the characterization of major and minor compounds.

Biochemical Characterization of Six Traditional Olive Cultivars: A Comparative Study

Olives are an essential ingredient in Turkish food culture. Turkey has grown to become one of the top five producers of olives and olive oils in the world. Olive trees in general are found in the coastal parts of the country. The fruits of six traditional cultivars of olive (Gemlik, Domat, Memecik, Ayvalik, Cilli, and Adana Topagi), grown in Adana, were characterized based on their fruit skin color, the amount of chlorophylls, fatty acids, antioxidant activity, and total phenolic compounds, as well as volatile compounds. The international cultivar Manzanilla, grown in the same orchards as the traditional cultivars, was also included in the study to make a comparison. Compared to the Manzanilla cultivar, Memecik showed the highest amount of total phenolic content and antioxidant activity with the highest level of lightness, blueness/yellowness, and color intensity. Ayvalik presented the highest level of greenness/redness. Although the highest fruit lightness and darkness were found in the Cilli cultivar, with the highest amount of chlorophyll a (2.63 mgL−1), there was more chlorophyll b in Adana Topagi fruits (3.34 mgL−1). The highest percentage of fatty acids was found in the Gemlik cultivar of 66.81%, among which oleic acid was the major component. The total aldehydes ranged between 33.43% and 50.60%. Compared to Manzanilla and the traditional cultivars, the Domat cultivar had the highest amount of hexanal of 44.42%. Adana Topagi had the highest amount of alcohols (61.34%) and acids (1.31%). Memecik registered the highest amount of ketones (17.86%) and terpenes (20.34%). Among all cultivars, Manzanilla displayed the highest amount of esters (2.30%). In this study, traditional cultivars were found to be the richest in health-promoting chemicals. Furthermore, a significant variability among the cultivars was revealed, implying that metabolic fingerprinting approaches could be used to differentiate cultivars once more research into the effects of the growing conditions and environmental factors on the chemical profiles of each cultivar is carried out.

Exploitation of virgin olive oil by-products (Olea europaea L.): phenolic and volatile compounds transformations phenomena in fresh two-phase olive pomace ('alperujo') under different storage conditions

BACKGROUND

Much effort has recently been spent for re-using virgin olive oil by-products as nutraceutical ingredients for human diet thanks to their richness in bioactive phenols, but their management is not easy for producers. We aimed to provide useful information for a better management of fresh olive pomace before drying, by studying the phenolic and volatile compounds transformations phenomena of fresh olive pomace stored under different conditions planned to simulate controlled and uncontrolled temperature conditions in olive oil mills.

RESULTS

The evolution of the phenolic and volatile compounds was studied by high-performance liquid chromatography-diode array detector mass spectrometry (HPLC-DAD-MS) and headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS). The phenolic profile varied rapidly during storage: the verbascoside content decreased about 70% after 17 days even at 4 °C, while the content of simple phenols such as hydroxytyrosol and caffeic acid increased over time. The low temperature was able to slow down these phenomena. A total of 94 volatile organic compounds (VOCs) were detected in the fresh olive pomace, with a prevalence of lipoxygenase (LOX) VOCs (78%), mainly aldehydes (19 490.9 μg kg^-1 ) despite the higher number of alcohols. A decrease in LOX volatiles and a quick development of the ones linked to off-flavors (carboxylic acids, alcohols, acetates) were observed, in particular after 4 days of storage at room temperature. Only storage at 4 °C allowed these phenomena to be slowed down.

CONCLUSION

To preserve the natural phenolic phytocomplex of fresh olive pomace before drying and to avoid off-flavors development, storage in open containers must be avoided and a short storage in cold rooms (7-10 days) is to be preferred. © 2021 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.