Multivariate approach to assess the chemical composition of Italian virgin olive oils as a function of variety and harvest period

Comparison between Traditional and Novel NMR Methods for the Analysis of Sicilian Monovarietal Extra Virgin Olive Oils: Metabolic Profile Is Influenced by Micro-Pedoclimatic Zones

Nuclear magnetic resonance (NMR) metabolomic analysis was applied to investigate the differences within nineteen Sicilian Nocellara del Belice monovarietal extra virgin olive oils (EVOOs), grown in two zones that are different in altitude and soil composition. Several classes of endogenous olive oil metabolites were quantified through a nuclear magnetic resonance (NMR) three-experiment protocol coupled with a yet-developed data-processing called MARA-NMR (Multiple Assignment Recovered Analysis by Nuclear Magnetic Resonance). This method, taking around one-hour of experimental time per sample, faces the possible quantification of different class of compounds at different concentration ranges, which would require at least three alternative traditional methods. NMR results were compared with the data of traditional analytical methods to quantify free fatty acidity (FFA), fatty acid methyl esters (FAMEs), and total phenol content. The presented NMR methodology is compared with traditional analytical practices, and its consistency is also tested through slightly different data treatment. Despite the rich literature about the NMR of EVOOs, the paper points out that there are still several advances potentially improving this general analysis and overcoming the other cumbersome and multi-device analytical strategies. Monovarietal EVOO's composition is mainly affected by pedoclimatic conditions, in turn relying upon the nutritional properties, quality, and authenticity. Data collection, analysis, and statistical processing are discussed, touching on the important issues related to the climate changes in Sicily and to the specific influence of pedoclimatic conditions.

Comprehensive widely targeted metabolomics to decipher the molecular mechanisms of Dioscorea opposita thunb. cv. Tiegun quality formation during harvest

Dioscorea opposita Thumb. cv. Tiegun is commonly consumed as both food and traditional Chinese medicine, which has a history of more than two thousand years. Harvest time directly affects its quality, but few studies have focused on metabolic changes during the harvesting process. Here, a comprehensive metabolomics approach was performed to determine the metabolic profiles during six harvest stages. Thirty eight metabolites with significant differences were determined as crucial participants. Related metabolic pathways including phenylalanine, tyrosine and tryptophan biosynthesis, stilbenoid, diarylheptanoid and gingerol biosynthesis, phenylpropanoid biosynthesis, flavonoid biosynthesis and tryptophan metabolism were the most active pathways during harvest. The results revealed that temperature has a significant impact on quality formation, which suggested that Dioscorea opposita thumb. cv. Tiegun harvested after frost had higher potential value of traditional Chinese medicine. This finding not only offered valuable guidance for yam production, but also provided essential information for assessing its quality.

An Appraisal of the Oleocanthal-Rich Extra Virgin Olive Oil (EVOO) and Its Potential Anticancer and Neuroprotective Properties

Dietary consumption of olive oil represents a key pillar of the Mediterranean diet, which has been shown to exert beneficial effects on human health, such as the prevention of chronic non-communicable diseases like cancers and neurodegenerative diseases, among others. These health benefits are partly mediated by the high-quality extra virgin olive oil (EVOO), which is produced mostly in Mediterranean countries and is directly made from olives, the fruit of the olive tree (Olea europaea L.). Preclinical evidence supports the existence of antioxidant and anti-inflammatory properties exerted by the polyphenol oleocanthal, which belongs to the EVOO minor polar compound subclass of secoiridoids (like oleuropein). This narrative review aims to describe the antioxidant and anti-inflammatory properties of oleocanthal, as well as the potential anticancer and neuroprotective actions of this polyphenol. Based on recent evidence, we also discuss the reasons underlying the need to include the concentrations of oleocanthal and other polyphenols in the EVOO's nutrition facts label. Finally, we report our personal experience in the production of a certified organic EVOO with a "Protected Designation of Origin" (PDO), which was obtained from olives of three different cultivars (Rotondella, Frantoio, and Leccino) harvested in geographical areas located a short distance from one another (villages' names: Gorga and Camella) within the Southern Italy "Cilento, Vallo di Diano and Alburni National Park" of the Campania Region (Province of Salerno, Italy).

Effect of Variety and Maturity Index on the Physicochemical Parameters Related to Virgin Olive Oil from Wudu (China)

Physical parameters (i.e., extraction yield, oil content), chemicals (i.e., fatty acids, phenolics) and oxidative stability associated with virgin olive oil (VOO) from ten varieties in Wudu, China, were analyzed as a function of maturity index and variety by multivariate analysis models. Most of the analytical parameters were significantly affected by the variety and maturity index, and the former was more influential than the latter. Phenolics were the principal factor dividing the ten varieties into four groups. High phenolic levels were observed in the 'Koroneiki' group and 'Manzanilla' group, but the oil extractability index differentiated between them, being the highest and lowest, respectively. The 'Koroneiki' group demonstrated high oil productivity and oil quality, which was worthy of promotion in large-scale cultivation. High amounts of linoleic enhanced the VOO health benefits of 'Ascolana tenera, Arbequina and Zhongshan24' group, but brought the risk of shortening the shelf-life. The 'Ulliri Bardhe, Empeltre, Ezhi8, Yuntai14 and Picual' group clustered for the higher relative value of oleic acid. The maturity index had significant negative effects on the content of total phenolics, oleacein, oleocanthal, and oleic acid, but had a positive effect on the extractability index, which suggested that varieties with low phenolics and oleic acid levels should be harvested early.

In-field hyperspectral imaging dataset of Manzanilla and Gordal olive varieties throughout the season

Because spectral technology has exhibited benefits in food-related applications, an increasing amount of effort is being dedicated to develop new food-related spectral technologies. In recent years, the use of remote sensing or unmanned aerial vehicles for precision agriculture has increased. As spectral technology continues to improve, portable spectral devices become available in the market, offering the possibility of realising in-field monitoring. This study demonstrates hyperspectral imaging and spectral olive signatures of the Manzanilla and Gordal cultivars analysed throughout the table-olive season from May to September. The data were acquired using an in-field technique and sampled via a non-destructive approach. The olives were monitored periodically during the season using a hyperspectral camera. A white reference was used to normalise the illumination variability in the spectra. The acquired data were saved in files named raw, normalised, and processed data. The normalised data were calculated by the sensor by correcting the white and black levels using the acquired reflectance values. The olive spectral signature of the images is saved in the processed data files. The images were labelled and processed using an algorithm to retrieve the olive spectral signatures. The results were stored as a chart with 204 columns and 'n' rows. Each row represents the pixel of an olive in the image, and the columns contain the reflectance information at that specific band. These data provide information about two olive cultivars during the season, which can be used for various research purposes. Statistical and artificial intelligence approaches correlate spectral signatures with olive characteristics such as growth level, organoleptic properties, or even cultivar classification.

Crop year, harvest date and clone effects on fruit characteristics, chemical composition and olive oil stability from an Empeltre clonal selection grown in Aragon

BACKGROUND

In this study, the effects of crop year, harvest date and clone on the fruit characteristics and chemical composition of Empeltre olive oils were evaluated. For this purpose, the weight and oil content of fruit and the fatty acid composition, polyphenol content and oxidative stability of the olive oil was analysed throughout ripening during three successive seasons.

RESULTS

The weight and moisture in the fruit, as well as the fatty acids and polyphenol content in the olive oil, were mainly affected by crop year. In contrast, the stability was strongly influenced by the harvest date. Both factors had an influence on the fruit's oil content. The clone was not a substantial component in terms of variability, although the interaction with crop year was notable for some of the characteristics. The oil content increased significantly along with the harvest date and reached maximum values in the last period (44.9%). Conversely, stability and polyphenols decreased significantly (depending on the year, by 30-70%) from October to December, reaching the highest mean values between 1 October and 10 November (15.5 h; 500 mg caffeic acid kg^-1 ). Oleic acid and monounsaturated/polyunsaturated fatty acids (MUFA/PUFA) did not show significant differences depending on the harvest date, but between years, with 2018 having the highest percentage of oleic acid (72.72%) and MUFA/PUFA (8.38).

CONCLUSION

Early harvesting of Empeltre olives would provide considerably more stable olive oils, regardless of the clone selected, with higher phenolic content. It would not affect the MUFA/PUFA ratio, mainly influenced by the crop year. © 2022 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Effect of Freezing on Gut Microbiota Composition and Functionality for In Vitro Fermentation Experiments

The gut microbiota has a profound effect on human health and is modulated by food and bioactive compounds. To study such interaction, in vitro batch fermentations are performed with fecal material, and some experimental designs may require that such fermentations be performed with previously frozen stools. Although it is known that freezing fecal material does not alter the composition of the microbial community in 16S rRNA gene amplicon and metagenomic sequencing studies, it is not known whether the microbial community in frozen samples could still be used for in vitro fermentations. To explore this, we undertook a pilot study in which in vitro fermentations were performed with fecal material from celiac, cow’s milk allergic, obese, or lean children that was frozen (or not) with 20% glycerol. Before fermentation, the fecal material was incubated in a nutritious medium for 6 days, with the aim of giving the microbial community time to recover from the effects of freezing. An aliquot was taken daily from the stabilization vessel and used for the in vitro batch fermentation of lentils. The microbial community structure was significantly different between fresh and frozen samples, but the variation introduced by freezing a sample was always smaller than the variation among individuals, both before and after fermentation. Moreover, the potential functionality (as determined in silico by a genome-scaled metabolic reconstruction) did not differ significantly, possibly due to functional redundancy. The most affected genus was Bacteroides, a fiber degrader. In conclusion, if frozen fecal material is to be used for in vitro fermentation purposes, our preliminary analyses indicate that the functionality of microbial communities can be preserved after stabilization.

Two bi-functional cytochrome P450 CYP72 enzymes from olive (Olea europaea) catalyze the oxidative C-C bond cleavage in the biosynthesis of secoxy-iridoids - flavor and quality determinants in olive oil

Olive (Olea europaea) is an important crop in Europe, with high cultural, economic and nutritional significance. Olive oil flavor and quality depend on phenolic secoiridoids, but the biosynthetic pathway of these iridoids remains largely uncharacterized. We discovered two bifunctional cytochrome P450 enzymes, catalyzing the rare oxidative C-C bond cleavage of 7-epi-loganin to produce oleoside methyl ester (OeOMES) and secoxyloganin (OeSXS), both through a ketologanin intermediary. Although these enzymes are homologous to the previously reported Catharanthus roseus secologanin synthase (CrSLS), the substrate and product profiles differ. Biochemical assays provided mechanistic insights into the two-step OeOMES and CrSLS reactions. Model-guided mutations of OeOMES changed the product profile in a predictable manner, revealing insights into the molecular basis for this change in product specificity. Our results suggest that, in contrast to published hypotheses, in planta production of secoxy-iridoids is secologanin-independent. Notably, sequence data of cultivated and wild olives point to a relation between domestication and OeOMES expression. Thus, the discovery of this key biosynthetic gene suggests a link between domestication and secondary metabolism, and could potentially be used as a genetic marker to guide next-generation breeding programs.

NMR-based metabolomic study of Apulian Coratina extra virgin olive oil extracted with a combined ultrasound and thermal conditioning process in an industrial setting

The innovative combination of ultrasound (Us) with a thermal exchanger to produce high quality extra virgin olive oil (EVOO) was studied using Nuclear Magnetic Resonance (NMR) spectroscopy and multivariate analysis (MVA). Major and minor metabolomic components of Apulian Coratina EVOO obtained using the two methods were compared. Early and late olive ripening stages were also considered. An increased amount of polyphenols was found for EVOOs obtained using the Us with respect to the conventional method for both early and late ripening stages (900.8 ± 10.3 and 571.9 ± 9.9 mg/kg versus 645.1 ± 9.3 and 440.8 ± 10.4 mg/kg). NMR spectroscopy showed a significant increase (P < 0.05) in polyunsaturated fatty acids (PUFA) as well as in the tyrosol and hydroxytyrosol derivatives, such as oleocanthal, oleacein, and elenolic acid, for both ripening stages. In conclusion, NMR spectroscopy provides information about the metabolomic components of EVOOs to producers, while the Us process increases the levels of healthy bioactive components.

Conservation of Native Wild Ivory-White Olives from the MEDES Islands Natural Reserve to Maintain Virgin Olive Oil Diversity

Food diversity, and in particular genetic diversity, is being lost at an alarming rate. Protection of natural areas is crucial to safeguard the world's threatened species. The Medes Islands (MI), located in the northwest Mediterranean Sea, are a protected natural reserve. Wild olive trees also known as oleasters make up part of the vegetation of the Meda Gran island. Among them, in 2012, a wild albino ivory-white olive tree with fruit was identified. Fruits were collected from this tree and their seeds were first sown in a greenhouse and then planted in an orchard for purposes of ex situ preservation. Seven out of the 78 seedling trees obtained (12%) produced ivory-white fruits. In autumn 2018, fruits from these trees were sampled. Although the fruits had low oil content, virgin olive oil with unique sensory, physicochemical, and stability characteristics was produced. With respect to the polyphenols content, oleacein was the main compound identified (373.29 ± 72.02 mg/kg) and the oleocanthal was the second most abundant phenolic compound (204.84 ± 52.58 mg/kg). Regarding pigments, samples were characterized by an intense yellow color, with 12.5 ± 4.6 mg/kg of chlorophyll and 9.2 ± 3.3 mg/kg of carotenoids. Finally, oleic acid was the main fatty acid identified. This study explored the resources of the natural habitat of the MI as a means of enrichment of olive oil diversity and authenticity of this traditional Mediterranean food.

Relationship of quality parameters, antioxidant capacity and total phenolic content of EVOO with ripening state and olive variety

The aim of this work was to study the evolution of quality parameters, fatty acid composition, antioxidant capacity and total phenolic content of olive oil obtained from two olive varieties (Manzanilla and Picual) with different maturation. Antioxidant capacity and total phenolic content were measured after submitting the olive oil to in vitro digestion and fermentation to mimic physiological conditions. Quality parameters were always within the legal limits to be called "Extra Virgin Olive Oil". Antioxidant capacity, total phenolic content, saturated fatty acids and monounsaturated fatty acids (MUFA) decreased along maturation, whereas polyunsaturated fatty acids (PUFA) increased in both varieties. Manzanilla showed higher PUFA content, whereas Picual had higher MUFA concentration, antioxidant capacity and total phenolic content. The fermented fraction of olive oil displayed a higher antioxidant capacity. Finally, the statistical approach demonstrated that the type of variety is more important than collection date regarding fatty acid composition and antioxidant capacity.

Purified oleocanthal and ligstroside protect against mitochondrial dysfunction in models of early Alzheimer's disease and brain ageing

As components of the Mediterranean diet (MedDiet) olive polyphenols may play a crucial role for the prevention of Alzheimer's disease (AD). Since mitochondrial dysfunction is involved in both, brain ageing and early AD, effects of 10 different purified phenolic secoiridoids (hydroxytyrosol, tyrosol, oleacein, oleuroside, oleuroside aglycon, oleuropein, oleocanthal, ligstroside, ligstroside aglycone and ligustaloside B) and two metabolites (the plant metabolite elenolic acid and the mammalian metabolite homovanillic acid) were tested in very low doses on mitochondrial function in SH-SY5Y-APP₆₉₅ cells - a cellular model of early AD. All tested secoiridoids significantly increased basal adenosine triphosphate (ATP) levels in SY5Y-APP₆₉₅ cells. Oleacein, oleuroside, oleocanthal and ligstroside showed the highest effect on ATP levels and were additionally tested on mitochondrial respiration. Only oleocanthal and ligstroside were able to enhance the capacity of respiratory chain complexes. To investigate their underlying molecular mechanisms, the expression of genes associated with mitochondrial biogenesis, respiration and antioxidative capacity (PGC-1α, SIRT1, CREB1, NRF1, TFAM, complex I, IV and V, GPx1, SOD2, CAT) were determined using qRT-PCR. Exclusively ligstroside increased mRNA expression of SIRT1, CREB1, complex I, and GPx1. Furthermore, oleocanthal but not ligstroside decreased Aβ 1-40 levels in SH-SY5Y-APP₆₉₅ cells. To investigate the in vivo effects of purified secoiridoids, the two most promising compounds (oleocanthal and ligstroside) were tested in a mouse model of ageing. Female NMRI mice, aged 12 months, received a diet supplemented with 50 mg/kg oleocanthal or ligstroside for 6 months (equivalent to 6.25 mg/kg b.w.). Young (3 months) and aged (18 months) mice served as controls. Ligstroside fed mice showed improved spatial working memory. Furthermore, ligstroside restored brain ATP levels in aged mice and led to a significant life extension compared to aged control animals. Our findings indicate that purified ligstroside has outstanding performance on mitochondrial bioenergetics in models of early AD and brain ageing by mechanisms that may not interfere with Aβ production. Additionally, ligstroside expanded the lifespan in aged mice and enhanced cognitive function.

Bacterial Biodiversity of Extra Virgin Olive Oils and Their Potential Biotechnological Exploitation

Bacterial diversity of 15 extra virgin olive oils, obtained from different Italian varieties, including Frantoio, Coratina, Bosana, and Semidana, was analyzed in this study. All bacterial isolates were genotyped using RAPD and REP-PCR method and grouped by means of cluster analyses. Sequencing of 16S rDNA of 51 isolates, representative of 36 clusters, led to the identification of Bacillus spp., Brevibacillus spp., Micrococcus spp., Staphylococcus spp., Pantoea spp., Kocuria spp., Lysinbacillus spp., and Lactobacillus spp., most of which reported for first time in olive oils. Phenotypic characterization of the 51 isolates, some of which ascribed to potentially probiotic species, indicate that two of them have beta-glucosidase activity while 37% present lipolytic activity. Preliminary evaluation of probiotic potential indicates that 31% of the isolates show biofilm formation ability, 29% acidic pH resistance, and 25% bile salt resistance. Finally, 29% of the isolates were sensitive to antibiotics while the remaining 71%, that include bacterial species well-recognized for their ability to disseminate resistance genes in the environment, showed a variable pattern of antibiotic resistance. The results obtained underline that microbial diversity of extra virgin olive oils represents an unexpected sink of microbial diversity and poses safety issues on the possible biotechnological exploitation of this microbial biodiversity.