GC–MS–olfactometric characterization of the key aroma compounds in Turkish olive oils by application of the aroma extract dilution analysis

HS-SPME-GC-MS and Chemometrics for the Quality Control and Clustering of Monovarietal Extra Virgin Olive Oil: A 3-Year Study on Terpenes and Pentene Dimers of Italian Cultivars

Terpenes and pentene dimers are less studied volatile organic compounds (VOCs) but are associated with specific features of extra virgin olive oils (EVOOs). This study aimed to analyze mono- and sesquiterpenes and pentene dimers of Italian monovarietal EVOOs over 3 years (14 cultivars, 225 samples). A head space-solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) method recently validated was used for terpene and pentene dimer quantitation. The quantitative data collected were used for both the characterization and clustering of the cultivars. Sesquiterpenes were the molecules that most characterized the different cultivars, ranging from 3.908 to 38.215 mg/kg; different groups of cultivars were characterized by different groups of sesquiterpenes. Pentene dimers (1.336 and 3.860 mg/kg) and monoterpenes (0.430 and 1.794 mg/kg) showed much lower contents and variability among cultivars. The application of Kruskal-Wallis test-PCA-LDA-HCA to the experimental data allowed defining 4 clusters of cultivars and building a predictive model to classify the samples (94.3% correct classification). The model was further tested on 33 EVOOs, correctly classifying 91% of them.

Investigating the Quality and Purity Profiles of Olive Oils from Diverse Regions in Selçuk, İzmir

The Selçuk district of Izmir is one of the most essential regions in terms of olive oil production. In this study, 60 olive oil samples were obtained from five different locations (ES: Eski Şirince Yolu, KK: Kınalı Köprü, AU: Abu Hayat Üst, AA: Abu Hayat Alt, and DB: Değirmen Boğazı) in the Selçuk region of Izmir during two (2019-2020 and 2020-2021) consecutive cropping seasons. Quality indices (free acidity, peroxide value, p-Anisidine value, TOTOX, and spectral absorption at 232 and 270 nm) and the fatty acid, phenolic, and sterol profiles of the samples were determined to analyze the changes in the composition of Selcuk olive oils according to their growing areas. When the quality criteria were analyzed, it was observed that KK had the lowest FFA (0.11% oleic acid, PV (6.66 meq O2/kg), p-ANV (11.95 mmol/kg), TOTOX (25.28), and K232 (1.99) values and K270 had the highest value. During the assessment of phenolic profiles, the ES group exhibited the highest concentration of the phenolic compound p-HPEA-EDA (oleocanthal), with a content of 93.58 mg/kg, equivalent to tyrosol. Upon analyzing the fatty acid and sterol composition, it was noted that AU displayed the highest concentration of oleic acid (71.98%) and β-sitosterol (87.65%). PCA analysis illustrated the distinct separation of the samples, revealing significant variations in both sterol and fatty acid methyl ester distributions among oils from different regions. Consequently, it was determined that VOOs originating from the Selçuk region exhibit distinct characteristics based on their geographical locations. Hence, this study holds great promise for the region to realize geographically labeled VOOs.

Analysis of Volatile Hydrocarbons (Pentene Dimers and Terpenes) in Extra Virgin Olive Oil: Optimization by Response Surface Methodology and Validation of HS-SPME-GC-MS Method

A head space-solid phase microextraction-gas chromatography-mass spectrometery (HS-SPME-GC-MS) method for the simultaneous analysis of pentene dimers from lipoxygenase (LOX) pathway, monoterpenes, and sesquiterpenes in extra virgin olive oil (EVOO) was proposed. A Doehlert design was performed; the conditions of the HS-SPME preconcentration step (extraction temperature, extraction time, sample amount, and desorption time) were optimized by response surface methodology, allowing defining the method operable design region. A quantitative method was set up using the multiple internal standard normalization approach: four internal standards were used, and the most suitable one was selected for area normalization of each external standard. The quantitative method was successfully validated and applied to a series of monocultivar EVOOs. This is the first paper in which a quantitative method using commercial standards has been proposed for the analysis of an important class of molecules of EVOO such as pentene dimers. The optimized method is suitable for routine analysis aimed at characterizing high quality EVOOs.

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.

Comparison of key aroma-active compounds between roasted and cold-pressed sesame oils

This was the first study to compare the key aroma-active compounds that contributed to the different aroma profiles between roasted and cold-pressed sesame oils. Aroma compounds were extracted by headspace solid-phase micro-extraction (HS-SPME) and simultaneous distillation extraction (SDE) and were analysed using gas chromatography-olfactometry-mass spectrometry (GC-O-MS) and aroma extract dilution analysis (AEDA). The numbers of aroma-active compounds with the flavour dilution (FD) factors between 1 and 2048 were 57 and 16 in the roasted and cold-pressed sesame oils, respectively. A total of 28 volatile compounds were identified as aroma-active compounds in sesame oils for the first time. Important aroma compounds (FD ≥ 8) were quantified by the external standard method, and their odour activity values (OAV) were calculated as the ratio of their concentrations to odour thresholds in oil. The numbers of key aroma-active compounds defined by OAVs ≥ 1 were 23 (OAVs = 1-385) and 8 (OAVs = 1-42), respectively, in the roasted and cold-pressed sesame oils. 2-Methoxy-4-vinylphenol (smoked, 1924 µg/kg, OAV = 385), 2-methoxyphenol (smoked, 1488 µg/kg, OAV = 114) and pyrazines (roasted and nutty, 578-22750 µg/kg, OAV = 1-67) were the most important aroma-active compounds in the roasted sesame oil, whereas hexanal (green and fruity, 3094 µg/kg, OAV = 42) was the most important aroma-active compound in the cold-pressed sesame oil, followed by (E,E)-2,4-decadienal (earthy, 4170 µg/kg, OAV = 31), dimethyl sulfone (sulphur-like, 406 µg/kg, OAV = 20) and octanal (green and fruity, 901 µg/kg, OAV = 16). This study provides valuable information for manufacturers to achieve precise flavour control of sesame oil products.

Instrumental Techniques to Classify Olive Oils according to Their Quality

This review includes an update of the publications on quality classification of olive oils into extra, virgin or lampante olive oil categories. Nowadays, the official method to carry out this classification is time-consuming and, sometimes, it is not systematic and/or objective. It is based on conventional physicochemical analysis and on a sensorial tasting of olive oils carried out by a panel of experts. The aim of this review was to explore and give value to the alternative techniques reported in the bibliography to complement the current official methods established for that classification of olive oils. Specifically considered were non-separation and separation analytical techniques which could contribute to correctly classify olive oils according to their physicochemical and/or sensorial characteristics. An in-depth description has been written on the methods used to differentiate these three types of olive oils and the main advantages and disadvantages of the proposed procedures. The techniques here reviewed could be a real and fast option to complement or even substitute some of the analysis included in the official method. Finally, general trends and detected difficulties found to address this issue have been discussed throughout the article.

Volatile composition analysis of tree peony (Paeonia section Moutan DC.) seed oil and the effect of oxidation during storage

Peony (Paeonia section Moutan DC.) seed oil is a novel vegetable oil with unique aromatic profile. The objectives of this study were to characterize the volatile compounds with optimized analysis conditions, and to study the effects of oxidation during storage. The Headspace Solid-phase Micro-extraction (HS-SPME) conditions were optimized with factors including extraction fiber, extraction time and temperature, as well as sample amount and desorption time. Then, the aromatic compounds extracted from peony seed oil were determined using the odor activity value (OAV) method coupled with the GC-olfactometry. Results found that the best HS-SPME conditions were DVB/CAR/PDMS fibers with magnetic stirring for 50 min of extraction at 60°C. The optimal sample amount was 4 g with 6 min of desorption. Forty-one volatile components were found, and 19 aromatic components were identified using GC-MS and GC-olfactometry. This is the first study to describe 4,7-dimethylbenzofuran in peony seed oil with a unique aroma of grass, light bitter, and fragrance. The stability of alcohol and terpenoids decreased as accelerated oxidation progresses. This study provides the theoretical basis for the sensory attributes, and shelf-life of peony seeds oil products for industry production and marketing.

Discrimination of botanical origin of olive oil from selected Greek cultivars by SPME-GC-MS and ATR-FTIR spectroscopy combined with chemometrics

BACKGROUND

Consumers today wish to know the botanical origin of the olive oil they purchase. The objective of the present study was the development of robust chemometric models based on gas chromatography-mass spectrometry (GC-MS) and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) for the purpose of botanical differentiation of three commercial Greek olive oil cultivars.

RESULTS

Using the solid-phase microextraction technique (SPME), volatile compounds (VC) were obtained and analyzed by GC-MS. Five hydrocarbons and one ester were selected by the forward stepwise algorithm, which best discriminated the olive oil samples. From ATR-FTIR analysis, the spectral regions chosen from the forward stepwise algorithm were associated with CO stretching vibration of the esters of triglycerides and the CH bending vibrations of the CH₂ aliphatic group and double bonds. Application of the supervised methods of linear and quadratic discriminant cross-validation analysis, based on VC data, provided a correct classification score of 97.4% and 100.0%, respectively. Corresponding statistical analyses were used in the mid-infrared spectra, by which 96.1% of samples were discriminated correctly.

CONCLUSION

ATR-FTIR and SPME-GC-MS techniques in conjunction with the appropriate feature selection algorithm and classification methods proved to be powerful tools for the authentication of Greek olive oil. The proposed methodology could be used in an industrial setting for determination of the botanical origin of Greek olive oil. © 2020 Society of Chemical Industry.

Evolution of Flavors in Extra Virgin Olive Oil Shelf-Life

Extra virgin olive oil (EVOO) is one of the most distinctive ingredients of the Mediterranean diet. There are many properties related to this golden ingredient, from supreme organoleptic characteristics to benefits for human health. EVOO contains in its composition molecules capable of exerting bioactivities such as cardio protection, antioxidant, anti-inflammatory, antidiabetic, and anticancer activity, among others, mainly caused by unsaturated fatty acids and certain minor compounds such as tocopherols or phenolic compounds. EVOO is considered the highest quality vegetable oil, which also implies a high sensory quality. The organoleptic properties related to the flavor of this valued product are also due to the presence of a series of compounds in its composition, mainly some carbonyl compounds found in the volatile fraction, although some minor compounds such as phenolic compounds also contribute. However, these properties are greatly affected by the incidence of certain factors, both intrinsic, such as the olive variety, and extrinsic, such as the growing conditions, so that each EVOO has a particular flavor. Furthermore, these flavors are susceptible to change under the influence of other factors throughout the oil's shelf-life, such as oxidation or temperature. This work offers a description of some of the most remarkable compounds responsible for EVOO's unique flavor and aroma, the factors affecting them, the mechanism that lead to the degradation of EVOO, and how flavors can be altered during the shelf-life of the oil, as well as several strategies suggested for the preservation of this flavor, on which the quality of the product also depends.

Virgin Olive Oil Volatile Compounds: Composition, Sensory Characteristics, Analytical Approaches, Quality Control, and Authentication

Volatile organic compounds strongly contribute to both the positive and negative sensory attributes of virgin olive oil, and more and more studies have been published in recent years focusing on several aspects regarding these molecules. This Review is aimed at giving an overview on the state of the art about the virgin olive oil volatile compounds. Particular emphasis was given to the composition of the volatile fraction, the analytical issues and approaches for analysis, the sensory characteristics and interaction with phenolic compounds, and the approaches for supporting the Panel Test in virgin olive oil classification and in authentication of the botanical and geographic origin based on volatile compounds. A pair of detailed tables with a total of approximately 700 volatiles identified or tentatively identified to date and tables dealing with analytical procedures, sensory characteristics of volatiles, and specific chemometric approaches for quality assessment are also provided.

Chemical Characterization of Three Accessions of Brassica juncea L. Extracts from Different Plant Tissues

Indian mustard or Brassica juncea (B. juncea) is an oilseed plant used in many types of food (as mustard or IV range salad). It also has non-food uses (e.g., as green manure), and is a good model for phytoremediation of metals and pesticides. In recent years, it gained special attention due to its biological compounds and potential beneficial effects on human health. In this study, different tissues, namely leaves, stems, roots, and flowers of three accessions of B. juncea: ISCI 99 (Sample A), ISCI Top (Sample B), and “Broad-leaf” (Sample C) were analyzed by HPLC-PDA/ESI-MS/MS. Most polyphenols identified were bound to sugars and phenolic acids. Among the three cultivars, Sample A flowers turned were the richest ones, and the most abundant bioactive identified was represented by Isorhamnetin 3,7-diglucoside (683.62 µg/100 mg dry weight (DW) in Sample A, 433.65 µg/100 mg DW in Sample B, and 644.43 µg/100 mg DW in Sample C). In addition, the most complex samples, viz. leaves were analyzed by GC-FID/MS. The major volatile constituents of B. juncea L. leaves extract in the three cultivars were benzenepropanenitrile (34.94% in Sample B, 8.16% in Sample A, 6.24% in Sample C), followed by benzofuranone (8.54% in Sample A, 6.32% in Sample C, 3.64% in Sample B), and phytone (3.77% in Sample B, 2.85% in Sample A, 1.01% in Sample C). The overall evaluation of different tissues from three B. juncea accessions, through chemical analysis of the volatile and non-volatile compounds, can be advantageously taken into consideration for future use as dietary supplements and nutraceuticals in food matrices.

Geographical origin impact on volatile composition and some quality parameters of virgin olive oils extracted from the "Ayvalık" variety

"Ayvalık" is one of the prominent olive cultivar used for producing virgin olive oil (VOO) in Turkey. In this study, 215 olive samples of "Ayvalık" were harvested from 14 different locations in North Aegean Region of Anatolia by hand-picking during three consecutive crop seasons. The early harvested cold press VOO samples were produced at lab-scale and the quality indices (free acidity, peroxide value and spectral absorption at 232, 266, 270 and 274 nm), induction time, colour values, fatty acid and volatile profiles were determined in order to examine changes on composition of the "Ayvalık" olive oils based on their growing area. Characteristically, it was found that volatile fraction of "Ayvalık" VOOs composed of aldehydes (29.72), terpene (12.68), alcohol (11.65), benzene ringed compound (4.71), ketone (3.49), organic acid (2.87), ester (1.84), furan (0.96) compounds on average percentage. It was highlighted with this research 61.84–87.36% of aldehydes, 0.00–91.11% of ketones, 0.00–46.11% of esters, and 34.53–92.06% of alcohols were generated only by lipoxygenase pathway. As a conclusion, Ayvalık VOOs had different chemical composition based on geographic origin. Therefore, it was considered that this work is so promising to directly accelerate that the number of geographic indicated VOOs linked to "Ayvalık" cultivar.

Volatile and Sensory Profiles of Algerian Extra-Virgin Olive Oil from Souidi and Zeletni Cultivars

In this study, the volatile and sensory profiles of monovarietal extra-virgin olive oil (EVOO) from two less widespread Algerian autochthonous cultivars (Souidi and Zeletni) were obtained using headspace solid-phase microextraction coupled to gas chromatography-mass spectrometry and a panel test, respectively. A total of 14 and 10 volatile compounds belonging to different chemical classes were identified and quantified in the Souidi and Zeletni EVOOs, respectively. Zeletni EVOO contains 2.07 times more (E)-2-hexenal than Souidi EVOO. In addition, the amounts of C6 compounds from LA and LnA, as well as the total amount of the compounds of the LOX pathway were higher in Zeletni than in the Souidi EVOO. Another important finding was the predominance of sesquiterpene β-ocimene in the composition of the volatile fraction of Souidi EVOO. The sensory profiles of the EVOOs analyzed were characterized by fruity, bitter and pungent sensory positive attributes, perceived at medium intensity in both oils studied.

Caracterización de los compuestos de aroma del aceite de sacha inchi (Plukenetia volubilis L.) por HS-SPME-GC-MS-O

Se identificaron los componentes aromáticos activos provenientes de muestras comerciales del aceite de sacha inchi, obtenidos de cultivos de Santa Rosa de Osos (Antioquia, Colombia), mediante la técnica de microextracción en fase sólida acoplada a cromatografía de gases, espectrometría de masas y olfatometría (HS-SPME-GC-MS-O). En la optimización de la técnica de extracción se definieron las siguientes condiciones: fibra de SPME de divinilbenceno/ carboxen/polidimetilsiloxano (DVB/CAR/PDMS), temperatura de extracción de 50 °C y tiempo de exposición de 40 min. Bajo estas condiciones, se encontraron un total de 20 compuestos aromáticos activos, donde se destacan el E-2-octenal, E-heptanal, (E,E)-3,5-octadien-2-ona, ácido hexanóico y (E,E)-2,4-heptadienal como los componentes con mayor aporte a la formación del aroma del aceite de sacha inchi.

Comparative Analysis of Volatiles of 15 Brands of Extra-Virgin Olive Oils Using Solid-Phase Micro-Extraction and Solvent-Assisted Flavor Evaporation

Aroma profiles, key aroma compound quantification, and cluster analysis of 15 brands of extra-virgin olive oils (EVOOs) from three countries (Spain, Italy, and Greece) were investigated in the current study. Aroma compounds were isolated from the oil by using solvent-assisted flavor evaporation (SAFE) and solid-phase micro-extraction (SPME) and analyzed by gas chromatography-olfactometry mass spectrometry (GC-MS/O). A total of 89 compounds were screened by SPME/SAFE-GC-MS/O with chromatographic columns in 15 brands of samples. Eighty and 54 compounds were respectively identified by SPME- and SAFE-GC-MS/O. Of those, 44 compounds were detected by both methods. Undecanol, (Z)-4-decenal, (E)-2-dodecenal, and 2-nonanone extracted by SAFE were not found in EVOOs before. Eight classes of aroma compounds were identified, including 17 alcohols, 22 aldehydes, 9 ketones, 4 acids, 14 esters, 5 aromatics, 12 alkene, and 6 others. Eleven compounds were identified as the key aroma compounds in alternative brands of EVOOs by SAFE-aroma extract dilution analysis (AEDA). Hexanal, (E)-2-hexenal, (E)-3-hexenol, acetic acid, and (E)-2-heptenal were the common key aroma compounds by AEDA and odor activity values (OAVs). From the cluster analysis of the heatmap, the aroma compounds of all the Spain EVOOs were similar, and there were some differences from the samples of Italy and Greece. It suggested that both the amount and concentration of aroma compounds determine the similarity of aroma in EVOOs.

Aroma Patterns Characterization of Braised Pork Obtained from a Novel Ingredient by Sensory-Guided Analysis and Gas-Chromatography-Olfactometry

Two types of braised pork were prepared from self-made braised sauce added to Maillard reaction intermediate (MRI) and white granulated sugar, respectively. Descriptive sensory analysis and gas chromatography-mass spectrometry (GC-MS) were conducted to investigate their differences in sensory and aroma compounds. The results showed that the effect of self-made braised sauce in braised pork was comparable to white granulated sugar. One-hundred-and-nine volatile flavor compounds were identified by GC-MS using headspace-solid phase microextraction (HS-SPME) and simultaneous distillation and extraction (SDE). Thirty-six odor active compounds with retention indexes ranging from 935–2465 were identified by aroma extract dilution analysis (AEDA). Additionally, their odor activity values (OAV) were calculated. It was found that 17 aroma compounds showed an OAV greater than 1. Among them, pentanal (almond, pungent), nonanal (fat, green), (E, E)-2,4-decadienal (fat, roast), phenylacetaldehyde (hawthorn, honey, sweet), dodecanal (lily, fat, citrus) and linalool (floral, lavender) reached the highest OAV values (>200), indicating a significant contribution to the aroma of two types of braised pork. These results indicated that the self-made braised sauce added with MRI could be used for cooking braised pork with good sensory characteristics.

Use of odorant series for extra virgin olive oil aroma characterisation

BACKGROUND

Extra virgin olive oil (EVOO) volatile composition is mainly used as a means of characterisation and authentication, especially for protected denomination of origin (PDO) products. This work investigated the volatile compounds from 25 EVOOs from four Spanish (Cornicabra, Manzanilla Castellana, Picual and Manzanilla Cacereña) and four Italian (Ortice, Ravece, Nocellara del Belice and Itrana) cultivars in terms of odour activity value (OAV). Forty-seven volatile compounds were analysed by solid phase microextraction gas chromatography/mass spectrometry (SPME-GC/MS). OAVs of volatile compounds with similar descriptors were grouped in order to establish eight odorant series: fruity, grass, apple, tomato, floral, woody-spicy, fatty and mushroom.

RESULTS

No differences in sensory descriptors were observed among the EVOOs analysed by official VOO sensory analysis. The method of odorant series applied herein was demonstrated to successfully characterise EVOO odour as expected from a sensory panel but using only instrumental analysis of volatile compounds, and giving additional reliable quantitative information. The results can be presented as a 'barcode', providing a visual and effective graphical representation allowing an easy and rapid description of EVOO sensory attributes using instrumental data.

CONCLUSION

The odorant series have the potential to better differentiate the aroma of food products, opening new possibilities allowing a schematic and effective visual representation to be used for EVOO quality control and consumer information, especially in new olive oil consuming countries. © 2018 Society of Chemical Industry.

Characterization of aroma, aroma-active compounds and fatty acids profiles of cv. Nizip Yaglik oils as affected by three maturity periods of olives

BACKGROUND

The present study aimed to investigate how olive maturity indices (MI) (2.5, 3.5 and 4.5 MI) affect the aroma, aroma-active compounds, fatty acid profiles and color properties of cv. Nizip Yaglik olive oils. Various techniques for extracting volatiles from oil materials are available in the literature. Aroma compounds were extracted by the solvent-assisted flavor evaporation extraction method for the first time in olive oil.

RESULTS

The type and number of aroma-active compounds varied according to maturity periods of olives. A total of 22, 21 and 20 different key odorants were found in aromatic extracts of samples with 2.5, 3.5 and 4.5 MI, respectively. The most potent aroma-active compounds based on flavor dilution (FD) factor values were hexanal (green) for 2.5 MI (FD: 1024) and 3.5 MI (FD: 512), as well as 1-penten-3-ol (green-leafy) for 4.5 MI (FD: 512).

CONCLUSION

Overall, olive oils obtained from unripe and medium-ripe olives had stronger green and fruity odours compared to ripe olives. Principal component analysis demonstrated that oils were clearly discriminated according to their general physicochemical analysis, fatty acids, aroma profiles and key odorants. The results of the present study show that the olive maturity period has a significant influence on the quality parameters of olive oil. © 2018 Society of Chemical Industry.

The possible ameliorative effect of Olea europaea L. oil against deltamethrin-induced oxidative stress and alterations of serum concentrations of thyroid and reproductive hormones in adult female rats

This study aimed to verify whether Olea europaea L. (olive) oil (OEO) exerted a protective effect against oxidative stress induced by deltamethrin (DM) and alterations of pituitary, thyroid and gonadal hormones in adult female rats. DM (0,00256 g/kg body weight),OEO (0,6 g/kg body weight) and DM with OEO were administered to rats orally for 28 days. Volatile compounds present in olive oil were analysed by GC-MS. Estradiol (E₂), Thyroxine (T4),Thyroid Stimulating Hormone (TSH), Triiodothyronine (T3), Follicle Stimulating Hormone (FSH), Luteinizing Hormone (LH), Progesterone (Pg) were measured in serum using Chemiluminescent Microparticle Immunoassay (CMIA). Lipid peroxidation (LPO), protein carbonyls (PCs), reduced glutathione (GSH) levels along with superoxide dismutase (SOD), catalase (CAT), glutathione-S-transferase (GST) and glutathione peroxidase (GPx) activities were determined in thyroid and ovarian tissues. Sesquiterpenes, (E,E)-α-farnesene (16.45%) and α-copaene (9,86%), were analysed as the main volatile compounds of OEO. The relative weight of ovaries and thyroid and body weight significantly decreased in rats treated with DM. DM caused significant alterations in TSH, T4, FSH, Pg and E₂ levels while T3 and LH concentrations remained unchanged when compared to control. DM also increased significantly LPO and PCs levels. In addition, GSH reserves as well as CAT, GPx, SOD and GST activities were suppressed in DM-received rats. The presence of OEO with DM returned the levels of oxidative stress markers, thyroid and reproductive hormones at the control values. Our results indicate that OEO is a powerful agent able to protect against DM oxidative stress and endocrine changes.

GC-O-MS technique and its applications in food flavor analysis

Gas chromatography-olfactometry-mass spectrometry (GC-O-MS) is a combination of gas chromatography-olfactometry (GC-O) and gas chromatography-mass spectrometry (GC-MS). GC-O-MS technique is a powerful tool to study food flavors and it has been widely applied for aroma and flavor analysis of various food items. In combination with different technologies, GC-O-MS can be applied to solve many flavor problems in the food industry such as quick mapping of aroma-active compounds, identification of key aroma-active compounds, cluster analysis based on the aroma-active compounds, relationship between odorants and sensory properties, and clarification of formation mechanism of important odorants. The newly proposed "molecular sensory science" concept (or sensory-directed flavor analysis) provides a much deeper research for the GC-O-MS application. Here, we have reviewed the operation, advantages and applications of GC-O-MS technique. Qualitative/quantitative analysis methods and sampling methods of aroma-active compounds have been described to introduce the different application areas of GC-O-MS. Case studies based on existing papers and our research have been discussed.

GC-MS olfactometric and LC-DAD-ESI-MS/MS characterization of key odorants and phenolic compounds in black dry-salted olives

BACKGROUND

Olives are processed in different ways depending on consumption habits, which vary between countries. Different de-bittering methods affect the aroma and aroma-active compounds of table olives. This study focused on analyzing the aroma and aroma-active compounds of black dry-salted olives using gas chromatography-mass spectrometry-olfactometry (GC-MS-O) techniques.

RESULTS

Thirty-nine volatile compounds which they have a total concentration of 29 459 µg kg^-1 , were determined. Aroma extract dilution analysis (AEDA) was used to determine key aroma compounds of table olives. Based on the flavor dilution (FD) factor, the most powerful aroma-active compounds in the sample were methyl-2-methyl butyrate (tropical, sweet; FD: 512) and (Z)-3-hexenol (green, flowery; FD: 256). Phenolic compounds in table olives were also analyzed by LC-DAD-ESI-MS/MS. A total of 20 main phenolic compounds were identified and the highest content of phenolic compound was luteolin-7-glucoside (306 mg kg^-1 ), followed by verbascoside (271 mg kg^-1 ), oleuropein (231 mg kg^-1 ), and hydroxytyrosol (3,4-DHPEA) (221 mg kg^-1 ).

CONCLUSION

Alcohols, carboxylic acids, and lactones were qualitatively and quantitatively the dominant volatiles in black dry-salted olives. Results indicated that esters and alcohols were the major aroma-active compounds. © 2018 Society of Chemical Industry.

Evaluation of Amazon fruits: chemical and nutritional studies on Borojoa sorbilis

BACKGROUND

Borojoa sorbilis (Ducke) is an Amazonian species with edible fruits that are widely consumed by the local population, but little studied and not yet economically explored. Thus the aim of this study was to describe the chemical composition, volatile compounds, nutritional aspects and antioxidant activity of the fruit pulp and peel of B. sorbilis.

RESULTS

Headspace solid-phase microextraction, using polydimethylsiloxane-divinylbenzene (PDMS-DVB) fiber, resulted in the identification of 59 substances in the pulp and peel of B. sorbilis fruits after analysis of the chromatograms obtained by gas chromatography-mass spectrometry using polar and nonpolar columns. Esters were the most abundant. Moisture, lipids, protein, dietary fiber, ash, carbohydrate, total energy value, titratable acid, soluble solids and pH were measured. Protein amount, fat content and antioxidant activity were low in both pulp and peel. Carbohydrate content was 179.2 and 134.9 g kg^-1 in pulp and peel, respectively.

CONCLUSION

This is the first report on the chemical characteristics, flavor and nutritional aspects of B. sorbilis fruit, which is essential to its economic exploitation. The high energy value associated with the carbohydrate content, plus the low fat content, contribute to a possible use of B. sorbilis fruits as a food supplement. © 2018 Society of Chemical Industry.

Characterization of Aroma-Active Compounds in Seed Extract of Black Cumin (Nigella sativa L.) by Aroma Extract Dilution Analysis

Turkish Nigella sativa L. seed extracts were used to detect the aroma and key odorant compounds of the spice using gas chromatography-mass spectrometry-olfactometry (GC-MS-O). Volatile compounds were extracted by the purge and trap extraction (PTE) method. A total of 32 volatile compounds consisting of different chemical classes acids (13), alcohols (7), phenols (3), terpene (1), esters (2), ketones (2), aldehyde (1), lactone (1) and hydrocarbons (2) were determined. The amounts of volatile compounds were found to be 21,544 µg kg−1. The application of aroma extract dilution analysis (AEDA) revealed the presence of 13 odor-active compounds alcohols (2), carboxylic acids (4), phenols (2), terpene (1), ketone (1), hydrocarbon (1) and unknown compounds (2) in Nigella sativa L. extract. Flavor dilution (FD) factors of key odorants ranged between 4 and 1024, while odor activity values (OAV) were in the range of 1.0 to 170.8. Acetoin was the only aroma-active ketone detected in Nigella sativa L. seed extracts. It had the strongest aroma (FD = 1024) and provided a buttery odor. This compound represented the most abundant compound of overall aroma profile with a concentration of 9394 µg kg−1, followed by isobutanoic acid (FD = 512 with a concentration of 218 µg kg−1) and contributed a powerful aroma and a cheesy characteristic odor.

A metabolic fingerprinting approach based on selected ion flow tube mass spectrometry (SIFT-MS) and chemometrics: A reliable tool for Mediterranean origin-labeled olive oils authentication

Selected Ion flow tube mass spectrometry (SIFT-MS) in combination with chemometrics was used to authenticate the geographical origin of Mediterranean virgin olive oils (VOOs) produced under geographical origin labels. In particular, 130 oil samples from six different Mediterranean regions (Kalamata (Greece); Toscana (Italy); Meknès and Tyout (Morocco); and Priego de Córdoba and Baena (Spain)) were considered. The headspace volatile fingerprints were measured by SIFT-MS in full scan with H₃O⁺, NO⁺ and O₂⁺ as precursor ions and the results were subjected to chemometric treatments. Principal Component Analysis (PCA) was used for preliminary multivariate data analysis and Partial Least Squares-Discriminant Analysis (PLS-DA) was applied to build different models (considering the three reagent ions) to classify samples according to the country of origin and regions (within the same country). The multi-class PLS-DA models showed very good performance in terms of fitting accuracy (98.90-100%) and prediction accuracy (96.70-100% accuracy for cross validation and 97.30-100% accuracy for external validation (test set)). Considering the two-class PLS-DA models, the one for the Spanish samples showed 100% sensitivity, specificity and accuracy in calibration, cross validation and external validation; the model for Moroccan oils also showed very satisfactory results (with perfect scores for almost every parameter in all the cases).

Global volatile profile of virgin olive oils flavoured by aromatic/medicinal plants

The global volatile profile of commercial virgin olive oils and flavoured olive oils with aromatic/medicinal plants, was established using liquid-liquid microextraction (LLME) and headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-quadrupole mass spectrometry (GC-qMS). More than 60 volatile organic compounds (VOCs belonging to different groups were identified using both methods. Olive oils volatile profile was slightly influenced by maceration process, which occurred at room temperature (20±2°C) for 15days. The predominant differences were observed in terpenoids group, since some of them were only identified in the flavoured olive oils, while others showed an increase with the maceration process. VOCs mass transfer from plants to olive oils could explain the observed results. Principal components analysis (PCA) applied to LLME/GC-qMS data allowed to distinguish the olive oils. The flavoured oils would increase the use of olive oil among consumers as consequence of the improvement of its aromatic profile and healthy properties.

Determination of Volatiles by Odor Activity Value and Phenolics of cv. Ayvalik Early-Harvest Olive Oil

Ayvalik is an important olive cultivar producing high quality oils in Turkey. In the present study, volatile and phenolic compositions of early-harvest extra virgin olive oil (cv. Ayvalik) were determined. The solvent-assisted flavor evaporation (SAFE) technique was used for the extraction of volatile components. The aromatic extract obtained by SAFE was representative of the olive oil odor. A total of 32 aroma compounds, including alcohols, aldehydes, terpenes, esters, and an acid, were identified in the olive oil. Aldehydes and alcohols were qualitatively and quantitatively the most dominant volatiles in the oil sample. Of these, six volatile components presented odor activity values (OAVs) greater than one, with (Z)-3-hexenal (green), hexanal (green-sweet) and nonanal (fatty-pungent) being those with the highest OAVs in olive oil. A total of 14 phenolic compounds were identified and quantified by liquid chromatography combined with a diode array detector and ion spray mass spectrometry. The major phenolic compounds were found as 3,4-DHPEA-EDA, 3,4-DHPEA-EA and p-HPEA-EDA.