Borago Officinalis L.: A Review Oon Extraction, Phytochemical, and Pharmacological Activities

Borago officinalis L., an annual herb belonging to the Boraginaceae family, is used in the traditional medical practices of various countries and for multiple treatments, including respiratory disorders, colds, influenza, diarrhea, cramps, inflammation, palpitation, hypertension menopause, and post-menopausal symptoms. Its pharmacological properties and biological activities - among them antioxidant, antimicrobial, anticancer, anti-inflammatory, insecticidal, antigenotoxic, and anti-obesity activity - were demonstrated in vitro and in vivo and are related to its rich content of bioactive compounds (mainly phenolic acids, flavonoids, anthocyanins, alkaloids, and terpenes) extracted from various parts of B. officinalis including leaves, flowers, seeds, and roots. This review summarizes all updated information on applied extraction processes, phytochemistry, pharmacology, and toxicity of B. officinalis.

Volatile compounds and aroma characteristics of mushrooms: a review

Mushrooms are popular due to their rich medicinal and nutritional value. Of the many characteristics of mushrooms, aroma has received extensive attention and research as a key determinant of consumer preference. This paper reviews the production, role and contribution of common volatile compounds (VCs) in wild and cultivated mushrooms, and explores the methods used to characterize them and the factors influencing aroma. To date, more than 347 common VCs have been identified in mushrooms, such as aldehydes, ketones, alcohols and sulfur-containing compounds. Extraction and identification of VCs is a critical step and combining multiple analytical methods is an effective strategy in mushroom aroma studies. In addition, the VCs and the aroma of mushrooms are affected by a variety of factors such as genetics, growing conditions, and processing methods. However, the mechanism of influence is unknown. Further studies on the production mechanisms of VCs, their contribution to aroma, and the factors influencing their formation need to be determined in order to fully elucidate aroma and flavor of mushrooms.

Evaluating the Potential of Boswellia rivae to Provide Sustainable Livelihood Benefits in Eastern Ethiopia

Frankincense is an oleo-gum-resin collected from wild Boswellia spp. trees, and widely used in perfumery, cosmetics, aromatherapy, incense, and other industries. Boswellia rivae, growing in Ethiopia, Somalia, and Kenya, is one source of frankincense, but is little-commercialized compared to species such as B. sacra, B. frereana, and B. papyrifera. In this study, we examine the resin essential oil chemistry and harvesting systems of B. rivae in order to evaluate its potential for increased trade and potential positive livelihood benefits. Boswellia rivae produces an essential oil rich in α-thujene (0.1-12.4%), α-pinene (5.5-56.4%), β-pinene (0.3-13.0%), δ-3-carene (0.1-31.5%), p-cymene (1.4-31.2%), limonene (1.8-37.3%), β-phellandrene (tr-5.6%), trans-pinocarveol (0.1-5.0%), trans-verbenol (0.1-11.2%), and trans-β-elemene (0-5.7%), similar to major commercial species, although it is difficult to detect mixing of B. rivae and Commiphora africana resins from chemistry alone. The B. rivae trees are not actively tapped, so resin collection has a neutral impact on the health of the trees, and resin production is unaffected by drought. Consequently, collecting resins acts as a key income supplementing livestock herding, as well as a safety net protecting pastoral communities from the severe negative effects of climate change-exacerbated drought on livestock. Therefore, Boswellia rivae is well positioned chemically, ecologically, and socially to support expanded trade.

Molecular and Phytochemical Variability of Endemic Juniperus sabina var. balkanensis from Its Natural Range

Juniperus sabina L. var. balkanensis R.P. Adams & Tashev is a recently described endemic variety from the Balkan Peninsula. Its strong sprouting ability and fast vegetative propagation, on one hand, and fragmented distribution, on the other, can lead to lower genetic diversity in local populations and to the differentiation of populations. As there has been no detailed investigation of this variety, we studied Balkan natural populations using phytochemical and molecular markers. Leaf essential oils (EOs) were chosen based on their proven usability in the population studies of Juniperus taxa, while ISSRs (Inter Simple Sequence Repeats) have been used due to their high resolution. In addition, since this variety is best described using molecular markers, the chloroplast trnS-trnG region was amplified from individuals from different populations having different chemotypes. Based on the essential oil profile, three chemotypes could be identified with a difference in their distribution. The analysis of molecular variance showed moderate differentiation of populations and regions, attesting to the start of the separation of three regions in the Balkans: west, east and south. The bioclimatic and environmental parameters and sex of the individual did not influence the EO profile, although some of the compounds present in low-to-medium concentrations showed strong correlation with several bioclimatic parameters.

Development and evaluation of an automated solvent-assisted flavour evaporation (aSAFE)

Artefact-avoiding isolation of the volatiles from foods is a crucial step before analysis of odour-active compounds by gas chromatography (GC). In the past 20 years, solvent extraction followed by solvent-assisted flavour evaporation (SAFE) has become the standard approach, particularly prior to GC–olfactometry. The manual valve of the SAFE equipment, however, leads to suboptimal yields and the risk of a contamination of the volatile isolate with non-volatiles. We thus developed an automated SAFE (aSAFE) approach by replacing the manual valve with an electronically controlled pneumatic valve. The aSAFE provides clearly higher yields than the manual SAFE (mSAFE), notably from extracts high in lipids and for odorants with comparably high boiling points. Additionally, aSAFE substantially reduces the risk of non-volatiles being transferred to the volatile isolate. Full automatisation is possible by combining the aSAFE approach with an automated liquid nitrogen refill system as well as an endpoint recognition and shut-off system.

Simultaneous Distillation–Extraction of Essential Oils from Rosmarinus officinalis L

The present study describes a procedure to isolate essential oils from Rosmarinus officinalis L. using simultaneous distillation–extraction (SDE). Rosmarinus officinalis L. can be used for medicinal purposes, as well in the cooking and cosmetics industries. SDE technique extraction combines a steam distillation combined with a continuous extraction using a solvent or a co-solvent mixture, providing faster extractions with low extraction solvent volumes. The effect of the solvent nature and the extraction time on the simultaneous distillation–extraction efficiency was evaluated. The best performance was achieved using pentane as a solvent for 1 h of extraction. The essential oils obtained by simultaneous distillation–extraction extracts were analyzed by gas chromatography with flame ionization detection (GC-FID). Extraction efficiencies ranged from 40 to 70% for the majority of the compounds tested, and the precision (measured by the relative standard deviation) varied between 6 and 35%. Among the compounds analyzed the most abundant in the Rosmarinus officinalis L. sample were 1,8-cineole, (-) –borneol, α-pinene, (S)-(-)- α–terpineol, (-)-bornyl acetate, linalool, and 2,2,6-trimethylcyclohexanone. The SDE method proved to be a suitable option for obtaining extracts free from cuticular waxes or chlorophylls.

Chemical Composition of the Unexplored Volatile Fraction of Betula glandulosa, a Prevalent Shrub in Nunavik, Quebec

The volatile fraction of the leaves of Betula glandulosa Michx. has been investigated for its secondary metabolite composition by GC-MS and GC/FID. The rapid expansion of this shrub species in subarctic landscapes, like the ones found in Nunavik (Northern Québec, Canada), highly impacts ecosystem dynamics. Yet, despite its abundance, few phytochemical investigations have yet been conducted on this species. In this study, we present the first phytochemical investigation of the volatile metabolites of B. glandulosa leaves. Although no essential oil was isolated, volatile compounds were extracted from the hydrosol by steam distillation. The main metabolites observed were linalool (14.6 - 19.0%), C 6 oxylipins (known as green leaf volatiles, GLV; total of 18.2 - 40.2%), eugenol (1.6 - 8.6%) and α -terpineol (3.3 - 4.8%). Dwarf birch is an important food source for insects and herbivores, so knowledge of its metabolite composition could help understand parts of its functional role in subarctic ecosystems. The composition of the volatile fraction could serve as marker for differentiating B. glandulosa from other dwarf birch species like Betula nana L.

Essential Oil Composition and Micromorphological Traits of Satureja montana L., S. subspicata Bartel ex Vis., and S. kitaibelii Wierzb. Ex Heuff. Plant Organs

The essential oil (EO) composition of Satureja plants is highly variable. Recent studies suggest that there is an even difference in the EO composition from different plant organs within the same plant. This study aims to examine the chemical profile of EOs and the micromorphological characteristics of different organs of three Satureja species. The relationship between the number of glandular trichomes and EOs profile and relative yield is also investigated. Individuals from five populations were visualized using a scanning electron microscope, while EOs of leaves, calyces, corollas, and whole aerial parts were isolated using simultaneous distillation and extraction and analyzed using gas chromatography/mass spectrometry. Three types of glandular trichomes were detected. Peltate trichomes were present on all plant organs of studied species, while two types of capitate trichomes show different organ and species preferences. The EOs profiles differed across the plant parts, but showed a species specific composition. Univariate and multivariate statistics were used to show a correlation between the peltate trichomes and EO yield, and chemophenetic significance of EO profiles.

The effects of different extraction methods on the aroma fingerprint, recombination and visualization of clam soup

Clam is a kind of nutritious, delicious and economical aquatic food around the world and is famous for its unique aroma. Instrumental analysis, sensory analysis, and comprehensive statistical analysis were performed to explain the relationship between aroma and odorants in clam soup. Six extraction methods combined with GC-MS and sniffing were utilized to obtain the aroma fingerprints of clam soup and to analyze the correlation with aroma perception. Solvent extraction methods were more effective than headspace extraction methods for the volatiles of clam soup. SAFE was the best method to obtain the most comprehensive information of volatiles of clam soup. The sequence of a combination of different extraction methods and SAFE would also affect the results of volatiles extracted from clam soup. Volatiles extracted via SDE, P&T, and SPME would add further information to the result of SAFE. A total of 119 volatile compounds were identified from clam soup by summarising the results of different extraction methods. The significant effect of 14 key odorants in clam soup on aroma perception was verified by aroma recombination and odorant omission tests. A neural network diagram of the aroma profile was designed to visualize the information of odor perception. Furthermore, the results would be beneficial for aroma research studies of aquatic food and the processing of clam products.

Role of lactic acid bacteria in flavor development in traditional Chinese fermented foods: A review

Traditional Chinese fermented foods are favored by consumers due to their unique flavor, texture and nutritional values. A large number of microorganisms participate in the process of fermentation, especially lactic acid bacteria (LAB), which are present in almost all fermented foods and contribute to flavor development. The formation process of flavor is complex and involves the biochemical conversion of various food components. It is very important to fully understand the conversion process to direct the flavor formation in foods. A comprehensive link between the LAB community and the flavor formation in traditional Chinese fermented foods is reviewed. The main mechanisms involved in the flavor formation dominated by LAB are carbohydrate metabolism, proteolysis and amino acid catabolism, and lipolysis and fatty acid metabolism. This review highlights some useful novel approaches for flavor enhancement, including the application of functional starter cultures and metabolic engineering, which may provide significant advances toward improving the flavor of fermented foods for a promising market.

Identification of key odorants in complex mixtures occurring in nature

Covering: up to 2019Soon after the birth of gas chromatography, mass spectrometry and olfactometry were used as detectors, which allowed impressive development to be achieved in the area of odorant determinations. Since the mid-80s, structured methods of gas chromatography-olfactometry have appeared, allowing the determination of which odor constituents play a key role in materials. Progressively, numerous strategies have been proposed for sample preparation from raw materials, the representativeness evaluation of extracts, the identification of odor constituents, their quantification, and subsequently, the recombination of the key odorants to mimic the initial odor. However, the multiplicity of options at each stage of the analysis leads to a confusing landscape in this field, and thus, the present review aims at critically presenting the available options. For each step, the most frequently used alternatives are described, together with their strengths and weaknesses based on theoretical and experimental justifications according to the literature. These techniques are exemplified by many applications in the literature on aromas, fragrances and essential oils, with the initial focus on wine odorants, followed by a short overview on the molecular diversity of key odorants, which illustrates most of the facets and complexities of odor studies, including the issues raised by odorant interactions such as synergies.

On-Line Coupling of Simultaneous Distillation-Extraction Using the Likens-Nickerson Apparatus with Gas Chromatography

Simultaneous distillation-extraction (SDE) using the Likens-Nickerson apparatus is a convenient technique used to isolate volatile organic compounds (VOCs) from complex liquid matrices. The technique combines steam distillation with solvent extraction. While analytical extractions are normally followed by off-line separation/detection, it is advantageous to couple extractions on-line with separation and detection systems that are employed in the same analytical workflow. Here, we have coupled the Likens-Nickerson apparatus on-line with a gas chromatograph hyphenated with a mass spectrometer. For that purpose, we have devised an automated liquid transfer setup comprising a peristaltic pump, control unit, customized transfer vial with a drain port, and an autosampler arm to deliver liquid extract aliquots at defined time points. The on-line SDE-GC/MS system enables one to record real-time extraction profiles. These profiles reveal extraction kinetics of various VOCs present in the extracted samples. The data sets were fitted with the first order kinetic equation to obtain numeric values characterizing the extraction process (rate constants ranging from 0.21 to 0.01 min^-1 for the ethyl esters from C₆ to C₁₉). A comparison of on-line and off-line results reveals that the on-line system is more dependable, while the off-line analysis leads to artifacts. To demonstrate the operation of the on-line SDE-GC/MS system, we performed analyses of selected real samples (beer). The real-time data sets revealed extraction kinetics for VOCs present in these samples. The devised extraction-analysis system allows the analysts to make an evidence-based decision on the extraction time for different groups of analytes in order to maximize extraction yield and minimize analyte losses.

Optimization of a headspace solid-phase micro-extraction method to quantify volatile compounds in plain sufu, and application of the method in sample discrimination

A rapid headspace solid-phase microextraction method was optimized to detect volatile components in three commercial plain sufu samples. The method was then used to qualify 14 aroma impact components that contribute significantly to the volatile profile in 12 commercial samples produced at three locations and laboratory-scale fermented samples aged for 3, 15, 30, and 90 days. Principal component analysis (PCA) was subsequently used to group the samples. The optimized method identified 148 volatile compounds in three commercial samples, and the concentrations of 14 aroma impact compounds varied significantly among commercial and laboratory samples. PCA confirmed that these samples could be discriminated according to their production location and aging time, thereby rendering this method a simple strategy for sample discrimination.

Flavor formation in different production steps during the processing of cold-smoked Spanish mackerel

This study aimed to determine the changes in the flavor profile during different operating units when making cold-smoked Spanish mackerel. Sensory evaluation and instrumental analysis of tenderness were applied to optimize the processing parameters. For the overall odor perception, distinct odor among fresh and processed samples could be distinguished using electronic nose (e-Nose). Purge-and-trap (P&T) extraction combined with gas chromatography-mass spectrometry (GC-MS) was used to identify volatile compounds. Alcohols were the major volatiles in Spanish mackerel over the whole processing, while 2-butanol was found in the highest concentration. Curing was an effective way to remove fishy odor. Drying decreased the concentration of volatiles, especially sulfur compounds. Odor formation in cold-smoked mackerel could be divided into four steps (curing, drying, cold smoking and heating) as a result of partial least squares discriminant analysis (PLS-DA).

Chemical Composition and Antimicrobial Activities of Artemisia argyi Lévl. et Vant Essential Oils Extracted by Simultaneous Distillation-Extraction, Subcritical Extraction and Hydrodistillation

Artemisia argyi Lévl. et Vant essential oil could be used as a good antimicrobial flavouring agent and applied in the food industry. In this study, three methods, including simultaneous distillation-extraction (SDE), subcritical extraction and hydrodistillation, were applied to extract A. argyi essential oil. Compared with subcritical extraction (1%) and hydrodistillation (0.5%), SDE gave a higher yield (1.2%). Components of the essential oils were analysed with gas chromatography-mass spectrometry (GC-MS), and the most abundant ingredients were caryophyllene oxide, neointermedeol, borneol, α-thujone and β-caryophyllene. These five components accounted for 82.93%, 40.90% and 40.33% for SDE, subcritical extraction, and hydrodistillation, respectively. Based on agar disc diffusion and minimum inhibitory concentration (MIC) assays, SDE oil showed a significant inhibitory effect towards Listeria monocytogenes, Escherichia coli, Proteus vulgaris, Salmonella enteritidis and Aspergillus niger. Furthermore, electron microscope observations (SEM) confirmed that SDE oil could obviously deform cell morphology and destroy the structure of cell walls. Performances showed that SDE was a promising process for extracting A. argyi essential oil with both high yield and antimicrobial activity.

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.

Fresh and grilled eel volatile fingerprinting by e-Nose, GC-O, GC-MS and GC × GC-QTOF combined with purge and trap and solvent-assisted flavor evaporation

Fresh and grilled eel were investigated with respect to their volatile compounds and different fingerprinting techniques. An electronic nose (e-Nose) was applied to distinguish the odor between fresh and grilled eels. Purge and trap (P&T) and solvent-assisted flavor evaporation (SAFE) method were used to extract volatile compounds and further analyzed by a gas chromatographic combined with quadrupole mass spectrometry (GC-MS) and a two-dimensional gas chromatographic combined with hybrid quadrupole time-of-flight mass spectrometry (GC × GC-QTOF). SAFE extracted more ketone, alcohol and high boiling volatiles in eels than P&T. Considering some distinct compounds extracted by P&T, a P&T and SAFE combined method was chosen. There were 155 volatiles detected in fresh and grilled eels, 93 volatiles were identified. Due to the higher peak capacity, GC × GC-QTOF detected 39 compounds more than GC-MS. The key characteristic volatiles of grilled eel were methyl propyl disulfide, dimethyl trisulfide, heptane, octane, and camphene. Volatile fingerprinting can be a reference benchmark for identification and quality appraisal of fresh and grilled eel products.

Volatile sulfur compounds in tropical fruits

Global production and demand for tropical fruits continues to grow each year as consumers are enticed by the exotic flavors and potential health benefits that these fruits possess. Volatile sulfur compounds (VSCs) are often responsible for the juicy, fresh aroma of tropical fruits. This poses a challenge for analytical chemists to identify these compounds as most often VSCs are found at low concentrations in most tropical fruits. The aim of this review is to discuss the extraction methods, enrichment techniques, and instrumentation utilized to identify and quantify VSCs in natural products. This will be followed by a discussion of the VSCs reported in tropical and subtropical fruits, with particular attention to the odor and taste attributes of each compound. Finally, the biogenesis and enzymatic formation of specific VSCs in tropical fruits will be highlighted along with the contribution each possesses to the aroma of their respective fruit.

Pistachio oil (Pistacia vera L. cv. Uzun): Characterization of key odorants in a representative aromatic extract by GC-MS-olfactometry and phenolic profile by LC-ESI-MS/MS

Volatile, aroma-active, and phenolic compounds of pistachio oil obtained from cv. Uzun were investigated in the current study. To obtain a representative aromatic extract, three of the most widely used extraction methods were compared using a representative test; the solvent-assisted flavour extraction (SAFE) aromatic extract from pistachio oil was found to be the most representative. A total of 50 aroma compounds were determined in pistachio oil and it was found that terpenes, aldehydes, and alcohols were the most abundant volatile compounds. Applying GC-MS-olfactometry and aroma extract dilution analysis (AEDA) resulted in a total of 14 aroma-active areas being detected in the extract of pistachio oil. In the phenolic fraction obtained by the LC-ESI-MS/MS method, a total of 12 phenolic compounds was found in the pistachio oil, of which seven compounds were reported for the first time. Eriodictyol-7-O-glucoside and protocatechuic acid were the most dominant phenolic compounds.

A study revealing the key aroma compounds of steamed bread made by Chinese traditional sourdough

Aroma of Chinese steamed bread (CSB) is one of the important parameters that determines the overall quality attributes and consumer acceptance. However, the aroma profile of CSB still remains poorly understood, mainly because of relying on only a single method for aroma extraction in previous studies. Therefore, the objective of this study was to determine the volatile aroma compounds of five different samples of CSB using three different aroma extraction methods, namely solid-phase microextraction (SPME), simultaneous distillation-extraction (SDE), and purge and trap (P&T). All samples showed a unique aroma profile, which could be attributed to their unique microbial consortia. (E)-2-Nonenal and (E,E)-2,4-decadienal were the most prevalent aromatic compounds revealed by SDE, which have not been reported previously, while ethanol and acetic acid proved to be the most dominant compounds by both SPME and P&T. Our approach of combining three different aroma extraction methods provided better insights into the aroma profile of CSB, which had remained largely unknown in previous studies.

Effect of cooking on aroma profile of red kidney beans (Phaseolus vulgaris) and correlation with sensory quality

Volatile aroma compounds of three varieties of red kidney beans (Phaseolus vulgaris) namely Kashmiri red, Sharmili and Chitra were extracted in raw state using solid-phase microextraction (SPME) and cooked state using simultaneous distillation extraction (SDE). During cooking a significant (p<0.05) reduction in the content of several aldehydes, alcohols and terpene hydrocarbons while an increase in content of various sulfurous compounds, terpene alcohols, ketones and pyrazines was noted. Descriptive sensory analysis showed that the maximum intensity of 'kidney bean', 'earthy' and 'smoky' odour was observed in Kashmiri red while Sharmili variety was characterised by 'sulfurous' odour. Correlation of volatile profile data with descriptive sensory analysis and odour activity values clearly established the role of compounds, such as methanethiol, diethyl sulfide, dimethyl disulfide, methional and dimethyl trisulfide, in contributing to 'cooked kidney bean' aroma, while dimethyl sulfoxide, dimethyl sulfone and ethyl methyl sulfone were responsible for 'sulfurous' aroma.

Volatile composition and sensory properties of Vanilla × tahitensis bring new insights for vanilla quality control

BACKGROUND

Vanilla × tahitensis produced in French Polynesia has a unique flavour among vanilla species. However, data on volatiles and sensory properties remain limited. In this study, the volatile composition and sensory properties of V. × tahitensis from three Polynesian cultivars and two origins (French Polynesia/Papua New Guinea) were determined by gas chromatography-mass spectrometry and quantitative descriptive analysis, respectively, and compared to Vanilla planifolia.

RESULTS

Vanilla species, origins and cultivars were differentiated by their volatile and sensory profiles using principal component analysis. The V. × tahitensis flavour from French Polynesia was characterized by a well-balanced sensory profile, having strong anise and caramel notes due to high levels of anisyl compounds. V. × tahitensis from Papua New Guinea was distinct from that of French Polynesia, having strong spicy, fruity, brown rum notes due to p-vinylguaiacol, p-cresol and esters. Vanilla planifolia showed stronger phenolic, woody, smoky notes due to guaiacol, creosol and phenol, which were found to be biomarkers of the species. Vanilla sensory properties were linked by partial least squares regression to key volatile compounds like guaiacol or creosol, which are indicators of lower quality.

CONCLUSION

This study brings new insights to vanilla quality control, with a focus on key volatile compounds, irrespective of origin.