Volatile constituents of Vietnamese pummelo, orange, tangerine and lime peel oils

Bioeconomy and ethnopharmacology - Translational perspective and sustainability of the bioresources of northeast region of India

ETHNOPHARMACOLOGICAL RELEVANCE

The ecological environment of Northeast region of India (NER), with its high humidity, has resulted in greater speciation and genetic diversity of plant, animal, and microbial species. This region is not only rich in ethnic and cultural diversity, but it is also a major biodiversity hotspot. The sustainable use of these bioresources can contribute to the region's bioeconomic development.

AIM OF THE STUDY

The review aimed to deliver various perspectives on the development of bioeconomy from NER bioresources under the tenets of sustainable utilization and socioeconomic expansion.

MATERIALS AND METHODS

Relevant information related to prospects of the approaches and techniques pertaining to the sustainable use of ethnomedicine resources for the growth of the bioeconomy were retrieved from PubMed, ScienceDirect, Google Scholar, Scopus, and Springer from 1984 to 2023. All the appropriate abstracts, full-text articles and various book chapters on bioeconomy and ethnopharmacology were conferred.

RESULT

As the population grows, so does the demand for basic necessities such as food, health, and energy resources, where insufficient resource utilization and unsustainable pattern of material consumption cause impediments to economic development. On the other hand, the bioeconomy concept leads to "the production of renewable biological resources and the conversion of these resources and waste streams into value-added products.

CONCLUSIONS

In this context, major emphasis should be placed on strengthening the economy's backbone in order to ensure sustainable use of these resources and livelihood security; in other words, it can boost the bio-economy by empowering the local people in general.

New Essential Oils from Ecuadorian Gynoxys cuicochensis Cuatrec. and Gynoxys sancti-antonii Cuatrec. Chemical Compositions and Enantioselective Analyses

The present study belonged to an unfunded project, dealing on the systematic description of unprecedented essential oils (EOs), distilled from 12 species of genus Gynoxys Cuatrec. In this very case, the aim was the first chemical and enantiomeric analyses of two volatile fractions, obtained from the leaves of Gynoxys cuicochensis Cuatrec. and Gynoxys sancti-antonii Cuatrec. These EOs were analyzed by GC-MS (qualitatively) and GC-FID (quantitatively), detecting 89 and 60 components from G. cuicochensis and G. sancti-antonii, respectively. Major components for G. cuicochensis EO, on a nonpolar and polar stationary phase, were α-pinene (29.4-29.6%), p-vinylguaiacol (3.3-3.6%), and germacrene D (20.8-19.9%). In G. sancti-antonii EO, the main compounds were α-pinene (3.0-2.9%), β-pinene (12.9-12.1%), γ-curcumene (19.7-18.3%), germacrene D (9.0% on the polar phase), ar-curcumene (5.3% on the polar phase), δ-cadinene (4.1-4.6%), α-muurolol (3.3-2.4%), α-cadinol (3.0% on both columns), and an undetermined compound, of molecular weight 220. In addition to chemical composition, the enantioselective analysis of the main chiral compounds was carried out on two different chiral selectors. In G. cuicochensis EO, (1R,5R)-(+)-α-pinene, (S)-(+)-β-phellandrene, (R)-(-)-piperitone, and (S)-(-)-germacrene D were enantiomerically pure, whereas β-pinene, sabinene, α-phellandrene, limonene, linalool, and terpinen-4-ol were observed as scalemic mixtures. On the other hand, in G. sancti-antonii EO, the pure enantiomers were (1S,5S)-(-)-α-pinene, (1R,5R)-(+)-sabinene, (R)-(-)-β-phellandrene, (S)-(-)-limonene, (1S,2R,6R,7R,8R)-(+)-α-copaene, (R)-(-)-terpinen-4-ol, and (S)-(-)-germacrene D, whereas β-pinene, linalool, and α-terpineol were present as scalemic mixtures. The principal component analysis demonstrated that G. cuicochensis volatile fraction was quite similar to many of the other EOs of the same genus, whereas G. sancti-antonii produced the most dissimilar EO. Furthermore, the enantioselective analyses showed the usual variable enantiomeric distribution, with a greater presence of enantiomerically pure compounds in G. sancti-antonii EO.

Egyptian mandarin peel oil's anti-scabies potential via downregulation-of-inflammatory/immune-cross-talk: GC-MS and PPI network studies

The current study investigated the scabicidal potential of Egyptian mandarin peel oil (Citrus reticulata Blanco, F. Rutaceae) against sarcoptic mange-in-rabbits. Analysis of the oil's GC-MS identified a total of 20 compounds, accounting for 98.91% of all compounds found. Mandarin peel oil topical application improved all signs of infection, causing a scabicidal effect three days later, whereas in vitro application caused complete mite mortality one day later. In comparison to ivermectin, histopathological analysis showed that the epidermis' inflammatory-infiltration/hyperkeratosis-had disappeared. In addition to TIMP-1, the results of the mRNA gene expression analysis showed upregulation of I-CAM-1-and-KGF and downregulation of ILs-1, 6, 10, VEGF, MMP-9, and MCP-1. The scabies network was constructed and subjected to a comprehensive bioinformatic evaluation. TNF-, IL-1B, and IL-6, the top three hub protein-coding genes, have been identified as key therapeutic targets for scabies. From molecular docking data, compounds 15 and 16 acquired sufficient affinity towards the three screened proteins, particularly both possessing higher affinity towards the IL-6 receptor. Interestingly, it achieved a higher binding energy score than the ligand of the docked protein rather than displaying proper binding interactions like those of the ligand. Meanwhile, geraniol (15) showed the highest affinity towards the GST protein, suggesting its contribution to the acaricidal effect of the extract. The subsequent, MD simulations revealed that geraniol can achieve stable binding inside the binding site of both GST and IL-6. Our findings collectively revealed the scabicidal ability of mandarin peel extract for the first time, paving the way for an efficient, economical, and environmentally friendly herbal alternative for treating rabbits with Sarcoptes mange.

Identification of Novel and Safe Fungicidal Molecules against Fusarium oxysporum from Plant Essential Oils: In Vitro and Computational Approaches

Phytopathogenic fungi are serious threats in the agriculture sector especially in fruit and vegetable production. The use of plant essential oil as antifungal agents has been in practice from many years. Plant essential oils (PEOs) of Cuminum cyminum, Trachyspermum ammi, Azadirachta indica, Syzygium aromaticum, Moringa oleifera, Mentha spicata, Eucalyptus grandis, Allium sativum, and Citrus sinensis were tested against Fusarium oxysporum. Three phase trials consist of lab testing (MIC and MFC), field testing (seed treatment and foliar spray), and computer-aided fungicide design (CAFD). Two concentrations (25 and 50 μl/ml) have been used to asses MIC while MFC was assessed at four concentrations (25, 50, 75, and 100 μl/ml). C. sinensis showed the largest inhibition zone (47.5 and 46.3 m2) for both concentrations. The lowest disease incidence and disease severity were recorded in treatments with C. sinensis PEO. Citrus sinensis that qualified in laboratory and field trials was selected for CAFD. The chemical compounds of C. sinensis PEO were docked with polyketide synthase beta-ketoacyl synthase domain of F. oxysporum by AutoDock Vina. The best docked complex was formed by nootkatone with -6.0 kcal/mol binding affinity. Pharmacophore of the top seven C. sinensis PEO compounds was used for merged pharmacophore generation. The best pharmacophore model with 0.8492 score was screened against the CMNP database. Top hit compounds from screening were selected and docked with polyketide synthase beta-ketoacyl synthase domain. Four compounds with the highest binding affinity and hydrogen bonding were selected for confirmation of lead molecule by doing MD simulation. The polyketide synthase-CMNPD24498 showed the highest stability throughout 80 ns run of MD simulation. CMNPD24498 (FW054-1) from Verrucosispora was selected as the lead compound against F. oxysporum.

Bioactive Phytochemicals of Citrus reticulata Seeds—An Example of Waste Product Rich in Healthy Skin Promoting Agents

Phytochemical investigation of Egyptian mandarin orange (Citrus reticulata Blanco, F. Rutaceae) seeds afforded thirteen known compounds, 1–13. The structures of isolated compounds were assigned using 1D and 2D NMR and HRESIMS analyses. To characterize the pharmacological activity of these compounds, several integrated virtual screening-based and molecular dynamics simulation-based experiments were applied. As a result, compounds 2, 3 and 5 were putatively identified as hyaluronidase, xanthine oxidase and tyrosinase inhibitors. The subsequent in vitro testing was done to validate the in silico-based experiments to highlight the potential of these flavonoids as promising hyaluronidase, xanthine oxidase and tyrosinase inhibitors with IC50 values ranging from 6.39 ± 0.36 to 73.7 ± 2.33 µM. The present study shed light on the potential of Egyptian mandarin orange’s waste product (i.e., its seeds) as a skin health-promoting natural agent. Additionally, it revealed the applicability of integrated inverse docking-based virtual screening and MDS-based experiments in efficiently predicting the biological potential of natural products.

Nutrients and bioactives in citrus fruits: Different citrus varieties, fruit parts, and growth stages

Citrus fruits are consumed in large quantities worldwide due to their attractive aromas and taste, as well as their high nutritional values and various health-promoting effects, which are due to their abundance of nutrients and bioactives. In addition to water, carbohydrates, vitamins, minerals, and dietary fibers are important nutrients in citrus, providing them with high nutritional values. Citrus fruits are also rich in various bioactives such as flavonoids, essential oils, carotenoids, limonoids, and synephrines, which protect from various ailments, including cancer and inflammatory, digestive, and cardiovascular diseases. The composition and content of nutrients and bioactives differ significantly among citrus varieties, fruit parts, and growth stages. To better understand the nutrient and bioactive profiles of citrus fruits and provide guidance for the utilization of high-value citrus resources, this review systematically summarizes the nutrients and bioactives in citrus fruit, including their contents, structural characteristics, and potential health benefits. We also explore the composition variation in different citrus varieties, fruits parts, and growth stages, as well as their health-promoting effects and applications.

Chemical composition, antioxidant and antimicrobial activity of essential oils from tangerine (Citrus reticulata L.), grapefruit (Citrus paradisi L.), lemon (Citrus lemon L.) and cinnamon (Cinnamomum zeylanicum Blume)

The phytochemical and biological properties of tangerine (Citrus reticulata L.), grapefruit (Citrus paradisi L.), lemon (Citrus lemon L.) and cinnamon (Cinnamomum zeylanicum Blume) essential oils were examined. The chemical composition of the essential oils determined using chromatography analysis revealed that D-limonene and cis-cinnamaldehyde were the main components. The antioxidant and antimicrobial activities of the essential oils have been studied by the DPPH radical-scavenging assay and the disc-diffusion method, respectively. All essential oils had antimicrobial activity against saprophytic (Bacillus subtilis, Penicillium chrysogenum, Fusarium moniliforme, Aspergillus niger, Aspergillus flavus, Saccharomyces cerevisiae) and pathogenic microorganisms (Escherichia coli, Salmonella abony, Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans), with the highest inhibitory activity being observed in cinnamon oil, followed by grapefruit zest oil, tangerine zest oil and lemon zest oil; the MIC ranging from 6 to 60 ppm. In addition, they exhibited high antioxidant activity with the highest antioxidant activity being determined for the grapefruit zest essential oil, followed by the lemon zest essential oil, the tangerine zest essential oil and the cinnamon essential oil. The demonstrated promising results for the antioxidant and antimicrobial activity of the studied essential oils would give reason for their inclusion in the development of bio-preservation strategies for food emulsion preservation.

Characterization of Oxygenated Heterocyclic Compounds and in vitro Antioxidant Activity of Pomelo Essential Oil

Purpose

Citrus essential oils are widely used for aromatherapy and the alternative treatment of chronic diseases. Beyond the aroma substances, they are known to contain bioactive nonvolatile components; however, little knowledge has been gained about nonvolatiles in the essential oil of pomelo (Citrus grandis Osbeck), the largest citrus fruit. The purpose of this study was to analyze the nonvolatile oxygenated heterocyclic compounds (OHCs) of pomelo essential oils and evaluate their in vitro antioxidant activities for further development.

Methods

Cold-pressed essential oil (CPEO) and distilled essential oil (DEO) were obtained from the peel of the Liangping pomelo cultivar. High-performance liquid chromatography (HPLC) coupled with a photodiode array and fluorescence detection method was developed to identify and quantify the OHCs of the two essential oils. Ferric reducing antioxidant power and 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2-phenyl-4,4,5,5-tetramethyl-imidazoline-1-oxyl 3-oxide (PTIO) radical scavenging assays were used to determine the antioxidative capabilities.

Results

Thirteen OHCs were identified in CPEO. Coumarins such as meranzin (2.0 mmol L⁻¹) and furanocoumarins such as isoimperatorin (1.3 mmol L⁻¹) composed the majority of nonvolatiles in CPEO. These OHCs were characterized by high proportion (58%) of side chain epoxides. Five OHCs, namely, auraptenol, 6ʹ,7ʹ-dihydroxybergamottin (6ʹ,7ʹ-DHB), imperatorin, isoimperatorin and 8-geranyloxypsoralen were first identified in pomelo CPEO. Eight OHCs were detected at trace amounts in pomelo DEO. Antioxidant assays showed that CPEO was multiple times more potent than DEO regarding the total reducing power and radical scavenging capacity. Clearance of PTIO, a stable reactive oxygen species, followed slow kinetics.

Conclusion

Coumarins and furanocoumarins, two families of OHCs, constituted most of the nonvolatile components in CPEO. The nonvolatiles contributed significantly to the in vitro antioxidant activity of CPEO. Pomelo CPEO showed good prospects as a potential long-lasting natural antioxidant.

Utilization of pomelo peels to manufacture value-added products: A review

Pomelo peel as a by-product from pomelo consumption is rich in various nutrients and functional compounds, while most of the by-product is disposed as wastes. The utilization of pomelo peels could not only result in valued-added products/ingredients, but also reduce the environmental threats. By mainly reviewing the recent articles, pomelo peels could be directly used to produce candied pomelo peel, tea, jams, etc. Additionally, functional components (essential oils, pectin, polyphenols, etc.) could be extracted from pomelo peels and applied in food, pharmaceutical and chemical fields. The extraction methods exerted important influences on the composition, physicochemical properties, bioactivities and structures of the resultant fractions. Furthermore, pomelo peel was exploited to make adsorbents, bioethanol, etc. For the future investigations, the functionality- or bioactivity-oriented regimes to recovery valuable components from pomelo peel should be developed in an economic, effective and eco-friendly way and their applicability in large-scale production should be addressed.

Effects of Citrus sinensis Essential Oil and Intrinsic and Extrinsic Factors on the Growth and ToxinProducing Ability of Clostridium botulinum Type A

Background: Considering the high fatality of botulism, the control of Clostridium botulinum and its neurotoxins has clinical importance. In this regard, using chemical preservatives, natural essential oils (Eos), and changes in the growth predisposing factors of bacteria are suitable methods to control the growth and toxin producing of C. botulinum in foods. Objective: The current survey was done to assess the effects of Citrus sinensis EO and intrinsic and extrinsic factors on the growth and toxin producing of C. botulinum type A. Materials and Methods: In this experiment with a factorial design, C. sinensis EO (0.0%, 0.015%, 0.03%, and 0.045%), nisin (0, 500, and 1500 IU/mL), nitrite (0, 20, and 60 ppm), pH (5.5 and 6.5), storage temperature (25 and 35° C), and sodium chloride (NaCl, 0.5% and 3%) were used to assess bacterial growth in the brain heart infusion medium. Finally, the mouse bioassay method was also used to assess toxicity. Results: Clostridium sinensis EO with a concentration of 0.045%, as well as the reduction of pH and temperature could significantly delay the growth of bacteria (P≤0.05) in contrast to the use of NaCl and nisin alone. However, all concentrations of sodium chloride (NaCl), nisin, and C. sinensis EO (< 0.045%) in interaction with each other, especially in combination with nitrite, showed good synergistic effects. Conclusion: These results suggested that using certain concentrations of C. sinensis EO and nisin, along with other suboptimal factors caused a significant decrease in the nitrite contents of foods with a significant reduction in the growth and toxin-producing ability of C. botulinum.

Volatile Compounds in Citrus Essential Oils: A Comprehensive Review

The essential oil fraction obtained from the rind of Citrus spp. is rich in chemical compounds of interest for the food and perfume industries, and therefore has been extensively studied during the last decades. In this manuscript, we provide a comprehensive review of the volatile composition of this oil fraction and rind extracts for the 10 most studied Citrus species: C. sinensis (sweet orange), C. reticulata (mandarin), C. paradisi (grapefruit), C. grandis (pummelo), C. limon (lemon), C. medica (citron), C. aurantifolia (lime), C. aurantium (bitter orange), C. bergamia (bergamot orange), and C. junos (yuzu). Forty-nine volatile organic compounds have been reported in all 10 species, most of them terpenoid (90%), although about half of the volatile compounds identified in Citrus peel are non-terpenoid. Over 400 volatiles of different chemical nature have been exclusively described in only one of these species and some of them could be useful as species biomarkers. A hierarchical cluster analysis based on volatile composition arranges these Citrus species in three clusters which essentially mirrors those obtained with genetic information. The first cluster is comprised by C. reticulata, C. grandis, C. sinensis, C. paradisi and C. aurantium, and is mainly characterized by the presence of a larger abundance of non-terpenoid ester and aldehyde compounds than in the other species reviewed. The second cluster is comprised by C. junos, C. medica, C. aurantifolia, and C. bergamia, and is characterized by the prevalence of mono- and sesquiterpene hydrocarbons. Finally, C. limon shows a particular volatile profile with some sulfur monoterpenoids and non-terpenoid esters and aldehydes as part of its main differential peculiarities. A systematic description of the rind volatile composition in each of the species is provided together with a general comparison with those in leaves and blossoms. Additionally, the most widely used techniques for the extraction and analysis of volatile Citrus compounds are also described.

Comprehensive two-dimensional gas chromatography-mass spectrometry combined with multivariate data analysis for pattern recognition in Ecuadorian spirits

The current methodology used in quality control of Ecuadorian beverages such as Pájaro azúl, Puro and Pata de vaca is carried out by using conventional gas chromatography; however, it does not allow the fingerprinting of these Ecuadorian spirit beverages and their possible cases of adulteration. In order to overcome this drawback, comprehensive two-dimensional gas chromatography-mass spectrometry (GC × GC-MS) was combined with multivariate data analysis, revealing that compounds like citronellal, citronellol, geraniol, methyl anthranilate, (-)-trans-α-bergamotene, (-)-cis-α-bergamotene and D-limonene can be considered key elements for pattern recognition of these traditional beverages and product adulteration cases. Thus, the two-dimensional chromatographic fingerprints obtained by GC × GC-MS coupled with chemometric analysis, using Principal Component Analysis and Fisher-ratio can be considered as a potential strategy for adulteration recognition, and it may used as a quality assurance system for Ecuadorian traditional spirits.

Beverage Emulsions: Key Aspects of Their Formulation and Physicochemical Stability

In the last few decades, lifestyle changes and the awareness of the importance of a balanced diet have led the population to increase the consumption of beverages based on fruit juices and/or vegetables. Fruit and vegetables contain health-related compounds that can impact on physiological processes, thus reducing the risk of certain diseases and improving the overall health status. Consumer demand for more appealing and tasting beverages has also increased. In this sense, fortification of beverages with health-related ingredients and/or flavors arises as a potential strategy for the development of new beverage-based products. Nevertheless, most of those compounds are not soluble in water, thus their incorporation in aqueous food systems, such as beverages, requires an emulsification step. Beverage emulsions are concentrated emulsified systems designed to be further diluted and/or incorporated in beverages and drinks as carriers of water insoluble ingredients. This review article aims at discussing the main key aspects of beverage emulsion formulation and their colloidal stability after being added to complex food systems.

Analysis of volatile fraction of sweetie (Citrus maxima × Citrus paradisi) and its parent fruit using proton transfer reaction mass spectrometry

Abstract

The quality of the fruit is affected by several main ingredients and the aroma plays a fundamental role during the selection of fruit by consumers. In the case where several fruit have similar aromas and only one of them has specific health properties, it is very important to find the differences in the volatile organic compounds (VOCs) composition to distinguish these samples. Such situations are often found for hybrid fruit. Sweetie is a hybrid of grapefruit and pummelo. Sweetie fruit is characterized by high antioxidant potential and a positive effect on human health. The aim of this study was to verify the unique volatile compositional traits of three species of citrus fruit. Proton transfer reaction Time-of-Flight mass spectrometry (PTR-TOF-MS) was utilized to obtain the mass-resolved fingerprints of VOCs. The chemical formula of these VOC masses was tentatively identified. Principal component analysis was performed to evaluate the differences between the groups.

Graphical abstract

Antibacterial Activity of Emulsified Pomelo (Citrus grandis Osbeck) Peel Oil and Water-Soluble Chitosan on Staphylococcus aureus and Escherichia coli

This study utilized pomelo steam distillation to isolate pomelo peel essential oil. The constituents were then analyzed through gas chromatography-mass spectrometry (GC-MS), and the antibacterial activity of the essential oil emulsions at different homogenizer speed conditions and concentrations of water-soluble chitosan (degree of acetylation, DA = 54.8%) against S. aureus and E. coli was examined. Analysis of the essential oil composition identified a total of 33 compounds with the main constituent, limonene accounting for 87.5% (940.07 mg/g) of the total. The pomelo peel oil was emulsified through homogenization at 24,000 rpm, resulting in a minimal inhibitory concentration (MIC) for E. coli that was 1.9 times lower than that of the essential oil without homogenization. In addition, a mixture of 0.4% essential oil emulsion and 0.03% water-soluble chitosan had the strongest synergetic antibacterial effect on S. aureus and E. coli at pH 7.4. In comparison with chitosan alone, the MIC value of this mixture was significantly 2.4 and 2.5 times lower. Hence, this study suggests using a mixture of emulsified pomelo peel oil and water-soluble chitosan to develop a novel natural food preservative, and that the processability of food, as well as the economic value of the byproducts of the Taiwan Matou pomelo and chitosan, could be increased.

Determination of Volatile Flavour Profiles of Citrus spp. Fruits by SDE-GC-MS and Enantiomeric Composition of Chiral Compounds by MDGC-MS

INTRODUCTION

Citrus fruits are known to have characteristic enantiomeric key compounds biosynthesised by highly stereoselective enzymatic mechanisms. In the past, evaluation of the enantiomeric ratios of chiral compounds in fruits has been applied as an effective indicator of adulteration by the addition of synthetic compounds or natural components of different botanical origin.

OBJECTIVE

To analyse the volatile flavour compounds of Citrus junos Sieb. ex Tanaka (yuzu), Citrus limon BURM. f. (lemon) and Citrus aurantifolia Christm. Swingle (lime), and determine the enantiomeric ratios of their chiral compounds for discrimination and authentication of extracted oils.

METHODOLOGY

Volatile flavour compounds of the fruits of the three Citrus species were extracted by simultaneous distillation extraction and analysed by gas chromatography-mass spectrometry. The enantiomeric composition (ee%) of chiral camphene, sabinene, limonene and β-phellandrene was analysed by heart-cutting multidimensional gas chromatography-mass spectrometry.

RESULTS

Sixty-seven (C. junos), 77 (C. limon) and 110 (C. aurantifolia) volatile compounds were identified with limonene, γ-terpinene and linalool as the major compounds. Stereochemical analysis (ee%) revealed 1S,4R-(-) camphene (94.74, 98.67, 98.82), R-(+)-limonene (90.53, 92.97, 99.85) and S-(+)-β-phellandrene (98.69, 97.15, 92.13) in oil samples from all three species; R-(+)-sabinene (88.08) in C. junos; and S-(-)-sabinene (81.99, 79.74) in C. limon and C. aurantifolia, respectively.

CONCLUSION

The enantiomeric composition and excess ratios of the chiral compounds could be used as reliable indicators of genuineness and quality assurance of the oils derived from the Citrus fruit species. Copyright © 2017 John Wiley & Sons, Ltd.

CitAP2.10 activation of the terpene synthase CsTPS1 is associated with the synthesis of (+)-valencene in 'Newhall' orange

Aroma is a vital characteristic that determines the quality and commercial value of citrus fruits, and characteristic volatiles have been analyzed in different citrus species. In sweet orange, Citrus sinensis, the sesquiterpene (+)-valencene is a key volatile compound in the fruit peel. Valencene synthesis is catalyzed by the terpene synthase CsTPS1, but the transcriptional mechanisms controlling its gene expression are unknown. Here, the AP2/ERF (APETALA2/ethylene response factor) transcription factor, CitAP2.10, is characterized as a regulator of (+)-valencene synthesis. The expression pattern of CitAP2.10 was positively correlated with (+)-valencene content and CsTPS1 expression. Dual-luciferase assays indicated that CitAP2.10 could trans-activate the CsTPS1 promoter. Ethylene enhanced expression of CitAP2.10 and this effect was abolished by the ethylene antagonist 1-methylcyclopropene. The role and function of CitAP2.10 in (+)-valencene biosynthesis were confirmed using the Arabidopsis homolog (AtWRI1), which also transiently activated the CsTPS1 promoter. Furthermore, transient over-expression of CitAP2.10 triggered (+)-valencene biosynthesis in sweet orange fruit. These results indicate that CitAP2.10 regulates (+)-valencene synthesis via induction of CsTPS1 mRNA accumulation.

Chemical Profile, Antibacterial and Antioxidant Activity of Algerian Citrus Essential Oils and Their Application in Sardina pilchardus

Stored fish are frequently contaminated by foodborne pathogens. Lipid oxidation and microbial growth during storage are also important factors in the shelf-life of fresh fish. In order to ensure the safety of fish items, there is a need for control measures which are effective through natural inhibitory antimicrobials. It is also necessary to determine the efficacy of these products for fish protection against oxidative damage, to avoid deleterious changes and loss of commercial and nutritional value. Some synthetic chemicals used as preservatives have been reported to cause harmful effects to the environment and the consumers. The present investigation reports on the extraction by hydrodistillation and the chemical composition of three citrus peel essential oils (EOs): orange (Citrus sinensis L.), lemon (Citrus limonum L.) and bergamot (Citrus aurantium L.) from Algeria. Yields for EOs were between 0.50% and 0.70%. The chemical composition of these EOs was determined by gas chromatography coupled with mass spectrometry (GC/MS). The results showed that the studied oils are made up mainly of limonene (77.37%) for orange essential oil (EO); linalyl acetate (37.28%), linalool (23.36%), for bergamot EO; and finally limonene (51.39%), β-pinene (17.04%) and γ-terpinene (13.46%) for lemon EO. The in vitro antimicrobial activity of the EOs was evaluated against Staphylococcus aureus (S. aureus) using the agar diffusion technique. Results revealed that lemon EO had more antibacterial effects than that from other EOs. Minimal inhibitory concentrations (MICs) showed a range of 0.25–0.40 μL/mL. Lemon and bergamot citrus peel EOs were added at 1 × MIC and 4 × MIC values to Sardina pilchardus (S. pilchardus) experimentally inoculated with S. aureus at a level of 3.5 log₁₀ CFU/g and stored at 8 ± 1 °C. The results obtained revealed that the 4 × MIC value of bergamot reduced completely the growth of S. aureus from day 2 until the end of storage. The presence of EOs significantly extended lipid stability. Samples treated with bergamot EO displayed greater antioxidant activity than lemon EO. In fact, the oxidation rate is inversely proportional to the concentration of EO. At 1 × MIC and 4 × MIC values of bergamot EO, the levels of malonaldehyde compared to the control samples were 1.66 and 1.28 mg malonaldehyde/kg at the end of storage, corresponding to inhibition percentages of 42.76% and 55.87%, respectively. These results suggest the possibility that citrus EOs could be used as a way of combating the growth of common causes of food poisoning and used as potent natural preservatives to contribute to the reduction of lipid oxidation in sardines.

Identification of character-impact odorants in a cola-flavored carbonated beverage by quantitative analysis and omission studies of aroma reconstitution models

Thirty aroma-active components of a cola-flavored carbonated beverage were quantitated by stable isotope dilution assays, and their odor activity values (OAVs) were calculated. The OAV results revealed that 1,8-cineole, (R)-(-)-linalool, and octanal made the greatest contribution to the overall aroma of the cola. A cola aroma reconstitution model was constructed by adding 20 high-purity standards to an aqueous sucrose-phosphoric acid solution. The results of headspace solid-phase microextraction and sensory analyses were used to adjust the model to better match authentic cola. The rebalanced model was used as a complete model for the omission study. Sensory results indicated that omission of a group consisting of methyleugenol, (E)-cinnamaldehyde, eugenol, and (Z)- and (E)-isoeugenols differed from the complete model, while omission of the individual components of this group did not differ from the complete model. These results indicate that a balance of numerous odorants is responsible for the characteristic aroma of cola-flavored carbonated beverages.

Flavor chemistry of lemon-lime carbonated beverages

The most potent aroma-active components of Sprite (SP), Sierra Mist (SM), and 7UP (7UP) were identified. Aroma extracts were prepared by liquid–liquid continuous extraction/solvent-assisted flavor evaporation (LLCE/SAFE). Twenty-eight compounds were detected by gas chromatography–olfactometry (GC-O) with linalool (floral, lavender), octanal (pungent orange), and 2,3-dehydro-1,8-cineole (minty) determined to be predominant aroma compounds based on their high flavor dilution (FD) factors by aroma extract dilution analysis (AEDA). The data indicate that lemon-lime flavor is composed of a small number of compounds (22 at the most in SM), and only a subset of these may be important because many compounds were detected only at low FD factors. Predominant aroma compounds (23) were quantified using static headspace solid phase microextraction (SPME) combined with stable isotope dilution assays (SIDA). In contrast to FD factors, the calculated odor-activity values (OAVs) indicate that octanal and limonene make the greatest contribution to the overall aroma of lemon-lime carbonated beverages, followed by nonanal, decanal, linalool, 1,8-cineole, and geranyl acetate. The results demonstrate that lemon-lime carbonated beverages share many of the same compounds but the relative abundance of these compounds varies by brand.

Fruit volatile profiles of two citrus hybrids are dramatically different from those of their parents

Volatile compounds released from the fruit of two hybrid Citrus genotypes (FxCh90 and FxCh77) were compared to those from their parental varieties, Fortune mandarin and Chandler pummelo. A series of 113 compounds were identified, including 31 esters, 23 aldehydes, 20 alcohols, 17 monoterpenoids, and other compounds. The differences in the volatile profile among these four genotypes were essentially quantitative. The most striking result was that the volatile profile of the hybrids was not intermediate between their parents and completely differed from that of Chandler, but came closer to Fortune. This was because 56 of the 113 volatile compounds in the hybrids showed significantly higher or lower levels than in any of the parents. Such transgressive behavior in these hybrids was not observed for other fruit quality traits, such as acidity or soluble solid content. The combination of volatile profiling and chemometrics can be used to select new Citrus genotypes with a distinct volatile profile.

Plants belonging to the genus Thymus as antibacterial agents: from farm to pharmacy

In traditional medicine, plants have been used since ancient times for the prevention and/or protection against infectious diseases. In recent years, the use of herbal medicines and food supplements containing botanical ingredients, as alternative therapy for infectious diseases, has been intensified due to their high content of antimicrobial agents such as polyphenols, i.e. flavonoids, tannins, and alkaloids. Plants from the genus Thymus are important medicinal herbs, which are known to contain antimicrobial agents, and are rich in different active substances such as thymol, carvacrol, p-cymene and terpinene. In this review, we summarise the available literature data about the in vitro antibacterial effects of the main plants belonging to the genus Thymus. We also provide information about cultivation, chemical composition of the essential oils obtained from these plants, and their use for medicinal purposes.

Antifungal Activity of Citrus Essential Oils

Citrus essential oils (CEOs) are a mixture of volatile compounds consisting mainly of monoterpene hydrocarbons and are widely used in the food and pharmaceutical industries because of their antifungal activities. To face the challenge of growing public awareness and concern about food and health safety, studies concerning natural biopreservatives have become the focus of multidisciplinary research efforts. In the past decades, a large amount of literature has been published on the antifungal activity of CEOs. This paper reviews the advances of research on CEOs and focuses on their in vitro and food antifungal activities, chemical compositions of CEOs, and the methods used in antifungal assessment. Furthermore, the antifungal bioactive components in CEOs and their potential mechanism of action are summarized. Finally, the applications of CEOs in the food industry are discussed in an attempt to provide new information for future utilization of CEOs in modern industries.

The GC/MS Analysis of Volatile Components Extracted by Different Methods from Exocarpium Citri Grandis

Volatile components from Exocarpium Citri Grandis (ECG) were, respectively, extracted by three methods, that is, steam distillation (SD), headspace solid-phase microextraction (HS-SPME), and solvent extraction (SE). A total of 81 compounds were identified by gas chromatography-mass spectrometry including 77 (SD), 56 (HS-SPME), and 48 (SE) compounds, respectively. Despite of the extraction method, terpenes (39.98~57.81%) were the main volatile components of ECG, mainly germacrene-D, limonene, 2,6,8,10,14-hexadecapentaene, 2,6,11,15-tetramethyl-, (E,E,E)-, and trans-caryophyllene. Comparison was made among the three methods in terms of extraction profile and property. SD relatively gave an entire profile of volatile in ECG by long-time extraction; SE enabled the analysis of low volatility and high molecular weight compounds but lost some volatiles components; HS-SPME generated satisfactory extraction efficiency and gave similar results to those of SD at analytical level when consuming less sample amount, shorter extraction time, and simpler procedure. Although SD and SE were treated as traditionally preparative extractive techniques for volatiles in both small batches and large scale, HS-SPME coupled with GC/MS could be useful and appropriative for the rapid extraction and qualitative analysis of volatile components from medicinal plants at analytical level.

Using limes and synthetic psoralens to enhance solar disinfection of water (SODIS): a laboratory evaluation with norovirus, Escherichia coli, and MS2

We investigated the use of psoralens and limes to enhance solar disinfection of water (SODIS) using an UV lamp and natural sunlight experiments. SODIS conditions were replicated using sunlight, 2 L polyethylene terephthalate (PET) bottles, and tap water with Escherichia coli, MS2 bacteriophage, and murine norovirus (MNV). Psoralens and lime acidity both interact synergistically with UV radiation to accelerate inactivation of microbes. Escherichia coli was ablated > 6.1 logs by SODIS + Lime Slurry and 5.6 logs by SODIS + Lime Juice in 30-minute solar exposures, compared with a 1.5 log reduction with SODIS alone (N = 3; P < 0.001). MS2 was inactivated > 3.9 logs by SODIS + Lime Slurry, 1.9 logs by SODIS + Lime Juice, and 1.4 logs by SODIS in 2.5-hour solar exposures (N = 3; P < 0.05). MNV was resistant to SODIS, with < 2 log reductions after 6 hours. Efficacy of SODIS against human norovirus should be investigated further.

Volatile constituents of wild citrus Mangshanyegan (Citrus nobilis Lauriro) peel oil

Volatiles of a wild mandarin, Mangshanyegan (Citrus nobilis Lauriro), were characterized by GC-MS, and their aroma active compounds were identified by aroma extract dilution analysis (AEDA) and gas chromatography-olfactometry (GC-O). The volatile profile of Mangshanyegan was compared with those of other four citrus species, Kaopan pummelo (Citrus grandis), Eureka lemon (Citrus limon), Huangyanbendizao tangerine (Citrus reticulata), and Seike navel orange (Citrus sinensis). Monoterpene hydrocarbons predominated in Mangshanyegan, in particular d-limonene and β-myrcene, which accounted for 85.75 and 10.89% of total volatiles, respectively. Among the 12 compounds with flavor dilution factors (FD) = 27, 8 oxygenated compounds, including (Z)- and (E)-linalool oxides, were present only in Mangshanyegan. The combined results of GC-O, quantitative analysis, odor activity values (OAVs), and omission tests revealed that β-myrcene and (Z)- and (E)-linalool oxides were the characteristic aroma compounds of Mangshanyegan, contributing to the balsamic and floral notes of its aroma.

Distribution of aroma volatile compounds in tangerine hybrids and proposed inheritance

BACKGROUND

With the desirable combination of sugars and acids, volatile compounds contribute to the essential organoleptic attributes of citrus. This study evaluated the aroma volatiles of 20 tangerine hybrids of the University of Florida breeding program. Volatiles were sampled from hand-squeezed juice by headspace solid-phase microextraction (SPME), and analyzed by gas chromatography-mass spectrometry. Principal component analysis (PCA) and cluster analysis (CA) were used to find similarities among samples due to volatile composition with effect of genetic background.

RESULTS

In total, 203 volatiles were detected in all samples. Volatiles in lower amounts were widely distributed among samples and were classified mainly as terpene hydrocarbons and oxygenated compounds, such as aldehydes, esters, alcohols and ketones. PCA, based on relative peak areas (content) clearly separated the samples higher in volatile content, mainly those with sweet orange genetic contributions in their background. CA, based on volatile presence/absence, grouped samples into five clusters, each showing distinctive volatile profiles.

CONCLUSION

The genetic background of tangerine hybrids affected volatile composition and content of samples. In general, tangerines were characterized by fewer volatiles (in both quality and quantity) and more aldehydes, and hybrids with sweet orange in their background had more sesquiterpenes and esters, which would likely affect their aroma.