Analysis of volatile compounds from Malaysian durians (Durio zibethinus) using headspace SPME coupled to fast GC-MS

Durian fruit pulp extract enhances intracellular glutathione levels, mitigating oxidative stress and inflammation for neuroprotection

Durian (Durio zibethinus L.) fruit pulp is a rich source of γ-glutamylcysteine (γ-EC), a direct precursor to the antioxidant glutathione (GSH). This study elucidated the in vitro neuroprotective potential of unripe durian fruit pulp extract (UDE) against H2O2-induced neurotoxicity in SH-SY5Y cells and neuroinflammation in lipopolysaccharide (LPS)-stimulated BV-2 cells. Treatments with γ-EC, GSH standards, or UDE exhibited no cytotoxicity in SH-SY5Y and BV-2 cells, except at high concentrations. A 4-h pretreatment with 100 µM γ-EC or UDE containing 100 µM γ-EC significantly increased SH-SY5Y cell viability post H2O2 induction. Moreover, a similar pretreatment reduced LPS-stimulated production of proinflammatory cytokines in BV-2 cells. The neuroprotective effect of UDE is primarily attributed to γ-EC provision and the promotion of GSH synthesis, which in turn elevates intracellular GSH levels and reduces proinflammatory cytokines. This study identifies γ-EC in UDE as a potential neuroprotective biomarker boosting intracellular GSH levels, providing insights into UDE's therapeutic potential.

To be or not to be fragrant: floral scent of some bat-pollinated cacti

Floral scent is a key olfactory cue in both diurnal and nocturnal pollination systems. In the case of nocturnal systems, such as bat-pollinated flowers, odour seems to play a more important role than visual cues. Cactaceae include many bat-pollinated species; however, few studies have investigated the olfactory cues in this family. We analysed and compared the chemical composition of the floral bouquet of three chiropterophilous cactus species, among which are a pair of congeners that differ considerably in scent intensity. Our research presents novel findings regarding the floral scent chemistry of chiropterophilous cactus species. We documented the first case of a bat-pollinated cactus whose flowers lack perceptible floral scent and in which no volatile compounds were detected in our chemical analyses. Additionally, we provide a comprehensive analysis of the chemical composition of the floral bouquet of the other two bat-pollinated species, revealing a resemblance among closely related species within the same genus. We highlight the need for further studies using biotests to investigate the mechanisms through which bats find flowers lacking scent.

An electrochemical biosensor for the rapid genetic identification of Musang King durian

More than 200 different cultivars of durian exist worldwide but Durio zibethinus or Musang King (MK) is the most premium and prized durian fruit among the recommended varieties. Early identification of this premium variety is critical to protect from non-authentic MK durian cultivars. However, the MK variety's morphological traits are nearly identical to other varieties. Currently, the identification of durian varieties is mostly performed via evaluation of leaf shape, fruit shape, aroma, taste and seed shape and this requires trained personnel for the morphology observation. To enable the rapid identification of the MK variety, PCR amplification of ten durian varieties using six gene candidates from the chloroplast genome was first performed to obtain DNA probes that were specific to the MK durian variety. PCR amplification of ten durian varieties using primers designed confirmed that the nadhA gene sequence showed an obvious difference in the MK variety from other durian varieties. The unique sequence of MK was used as a DNA probe to develop an electrochemical biosensor for the direct identification of the MK durian variety. The electrochemical biosensor was based on the hybridization response of the immobilized DNA probe with the target DNA from the MK variety and was monitored via differential pulse voltammetry technique. Under optimal conditions, the DNA electrochemical biosensor showed a low detection limit at 10% of MK genomic DNA concentration with a wide linear calibration range of 0.05-1.5 µM (R² = 0.9891) and RSD value of 3.77% (n = 3). The results of the developed DNA biosensor provide high promise for the development of portable sensors employed in the determination of MK variety in the field.

Identification of characteristic volatiles and metabolomic pathway during pork storage using HS-SPME-GC/MS coupled with multivariate analysis

Previous researches have been conducted evaluating the volatile compounds of pork. However, data regarding the changes in volatiles and metabolic pathways during pork storage were inadequately investigated. Herein, a headspace solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC/MS) coupled multivariate analysis was proposed for characterizing the profiles of volatile compounds and metabolic pathways during pork storage. A total of 37 metabolites, including aldehydes, ketones, alcohols etc. were successfully identified. Multivariate statistical analysis revealed a substantial variation in metabolite phenotype among samples over the pork storage period, with 12 characteristic metabolites and 5 potential characteristic metabolites screened as biomarkers. Moreover, three metabolomic pathways analysis and transformation between each other (thermal reactions, lipid metabolism and amino acid metabolism) reveals the underlying mechanisms of metabolites change of pork. Therefore, the present study may provide insight into future understanding of the variation in the pork metabolite profiles.

Comparative Study on Volatile Compounds and Taste Components of Different Durian Cultivars Based on GC-MS, UHPLC, HPAEC-PAD, E-Tongue and E-Nose

In order to comprehensively evaluate the aroma-active substances and taste components of durian, solid-phase microextraction combined with gas chromatography mass spectrometry (SPME/GC-MS), high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD) and ultra-high-performance liquid chromatography (UHPLC) were used to test the key components of three popular durian cultivars. A total of 27 volatile compounds, 5 sugars, 27 organic acids and 19 free amino acids were detected in Black Thorn (BT) durian. A total of 38 volatile compounds, 4 sugars, 27 organic acids and 19 free amino acids were detected in Monthong (MT) durian. A total of 36 volatile compounds, 4 sugars, 27 organic acids and 20 free amino acids were detected in Musang King (MK) durian. Finally, the flavor differences of the three durians were evaluated using electronic nose (e-nose) and electronic tongue (e-tongue), and different cultivars were classified through principal component analysis (PCA).

Discrimination of 11 Malaysian Durian Cultivars Based on Sulfur-Containing Volatiles and Esters Using Multivariate Data Analysis

There are reports documenting the volatile oils of several durian cultivars in Malaysia. However, there is limited information on the rapid discrimination of the durian cultivars based on the composition of the total volatiles and individual volatile compounds. Thus, the present work aims to discriminate 11 Malaysian durian cultivars based on their volatile compositions using multivariate data analysis. Sulfur-containing volatiles are the major volatiles in D175 (Udang Merah), D88 (Darling), D13 (Golden Bun), DXO (D24 Special), D17 (Green Bamboo), D2 (Dato Nina), and D168 (Hajah Hasmah) durian cultivars, while esters are predominant in D99 (Kop Kecil), D24 (Bukit Merah), and D160 (Musang Queen) durian cultivars. D197 (Musang King) cultivar has an almost equal composition of sulfur-containing volatiles and esters. In the ester predominated volatile durian oil, ethyl 2-methylbutanoate and propyl 2-methylbutanoate are the major volatile compounds, while the durian cultivars with predominant sulfur-containing volatiles mainly contain diethyl disulfide, diethyl trisulfide, and 3,5-dimethyl-1,2,4-trithiolane. The durian cultivars were clustered into 8 clusters using principal component analysis, with 3 clusters consisting of 2 cultivars, and with the remaining cultivars clustered individually. The highly sought-after durian cultivars, D160 and D197, were clustered into one. Hierarchal clustering analysis identified the distinct compounds which discriminate every durian cultivar.

Bioactive Compounds, Nutritional Value, and Potential Health Benefits of Indigenous Durian (Durio Zibethinus Murr.): A Review

Durian (Durio zibethinus Murr.) is an energy-dense seasonal tropical fruit grown in Southeast Asia. It is one of the most expensive fruits in the region. It has a creamy texture and a sweet-bitter taste. The unique durian flavour is attributable to the presence of fat, sugar, and volatile compounds such as esters and sulphur-containing compounds such as thioacetals, thioesters, and thiolanes, as well as alcohols. This review shows that durian is also rich in flavonoids (i.e., flavanols, anthocyanins), ascorbic acid, and carotenoids. However, limited studies exist regarding the variation in bioactive and volatile components of different durian varieties from Malaysia, Thailand, and Indonesia. Experimental animal models have shown that durian beneficially reduces blood glucose and cholesterol levels. Durian extract possesses anti-proliferative and probiotics effects in in vitro models. These effects warrant further investigation in human interventional studies for the development of functional food.

Metabolic variation in the pulps of two durian cultivars: Unraveling the metabolites that contribute to the flavor

Durian (Durio zibethinus M.) is a major economic fruit crop in Thailand. In this study, two popular cultivars, namely Chanee and Mon Thong, were collected from three orchards located in eastern Thailand. The pulp metabolome, including 157 annotated metabolites, was explored using capillary electrophoresis-time of flight/mass spectrometry (CE-TOF/MS). Cultivars and harvest years had more impact on metabolite profile separation than cultivation areas. We identified cultivar-dependent metabolite markers related to durian fruit quality traits, such as nutritional value (pyridoxamine), odor (cysteine, leucine), and ripening process (aminocyclopropane carboxylic acid). Interestingly, durian fruit were found to contain high amounts of γ-glutamylcysteine (810.3 ± 257.5 mg/100 g dry weight) and glutathione (158.1 ± 80.4 mg/100 g dry weight), which act as antioxidants and taste enhancers. This metabolite information could be related to consumer preferences and exploited for durian fruit quality improvement.

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.

Insights into the Key Compounds of Durian (Durio zibethinus L. 'Monthong') Pulp Odor by Odorant Quantitation and Aroma Simulation Experiments

Sixteen compounds, previously identified as potent odorants by application of an aroma extract dilution analysis and the gas chromatography-olfactometry analysis of static headspace samples, were quantitated in the pulp of durians, variety Monthong, and odor activity values (OAVs) were calculated by dividing the concentrations obtained by the odor thresholds of the compounds in water. In combination with data recently reported for hydrogen sulfide and short-chain alkanethiols, OAVs > 1 were obtained for 19 compounds, among which ethyl (2S)-2-methylbutanoate (fruity; OAV 1700000), ethanethiol (rotten onion; OAV 480000), and 1-(ethylsulfanyl)ethane-1-thiol (roasted onion; OAV 250000) were the most potent, followed by methanethiol (rotten, cabbage; OAV 45000), ethane-1,1-dithiol (sulfury, durian; OAV 23000), and ethyl 2-methylpropanoate (fruity; OAV 22000). Aroma simulation and omission experiments revealed that the overall odor of durian pulp could be mimicked by only two compounds, namely, ethyl (2S)-2-methylbutanoate and 1-(ethylsulfanyl)ethane-1-thiol, when combined in their natural concentrations.

Fruit and seed traits of the elephant-dispersed African savanna plant Balanites maughamii

Balanites maughamii appears to be an obligate elephant-dispersed species. Its fruits are strongly scented and produce a large range of volatiles, particularly aliphatic acids such as hexanoic and isovaleric acid. The seed coat can resist a compression force of >1.5 kN. Seeds removed from the seed coat, and those from compressed seeds or from elephant dung, have better germination than seeds enclosed by undamaged seed-coats, which largely failed to germinate over a 2-mo period. Mastication by elephants may be necessary to split the seed coat to allow germination and the germinant to emerge from the seed coat. We identify four traits of elephant-dispersed fruits; they are dull-coloured, presented on the ground, strongly scented and have exceptionally strong seed coats.

Nanocellulose-Zeolite Composite Films for Odor Elimination

Free standing and strong odor-removing composite films of cellulose nanofibrils (CNF) with a high content of nanoporous zeolite adsorbents have been colloidally processed. Thermogravimetric desorption analysis (TGA) and infrared spectroscopy combined with computational simulations showed that commercially available silicalite-1 and ZSM-5 have a high affinity and uptake of volatile odors like ethanethiol and propanethiol, also in the presence of water. The simulations showed that propanethiol has a higher affinity, up to 16%, to the two zeolites compared with ethanethiol. Highly flexible and strong free-standing zeolite-CNF films with an adsorbent loading of 89 w/w% have been produced by Ca-induced gelation and vacuum filtration. The CNF-network controls the strength of the composite films and 100 μm thick zeolite-CNF films with a CNF content of less than 10 vol % displayed a tensile strength approaching 10 MPa. Headspace solid phase microextraction (SPME) coupled to gas chromatography-mass spectroscopy (GC/MS) analysis showed that the CNF-zeolite films can eliminate the volatile thiol-based odors to concentrations below the detection ability of the human olfactory system. Odor removing zeolite-cellulose nanofibril films could enable improved transport and storage of fruits and vegetables rich in odors, for example, onion and the tasty but foul-smelling South-East Asian Durian fruit.

Effect of temperature-controlled fermentation on physico-chemical properties and lactic acid bacterial count of durian (Durio zibethinus Murr.) pulp

Effects of controlled-temperature fermentation on several physico-chemical properties, lactic acid bacteria (LAB) counts and aroma of durian pulp were examined by storing fresh durian pulp was mixed with 2 % (w/w) salt and stored at 15 °C, 27 °C and 40 °C for 10 days. Storage at 15 °C did not affect the properties of the pulp much. However, at 27 °C and 40 °C, pH and total soluble solids decreased up to 60 % and 52 %, respectively, with greater losses at 27 °C. Titratable acidity, which increased at 27 °C, was due to lactic and acetic acids formation. Loss of sucrose and increases in glucose were greater at 27 °C. LAB population increased up to Day 3 of storage, and then decreased slightly. Principal component analysis based on aroma examination using a zNose(TM) showed better retention of aroma profile at 27 °C. Overall, durian fermented at 27 °C was more acceptable than the one prepared at 40 °C, and it is ready to be consumed between Day 4 and 6.

Sulphur-containing compounds of durian activate the thermogenesis-inducing receptors TRPA1 and TRPV1

Durian (Durio zibethinus Murr.) is classified as a body-warming food in Indian herbalism, and its hyperthermic effect is empirically known in Southeast Asia. To investigate the mechanism underlying this effect, we focused on the thermogenesis-inducing receptors, TRPA1 and TRPV1. Durian contains sulphides similar to the TRPA1 and TRPV1 agonists of garlic. Accordingly, we hypothesized that the thermogenic effect of durian is driven by sulphide-induced TRP channel activation. To investigate our hypothesis, we measured the TRPA1 and TRPV1 activity of the sulphur-containing components of durian and quantified their content in durian pulp. These sulphur-containing components had a stronger effect on TRPA1 than TRPV1. Furthermore, sulphide content in the durian pulp was sufficient to evoke TRP channel activation and the main agonist was diethyl disulphide. From these results, we consider that the body-warming effect of durian is elicited by TRPA1 activation with its sulphides, as can be seen in spices.

Characterization of the major odor-active compounds in Thai durian ( Durio zibethinus L. 'Monthong') by aroma extract dilution analysis and headspace gas chromatography-olfactometry

An aroma extract dilution analysis applied on the volatile fraction isolated from Thai durian by solvent extraction and solvent-assisted flavor evaporation resulted in 44 odor-active compounds in the flavor dilution (FD) factor range of 1-16384, 41 of which could be identified and 24 that had not been reported in durian before. High FD factors were found for ethyl (2S)-2-methylbutanoate (fruity; FD 16384), ethyl cinnamate (honey; FD 4096), and 1-(ethylsulfanyl)ethanethiol (roasted onion; FD 1024), followed by 1-(ethyldisulfanyl)-1-(ethylsulfanyl)ethane (sulfury, onion), 2(5)-ethyl-4-hydroxy-5(2)-methylfuran-3(2H)-one (caramel), 3-hydroxy-4,5-dimethylfuran-2(5H)-one (soup seasoning), ethyl 2-methylpropanoate (fruity), ethyl butanoate (fruity), 3-methylbut-2-ene-1-thiol (skunky), ethane-1,1-dithiol (sulfury, durian), 1-(methylsulfanyl)ethanethiol (roasted onion), 1-(ethylsulfanyl)propane-1-thiol (roasted onion), and 4-hydroxy-2,5-dimethylfuran-3(2H)-one (caramel). Among the highly volatile compounds screened by static headspace gas chromatography-olfactometry, hydrogen sulfide (rotten egg), acetaldehyde (fresh, fruity), methanethiol (rotten, cabbage), ethanethiol (rotten, onion), and propane-1-thiol (rotten, durian) were found as additional potent odor-active compounds. Fourteen of the 41 characterized durian odorants showed an alkane-1,1-dithiol, 1-(alkylsulfanyl)alkane-1-thiol, or 1,1-bis(alkylsulfanyl)alkane structure derived from acetaldehyde, propanal, hydrogen sulfide, and alkane-1-thiols. Among these, 1-(propylsulfanyl)ethanethiol, 1-{[1-(methylsulfanyl)ethyl]sulfanyl}ethanethiol, and 1-{[1-(ethylsulfanyl)ethyl]sulfanyl}ethanethiol were reported for the first time in a natural product.

Short anaerobiosis period prior to cold storage alleviates bitter pit and superficial scald in Granny Smith apples

BACKGROUND

Californian Granny Smith apples are very susceptible to bitter pit (BP) and superficial scald symptoms that develop during cold storage. The main preventive means are diphenylamine dipping and/or gaseous application of the ethylene inhibitor 1-methylcylclopropene (1-MCP), which is effective against superficial scald but not against BP. This study investigated the efficacy of a non-chemical alternative, low-O(2) (LO2) stress, in preventing these two physiological disorders.

RESULTS

Application of LO2 stress at 20 degrees C for 10 days prior to cold storage of Granny Smith apples reduced superficial scald and BP incidence and severity during 8 months at 0 degrees C. LO2 treatments induced volatile alcohols and reduced ethylene and 6-methyl-5-hepten-2-one (MHO-on) production, thereby reducing superficial scald development after 4 months at 0 degrees C. In addition, LO2-treated fruits had higher pectin methyl esterase (MdPME) gene expression, similar to that of 1-MCP-treated fruits, associated with their higher firmness. Conversion of MHO-on to 6-methyl-5-hepten-2-ol (MHO-ol) in LO2-treated fruits may explain the lower scald development.

CONCLUSION

The ratio between MHO-on and MHO-ol might serve as an index of superficial scald severity. Reduction of BP symptoms in LO2-treated fruits could be due to accumulation of volatile alcohols in the peel tissue.

Superficial scald and bitter pit development in cold-stored transgenic apples suppressed for ethylene biosynthesis

The plant hormone ethylene regulates climacteric fruit ripening and plays a major role in the development of superficial scald in apple fruits during cold storage. The effect of cold storage at 0 degrees C on development of superficial scald and bitter pit (BP) in transgenic Greensleeves (GS) apples suppressed for ethylene biosynthesis was investigated. Four apple lines were used: untransformed GS; line 68G, suppressed for 1-aminocyclopropane-1-carboxylic acid (ACC) oxidase (ACO); and lines 103Yand 130Y, suppressed for ACC synthase (ACS). Fruits from the transformed lines 68G, 103Y, and 130Y produced very little ethylene during 3 months of cold storage at 0 degrees C and after subsequent transfer to 20 degrees C, whereas untransformed fruits produced significant ethylene during cold storage, which increased dramatically at 20 degrees C. Respiration, expressed as CO(2) production, was similar in all four apple lines. After 2 months at 0 degrees C, all apple lines showed some BP symptoms, but lines 68G and 103Y were more affected than untransformed GS or line 130Y. Both transformed and untransformed apples produced alpha-farnesene, but concentrations were lower in yellow fruit than in green fruit in all lines but 68G. Line 68G produced the most alpha-farnesene after 2 months at 0 degrees C, including both (E,E) alpha-farnesene and (Z,E) alpha-farnesene. Concentrations of (E,E) alpha-farnesene were 100 times greater than those of (Z,E) alpha-farnesene in all lines. After 4 months at 0 degrees C plus 1 week at 20 degrees C, untransformed GS apples exhibited the most superficial scald, whereas fruits from lines 68G and 103Y were less affected and line 130Y had no scald. Superficial scald severity was higher in green fruit than in yellow fruit in all affected lines. These lines also exhibited significant production of 6-methyl-5-hepten-2-one (MHO), a major oxidation product of (E,E) alpha-farnesene. Line 130Y neither exhibited superficial scald nor produced MHO. It is shown here that even transgenic apples suppressed for ethylene biosynthesis genes can produce alpha-farnesene, which in turn can oxidize to free radicals and MHO, leading to scald development.