Effects of 1-MCP on the Physiological Attributes, Volatile Components and Ester-Biosynthesis-Related Gene Expression during Storage of ‘Jinyan’ Kiwifruit

The effects of 1.0 μL/L 1-methylcyclopropene (1-MCP) treatment on aroma quality and ester-biosynthesis-related gene expression of ‘Jinyan’ kiwifruit during room storage were examined, aiming to provide a theoretical basis and technical reference for the postharvest storage of kiwifruit. The results demonstrate that 1-MCP treatment conspicuously inhibited respiration rate, delayed a decrease in fruit firmness and increased soluble solid content (SSC) in ‘Jinyan’ kiwifruit. Compared to the control, the relative content of aroma components markedly changed in 1-MCP treatment kiwifruit during fruit ripening. The characteristic aroma of ‘Jinyan’ kiwifruit included ethyl butanoate, methyl butanoate, E-2-hexanal and hexenal, and 1-MCP treatment significantly reduced the ester content in kiwifruit. During the entire shelf life, the expression levels of AcLOX1, AcLOX5, AcLOX6, AcHPL and AcAAT were significantly inhibited in 1-MCP-treated fruit. However, the transcript level of AcADH was not suppressed by 1-MCP. The lower content of ester volatiles maybe ascribed to the suppression of AcLOXs, AcHPL and AcAAT.

Fruit Volatile Fingerprints Characterized among Four Commercial Cultivars of Thai Durian (Durio zibethinus)

Ripe durian fruits produce unique volatiles of pungent odor comprising esters, alcohols, ketones, and sulfur-containing compounds. Recently, “Chanthaburi 1” hybrid bred from 2 famous commercial cultivars of “Chanee” and “Monthong” claimed to be less fragrant during ripening, but there was no report. The present study compared the volatile profiles from 3 Thai commercial cultivars of “Kanyao,” “Chanee,” and “Monthong” compared to “Chanthaburi 1”, and the relationships of the cultivars were organized using the volatile fingerprints. Out of 41 volatile compounds detected by SPME/GC-MS in ripe durian flesh, 33 compounds were esters, but only 14 esters were found in “Chanthaburi 1.” Ripe flesh of most durian cultivars contains ethyl-2-methyl butanoate and ethyl hexanoate as the active volatiles. “Chanthaburi 1” contained fewer components with low odor activity value (OAV) of the volatiles. “Chanee” ripe flesh exhibited the strongest durian smell among the four varieties, whereas “Monthong” exhibited a strong apple-like fruity odor and “Kanyao” was more green fruity. Diethyl disulfide and 3, 5 dimethyl-1, 2, 4-trithiolane contributing pungent smells of garlic or onion were found only in “Chanthaburi 1” and “Monthong.” In terms of detected volatiles, “Kanyao” and “Chanee” were highly close when “Monthong” was apart. PCA analysis revealed that “Chanthaburi 1” contained ester compounds ancestrally related to the parents, “Chanee” in the component I and “Monthong” in the component II. These data could be beneficial for managing the status of Thai durians in global markets.

Open Culture Ethanol-Based Chain Elongation to Form Medium Chain Branched Carboxylates and Alcohols

Chain elongation fermentation allows for the synthesis of biobased chemicals from complex organic residue streams. To expand the product spectrum of chain elongation technology and its application range we investigated 1) how to increase selectivity towards branched chain elongation and 2) whether alternative branched carboxylates such as branched valerates can be used as electron acceptors. Elongation of isobutyrate elongation towards 4-methyl-pentanoate was achieved with a selectivity of 27% (of total products, based on carbon atoms) in a continuous system that operated under CO2 and acetate limited conditions. Increasing the CO2 load led to more in situ acetate formation that increased overall chain elongation rate but decreased the selectivity of branched chain elongation. A part of this acetate formation was related to direct ethanol oxidation that seemed to be thermodynamically coupled to hydrogenotrophic carboxylate reduction to corresponding alcohols. Several alcohols including isobutanol and n-hexanol were formed. The microbiome from the continuous reactor was also able to form small amounts of 5-methyl-hexanoate likely from 3-methyl-butanoate and ethanol as substrate in batch experiments. The highest achieved concentration of isoheptanoate was 6.4 ± 0.9 mM Carbon, or 118 ± 17 mg/L, which contributed for 7% to the total amount of products (based on carbon atoms). The formation of isoheptanoate was dependent on the isoform of branched valerate. With 3-methyl-butanoate as substrate 5-methylhexanoate was formed, whereas a racemic mixture of L/D 2-methyl-butanoate did not lead to an elongated product. When isobutyrate and isovalerate were added simultaneously as substrates there was a large preference for elongation of isobutyrate over isovalerate. Overall, this work showed that chain elongation microbiomes can be further adapted with supplement of branched-electron acceptors towards the formation of iso-caproate and iso-heptanoate as well as that longer chain alcohol formation can be stimulated.

Influences of C5 esters addition on anti-knock and auto-ignition tendency of a gasoline surrogate fuel

The research octane numbers and auto-ignition characteristics of a toluene primary reference fuel (TPRF), when blended with three C5 esters, γ-valerolactone (GVL), methyl butanoate (MB), and methyl crotonate (MC), were investigated on a cooperative fuel research (CFR) engine and a constant volume combustion chamber (CVCC). In fuel preparation, ethanol was used to improve the miscibility, and the total additive comprised 1/3 ethanol and 2/3 GVL/MB/MC on a molar basis. The experimental results first reveal that the addition of the three series of additives boost fuel octane rating, and their boosting effects rank as MB > GVL ∼ MC when fuels are blended on a molar basis. In contrast, the auto-ignition tendency of the three series of fuel blends, when blended on the molar basis, ranks as the MC blends > the GVL blends> the MB blends. Different from the similar reactivities observed for the MC blends and the GVL blends in the RON tests, the MC blends exhibit higher auto-ignition propensity than the GVL blends, probably because the higher enthalpy of vaporization of GVL causes a more significant cooling effect. Finally, different from the literature studies that reported similar reactivities for pure MB and MC, in this study MB shows lower reactivity than MC when blending with the TPRF gasoline surrogate.

Species-Specific Induction of Plant Volatiles by Two Aphid Species in Apple: Real Time Measurement of Plant Emission and Attraction of Lacewings in the Wind Tunnel

Upon damage by herbivores, plants release herbivory-induced plant volatiles (HIPVs). To find their prey, the pest’s natural enemies need to be fine-tuned to the composition of these volatiles. Whereas standard methods can be used in the identification and quantitation of HIPVs, more recently introduced techniques such as PTR-ToF–MS provide temporal patterns of the volatile release and detect additional compounds. In this study, we compared the volatile profile of apple trees infested with two aphid species, the green apple aphid Aphis pomi, and the rosy apple aphid Dysaphis plantaginea, by CLSA-GC–MS complemented by PTR-ToF–MS. Compounds commonly released in conjunction with both species include nonanal, decanal, methyl salicylate, geranyl acetone, (Z)-3-hexenyl acetate, (Z)-3-hexenyl butanoate, (Z)-3-hexenyl 2-methyl-butanoate, (E)-β-caryophyllene, β-bourbonene and (Z)-3-hexenyl benzoate. In addition, benzaldehyde and (E)-β-farnesene were exclusively associated with A. pomi, whereas linalool, (E)-4,8-dimethyl-1,3,7-nonatriene were exclusively associated with D. plantaginea. PTR-ToF–MS additionally detected acetic acid (AA) and 2-phenylethanol (PET) in the blends of both trees attacked by aphid species. In the wind tunnel, the aphid predator, Chrysoperla carnea (Stephens), responded strongly to a blend of AA and PET, much stronger than to AA or PET alone. The addition of common and species-specific HIPVs did not increase the response to the binary blend of AA and PET. In our setup, two host-associated volatiles AA + PET appeared sufficient in the attraction of C. carnea. Our results also show the importance of combining complementary methods to decipher the odor profile associated with plants under pest attack and identify behaviourally active components for predators.

Multi-Statistical Approach for the Study of Volatile Compounds of Industrial Spoiled Manzanilla Spanish-Style Table Olive Fermentations

Table olives can suffer different types of spoilage during fermentation. In this work, a multi-statistical approach (standard and compositional data analysis) was used for the study of the volatile organic compounds (VOCs) associated with altered (butyric, sulfidic, and putrid) and non-altered (normal) Manzanilla Spanish-style table olive fermentations. Samples were collected from two industrial fermentation yards in Seville (Spain) in the 2019/2020 season. The VOC profiles of altered (n = 4) and non-altered (n = 6) samples were obtained by headspace solid-phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS). Ninety-one VOCs were identified and grouped into alcohols (30), esters (21), carbonyl compounds (12), acids (10), terpenes (6), phenols (6), sulfur compounds (2), and others (4). The association of the VOCs with spoilage samples depended on the standard or compositional statistical methodology used. However, butyric spoilage was strongly linked by several techniques to methyl butanoate, ethyl butanoate, and butanoic acid; sulfidic spoilage with 2-propyl-1-pentanol, dimethyl sulfide, methanol, 2-methylbutanal, 2-methyl-2-butenal, ethanol, 2-methyl-3-buten-2-ol, and isopentanol, while putrid was mainly related to D-limonene and 2-pentanol. Our data contribute to a better characterisation of non-zapatera spoiled table olive fermentations and show the convenience of using diverse statistical techniques for a most robust selection of spoilage VOC markers.

Volatile Constituents of Cistanche tubulosa and Their Antioxidant and Antimicrobial Potentials

The hydrodistilled volatile constituents of Cistanche tubulosa (commonly known as Desert Ginseng) have been chemically and biologically investigated. Based on the retention times and mass fragmentation of the obtained GC-MS chromatogram, 106 individual components which representing ≈ 99.29 % of the total volatile constituents have been identified. The major compounds (66.57% of the total composition) were identified as hexanal (15.98%), trans-sabinyl acetate (12.22%), allo-aromadendrene (9.30%), nonanoic acid (6.66%), 3Z- hexeny-2-methyl butanoate (6.09%), valeranone (5.25%), (E, E)-α-Farnesene (3.18%), a-pinene (3.06%), linalool isovalerate (3.03%) and a-humulene (1.8%). Estimation of the antioxidant activity of EO showed promising effect at 80 mg/mL concentration, it exerted 62.40, 863.29 and 62.72 % inhibition compared to TBHQ that showed 78.62, 77.56 and 79.23 % inhibition using DPPH, ABTS and β-carotene/Linoleic acid, respectively. The antioxidant activity was pronounced at 80 mg/mL than other concentrations. The volatile constituents showed inhibitory activity against gram positive bacteria ranged from 2.23 mg/100 mL ( for staphylococcus aureus ), and 15.68 mg/100 mL (for Bacillus cereus) compared to ciprofloxacin which showed inhibitory activity 0.185, and 0.182 mg/100 mL, respectively. Moreover, the MIC of volatiles towards gram negative bacteria are ranged from 18.35 (Escherichia coli) to 31.61 mg/100 mL (Klebsiella pneumonia) compared to ciprofloxacin with 0.184 to 0.188 mg/mL respectively. Additionally, the antifungal activity against candida albicans was rather promising (4.36 mg/mL).

Catalytic combustion of methyl butanoate over HZSM-5 zeolites

A catalytic combustion mechanism of methyl butanoate over HZSM-5 was proposed and validated by experimental data and theoretical calculations.