Methyl Caproate Research Articles

Correlation Analysis between Microbial Communities and Flavor Compounds during the Post-Ripening Fermentation of Traditional Chili Bean Paste.

Chili bean paste is a traditional flavor sauce, and its flavor compounds are closely related to its microflora. This study focused on investigating the content of bioactive compounds, flavor compounds, and microbial communities during the post-ripening fermentation of chili bean paste, aiming to provide a reference for improving the flavor of chili bean paste by regulating microorganisms. Compared to no post-ripening fermentation, the content of organic acids increased significantly (p < 0.05), especially that of citric acid (1.51 times). Glutamic acid (Glu) was the most abundant of the 17 free amino acids at 4.0 mg/g. The aroma profiles of the samples were significantly influenced by fifteen of the analyzed volatile compounds, especially methyl salicylate, methyl caproate, and 2-octanol (ROAV > 1). Latilactobacillus (27.45%) and Pseudomonas (9.01%) were the dominant bacterial genera, and Starmerella (32.95%) and Pichia (17.01%) were the dominant fungal genera. Weissella, Lacticaseibacillus, Pichia, and Kazachstania had positive effects on volatile flavoring compounds, which enriched the texture and flavor of the chili bean paste. Therefore, the microbial-community activity during the post-ripening fermentation is the key to enhance the flavor quality of the product.

Monitoring of Volatile Compounds of Ready-to-Eat Kiwifruit Using GC-IMS.

Ready-to-eat kiwifruit has gained significant market value in recent years due to its convenience and the increasing consumer demand for healthy ready-to-eat snacks. The volatile compound content (VOC) in ready-to-eat kiwifruit is a crucial factor determining its flavor and aroma. VOC is an important characteristic that positively affects the overall evaluation of ready-to-eat kiwifruit. In this study, we utilized gas chromatography-ion mobility spectrometry (GC-IMS) to investigate changes in the composition of VOCs in ready-to-eat kiwifruit during different storage periods (every 12 h). Our results revealed the presence of 55 VOCs in ready-to-eat kiwifruit, with alcohols, esters, and ketones being the dominant compounds responsible for the aromatic flavor. Among these compounds, methyl caproate, ethyl butyrate, and ethyl propionate provided specific fruit flavors to ready-to-eat kiwifruit, whereas esters played a secondary role. Furthermore, varying trends were observed for different compound types as the storage period increased: alcohols exhibited a decreasing trend, whereas ester products and some sulfur-containing compounds showed an increase. Additionally, fingerprint profiles of volatile compounds were established for each storage period, enabling the identification of characteristic substances. This comprehensive analysis of volatile flavor substances during the ripening of ready-to-eat kiwifruit will greatly contribute to enhancing its sensory quality, consumer appeal, and overall marketability.

Volatile Compound Profiling of Seven Tuber Species Using HS-SPME-GC-MS and Classification by a Chemometric Approach.

Edible mushrooms are important providers of nutrients and are well recognized for their particular organoleptic properties. The volatiles that Tuber releases serve purposes beyond simply appealing to our sense of smell. Truffles have different smells and tastes due to the fact that they contain different volatile components; therefore, aroma is essential in defining the organoleptic properties and quality of truffles. In this research, seven Tuber species, namely, Tuber ferrugineum, Tuber nitidum, Tuber excavatum, Tuber rufum, Tuber puberulum, Tuber aestivum, and Tuber borchii were selected. The primary objective of this study was to carry out the first in-depth investigation of the volatile compounds and chemometric analysis of seven truffle species from the Tuber genus that are grown in Turkey. The SPME headspace combined with GC-MS analysis identified 60 volatiles from different classes, with the abundance of terpenes being followed in a decreasing order by alcohols, aldehydes, sulfides, ketones, and other aromatic compounds. According to the chemometric analysis, methional, 3-methyl-4,5-dihydrothiophene, p-(methylthio) benzaldehyde, 3-octene, linalyl acetate, methyl caproate, and β-trans-ocimene could be highlighted as markers for T. borchii grown in Turkey. This investigation was conducted for the first time using T. ferrugineum, T. puberulum, and T. nitidum. The comparison of the volatile profile of these tubers' species displayed branded differences. Thus, the knowledge gained from this research may pave the way to identify the key aroma contributors in the chosen Tuber species.

The Effect of Milling with Combined Surfactants on the Magnetic Properties and Microstructure of Submicron Sm2Fe17N3 Powders

The results of the application of a combination of several surfactants in preparing submicron hard magnetic Sm2Fe17N3 powders by milling in a centrifugal mill are reported. Along with methyl caproate, to protect the powder against oxidation, the efficiency of siloxane has been studied. The application of the combined surfactants allowed us to increase both the (BH)max of the Sm2Fe17N3 powder to 23.6 MG Oe and its corrosion resistance. The effect of milling kinetics on the angular dependence of the coercive force Hc has been determined. Information on the primary mechanism of magnetization reversal of the powders has beenobtained.

Bioactive volatile compounds from Penicillium digitatum-infected apples: Oviposition attractants for yellow peach moth Conogethes punctiferalis (Lepidoptera: Crambidae)

IntroductionPlant-associated microbes critically shape the dynamics of plant-and insect-associated communities. In previous studies, we reported that the yellow peach moth Conogethes punctiferalis (YPM) preferred to Penicillium digitatum-infected apples (PDA) for oviposition. However, the underlying mechanisms remains unclear.MethodsIn the present study, the behavioral and physiological experiments were conducted to determine how P. digitatum affects the oviposition selection of mated YPM females via altering host plant volatile organic compounds (VOCs).ResultsMated YPM females were attracted to and laid more eggs on PDA than on non-infected apples (NIA), mechanically damaged apples (MDA), and P. digitatum in potato dextrose agar medium (PPD) in the oviposition selection experiments. Four-arm olfactometer assays further confirmed that odors in PDA were responsible for the attractiveness of mated YPM females. Further analyses showed that 38 VOCs were collected and identified from all treatments by GC-MS, with five specific VOCs (methyl 2-methylbutyrate, styrene, methyl caproate, butyl caprylate, and n-tetradecane) emitting from PDA. A principal component analysis (PCA) based on the absolute contents of 38 VOCs revealed a clear separation of PDA from NIA, MDA, and PPD. Moreover, when P. digitatum-induced specific VOCs were added to apples in individual or synthetic blends, there was a significantly higher percentage of mated YPM females to apples with individual or synthetic blends consisting of methyl 2-methylbutyrate, butyl caprylate, or n-tetradecane in Y-tube olfactometer experiments, suggesting that these three specific VOCs acted as predominant olfactory signals for mated YPM females to PDA.DiscussionTaken together, the microbe P. digitatum was an important driver of the interactions between YPMs and host plants by altering plant volatiles. These findings may form the basis for developing attractant baits for field trapping YPMs in the future.

Novel application of HS-GC-IMS with PCA for characteristic fingerprints and flavor compound variations in NFC Chinese bayberry (Myrica rubra) juice during storage

The flavor fingerprint of NFC Chinese bayberry (Myrica rubra) juice treated by high hydrostatic pressure (HHP) was developed, and the volatile flavor compound variations formed during storage at 4 °C for 28 days were investigated by headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS) fingerprinting combined with principal component analysis (PCA). During the bayberry juice storage period, the HS-GC-IMS provided information on the characteristics and intensity of 52 volatile flavor compounds (ten terpenes, fifteen aldehydes, fourteen esters, nine alcohols, three ketones and one furan) and was used to observe the changes in flavor compounds in bayberry juice during storage. The results showed that the contents of (E)-2-hexenal, (Z)-3-hexen-1-ol, linalool and 6-methyl-5-hepten-2-one increased first with prolonged storage time. While the methyl caproate and methyl isobutyrate contents continued to decrease, the 3-pentanone, 2-methylbutanal and 2-methacrolein contents increased gradually. In addition, ethanol (note “alcohol”) and ethyl acetate (note “overripe”) were found to contribute to off-flavor accumulation. The visual plots for HS-GC-IMS and PCA had good consistency, and their combination was excellent for characterizing the aroma characteristics of bayberry juice from different storage periods. This work can provide useful knowledge for understanding the flavors of NFC Chinese bayberry during storage.

Measurement and modeling of thermal conductivity for short chain methyl esters: Methyl butyrate and methyl caproate

Fatty acid methyl esters (FAMEs) are the main component of biodiesels. Before the industrial application of FAMEs, it is essential to investigate the thermophysical properties of FAMEs. Thermal conductivity of fuels is used in various processes, such as the design of the heat transfer system and the determination of the temperature distribution of engines. Thus, it is of great significance to acquire accurate experimental data and develop reliable models for obtaining accurate thermal conductivity data of FAMEs. In this work, thermal conductivities of two short-chain FAMEs, methyl butyrate (MeC4:0) and methyl caproate (MeC6:0) were studied experimentally and theoretically. The thermal conductivities of these two FAMEs were measured by the transient hot-wire method at T = 303 to 523 K and p = 0.1 MPa to 15 MPa, the data were correlated as a polynomial function of temperature and pressure, the AADs are 0.38% for MeC4:0 and 0.42% for MeC6:0, respectively. Moreover, the experimental thermal conductivities agree well with the available data from literature. In addition, three classical models (Latini model, Sastri model, Liu model) were used to represent the present experimental data and the results show that Liu model with re-fitted parameters performs better in the prediction of the thermal conductivity of FAMEs, with regard to accuracy.

Nutrient and Sensory Metabolites Profiling of Averrhoa Carambola L. (Starfruit) in the Context of Its Origin and Ripening Stage by GC/MS and Chemometric Analysis.

Averrhoa carambola L. is a tropical tree with edible fruit that grows at different climatic conditions. Despite its nutritive value and reported health benefits, it is a controversial fruit owing to its rich oxalate content. The present study aimed at investigating aroma and nutrient primary metabolites distribution in A. carambola fruits grown in Indonesia, Malaysia (its endemic origin) versus Egypt, and at different ripening stages. Two techniques were employed to assess volatile and non-volatile metabolites including headspace solid-phase micro-extraction (HS-SPME) joined with gas chromatography coupled with mass-spectrometry (GC-MS) and GC-MS post silylation, respectively. Twenty-four volatiles were detected, with esters amounting for the major class of volatiles in Egyptian fruit at ca. 66%, with methyl caproate as the major component, distinguishing it from other origins. In contrast, aldehydes predominated tropically grown fruits with the ether myristicin found exclusively in these. Primary metabolites profiling led to the identification of 117 metabolites viz. sugars, polyols and organic acids. Fructose (38–48%) and glucose (21–25%) predominated sugar compositions in ripe fruits, whereas sorbitol was the major sugar alcohol (2.4–10.5%) in ripe fruits as well. Oxalic acid, an anti-nutrient with potential health risks, was the major organic acid detected in all the studied fruits (1.7–2.7%), except the Malaysian one (0.07%). It increases upon fruit ripening, including considerable amounts of volatile oxalate esters detected via SPME, and which must not be omitted in total oxalate determinations for safety assessments.

Characterization of free and glycosidically bound volatile compounds from tamarillo (Solanum betaceum Cav.) with considerations on hydrolysis strategies and incubation time

Two different hydrolysis strategies, namely acid hydrolysis (pH 0 and 3) and enzyme hydrolysis (Rapidase AR2000, β-glucosidase, 5.6 nkat/mg), and the effect of hydrolysis time on the liberation of glycosidically bound volatiles from tamarillo (Solanum beaceum Cav.), were evaluated. Free and bound volatile profiles in tamarillo were also compared. Enzymatic hydrolysis was favoured for the liberation of aldehydes, esters, and terpenes. Harsh acidic hydrolysis (pH 0) was particularly effective at releasing C13-norisoprenoids including 3-hydroxy-β-damascone and 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN), but those compounds cannot contribute to the pleasant odour. Moreover, the longer the duration of enzymatic hydrolysis, the higher was the concentration of alcohols, terpenes, benzenoids, ketones, and volatile phenols. On the other hand, 33 free and 49 bound volatiles were identified in tamarillo with a complementary profile: the major free volatiles were alcohols ((Z)-3-hexenol, 1-hexanol) and esters (methyl caproate, methyl butanoate and ethyl butanoate), while bound volatile compounds showed higher concentrations of benzenoids (benzyl alcohol and phenylethyl alcohol) and terpenes, including prenol, linalool and α-terpineol. Many glycosidically bound volatiles are available as aroma reservoirs in tamarillo, and to liberate these compounds during tamarillo-based product development, attention should be given to hydrolysis strategies and incubation time.

Valorization of rice husk silica waste: Organo-amine functionalized castor oil templated mesoporous silicas for biofuels synthesis

Rice husk is a rich source of waste silica which has potential for application in the preparation of porous materials for use as catalyst supports or sorbents. Here we report on the synthesis of rice husk silica (RHS) and mesoporous templated rice husk silica (MT-RHS) using sodium silicate, obtained from rice husk ash, and castor oil as a pore directing agent. The resulting silicas were functionalized with 3-aminopropyltriethoxysilane (APTS) or 3-diethylaminopropyltrimethoxysilane (DEPA), and their catalytic activity evaluated in the transesterification of model C4–C12 triglycerides (TAG) to their corresponding fatty acid methyl esters, of relevance to biodiesel synthesis. Castor oil templating enhances the surface area of rice husk silica, and introduces uniform 4 nm mesopores, albeit as a disordered pore network. Post-synthetic grafting of silica by APTS or DEPA resulted in base site loadings of 0.5 and 0.8 mmolg−1 respectively on RHS and MT-RHS. Turnover frequencies of amine-functionalized MT-RHS were 45–65% greater than those of their amine-functionalized RHS counterparts for tributyrin transesterification. Switching from a primary (APTS) to tertiary (DEPA) amine increased activity three-fold, delivering 80% tributyrin conversion to methyl butyrate in 6 h. DEPA-MT-RHS was effective for the transesterification of C8 and C12 triglycerides, with methyl caproate and methyl laurate selectivities of 93% and 71% respectively in 24 h.

Volatile organic compounds of Hanseniaspora uvarum increase strawberry fruit flavor and defense during cold storage.

Volatile organic compounds (VOCs) of antagonistic yeasts are considered as environmental safe fumigants to promote the resistance and quality of strawberry (Fragaria ananassa). By GC‐MS assays, VOCs of Hanseniaspora uvarum (H. uvarum) fumigated strawberry fruit showed increased contents of methyl caproate (5.8%), methyl octanoate (5.1%), and methyl caprylate (10.9%) in postharvest cold storage. Possible mechanisms of H. uvarum VOCs involved in regulations of the defense‐related enzymes and substances in strawberry were investigated during postharvest storage in low temperature and high humidity (2 ± 1°C, RH 90%–95%). Defense‐related enzymes assays indicated H. uvarum VOCs stimulated the accumulation of CAT, SOD, POD, APX, PPO, and PAL and inhibited biosynthesis of MDA in strawberry fruit under storage condition. Moreover, the expression levels of related key enzyme genes, such as CAT, SOD, APX42, PPO, and PAL6, were consistently increased in strawberry fruit after H. uvarum VOCs fumigation.

Experimental investigations on the liquid thermal conductivity of five saturated fatty acid methyl esters components of biodiesel

Abstract The utilization of biodiesel is a promising way to replace fossil fuels, and thermal conductivity of biodiesel is a very important thermophysical property for its applications. In this work, the transient hot-wire instrument with one bare platinum wire was used to measure the thermal conductivity of five pure components of biodiesel in liquid phase at atmospheric pressure. The measured substances include methyl butyrate, methyl pentanoate, methyl caproate, methyl caprylate, and methyl pelargonate, and the temperature range was from (283 to 358) K, (285 to 362) K, (263 to 368) K, (273 to 393) K, (278 to 383) K, respectively. The total standard uncertainty of the experimental results was estimated to be less than 2% and the repeatability was better than ±0.5%. The thermal conductivity data of each substance were fitted as a function of temperature. The average absolute relative deviation and maximum absolute relative deviation between the experimental data and calculated results were 0.17% and 0.44% for methyl butyrate, 0.25% and 0.58% for methyl pentanoate, 0.16% and 0.44% for methyl caproate, 0.15% and 0.47% for methyl caprylate, 0.15% and 0.33% for methyl pelargonate, respectively.

High-pressure liquid densities of fatty acid methyl esters: Measurement and prediction with PC-SAFT equation of state

In this work, experimental density data were reported for six fatty acid methyl esters, including methyl butyrate, methyl valerate, methyl caproate, methyl pelargonate, methyl heptanoate, and methyl caprylate. The densities were measured from 293.15 K to 363.15 K and pressures up to 60 MPa by a vibrating-tube densimeter. The relative uncertainty of the measurement is estimated less than 0.001 with a confidence level of 0.95. The high pressure densities were correlated with a Tait-type equation. The overall average relative deviation between experimental data and calculated results from Tait equation for the six fatty acid esters is 0.010%. The derived thermodynamic properties, such as isobaric thermal expansivity and isothermal compressibility, were obtained from the experimental density results. Additionally, for the studied esters, the molecular parameters of the PC-SAFT equation of state were obtained based on the corresponding vapor pressures and liquid densities. The PC-SAFT equation was used to predict the high pressure densities of the esters, and good agreements were observed.

Experimental vapor pressures (from 1 Pa to 100 kPa) of six saturated Fatty Acid Methyl Esters (FAMEs): Methyl hexanoate, methyl octanoate, methyl decanoate, methyl dodecanoate, methyl tetradecanoate and methyl hexadecanoate

Vapor pressures of six saturated Fatty Acid Methyl Esters (FAMEs), methyl hexanoate (or methyl caproate), methyl octanoate (or methyl caprylate), Methyl decanoate (or methyl caprate), methyl dodecanoate (or methyl laurate), methyl tetradecanoate (or methyl myristate), and methyl hexadecanoate (or methyl palmitate) were measured from 1Pa to 100kPa and at temperature range between 262 and 453K using a static apparatus. The experimental data (P-T) were compared with the available literature data.

Gelatin‐Modified Polyurethanes for Soft Tissue Scaffold

Recently, in the field of biomaterials for soft tissue scaffolds, the interest of their modification with natural polymersis growing. Synthetic polymers are often tough, and many of them do not possess fine biocompatibility. On the other hand, natural polymers are biocompatible but weak when used alone. The combination of natural and synthetic polymers gives the suitable properties for tissue engineering requirements. In our study, we modified gelatin synthetic polyurethanes prepared from polyester poly(ethylene-butylene adipate) (PEBA), aliphatic 1,6-hexamethylene diisocyanate (HDI), and two different chain extenders 1,4-butanediol (BDO) or 1-ethoxy-2-(2-hydroxyethoxy)ethanol (EHEE). From a chemical point of view, we replaced expensive components for building PU, such as 2,6-diisocyanato methyl caproate (LDI) and 1,4-diisocyanatobutane (BDI), with cost-effective HDI. The gelatin was added in situ (in the first step of synthesis) to polyurethane to increase biocompatibility and biodegradability of the obtained material. It appeared that the obtained gelatin-modified PU foams, in which chain extender was BDO, had enhanced interactions with media and their hydrolytic degradation profile was also improved for tissue engineering application. Furthermore, the gelatin introduction had positive impact on gelatin-modified PU foams by increasing their hemocompatibility.

Synthesis, Characterization and Drug Release of Biocompatible/Biodegradable Non-toxic Poly(urethane urea)s Based on Poly(ε-caprolactone)s and Lysine-Based Diisocyanate

Segmented poly(urethane urea)s (SPUUs) based on aliphatic diisocyanato (2,6-diisocyanato methyl caproate (lysine-based diisocyanate, LDI)), poly(ε-caprolactone diol)s (PCLs) with molecular weights 530, 1250 and 2000, and 1,4-butanediamine were synthesized in absence of catalyst. The resulting SPUUs, with different soft segment length, were characterized by suitable analytical techniques. The synthesized SPUUs had high molecular weights, low glass-transition temperatures (≤−15°C) and high elongation-at-break. The degradation of SPUUs in alkaline solution and in vitro drug release of sulfamethoxazole in pH 7.4 buffer were investigated. In addition, the degradation behavior of PCL1250-based SPUU was investigated by exposing to a buffer solution and biochemical oxygen demand (BOD) tests in an activated sludge. The drug release data was analyzed by an empirical equation ((M t/M ∞)=ktn ). Finally, NIH3T3 fibroblasts have been used for cell-adhesion studies on these materials to investigate the biocompatibility. The synthesized SPUUs combine physical and bioresponsive and biodegradable properties that might be employed in wound dressing, drug delivery and tissue-engineering applications.

Acidity control of ruthenium pillared clay and its application as a catalyst in hydrogenation reactions

Aluminum pillared clay was used as a support for the preparation of catalysts containing ruthenium as active metal, in the presence or not of a promoter (tin) and an acid reducer (barium). The catalysts were characterized and tested for hydrogenation of dimethyl adipate reactions. The results showed a high conversion, typically above 95%, in all studied systems. This conversion occurs irrespectively of the presence of active metal; therefore, it may be due to the support's intrinsic activity. The acidity was identified as the main cause of this activity. A barium treatment of these catalysts significantly reduced this acidity, thus making more selective the available systems. The catalysts treated with barium reduced the formation of undesirable products up to 45%. Similarly, the presence of tin helped to obtain valuable products such as gamma-caprolactone and methyl caproate, which reached high selectivity values (18.6% and 16.9%, respectively).

Release Behavior of Flavor Encapsulated CD in Slurry Solution Under Boiling Conditions

Cyclodextrin (CD) can control flavor release rate and protect the flavor from volatilization by the formation of inclusion complex with flavor compounds. However, the flavor release rate during cooking, particularly in boiling water has hardly been understood. In this study, flavor release rate of flavor encapsulated CD in slurry or turbid solution under boiling condition was investigated. The release rate constants of methyl caproate and d-limonene depended on the CD concentration, whereas, those of phenyl ethanol hardly did. The plot of a reciprocal number of apparent release rate constant to CD concentration for d-limonene stability constant under boiling condition was obtained. Stability constants for d-limonene in α-CD and β-CD were 185 and 38 M−1, respectively. These stability constants were smaller than the order of 1000 M−1 at room temperature. These results suggested that the addition of CD for protection of flavors in boiling water might have small effect in comparison to that at room temperature. The behavior of flavor release in the boiling water correlated well with the first-order release rate equation, which can be described by the film theory of the interfacial mass transfer.

Dimethyl adipate hydrogenation at presence of Pt based catalysts

Dimethyl adipate hydrogenations catalyzed by Pt/Al 2O 3 and Pt/TiO 2 have been studied. Catalysts were prepared with the conventional impregnation method. Physical–chemical characterization of the catalytic systems was made with the use of different techniques: N 2 and H 2 sorption, scanning electron microscopy (SEM), energy-dispersive electron (EDS) probe X-ray analysis, temperature programmed reduction (TPR) and inductively coupled plasma optics emission spectrometry (ICP-OES). Metals dispersion in the catalysts is directly related to the superficial area of the supports, and partially covered particles (in the case of the TiO 2) can be present. Support modifies the behavior of metals in its surface for different ways: SMSI effect (TiO 2) or acidity (Al 2O 3). The catalyst supported on Al 2O 3 is more active, reaching 52.91% conversion after 10 h of reaction, while at the same period of time, the catalyst supported on TiO 2 converted only 15.56% of the substrate. Methyl caproate, adipic acid mono-methyl ester and caprolactone were obtained as main products by Pt/Al 2O 3 catalyst. These products indicate that carboxylic groups have not been activated enough, leading to formation of significant amount of hydrogenation products different from 1,6-hexanediol (diol). Pt/TiO 2 catalyst obtained methyl caproate, caprolactone, hexane and diol, where hexane formation occurred from methyl caproate. Diol formation occurred after 5 h of reaction and it indicates participation of platinum and TiO 2 as active catalytic sites.

Aroma synthesis by immobilized lipase from Mucor sp.

The ability of Mucor sp. lipase immobilized on Amberlite IRC 50 to catalyze the synthesis of flavor esters was investigated in organic media (cyclohexan) at 35 °C. Propionic, butyric, caproic acids, as well as methanol, ethanol, allyl, butanol, isoamyl, geraniol, citronellol and farnesol alcohols were used as substrates in equimolar ratio. Most of the esters were synthesized in good yield (>90%). Different conversion yields were observed according to the affinity of the lipase toward the acids (short or long), or the alcohols (linear or branched and short or long). Rapid and higher conversions of 92 and 98% were observed for methyl caproate and ethyl caproate, respectively after 4 h reaction, and a yield of 95, 100, 93% were obtained for butyl butyrate, butyl caproate and allyl caproate, respectively after 24 h reaction in used conditions.