Production Of Esters Research Articles

Optimization of Dielectric Properties of Pongamia Pinnata Methyl Ester for Power Transformers Using Response Surface Methodology

In this present work, effort was taken to develop a response surface model based on response surface methodology (RSM) paired with Box–Behnken design (BBD). Investigations were carried out to optimize the transesterification of Pongamia Pinnata oil (PPO) under various process conditions such as time (60–180 min), temperature (60 °C–100 °C), and catalyst (1%–3%). The production of PPO methyl ester (PPOME) by the esterification process is carried out using the PPO and methanol (CH3OH) in a 1:6 molar ratio that is fixed as a constant. Here, the input variables are the process variables (independent) and the output variables are the response variables (dependent). The response variables are the breakdown voltage (BDV), kinematic viscosity (KV), and fire point (FRP). The effect of the process variables on the response variables is modeled using RSM paired BBD. The experimental sequence was designed to find the optimum composition of input parameters and output parameters. The associative effects of the input and output variables were designed as a 2-D contour plot and 3-D response surface plots, and the interactive effects were studied using the plots. After optimization, the optimum conditions of the input variables over the BDV, KV, and FRP were found to be the time of 142.07 min, the temperature of 81.52 °C, and the catalyst of 2.41%. The dielectric properties of PPOME were found to be 61.54 kV, 20.50 cSt, and 281.43 °C, which are in the vicinity of the laboratory experimental results. Those indicate that the treatment of PPO with the optimum quantity of the process variables gives an excellent dielectric response.

Chem-bio interface design for rapid conversion of CO2 to bioplastics in an integrated system

Chem-bio interface design for rapid conversion of CO2 to bioplastics in an integrated system

Ethylene promotes ester biosynthesis through PuERF13/PuDof2.5 synergically activated PuAAT1 during ripening of cold-stored ‘Nanguo’ pear

Aroma is an important trait of ‘Nanguo’ pear (Pyrus ussuriensis Maxim.), and esters are the main aroma components in the fruit. Refrigeration prolongs the storage period of the fruit but results in evident loss of esters. Here, we treated the refrigerated fruit with 1000 μL L−1 Ethephon solution and found that exogenous ethylene treatment raised the biosynthesis of ten individual esters, and up-regulated the expression of PuAAT1, PuERF13 and PuDof2.5 genes of cold-stored pears. PuDof2.5 activated the transcription of PuAAT1 by binding to its promoter. Moreover, PuERF13 interacted with PuDof2.5, which caused an increase in ester biosynthesis of cold-stored ‘Nanguo’ pear treated with exogenous ethylene. Our findings indicate that ethylene promotes ester production through activation of main gene, PuAAT1, regulated by PuERF13 and PuDof2.5.

Physicochemical property, bacterial diversity, and volatile profile during ripening of naturally fermented dry mutton sausage produced from Jianzhou big-eared goat.

Physicochemical properties, bacterial communities, and volatile compounds of mutton sausage produced from Jianzhou Big-Eared goat meat during natural ripening were investigated. Firmicutes and Bacteroidetes accounted for over 66% of all operational taxonomic units (OTUs) throughout the whole process, with Lachnospiraceae_NK4A136_group and Staphylococcus as the predominant genus during the early and later ripening periods, respectively. The evolution of microbial composition became less rich and diverse. The uncultured bacterium, the Lachnospiraceae_NK4A136_group, and Staphylococcus were marker bacteria on days 0, 7, and 26, respectively, with none on day 16. The bacteria distribution seemed to influence the volatile profile of mutton sausage throughout processing, with the bacterial composition on day 0 and day 7 clustered separately from day 16 and day 26, and the same pattern for the volatile profile. Meanwhile, the concentration of total volatile fraction significantly increased, and the majority of the volatile compounds were generated during late ripening. Non-anal, hexanal, decanal, heptanal, dodecyl aldehyde, benzaldehyde, 3-methylbutanal, γ-dodecalactone, 2-pentylfuran, and 1-octen-3-ol were key volatile compounds, contributing to the overall mutton sausage flavors. Based on Spearman’s correlation analysis, Staphylococcus as well as Psychrobacter were positively correlated with the production of the key volatile compounds, and other bacteria such as Lachnospiraceae_NK4A136_group, Bacteroides, Lactobacillus, Prevotella_1, Odoribacter, and so on were associated with the production of most alcohols and esters.

Comparative analysis of sugar, acid, and volatile compounds in CPPU-treated and honeybee-pollinated melon fruits during different developmental stages

Plant growth regulator N-(2-chloro-4-pyridyl)-N′-phenylurea (CPPU) is widely used in fruit production. However, the mechanism in which CPPU affects melon fruit quality, especially aroma compound, remains unclear. Here, gas chromatography–mass spectrometry was performed to detect the sugar, citric acid, and aroma content in CPPU-treated and pollinated melon fruit. Results showed that the application of CPPU decreased the sugar and aroma content in melon fruit. The relative content of several important esters, including isobutyl acetate, ethyl acetate, 2-methylbutyl acetate, methyl acetate, benzyl acetate, and phenethyl acetate, in CPPU-treated fruits was significantly lower than that in honeybee-pollinated fruits. The content of many amino acids (isoleucine, leucine, valine, methionine, and l-phenylalanine), which could be metabolized into aroma compounds, in CPPU-treated fruits was significantly higher than that in honeybee-pollinated fruits. In conclusion, CPPU application interferes with amino-acid metabolism and affects the production of aromatic esters in melon fruit.

Comparative modelling, molecular docking and immobilization studies on Rhizopus oryzae lipase: evaluation of potentials for fatty acid methyl esters synthesis

Elucidation of lipase–substrate interactions will guide the proper industrial use and applicability of the enzyme. The aim of this study was to predict the 3 D structure of Rhizopus oryzae ZAC3 (RoZAC3) lipase, study its interactions with some natural substrates and evaluate the feasibility of fatty acid methyl esters (FAME) production by the immobilized lipase. Protein identification of RoZAC3 lipase was carried out using LC-MS/MS. The 3 D structure of the lipase was built using homology modelling and natural substrates such as tributyrin, tripalmitin and triolein were docked to the optimized 3 D model for investigation of enzyme-ligand interactions. RoZAC3 lipase, immobilized by adsorption on Lewatit VP OC 1600 was applied in the synthesis of fatty acid methyl esters (FAME). From the phylogenetic analysis, it was observed that RoZAC3 lipase was closely related (48%) to Rhizopus javanicus lipase (Q7M4U7). The predicted 3 D model was validated using the SWISS model validation server. Ramachandran and ERRAT plots were used to assess the amino acid environment and overall quality of the model. From the docking studies, the values of the binding energies obtained for tributyrin, tripalmitin and triolein were − 5.37, −5.27 and −5.77 respectively. At an enzyme:immobilization support ratio of 50 mg/g, transesterification reaction duration of 18 h and a temperature of 40 oC, the conversion reached above 80%. The molecular docking studies provided information on the interaction/modifications between the RoZAC3 lipase and triacylglycerols that can be exploited for numerous applications. The immobilized lipase could serve in hydro-esterification reactions adaptable for biodiesel production. Communicated by Ramaswamy H. Sarma

Engineering cell morphology by CRISPR interference in Acinetobacter baylyi ADP1.

Microbial production of intracellular compounds can be engineered by redirecting the carbon flux towards products and increasing the cell size. Potential engineering strategies include exploiting clustered regularly interspaced short palindromic repeats interference (CRISPRi)-based tools for controlling gene expression. Here, we applied CRISPRi for engineering Acinetobacter baylyi ADP1, a model bacterium for synthesizing intracellular storage lipids, namely wax esters. We first established an inducible CRISPRi system for strain ADP1, which enables tightly controlled repression of target genes. We then targeted the glyoxylate shunt to redirect carbon flow towards wax esters. Second, we successfully employed CRISPRi for modifying cell morphology by repressing ftsZ, an essential gene required for cell division, in combination with targeted knock-outs to generate significantly enlarged filamentous or spherical cells respectively. The engineered cells sustained increased wax ester production metrics, demonstrating the potential of cell morphology engineering in the production of intracellular lipids.

Effects of herb (mint, ginger, and cinnamon) addition on the formation of 3‐monochloropropanediol esters in the refined olive oil

The inhibitory effects of using extracts and leaf powders from mint (Mentha spicata), ginger (Zingiber officinale), and cinnamon (Cinnamomum verum) were investigated on the formation of 3-monochloropropanediol esters (3-MCPD esters) in the refined olive oil at temperatures 100–200°C using Taguchi's experimental design. The initial concentration of 3-MCPD esters in the refined olive oil before the treatment was 0.33 mg/100 g of oil. The greatest reducing effect was found for mint powder (0.16 mg/100 g of oil). The inhibitory effects of extracts and powders were similar. Based on the Taguchi's approach for the analysis of the data, the best level for the extract and/or the powder of mint or ginger was 0.04 mg for 100 g refined olive oil. During the storage of refined olive oil for 1 and 2 months, mint and ginger as both dry extract and plant powder reduced the formation of 3-MCPD esters. Practical applications In the current study, during 1 and 2 months of storage of refined olive oil, decreases in the production of 3-monochloropropanediol esters were observed in samples containing mint and ginger (as a powder or in their extract forms). Therefore, to avoid the production of this toxic chemical in olive oil after it is packaged, mint and ginger can be combined with the oil immediately after its refining stage. Results from the current study can encourage manufacturers to use these natural antioxidants for inhibiting the formation of 3-monochloropropanediol esters.

Characterization of Saccharomyces Strains Isolated from “Kéknyelű” Grape Must and Their Potential for Wine Production

Novel wine yeast strains have the potential to satisfy customer demand for new sensorial experiences and to ensure that wine producers have strains that can produce wine as efficiently as possible. In this respect, hybrid yeast strains have recently been the subject of intense research, as they are able to combine the favourable characteristics of both parental strains. In this study, two Saccharomyces “Kéknyelű” grape juice isolates were identified by species-specific PCR and PCR-RFLP methods and investigated with respect to their wine fermentation potential. Physiological characterization of the isolated strains was performed and included assessment of ethanol, sulphur dioxide, temperature and glucose (osmotic stress) tolerance, killer-toxin production, glucose fermentation ability at 16 °C and 24 °C, and laboratory-scale fermentation using sterile “Kéknyelű” must. Volatile components of the final product were studied by gas chromatography (GC) and mass spectrometry (MS). One isolate was identified as a S. cerevisiae × S. kudriavzevii hybrid and the other was S. cerevisiae. Both strains were characterized by high ethanol, sulphur dioxide and glucose tolerance, and the S. cerevisiae strain exhibited the killer phenotype. The hybrid isolate showed good glucose fermentation ability and achieved the lowest residual sugar content in wine. The ester production of the hybrid strain was high compared to the control S. cerevisiae starter strain, and this contributed to the fruity aroma of the wine. Both strains have good oenological characteristics, but only the hybrid yeast has the potential for use in wine fermentation.

Assessment of Spontaneous Fermentation and Non-Saccharomyces Sequential Fermentation in Verdicchio Wine at Winery Scale

The use of non-Saccharomyces yeasts in sequential fermentation is a suitable biotechnological process to provide specific oenological characteristics and to increase the complexity of wines. In this work, selected strains of Lachancea thermotolerans and Starmerella bombicola were used in sequential fermentations with Saccharomyces cerevisiae and compared with spontaneous and pure S. cerevisiae fermentation trials in Verdicchio grape juice. Torulaspora delbrueckii together with the other two non-Saccharomyces strains (L. thermotolerans, S. bombicola) in multi-sequential fermentations was also evaluated. Wines, obtained under winery vinification conditions, were evaluated for their analytical and sensorial profile. The results indicated that each fermentation gave peculiar analytical and aromatic features of the final wine. L. thermotolerans trials are characterized by an increase of total acidity, higher alcohols and monoterpenes as well as citric and herbal notes. S. bombicola trials showed a general significantly high concentration of phenylethyl acetate and hexyl acetate and a softness sensation while multi-sequential fermentations showed a balanced profile. Spontaneous fermentation was characterized by the production of acetate esters (ethyl acetate and isoamyl acetate), citrus and herbal notes, and tannicity. The overall results indicate that multi-starter fermentations could be a promising tool tailored to the desired features of different Verdicchio wine styles.

DES-Based Biocatalysis as a Green Alternative for the l-menthyl Ester Production Based on l-menthol Acylation.

The deep eutectic solvent (DES)-based biocatalysis of l-menthol acylation was designed for the production of fatty acid l-menthyl ester (FME) using fatty acid methyl ester (FAME). The biocatalytic reaction was assisted by a lipase enzyme in the DES reaction medium. ւՒ-menthol and fatty acids (e.g., CA—caprylic acid; OA—oleic acid; LiA—linoleic acid; and LnA—linolenic acid) were combined in the binary mixture of DES. In this way, the DES provided a nonpolar environment for requested homogeneity of a biocatalytic system with reduced impact on the environment. The screening of lipase enzyme demonstrated better performance of immobilized lipase compared with powdered lipase. The performance of the biocatalytic system was evaluated for different DES compositions (type and concentration of the acid component). l-menthol:CA = 73:27 molar ratio allowed it to reach a maximum conversion of 95% methyl lauric ester (MLE) using a NV (Candida antarctica lipase B immobilized on acrylic resin) lipase biocatalyst. The recyclability of biocatalysts under optimum conditions of the system was also evaluated (more than 80% recovered biocatalytic activity was achieved for the tested biocatalysts after five reaction cycles). DES mixtures were characterized based on differential scanning calorimetry (DSC) and refractive index analysis.

Study on microbial community of "green-covering" Tuqu and the effect of fortified autochthonous Monascus purpureus on the flavor components of light-aroma-type Baijiu.

"Green-covering" Tuqu (TQ), as one of Xiaoqu, is a special fermentative starter (also known as Jiuqu in Chinese) that originated in southern China and is characterized by a layer of green mold covering (Aspergillus clavatus) the surface and (sometimes) with a red heart. It plays a vital role in producing light-aroma-type Baijiu (LATB). However, to date, the microbiota that causes red heart of TQ remain largely unexplored, and it is still unclear how these microbiota influence on the quality of LATB. In this study, two types of TQ, one with a red heart (RH) and another with a non-red heart (NRH), were investigated by high throughput sequencing (HTS) and directional screening of culture-dependent methods. The obtained results revealed the differences in the microbial communities of different TQ and led to the isolation of two species of Monascus. Interestingly, the results of high performance liquid chromatography (HPLC) detection showed that citrinin was not detected, indicating that Monascus isolated from TQ was no safety risk, and the contents of gamma-aminobutyric acid in the fermented grains of RH were higher than that of NRH during the fermentation. Selecting the superior autochthonous Monascus (M1) isolated from the TQ to reinoculate into the TQ-making process, established a stable method for producing the experimental "red heart" Tuqu (ERH), which confirmed that the cause of "red heart" was the growth of Monascus strains. After the lab-scale production test, ERH increased ethyl ester production and reduced higher alcohols production. In addition, Monascus had an inhibitory effect on the growth of Saccharomyces and Aspergillus. This study provides the safe, health-beneficial, and superior fermentation strains and strategies for improving the quality of TQ and LATB.

An Efficient Zr-ZSM-5-st Solid Acid Catalyst for the Polyol Esterification Reaction

In this study, Zr active species were implanted into a ZSM-5 zeolite framework to form a solid acid catalyst through steam treatment and the liquid-solid isomorphous substitution process. The as-synthesized Zr-ZSM-5-st catalyst ensured excellent esterification of trimethylolpropane and fatty acids (FAs) to achieve a polyol ester production yield of 94.41%. Combined with N2 physisorption, X-ray diffraction, Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, transmission electron microscopy mapping, X-ray photoelectron spectroscopy, NH3 temperature-programmed desorption, and inductively coupled mass plasma spectroscopy were conducted. The results revealed that the excellent performance of Zr-ZSM-5-st catalyst could be attributed to the enhanced acidity and the developed surface area and pore structure.

Valorization of palm oil via cross-metathesis reaction using 1-octene

The use of palm oil-derived polyol in polyurethane manufacturing is restricted owing to its poor hydroxyl value, which results in a suboptimal polyurethane network. Palm oil could be first chemically modified by cross metathesis (CM) into olefin and ester products with terminal double bonds prior to converting it to the polyols with optimum hydroxyl value. Due to the catalyst degradation and the unwanted self-metathesis reaction, the plant oil CM employing ethylene has been limited by its poor selectivity and low yield. The goal of present research is to investigate the palm oil CM using 1-octene from the aspects of parametric and kinetic analysis. The use of 1-octene was hypothesized to prevent the formation of undesired catalytic intermediates and hence allowing the ruthenium-based Hoveyda Grubbs second generation catalyst (2nd HGC) to maintain its activity and stability. Adopting one factorial at time (OFAT) in a batch system, the effect of different parameters on cross-metathesis of palm oil was examined. The variation in reaction time, temperature, reactant molar ratio of 1-octene to triolein (MOC/TR), and catalyst loadings were correlated to triolein conversion, yield, and selectivity of 1-decene. The products such as 1-decene and glyceryl tri-9-decenoate were quantified using Gas Chromatography-Mass Spectrometry (GC-MS). The maximum triolein conversion and 1-decene yield, 97.78% and 293.36% respectively, were obtained when the cross metathesis of palm oil using 1-octene occurred at 343 K for 2 h with MOC/TR of 8 and catalyst loading of 5 ppm. After three consecutive catalytic tests carried out at best operating condition, the insignificant decline in the reaction performance evidenced that the 2nd HGC catalyst remained active and stable. It was also found that the power-law model well predicted the concentration profile of the cross-metathesis of palm oil using 1-octene, estimating activation energy of 22583 J/mol. This study developed a new technically feasible process for adding value to palm oil, by enabling the use of palm oil as a feedstock for the production of polyol.

Salt tolerance and ester production mechanisms of Candida etchellsii in Chinese horse bean-chili-paste

Candida etchellsii is a predominant strain in Chinese horse bean-chili-paste, a famous and traditional condiment with high salt content. In this study, physiological properties, ester production capacity and gene expression of C. etchellsii under salt stress were investigated, and the results showed that the strain evoked miscellaneous regulations to resist high salt stress. Under salt stress, C. etchellsii would accumulate intracellular glycerol, Na+ and K+ to balance osmotic pressure. Interestingly, the strain showed much stronger capacity to yield ethyl hexanoate and hexyl acetate after 5% and 20% (w/v) NaCl treatment whether in esterification or alcoholysis system. Furthermore, transcriptome data indicated that the genes associated with carbohydrate metabolism and amino acid metabolism had significantly different expression, and their regulations were consistent with the results of physiological analysis. The results obtained in this study could contribute to understand the salt tolerance mechanism of C. etchellsii and provide a theoretical support for its application in traditional food fermentation.

Efficient Process for the Production of Alkyl Esters.

This article reports a scalable process development for the production of alkyl esters through the esterification route by utilizing fly ash as a catalyst. The catalyst consisting of mixed oxides such as alumina, iron oxide, calcium oxide, magnesium oxide, and silica was employed for the esterification reaction without modification. The catalyst was evaluated for the conversion of feedstock containing variable amounts of free fatty acids, mono/dibasic acid, and alcohol/polyols into the corresponding alkyl esters. Three types of fly ash catalysts, viz., FS-1, FP-1, and FC-1, were chosen from three different industrial sources. Synthesis of dimethyl adipate was studied as a model reaction. FS-1 fly ash gave the highest yield of dimethyl adipate, whereas FC-1 gave a low yield of dimethyl adipate. The recyclability of FS-1 was evaluated for three cycles, and no loss of yield was observed. Furthermore, the catalyst FS-I was found to be capable of producing good yields for various esterification reactions with different substrates.

Alcohol acyl transferase genes at a high-flavor intensity locus contribute to ester biosynthesis in kiwifruit.

Volatile esters are key compounds contributing to flavor intensity in commonly consumed fruits including apple (Malus domestica), strawberry (Fragaria spp.), and banana (Musa sapientum). In kiwifruit (Actinidia spp.), ethyl butanoate and other esters have been proposed to contribute fruity, sweet notes to commercial cultivars. Here, we investigated the genetic basis for ester production in Actinidia in an A. chinensis mapping population (AcMPO). A major quantitative trait loci for the production of multiple esters was identified at the high-flavor intensity (HiFI) locus on chromosome 20. This locus co-located with eight tandemly arrayed alcohol acyl transferase genes in the Red5 genome that were expressed in a ripening-specific fashion that corresponded with ester production. Biochemical characterization suggested two genes at the HiFI locus, alcohol acyl transferase 16-b/c (AT16-MPb/c), probably contributed most to the production of ethyl butanoate. A third gene, AT16-MPa, probably contributed more to hexyl butanoate and butyl hexanoate production, two esters that segregated in AcMPO. Sensory analysis of AcMPO indicated that fruit from segregating lines with high ester concentrations were more commonly described as being "fruity" as opposed to "beany". The downregulation of AT16-MPa-c by RNAi reduced ester production in ripe "Hort16A" fruit by >90%. Gas chromatography-olfactometry indicated the loss of the major "fruity" notes contributed by ethyl butanoate. A comparison of unimproved Actinidia germplasm with those of commercial cultivars indicated that the selection of fruit with high concentrations of alkyl esters (but not green note aldehydes) was probably an important selection trait in kiwifruit cultivation. Understanding ester production at the HiFI locus is a critical step toward maintaining and improving flavor intensity in kiwifruit.

Production of biodiesel and water conservation through conversion of free fatty acids from a domestic wastewater drain

ABSTRACT Wastewater discharge from restaurants, hotels, household kitchens, confectionaries, meat, fruits, and vegetable processing units contain free fatty acids (FFAs) from fats, oils, and greases (FOG). These FFAs are one of the major causes of sewer overflows and blockages that cause health and environmental issues. This study has investigated the use of sewer wastewater as a source of lipids for the production of alkyl esters (Biodiesel) and provides a characterization of the resulting processed water. Amberlyst A21 basic resin in a column reactor was used to recover the FFAs by adsorption from an oily layer collected from the domestic wastewater drain (Chakri drain, Rawalpindi, Pakistan) having a 33.0 ± 2.08% oily fraction with 59.7 ± 1.1% FFAs. The recovered ethanol washed FFAs from the Amberlyst A21 surface were then turned into Fatty Acid Ethyl Esters (FAEEs) in the presence of an acidic resin catalyst Amberlyst 15. The esterification reaction was studied at temperatures 50, 60, and 70°C, molar ratios of 1:2 to 1:3, acidic resin weight % of 2 to 6, and reaction time of 2 to 8 hr, respectively. A maximum FFAs conversion into esters of 91.38 ± 1.13% was noted at an esterification temperature of 70°C, molar ratio of 1:3, acidic resin weight of 6%, and a reaction time of 8 h. The fractional distillation of the esterified reaction product at 100°C improved the ester content in the reaction mixture up to 96.6 ± 0.18%, with a distilled biodiesel yield of 95.52 ± 0.21%. The collected top oily layer from sewer drain wastewater was found to have a density 947.31 kg/m3, kinematic viscosity 32.69 mm2/sec, flash point 283°C, and LHV and HHV of 26 and 28 MJ/kg, respectively, while for the produced biodiesel the density was 886 kg/m3, kinematic viscosity 4.3 mm2/sec, flash point 137°C, and LHV and HHV of 39 and 41 MJ/kg was noted, respectively. Only oily layer free wastewater after passing through PAC was found to meet Pakistan NEQS, with COD <150 mg/L, pH 6–8, Alkalinity <1000 mg/L, and Ammonia-nitrogen <40 mg/L. For every 1000 gallons of domestic sewer drain wastewater treated per 8 h work shift or 3 work shifts in a day with FFAs recovered and their conversion into biodiesel, a net profit of 54.89 and 93.32 million Pakistani rupees can be gained in the first year and then in successive years, respectively. Thus, this research provides a way to produce renewable energy fuel, biodiesel from the waste lipids (FFAs) of wastewater drains to meet the energy requirements and a solution for the conservation of water bodies.

Structure‐guided preparation of fuctional oil rich in 1,3‐diacylglycerols and linoleic acid from Camellia oil by combi‐lipase

Diacylglycerol (DAG)-enriched oil has been attracting attention because of its nutritional benefits and biological functions, although the composition of its various free fatty acids (FFAs) and an unclear relationship between substrate and yield make it difficult to be identified and qualified with respect to its production. In the present study, linoleic acid-enriched diacylglycerol (LA-DAG) was synthesized and enriched from Camellia oil by the esterification process using the combi-lipase Lipozyme TL IM/RM IM system. The relationship between FFA composition and DAG species productivity was revealed. The results showed that heterogeneous FFA with a major constituent (more than 50%) exhibited higher DAG productivity and inhibited triacylglycerol productivity compared to homogeneous constituents. Joint characterization by high-performance liquid chromatography-evaporative light scattering detection, gas chromatography-mass spectrometry and ultra-performance liquid chromatography-heated electrospray ionization-tandem mass spectrometry identified that DAG components contained dilinoleic acid acyl glyceride, linoleyl-oleyl glyceride and dioleic acid acyl glyceride in esterification products. Under the optimum conditions, 60.4% 1,3-DAG and 61.3% LA-DAG in the crude product at 1h reaction were obtained, and further purified to 81.7% LA-DAG and 94.7% DAG via silica column chromatography. The present study provides a guideline for the identification of DAG species, as well as a structure-guided preparation method of DAG-enriched oils via the cost-effective combi-lipase. © 2022 Society of Chemical Industry.

Genome sequencing and oenologically relevant traits of the Uruguayan native yeast &lt;i&gt;Issatchenkia terricola&lt;/i&gt;

Issatchenkia terricola 0621 is a non-Saccharomyces yeast strain isolated from Tannat grapes from Uruguayan vineyards; it stands out for its ability to produce high levels of β-glucosidase activity, which contributes to the aromatic complexity of wines. To delve into the potential oenological applications of this strain, its high-quality genome was obtained and explored, allowing the main central carbon and nitrogen metabolic pathways to be reconstructed. I. terricola is able to utilise glycerol as the sole carbon source in a way that has not previously been described for yeasts. The genes of the fermentome and those involved in stress resistance during winemaking were also identified, and differences were found when compared to S. cerevisiae, which may explain why I. terricola is unable to complete fermentation. The pathways responsible for natural aroma synthesis were also reconstructed, and the production of aromatic acids, alcohols, esters, acetates and lactones was verified experimentally. Finally, sequences encoding for β-glucosidases, in addition to the previously characterised one, were identified in the genome. The work presented here lays the groundwork for experimental research focused on the dissection of the metabolism of a native non-Saccharomyces strain and its application for oenological and biotechnological purposes.