High Ester Content Research Articles

Chemical and sensory characteristics of lingonberry (Vaccinium vitis-idaea) alcoholic beverages produced using Saccharomyces cerevisiae, Torulaspora delbrueckii and Metschnikowia pulcherrima yeasts

Even though lingonberry (Vaccinium vitis-idaea) is categorised as a superfruit due to its bioactive composition, its challenging flavour profile leads to difficulty in valorisation. In addition, fermentation of lingonberry is limited due to presence of the antimicrobial benzoic acid. This study employed baker’s yeast mediated benzoic acid decrease, followed by conventional (Saccharomyces cerevisiae) and non-conventional (Torulaspora delbrueckii and Metschnikowia pulcherrima) fermentation to produce alcoholic lingonberry beverages. Profiling of the lingonberry alcoholic beverages was done through characterisation of volatile compounds with GC-MS and of sensory properties with a semi-trained panel. The benzoic acid decrement step was successful in reducing the content from 0.66 g/L to 0.04 g/L. Alcoholic beverages were created with an average alcohol content of 7.34% (±0.26). There were increments in the ester- and alcohol- odours alongside a decrease in the original lingonberry flavour. This was supported by higher contents of esters and higher alcohols along with a decrease of certain terpenes in alcoholic beverages. All alcoholic beverages were perceived as notably sour and thus, only minor differences were observed between the used yeasts. In particular, M. pulcherrima yeast produced a sweeter and less sour alcoholic beverage compared to the original juice. Overall, benzoic acid reduction facilitates in yeast fermentation to improve market potential of the underutilised berry in alcoholic beverage production.

Formation of esters by the Baeyer–Villiger reaction during oxidation of 1-chlorohexadecane with air oxygen in the presence of cobalt hydroxystearate– N-hydroxyphthalimide catalytic system

To obtain multifunctional additives for the processing of polyvinyl chloride, the process of oxidation of 1-chlorohexadecane with atmospheric oxygen in the presence of the catalytic system cobalt hydroxystearate– N-hydroxyphthalimide was studied. It was found that the ongoing Baeyer–Villiger reaction with the participation of hydroperoxides leads to a high content of esters in the oxidate, which improves the plasticizing effect of the resulting additives.

Correlation between the Characteristic Flavour and Microbial Community of Xuanwei Ham after Ripening

Xuanwei ham is a traditional fermented meat product in China with a unique production process and excellent-quality reputation at home and abroad. To reveal the microbial community succession of Xuanwei ham at different post-ripening times (W1-4) and its relationship with flavour formation, the microbial community, free amino acids, and volatile flavour compounds (VOCs) were analysed by high-throughput sequencing, liquid chromatography (LC), and gas chromatography–mass spectrometry (GC-MS), respectively. A total of 25 free amino acids were detected, among which W3 contained the fewest, and most were generally lower than in hams in the other three years. Fifty-nine VOCs were detected, among which 17 were esters, and the highest ester content was found in W4. Analysis of the bacterial community composition revealed that the bacterial community composition of ham samples from W3 and other years differed greatly, and at the gate level, the dominant bacterial group of Xuanwei ham from different years was Pseudomonadota. At the genus level, the most abundant genera in W1, W2, and W4 were all dominated by Sarocladium, Klebsiella, and Vibrio, with Klebsiella being the most abundant in W1. The most abundant genus in W3 was Vibrio, and the second most dominant genera were Sarocladium and Gammaretrovirus. In short, this study provides a theoretical basis for the storage, quality, and improvement of Xuanwei ham.

Mexican Coccoloba uvifera L. Leaf and Fruit Extracts: Identification of Pentacyclic Triterpenes and Volatile Profile by GC-MS.

Mexican Coccoloba uvifera fruit contains polyphenols, flavonoids, and anthocyanins, while in the leaves, lupeol, α- and β-amyrin have been previously identified by HPLC. However, the low resolution by HPLC of pentacyclic triterpenes (PTs) is a limitation. Moreover, the volatile profile of C. uvifera fruit is still unknown. Therefore, this study aimed to identify PTs in C. uvifera leaf and fruit extracts by CG-MS analysis and to determine the volatile profile of C. uvifera pulp by headspace solid-phase microextraction. The results showed trimethylsilylated compounds of standards lupeol, α- and β-amyrin, indicating that the silylation reaction was suitable. These trimethylsilylated compounds were identified in leaf and fruit extracts. The fruit volatile profile revealed the presence of 278 esters, 20 terpenes, 9 aldehydes, 5 alcohols, and 4 ketones. The fruit showed a high content of esters and terpenes. Due to their flavour properties, esters are essential for the food, cosmetics, and pharmaceutics industries. Moreover, terpenes in the fruit, such as menthone, β-elemene, junipene, and β-caryophyllene have the potential as anticancer and phytopathogen agents. The results indicated that GC-MS is an alternative to HPLC approaches for identifying PTs. Besides, identifying volatile compounds in the fruit will increase the value of this plant and expand its application. Identifying PTs and volatile compounds in Mexican C. uvifera leads to a better understanding of the potential benefits of this plant. This would increase the consumption of Mexican C. uvifera fresh or as functional ingredients in nutraceutical or pharmaceutical products.

Effect of co-inoculation of Saccharomyces and non-Saccharomyces yeasts and nutrients addition during malolactic fermentation on apple cider composition

Apple cider production is a complex fermentation process that involves the conversion of apple juice into cider through the actions of yeast and malolactic bacteria. This study aimed to investigate the effects of the co-inoculation of Saccharomyces and non-Saccharomyces yeasts, as well as nutrient supplementation in the presence of malolactic bacteria Oenoccocus oeni on the composition of apple cider. The amino acid profile of the samples was not significantly influenced by the addition of lactic bacteria or nutrients in cider processing. The highest ester content was recorded in the single yeast strain fermented ciders (55.32%–88.13%). This increase was visible also for the malolactic ciders, independent from nutrient supplementation. Co-inoculated Saccharomyces and Torulaspora delbrueckii ciders showed increased higher alcohols contents, both after the alcoholic (42.66%–53.51%) and malolactic fermentations (42.81%–65.94%). Following the hydroxycynnamic acids class (141.47–327.44 mg/L), flavonoids (114.81–253.44 mg/L) were the second most abundant class of phenolic compounds in ciders, which generally registered a considerable increase following malolactic fermentation. The sour/acidic taste was the most prevalent sensory attribute of the cider. Lower values were recorded for sweet, bitter, and astringent. The strongest apple aroma was perceived in the co-inoculated Saccharomyces and T. delbrueckii yeast strains. The co-fermentation of Saccharomyces and Torulaspora delbrueckii yeasts led to increased levels of desirable aroma compounds, contributing to a more complex and appealing sensory profile, while the nutrient supplementation provided an improved malolactic fermentation efficiency and overall cider quality.

Impact of Pure, Co-, and Sequential Fermentations with Hanseniaspora sp. and Saccharomyces cerevisiae on the Volatile Compounds of Ciders

Pure, co-, and sequential fermentations of Hanseniaspora uvarum, H. guilliermondii, and Saccharomyces cerevisiae strains were evaluated to improve the aromatic quality of ciders. In sequential fermentations, Hanseniaspora strains were used as starter, followed by S. cerevisiae inoculation succeeding one, two, and three days of fermentation. Kinetics, physicochemical parameters, and volatile compounds were assessed during 10 days of fermentation. The headspace technique was used to capture the volatile compounds from the ciders obtained in each experiment and analyzed by gas chromatography. Fermentations with pure strains of Hansenisaspora sp. showed a high population (>1010 CFU/mL) but had a low fermentation rate (2.3–3.8 CO2 g/L/d), low consumption of amino acids (20–40 mg/L) with a high residual content, high sugar consumption (80–90 g/L), and low alcohol content (<2.0% v/v). The H. uvarum strain produced a notably high ester content (245 mg/L). In the co-fermentations, H. guilliermondii with S. cerevisiae highlighted a significant production of higher alcohols, similar to that produced by S. cerevisiae alone (152–165 mg/L). In general, the maximum fermentation rate of the sequential inoculations was lower than co-fermentations but showed low residual nitrogen content (<69 mg/L) and good conversion of sugars into ethanol (4.3–5.7% v/v). The highest concentrations of volatile compounds were observed in treatments involving the two non-conventional strains: H. uvarum with S. cerevisiae inoculation after three days (564 mg/L) and H. guilliermondii after just one day (531 mg/L) of fermentation. These differences stemmed from the metabolic activity of the strains. H. uvarum was influenced by the presence of Saccharomyces, whereas H. guilliermondii did not exhibit this effect. Thus, a pure H. uvarum inoculum has the potential to produce a demi-sec cider with low alcohol content and high content of esters, contributing to a fruity aroma. In addition, ciders with sequential inoculation were the most promising for dry cider processing concerning fermentation parameters and bioaroma enrichment.

In situ Transesterification of Crambe Seeds with Dimethyl Carbonate Using an Enzymatic Catalyst

In situ transesterification of crambe seeds oil was investigated to produce fatty acid methyl esters using dimethyl carbonate as acyl acceptor and lipase Novozyme 435® as the catalyst. First, the effects of solvent-to-seeds ratio, seed pretreatment, and extraction time were evaluated on the seed oil removal, comparing the results with conventional Soxhlet extraction. Then, the effects of enzyme loading (5 to 30 wt.% based on the oil mass) and reaction time (60 to 540 min) were evaluated on the simultaneous extraction and reaction. The highest oil extraction yield (ca. 26 wt.%) was achieved at the solvent-to-seeds ratio of 6 mL g-1 and 360 min. The oil obtained from seeds that received thermal pretreatment showed a higher concentration of minor compounds. The highest ester content (76.71 wt.%) was obtained with an enzyme loading of 20 wt.%, solvent-to-seeds ratio of 6 mL g-1, for 480 min. The reaction samples showed a predominance of erucate and oleate esters, with identification of the co-products formation (glycerol carbonate and glycerol dicarbonate), and ca. 5 wt.% of acylglycerols.

БИОХИМИЧЕСКИЕ И ТЕХНОЛОГИЧЕСКИЕ ОСОБЕННОСТИ СОРТОВ, ФОРМ И КЛОНОВ ВИНОГРАДА СЕЛЕКЦИИ ФГБНУ СКФНЦСВВ

The current area of research is a comprehensive study of varieties, forms and clones of local breeding for a reasonable selection of modern varieties. The aim of the study was to study the biochemical and technological characteristics of varieties, forms and clones of grapes bred by NCFSCHVW in the edaphoclimatic conditions of the Kuban. The objects of research were varieties, forms, clones of the NCFSCHVW breeding (9 white-berry, 11 dark-berry and 4 control varieties), as well as fresh grape must and dry wine materials obtained from them. Wine materials were prepared according to classical technologies for low-oxidized white wines and red wines with a «floating cap». The mass concentrations of sugars and titratable acids were determined in the must. Physicochemical and organoleptic characteristics, indicators, composition of aroma-forming components and individual organic acids were determined in wine materials. A complex of phenolic substances, vitamins and vitamin-like substances was studied in red wine materials. It was established that the must of the studied samples had moderate mass concentrations of sugars and titratable acids: white berry 19.1-22.5 g/100 cm3 and 7.6-8.3 g/dm3 , respectively; dark berries 20.2-24.4 g/100 cm3 and 6.8-8.0 g/dm3 , respectively. It was noted that the group of Tana forms was distinguished by a higher volume fraction of ethyl alcohol of 11.8-12.5 % vol. In a sample of dry wine material Tana 95, a higher content of esters (89.8 mg/dm3 ) was noted, among red ones – in wine materials Tana 33 (116.8 mg/dm3 ), Kurchanskiy (100.1 mg/dm3 ) and Cabernet Kuban (105.2 mg/dm3 ). The mass concentration of higher alcohols in dry wine materials from the white berry forms of Tana (295.9-349.8 mg/dm3 ) exceeded the classic varieties and proto-clones from the Chardonnay and Riesling lines (192.6-264.4 mg/dm3 ). Vladimir stood out by the amount of phenolic substances (3603 mg/dm3 ), Tana 85 distinguished according to the accumulation of anthocyanins. Kurchanskiy, Vladimir and Tana 85 were isolated according to the amount of vitamins and vitamin-like substances.

Liquefaction of Waste Rendering Fat Using Iron‐Containing Catalysts

AbstractWaste rendering fat (WRF) is a solid residuum from rendering plants. WRF is inedible, even for animals, a mixture of lipids with a high content of (mono‐, di‐, tri‐) glycerol esters and free fatty acids. This study focuses on catalytic liquefaction and deoxygenation of WRF with four different iron‐based catalysts, namely, commercial Fe2O3 and three laboratory‐prepared alkali‐activated zeolite foams different in the iron precursor used for impregnation. Three various reaction times were tested. Laboratory‐prepared catalysts enabled a better yield of organic liquid than commercial ones. All catalysts had a positive efficiency of deoxygenation at all reaction times. The combination of Fe(II) and Fe(III) during the catalyst preparation had a beneficial effect.

Retention of high-value tocols during enzymatic esterification of palm fatty acid distillate using liquid lipase for improving the economics and sustainability of biodiesel production

Liquid lipase has recently been gaining popularity in converting secondary lipid feedstocks to biodiesel. However, it was unknown whether enzymatic biodiesel production could affect the retention of high-value phytonutrient(s) in the feedstocks. For the first time, the retention of tocols (a highly potent antioxidant) during enzymatic conversion of palm fatty acid distillate (PFAD) to biodiesel using a low-cost liquid lipase, Eversa® Transform 2.0, was studied. This study investigated the effects of methanol dosage on ester and fatty acid contents alongside tocols retention. The highest ester content (92.03 wt%) was achieved within a short reaction time of 4 h using 2 wt% enzyme concentration and 3:1 methanol-to-PFAD molar ratio. Interestingly, tocols retention was found to be correlated to the extent of fatty acid conversion. The maximum tocols retention was determined to be 91.98%. After vacuum distillation, the tocols content was enriched 25-fold (∼66,000 ppm) in the heavy phase, whereas the ester content increased to ∼96 wt% in a light-colored distillate (biodiesel). In conclusion, it is feasible to efficiently produce high-value phytonutrient(s) alongside biodiesel from secondary feedstock via an enzymatic route using a liquid lipase. The findings from this work provide the industry an opportunity to improve process economics and sustainability of biodiesel production.

Flavor characteristics of hulless barley wine fermented with mixed starters by molds and yeasts isolated from Jiuqu

The traditional natural Jiuqu for brewing hulless barley wine contains a variety of complex microorganisms and enzymes. The uncertainty of microbial composition in Jiuqu and the existence of some miscellaneous microorganisms are not conducive to the production of high-quality hulless barley wine. In order to improve the flavor quality of hulless barley wine, the mixed starter was designed to reconstruct the fermentation microbial flora. Mold strains with high saccharification ability and yeast strains with good fermentation performance were screened from the traditional natural Jiuqu for brewing hulless barley wine and were identified. And then, mixed starters by molds and yeasts were used to ferment hulless barley wines on a laboratory scale. The physicochemical indexes, sensory evaluation, volatile flavor compounds and electronic nose (E-nose) analysis of hulless barley wine brewed by different combinations of mold and yeast were analyzed. The hulless barley wine (W4 wine) brewed by the mixed starter Q4, which combined by Rhizopus oryzae, Saccharomyces cerevisiae and Wickerhamomyces anomalus, had the best volatile flavor and sensory score. This improvement was mainly reflected in the higher content of esters (252.62 ± 0.02 mg/L) and alcohols (72.77 ± 2.03 mg/L), with esters accounting for 67.37 % of the volatile flavor compounds. In addition, the sensory score of "bitter" was the lowest in W4 wine while the scores of "sweet", "wine-aroma" and "fruit-aroma" were the highest. These results demonstrated that the mixed starter Q4 could effectively improve the flavor of hulless barley wine.

Tissue-Specific Recovery Capability of Aroma Biosynthesis in ‘Golden Delicious’ Apple Fruit after Low Oxygen Storage

The impact of low-oxygen (2 kPa) controlled atmosphere storage on the recovery of aroma biosynthesis in ‘Golden Delicious’ (GD) apple tissues during their subsequent shelf life was investigated. The results showed that the highest ester content was found in skin tissue, followed by Flesh 2 and Flesh 1. The 2 kPa O2 storage of GD apples resulted in a decrease in the emission of volatile esters and alcohols, but an increase in aldehyde emission. Notably, compared with skin tissue, the flesh tissue of 2 kPa O2-stored GD apples had a relatively high recovery capacity of ester biosynthesis but a low recovery capacity of alcohol synthesis for its shelf life. The impact was associated with increased levels in the MdLOX1a and MdAATs (MdAAT1 and MdAAT2) transcripts, as well as a decreased level in the MdHPL transcript in the flesh tissue. In addition, a complex regulatory network of ethylene on fruit aroma biosynthesis in response to low-oxygen conditions was also indicated. Collectively, there was a tissue-specific recovery capability of aroma biosynthesis in GD apples after low-oxygen storage.

Correlation between the chemical, microbiological and sensory characteristics of cream cheese using a mixed and single probiotic culture.

The use of mixed culture in the fermentation industry requires more complicated equipment, processes, and monitoring systems; therefore, a single culture may be preferable. This study aimed to investigate the correlation between chemical and microbiological properties and sensory characteristics. In addition, this study aimed to determine the different characteristics of cheese made using single probiotic cultures of Lactobacillus plantarum Dad-13 and Lactobacillus plantarum Kita-3 and mixed culture. The obtained results showed that the chemical characteristics of cream cheese made using single cultures were similar to those of cream cheese made using mixed cultures. The viability of the cells remained high after 35 days of storage for the single culture, which was not the case for the mixed culture. In terms of sensory analysis, cream cheese made using the single culture L. plantarum Kita-3 showed higher overall liking score among the samples, which might correlate with the high ester and ketone content. In addition, there was a strong relationship between the ethyl octanoate and methyl butanol contents and the overall liking score. The results of this study showed that the use of a single culture of L. plantarum Kita-3 could improve the sensory characteristics of cream cheese with probiotic properties. This study also contributed to the development of cream cheese production, particularly in the screening of potential starters.

Comparative evaluation of the microbial diversity and metabolite profiles of Japanese-style and Cantonese-style soy sauce fermentation.

Microorganisms play essential roles in flavor formation during soy sauce fermentation. Different soy sauce fermentation types significantly affect flavor formation. However, comparisons of microbial communities and metabolites between different fermentation types have been little studied. Here, we investigated variation in microbial communities, metabolite profiles, and metabolic pathways during Japanese-type (JP) and Cantonese-type (CP) fermentation. Free amino acids and volatile compound profiles varied significantly between fermentation types, with JP samples containing higher contents of esters (39.84%; p < 0.05), alcohols (44.70%; p < 0.05) in the 120 d fermentation samples. Volatile compound profiles varied significantly between fermentation types, with JP samples containing higher contents of esters, alcohols, and free amino acids (p < 0.05). Metagenomic analysis indicated that both JP and CP communities were dominated by Tetragenococcus, Staphylococcus, Weissella (bacteria), and Aspergillus (fungi), but the two communities varied differently over time. Tetragenococcus drastically increased in abundance throughout the fermentation (from 0.02 to 59.2%) in JP fermentation, whereas Tetragenococcus (36.7%) and Staphylococcus (29.7%) dominated at 120 d of fermentation in CP fermentation. Metagenomic functional profiles revealed that the abundances of most genes involved with carbohydrate, amino acid, and lipid metabolism exhibited significant differences between fermentation types (p < 0.05) during the middle to late fermentation stages. Furthermore, predicted metabolic pathways for volatile substance biosynthesis differed between JP and CP fermentation, likely explaining the differences in flavor metabolite profiles. In addition, most of the genes associated with flavor generation were affiliated with Tetragenococcus, Weissella, Staphylococcus, Bacillus, and Aspergillus, suggesting that these microbes play important roles in flavor production during soy sauce fermentation. This study significantly improves our understanding of microbial functions and their metabolic roles in flavor formation during different soy sauce fermentation processes.

Attached microalgae converting spent coffee ground into lipid for biodiesel production and sequestering atmospheric CO2 simultaneously

The impacts of simultaneous exposures of arbitrary light intensities and photoperiods on attached Chlorella vulgaris microalgal growth onto spent coffee ground (SCG) were studied, and subsequently optimized using Response Surface Methodology (RSM) tool. The statistical analysis revealed the optimum light intensity and photoperiod were achieved at 100 μmol/m2s and 20:4 dark:light hours/cycle, respectively, producing microalgal density of 0.358 g/g and lipid productivity of 16.8 mg/Lday. The biodiesel yielded from the optimum condition possessed high cetane number and oxidative stability due to the high saturated fatty acid methyl esters (FAME) content of 63.7 %. In fact, the major FAME compositions ranged within C16 to C18 which were favourable for quality biodiesel production. Furthermore, the viability of SCG to serve as a carbon source was also evidenced by the high productivities of microalgal protein and carbohydrate at 94 and 168 mg/L day, respectively. The capability of attached microalgal cultivation in sequestering atmospheric CO2 was finally unveiled, with high CO2 capture rate being recorded at 9.38 mg/L h. Accordingly, growing attached microalgae onto SCG was recognized as an alternative approach for sustainable CO2 reduction, while producing green diesel to assuage the global warming phenomenon.

Effect of Strobilanthes tonkinensis Lindau Addition on Black Tea Flavor Quality and Volatile Metabolite Content.

The characteristic aroma of Chinese black tea (BT) produced in summer usually lacks intensity and persistence, reducing consumer acceptance and market demand. Strobilanthes tonkinensis Lindau (STL) possesses excellent biological characteristics, making it a promising novel tea ingredient. We investigated the effects of different addition methods and concentrations for the novel additive STL on the sensory quality of BT. A 20:1500 g/g addition to rolled tea leaves was identified as the best BT with STL (BoS) treatment. We identified 141 volatile metabolites (VMs) for the first time in STL, with high alcohol, ester, ketone, enyne, alkyne, and alkane contents. Partial least-squares discriminant analysis distinguished the samples and revealed 28, 26, and 14 differential VMs in STL vs. BoS, BT vs. STL, and BT vs. BoS comparisons, respectively. Using a combination of Venn, multiple experiment viewer, and odor activity value analysis, 16 key differential VMs were identified. Compared to BT, the 1-octen-3-ol, 1-hexanol, 1-dodecanol, (E)-3-hexen-1-ol, phenylethyl alcohol, and 2-methoxy-3-(2-methylpropyl)-pyrazine contents in BoS were 394.7%, 53.6%, 34.1%, 24.4%, 9.9%, and 5.7% higher, respectively. BoS combined the aromatic properties of BT and STL into a sweet and glutinous rice flavor. The results provide theoretical support for future research and development of novel BT-based products.

Fungal Fermented Palm Kernel Expeller as Feed for Black Soldier Fly Larvae in Producing Protein and Biodiesel.

Being the second-largest country in the production of palm oil, Malaysia has a massive amount of palm kernel expeller (PKE) leftover. For that purpose, black soldier fly larvae (BSFL) are thus employed in this study to valorize the PKE waste. More specifically, this work elucidated the effects of the pre-fermentation of PKE via different amounts of Rhizopus oligosporus to enhance PKE palatability for the feeding of BSFL. The results showed that fermentation successfully enriched the raw PKE and thus contributed to the better growth of BSFL. BSFL grew to be 34% heavier at the optimum inoculum volume of 0.5 mL/10 g dry weight of PKE as compared to the control. Meanwhile, excessive fungal inoculum induced competition between BSFL and R. oligosporus, resulting in a reduction in BSFL weight. Under optimum feeding conditions, BSFL also registered the highest lipid yield (24.7%) and protein yield (44.5%). The biodiesel derived from BSFL lipid had also shown good compliance with the European biodiesel standard EN 14214. The high saturated fatty acid methyl esters (FAMEs) content (C12:0, C14:0, C16:0) in derived biodiesel made it highly oxidatively stable. Lastly, the superior degradation rate of PKE executed by BSFL further underpinned the sustainable conversion process in attaining valuable larval bioproducts.

Fatty acid ethyl esters production from distillers corn oil by enzymatic catalysis

AbstractDistillers corn oil (DCO), a by‐product from the corn ethanol production, is an alternative source of glycerides to produce biodiesel. In the present work, this feedstock was enzymatically converted into fatty acid ethyl esters (FAEE). DCO presented relative density of 0.912 g/cm3, peroxide index of 3.05 ± 0.3 (meq/1000 g of sample) and acidity of 13.1 ± 1.96 (wt.%), with prevalence of the oleic (18:1) and linoleic (18:2) acids (sum equal to 76.9%). Three strategies were evaluated to improve the FAEE content: ethanol stepwise addition (ethanol:oil molar ratio of 4:1 (1/2 of ethanol at 0 and 1.5 h) and 3:1 (1/3 of ethanol at 0 h and 2/3 at 1.5 h or 1/3 of ethanol at 0, 1 and 2 h)); consecutive reactions (with Novozym 40086 [Rhizomucor miehei lipase] as biocatalyst); and mixture of enzymes (Novozym 40086 (6 wt.%) + Novozym 435 (Candida antarctica B lipase) (2 wt.%). The concept of combi‐lipases was evaluated for the first time using this raw material, resulting in a high ester content (&gt;96%). The higher ester yields attained with DCO, compared to refined corn oil (33%) can be related to the better solubilization of ethanol and/or glycerol by‐product in the medium with DCO. The combi‐lipase system kept high than 80% of this initial activity after three repeated batches of reaction. The use of DCO enables the integration of corn ethanol and biodiesel production within the same general facility, which has logistic, environmental and, economic relevance.

Microbial communities and flavor formation in the fermentation of Chinese strong-flavor Baijiu produced from old and new Zaopei

Differences between the old and young pit mud in a pit cellar enlarged differences in Zaopei (ZP) fermentation to varying degrees, ultimately affecting the aromatic quality of the Baijiu that is produced. The whole fermentation process could be divided into two phases, namely phase I (0_15 days) and phase II (25_40 days) based on the dynamics of the diversity of microbial communities. Starch and reducing sugar in phase I were used more rapidly by microflora, leading to a higher ethanol production in ZP within an old pit mud (OZP) and a higher acidity in ZP within a new pit mud (NZP), and resulting in different microbial succession patterns therein. Lactobacillus became the dominant bacteria more rapidly in OZP but maintained its abundance in NZP. Monascus and Trichosporon were the unique dominant functional fungi observed in the phase II of OZP. Two bacterial and six fungal genera were identified as core functional microorganisms linked to the variations in volatile metabolites during the fermentation process, ultimately resulting in a higher ester content in OZP and improved liquor quality. This study demonstrated the effect of new and old pit muds on ZP fermentation, and its findings can guide the future artificial regulation of NZP.

Multi-objective tailored optimization deciphering carbon partitioning and metabolomic tuning in response to elevated CO2 levels, organic carbon and sparging period.

Microalgae have garnered much contemplation as candidates to fix CO2 into valuable compounds. Although microalgae have been studied to produce various metabolites, they have not yet proved successful for commercialization. Since, handling such problems practically requires satisfying multiple parameters simultaneously, we put forth a multi-parameter optimization strategy to manipulate the carbon metabolism of Scenedesmus sp. to improve biomass production and enhance CO2 fixation to increase the production of fuel-related metabolites. The Box-Behnken design method was applied with CO2 concentration, CO2 sparging time and glucose concentration as independent variables; biomass and total fatty acid methyl ester (total FAME) content were analyzed as response variables. The strain is supplemented with both CO2 and glucose with an aim to enhance carbon flux and rechannel it towards carbon fixation. As per the results obtained in this study, Scenedesmus sp. could effectively exploit high CO2 concentration (15%) for longer duration under high concentration of glucose supplementation (9g/L) producing a biomass of 635.24±39.9μg/mL with a high total fatty acid methyl ester (FAME) content of 71.29±4.2μg/mg, significant acetyl-CoA carboxylase enzyme activity and a favorable fatty acid profile: 35.8% palmitic acid, 10.5% linoleic acid and 30.6% linolenic acid. The carbohydrate content was maximum at 10% CO2 sparged for the longest duration of 90min under glucose concentration of 9g/L. This study puts forth an optimal design that can provide evidence on comprehending the carbon assimilation mechanism to enhance production of biomass and biofuels and provide conditions to microalgal species to tolerate CO2 rich flue gas.