Search Results (28)

Dates (Phoenix dactylifera L.) are nutrient-rich fruits with health-promoting properties and broad applications in the food and beverage industries. This study analyzes the chemical properties and volatile profile of fermented date products—juice, alcoholic derivative, and vinegar—to develop a high-quality vinegar with distinct sensory traits. Using HS-SPME-GC-MS, about 50 volatile compounds were identified across six major chemical classes. Juice processing significantly increased volatile release, especially fusel alcohols and furanic aldehydes, due to thermal and mechanical disruption. Fermentation further modified the volatilome, with increased esters and acids in alcoholic and vinegar products. Vinegar was characterized by high levels of acetic acid, fatty acids, phenols, and acetoin (855 mg/L), indicating active microbial metabolism. Ethanol and acidity levels met international standards. Total phenolic content rose from juice (138 mg/L) to vinegar (181 mg/L), reflecting microbial enzymatic activity and acid-driven extraction. These results highlight the metabolic complexity, sensory richness, and functional potential of date-derived fermented products while promoting sustainable use of underutilized fruit resources. Full article

The production of spirits generates significant amounts of waste in the form of fusel oils-previously treated mainly as an environmental problem. This paper presents an innovative installation designed to recover valuable components from this difficult waste. The key achievement is the effective separation and recovery of pyrazine derivatives-natural aromatic compounds with high utility value in the food, cosmetics and pharmaceutical industries. The designed system allows for the recovery of as much as 98% of pyrazines and isoamyl alcohol and isobutanol fractions with a purity above 96%, which is a significant advance compared to previous disposal methods. The installation was designed to be consistent with the idea of a circular economy, maximizing the use of by-products and minimizing losses. The results of the work indicate that fusel oils, previously perceived as waste, can become a source of valuable secondary raw materials, and the presented solution opens up new possibilities for the sustainable development of the alcohol industry. Full article

Fruit brandy equipment commonly uses partial condensation (dephlegmation) to generate reflux in the distillation column. Here, we examined the effect of dephlegmation on the composition of fruit brandies in both lab-scale and large-scale settings. In lab-scale experiments, the dephlegmator led to a pronounced enrichment of ethanol in the distillate due to preferred condensation of water, while the concentration of flavor compounds was differentially affected. Some compounds were enriched in the distillate, some were depleted, and some were unaffected by dephlegmation compared with the control without a dephlegmator. Large-scale fruit brandy equipment relying exclusively on dephlegmation was compared as standard with an enrichment section containing three trays. In the equipment relying on dephlegmation, tail components such as fusel alcohols were less well separated from the middle run, which led to a reduced yield of clean spirit in the middle run. In triangle tests, the spirits from the two devices could be clearly differentiated, but there was no clear preference for one spirit or the other. This study provides for the first time detailed data on the influence of dephlegmators on the behavior of flavor compounds during fruit brandy distillation. Full article

Ethanol production by fermentation results in obtaining, in addition to the main product, ethyl alcohol, by-products and secondary products, which include carbon dioxide, fusel oil, and ester–aldehyde cut. Fusel oil, despite its low yield and the large volume of ethanol production, accumulates at distilleries, which ultimately raises the question of its disposal or the rational use of this by-product. Fusel oil, being a complex mixture, can serve as a source of technical alcohols used in various sectors of the economy, including the food industry, pharmaceuticals, organic synthesis, perfume, and cosmetics industries, as well as the production of paints and varnishes. However, the complexity of using fusel oil lies in its difficult separation. The reason for this is the presence of water, which forms low-boiling azeotropes with aliphatic alcohols. Our study aimed to develop a process flow diagram (PFD) that allows individual components from fusel oil to be obtained without extraneous separating agents (not inherent in fusel oil). This condition is necessary to obtain products labeled as natural for further use in the food, perfume, cosmetic, and pharmaceutical industries. The distinctive feature of this work is that the target product is not only isoamyl alcohol but also all other alcohols present in the composition of fusel oil. To achieve this goal and create a mathematical model, the Aspen Plus V14 application, the Non-Random Two Liquid (NRTL) thermodynamic model, and the Vap-Liq/Liq-Liq phase equilibrium were used. Fusel oil separation was modeled using a continuous separation PFD to obtain ethanol, water, isoamyl alcohol, and raw propanol and butanol cuts. The Sorel and Barbet distillation technique was used to isolate ethanol. The isolation of isopropanol and 1-propanol, as well as isobutanol and 1-butanol, was modeled using the batch distillation method. The isolation of fusel oil components was based on their thermodynamic properties and the selection of appropriate techniques for their separation, such as extraction, distillation, pressure swing distillation, and decantation. The simulation of fusel oil separation PFD showed the possibility of obtaining the components of a complex mixture without separating agents, as discussed earlier. Ethanol corresponds to the quality of rectified ethyl alcohol, and 1-butanol and isoamyl alcohols to anhydrous alcohols, whereas isopropanol (which contains an admixture of ethanol), 1-propanol, and isobutanol are obtained as aqueous solutions of different concentrations of alcohols. However, due to a distillation boundary in the raw propanol and butanol cuts, these mixtures cannot be separated completely, which leads to the production of intermediate fractions. To eliminate intermediate fractions and obtain anhydrous isopropanol, 1-propanol, and isobutanol in the future, it is necessary to solve the dehydration problem of either fusel oil or the propanol–butanol mixture. Full article

In this research work, the feasibility of using fusel oil, a by-product of the sugar–alcohol industry, as an LVLC solvent in blends with straight vegetable oils (SVOs) and diesel was investigated. Concretely, diesel/fusel oil/sunflower oil (D/FO/SO) and diesel/fusel oil/castor oil (D/FO/CO) triple blends were prepared and characterized by measuring the most important physicochemical properties, i.e., viscosity, density, cold flow properties, flash point and cetane number. An appreciable improvement in cold flow values has been achieved with triple blends, without compromising properties such as calorific value and cetane number. Likewise, the triple blends meet the viscosity and density requirements specified by the European quality standard EN 14214 and the American standard ASTM D6751. After characterization, the triple blends were used on a diesel engine, evaluating different parameters such as power output, opacity, exhaust emissions (CO and NO_x) and consumption at different engine loads. The results indicate that as the biofuel content in the blend increases, engine power decreases while fuel consumption rises. Nevertheless, the values obtained with D/FO/CO are better than those for D/FO/SO and are also very similar to those of fossil diesel. Regarding opacity values and NO_x emissions obtained with the utilization of the triple blends, they are lower than those produced by diesel. However, in the case of CO emissions, it depends on the type of oil used, with the samples prepared with castor oil exhibiting the best results. Full article

Beauveria bassiana is an entomopathogenic fungus that parasitizes and kills insects. The role of volatile organic compounds (VOCs) emitted by B. bassiana acting as semiochemicals during its interaction with lepidopterans is poorly explored. Here, we studied the effect of VOCs from B. bassiana and 3-methylbutanol (as a single compound) on the feeding behavior of L2 larvae of Spodoptera frugiperda in sorghum plants. Additionally, we assessed whether fungal VOCs induce chemical modifications in the plants that affect larval food preferences. Metabolomic profiling of plant tissues was performed by mass spectrometry and bioassays in a dual-choice olfactometer. The results showed that the larval feeding behavior was affected by the B. bassiana strain AI2, showing that the insect response is strain-specific. Furthermore, 80 µg of 3-methylbutanol affected the number of bites. The larval feeding choice was dependent on the background context. Fragment spectra and a matching precursor ion mass of 165.882 m/z enabled the putative identification of 4-coumaric acid in sorghum leaves exposed to fungal VOCs, which may be associated with larval deterrent responses. These results provide valuable insights into the bipartite interaction of B. bassiana with lepidopterans through VOC emission, with the plant as a mediator of the interaction. Full article

In the last decade, “expressions” of grape marc spirits aged in wooden barrels of characteristic amber color and complex sensory attributes have been introduced. Yet studies on constituents migrating from the barrel to the beverage are scarce, and their metabolic profile remains unexplored. Furthermore, the literature on the assessment of their antioxidant activity is limited. NMR metabolomics and spectrophotometry have been implemented in 38 samples to elucidate the impact of the aging procedure on the metabolites’ composition and establish whether these beverages exhibit antioxidant activity. Provenance was related to fusel alcohols, esters, acetaldehyde, methanol, saccharides, and 2-phenylethanol, while ethyl acetate and ethyl lactate contributed to discriminating samples of the same winery. Identified metabolites such as vanillin, syringaldehyde, and sinapaldehyde were related to the aging procedure. The maturation in the barrel was also associated with an increase in xylose, glucose, fructose, and arabinose. The antioxidant potential of the aged Greek grape marc spirits resulting from their maturation in oak barrels was highlighted. The metabolic profiling and antioxidant potential of aged Greek grape marc spirits were assessed for the first time. Finally, the enrichment of the aromatic region was noted with the presence of metabolites with a furanic and phenolic ring derived, respectively, from the polysaccharides’ degradation or the thermal decomposition of lignin. Full article

Excessive fusel alcohols in red wine will bring an uncomfortable bitterness and generate an intoxicating effect, which affects the quality and attractivity of the red wine. In order to achieve better regulation of fusel alcohols in red wine, strains with LEU1 and PDC5 deletions were constructed, and seven engineered yeast strains based on THI3 and BAT2 deletions were applied to red wine fermentation to dissect the effects of four critical genes on fusel alcohols during wine fermentation. The fermentation results of these recombinant strains showed that the deletion of THI3 increased the contents of n-propanol, isobutanol, and isoamyl alcohol by 48.46%, 42.01%, and 7.84%, respectively; the deletion of BAT2 decreased isoamyl alcohol and isobutanol by 32.81% and 44.91%; the deletion of PDC5 and LEU1 decreased isoamyl alcohol by 40.21% and 68.28%, while increased isobutanol by 24.31% and 142%, respectively; the deletion of THI3 exerted a negative influence on the reduction of isoamyl alcohol caused by BAT2 or PDC5 deletion; the deletion of THI3 and PDC5 had a synergistic effect on the increase of isobutanol, while BAT2 and PDC5 deletion presented no additive property to the decrease of isoamyl alcohol. Hence, it is concluded that either BAT2, PDC5, or LEU1 deletion can effectively decrease fusel alcohols, especially isoamyl alcohol, which provides an important reference for the control of fusel alcohols in red wine. Full article

The baijiu spirit is often the focus of fraudulent activity due to the widely varying prices of the products. In this work, Solid Phase Microextraction Gas Chromatography (SPME GCMS), Fourier Transform Infrared (FTIR) Spectroscopy and ¹H qNMR spectroscopy were evaluated as potential methods to authenticate baijiu samples. Data were collected for 30 baijiu samples produced by seven different distilleries. The data from the SPME GCMS and FTIR methods were treated by a Principal Component Analysis to identify clusters that would suggest chemical differences in the products from different distilleries. The results suggest that SPME GCMS has the potential to be a fully portable method for baijiu authentication. FTIR did not appear suitable for authentication but can be used to find the %ABV range of the sample. ¹H quantitative NMR (¹H qNMR) was utilized to quantify the ethanol concentrations and calculate the observable congener chemistry comprising ester, ethanol, methanol, fusel alcohol, and organic acids. Discrepancies in ethanol content were observed in three samples, and a lack of major congeners in two samples indicates the possible presence of a counterfeit product. Detailed and quantitative congener chemistry is obtainable by NMR and provides a possible fingerprint analysis for the authentication and quality control of baijiu style, producer, and the length of the ageing process. Full article

Non-Saccharomyces yeasts represent a very appealing alternative to producing beers with zero or low ethanol content. The current study explores the potential of seven non-Saccharomyces yeasts to produce low-alcohol or non-alcoholic beer, in addition to engineered/selected Saccharomyces yeasts for low-alcohol production. The yeasts were first screened for their sugar consumption and ethanol production profiles, leading to the selection of strains with absent or inefficient maltose consumption and consequently with low-to-null ethanol production. The selected yeasts were then used in larger-scale fermentations for volatile and sensory evaluation. Overall, the yeasts produced beers with ethanol concentrations below 1.2% in which fusel alcohols and esters were also detected, making them eligible to produce low-alcohol beers. Among the lager beers produced in this study, beers produced using Saccharomyces yeast demonstrated a higher acceptance by taster panelists. This study demonstrates the suitability of non-conventional yeasts for producing low-alcohol or non-alcoholic beers and opens perspectives for the development of non-conventional beers. Full article

The aim of this study was to produce several flavor esters via esterification of octanoic acid with different commercial short-chain alcohols (methanol, propanol, isoamyl alcohol, hexanol and benzyl alcohol) and fusel oil in solvent-free systems. Lipase Eversa^® Transform 2.0 immobilized via mechanism of interfacial activation on poly(styrenene-divinylbenzene) (PSty-DVB) beads was used as heterogeneous biocatalyst and its catalytic performance was compared with that of the soluble lipase. The heterogeneous biocatalyst was prepared by employing 5 mmol·L⁻¹ buffer sodium acetate at pH 5.0 and 25 °C using an initial protein loading of 40 mg·g⁻¹. The maximum amount of immobilized protein reached was 31 mg·g⁻¹, corresponding to an immobilization yield of 80%. Mass transfer studies demonstrated that the lipase was preferentially adsorbed inside the pores of the support, which was confirmed by scanning electron microscopy analysis. Lipase immobilization can be described by a pseudo-first-order kinetic model via a physisorption process. When used as biocatalysts of the target reactions, the highest conversion percentage (between 65% and 85% of acid conversion after 60–90 min of reaction) values were achieved for esterification reactions catalyzed by immobilized lipase. Reusability tests revealed high retention of the original activity of the immobilized lipase after six successive batch reactions using isoamyl alcohol (47%) and fusel oil (72%). The proposed reaction systems can be considered green processes (EcoScale score above 80), with exception of methanol medium, classified as an acceptable green process (EcoScale score of 68). These results show that the heterogeneous biocatalyst prepared can be an economic and sustainable option for flavor esters production on an industrial scale. Full article

Enzymatic synthesis of short-chain esters (flavours) might enable their labelling as natural, increasing their value. Covalently immobilised Rhizopus oryzae lipase (EO-proROL) was used to synthesise isoamyl butyrate and acetate. In cyclohexane, the best performer reaction solvent, 1.8 times higher yield of isoamyl butyrate (ca. 100%) than isoamyl acetate (ca. 55%) was obtained. Optimum initial acid concentration (410 mM) and acid:alcohol mole ratio (0.5) were established by a central composite rotatable design to maximise isoamyl butyrate single-batch and cumulative production with reused enzyme. These conditions were used to scale up the esterification (150 mL) and to assess yield, initial esterification rate, productivity and enzyme operational stability. Commercial isoamyl alcohol and fusel oil results were found to be similar as regards yield (91% vs. 84%), initial reaction rate (5.4 µM min⁻¹ with both substrates), operational stability (40% activity loss after five runs with both) and productivity (31.09 vs. 28.7 mM h⁻¹). EO-proROL specificity for the structural isomers of isoamyl alcohol was also evaluated. Thus, a successful biocatalyst and product conditions ready to be used for isoamyl ester industrial production are here proposed. Full article

Peach flesh colors and aromas impact greatly on consumer behaviors and these two traits are closely associated in white- and yellow-fleshed peaches. However, current understanding of their aromas is rather limited and confined to the concentration differences of some volatiles. Therefore, this study aims to compare the overall aromas of the white-fleshed peach ‘Hu Jing Mi Lu’ (HJML) and yellow-fleshed peach ‘Jin Yuan’ (JY), two fresh cultivars with intense aromas and industrial influence by applications such as HS-SPME/GC-MS analysis, odor activity value evaluations, and odor note analysis. The significant contributions of 26 odor-active compounds to their aromas were revealed. Among which, 15 compounds showed no concentration differences and contributed to the fruity, floral, sweet, etc., odors in both HJML and JY; (E)-2-nonenal, 1-pentanol, and styrene showed significantly higher concentrations in HJML and conveyed much stronger fusel-like and balsamic odors; likewise, (Z)-3-hexenyl acetate, octanal, nonanal, and 3,5-octadien-2-one showed significantly higher concentrations in JY and conveyed much stronger banana, citrus-like, and honey odors; besides, benzyl alcohol, 1-heptanol, 1-octen-3-ol, and 3-octanone with woody, earthy, mushroom, and lavender odors were exclusively detected in HJML. Overall, apart from the common and stronger specific odors in either the white- or yellow-fleshed peach cultivar, the white-fleshed peach was endowed with a unique aroma. Full article

Global demand for renewable and sustainable energy is increasing, and one of the most common biofuels is ethanol. Most ethanol is produced by Saccharomyces cerevisiae (yeast) fermentation of either crops rich in sucrose (e.g., sugar cane and sugar beet) or starch-rich crops (e.g., corn and starchy grains). Ethanol produced from these sources is termed a first-generation biofuel. Yeast fermentation can yield a range of additional valuable co-products that accumulate during primary fermentation (e.g., protein concentrates, water soluble metabolites, fusel alcohols, and industrial enzymes). Distillers’ solubles is a liquid co-product that can be used in animal feed or as a resource for recovery of valuable materials. In some processes it is preferred that this fraction is modified by a second fermentation with another fermentation organism (e.g., lactic acid bacteria). Such two stage fermentations can produce valuable compounds, such as 1,3-propanediol, organic acids, and bacteriocins. The use of lactic acid bacteria can also lead to the aggregation of stillage proteins and enable protein aggregation into concentrates. Once concentrated, the protein has utility as a high-protein feed ingredient. After separation of protein concentrates the remaining solution is a potential source of several known small molecules. The purpose of this review is to provide policy makers, bioethanol producers, and researchers insight into additional added-value products that can be recovered from ethanol beers. Novel products may be isolated during or after distillation. The ability to isolate and purify these compounds can provide substantial additional revenue for biofuel manufacturers through the development of marketable co-products. Full article

Within a biorefinery context, bioethanol is a promising platform molecule since it can be used as raw material to produce a wide spectrum of valuable industrial products such as H₂ and light olefins. However, the presence of impurities limits the conversion of bioethanol in these products. Herein, we aimed to determine the proper pretreatment and fermentation conditions to yield bioethanol with a low content of impurities, such as 3-methyl-1-butanol, by using sugarcane press-mud as feedstock. To do so, a Box-Behnken methodology was employed to select proper pretreatment and fermentation conditions. Factors assessed were temperature, stirring, and pH during fermentation of hydrolysates coming from two different pretreatment methods named as hydrothermal and acid hydrolysis. Results showed that the fermentation temperature should be kept between 26–30 °C to assure at least 91 g/L ethanol. The fusel alcohol content would be reduced by 22% at 30 °C, pH = 4.5, and 200 rpm if sugarcane press-mud is pretreated under acid hydrolysis conditions (T = 130 °C, t = 1 h, 16 g HNO₃/kg solid). Further studies should aim to integrate these conditions within a biorefinery concept to yield valuable products such as H₂ and ethylene. Full article