Isoamyl Acetate Concentration Research Articles

Selection of Salt-Tolerance and Ester-Producing Mutant Saccharomyces cerevisiae to Improve Flavour Formation of Soy Sauce during Co-Fermentation with Torulopsis globosa.

Soy sauce, as a traditional seasoning, is widely favoured by Chinese and other Asian people for its unique colour, smell, and taste. In this study, a salt-tolerance Saccharomyces cerevisiae strain HF-130 was obtained via three rounds of ARTP (Atmospheric and Room Temperature Plasma) mutagenesis and high-salt based screening. The ethanol production of mutant HF-130 was increased by 98.8% in very high gravity fermentation. Furthermore, ATF1 gene was overexpressed in strain HF-130, generating ester-producing strain HF-130-ATF1. The ethyl acetate concentration of strain HF-130-ATF1 was increased by 130% compared to the strain HF-130. Finally, the soy sauce fermentation performance of Torulopsis globosa and HF-130-ATF1 was compared with T. globosa, HF-130, HF-130-ATF1, and Torulopsis and HF-130. Results showed ethyl acetate and isoamyl acetate concentrations in co-fermentation of T. globosa and HF-130-ATF1 were increased by 2.8-fold and 3.3-fold, respectively. In addition, the concentrations of ethyl propionate, ethyl caprylate, phenylethyl acetate, ethyl caprate, isobutyl acetate, isoamyl alcohol, phenylethyl alcohol, and phenylacetaldehyde were also improved. Notably, other three important flavour components, trimethylsilyl decyl ester, 2-methylbutanol, and octanoic acid were also detected in the co-fermentation of T. globosa and HF-130-ATF1, but not detected in the control strain T. globosa. This work is of great significance for improving the traditional soy sauce fermentation mode, and thus improving the flavour formation of soy sauce.

Online monitoring of higher alcohols and esters throughout beer fermentation by commercial Saccharomyces cerevisiae and Saccharomyces pastorianus yeast.

Higher alcohols and esters are among the predominant classes of volatile organic compounds (VOCs) that influence the quality of beer. The concentrations of these compounds are determined through a specific yeast strain selection and fermentation conditions. The effect of yeast strains on the formation of higher alcohols and esters throughout fermentations (at 20°C) was investigated. Flavour-relevant esters (ethyl acetate, isoamyl acetate, ethyl hexanoate and ethyl octanoate) and higher alcohols (isoamyl alcohol, isobutyl alcohol and phenylethyl alcohol) were monitored throughout the fermentation using proton transfer reaction-time of flight-mass spectrometry (PTR-ToF-MS) coupled with an automated sampling system for continuous measurements. Compound identification was confirmed by analysis of samples using gas chromatography-mass spectrometry (GC-MS). Results demonstrated the specific time points where variation in higher alcohol and ester generation between yeast strains occurred. In particular, the concentrations of isoamyl acetate, ethyl octanoate and isoamyl alcohol between yeast strains were significantly different over the first 2 days of fermentation; whereas, after Day 3, no significant differences were observed. The two Saccharomyces pastorianus strains produced comparable concentrations of the key higher alcohols and esters. However, the key higher alcohol and ester concentrations varied greatly between the two S.cerevisiae strains. The use of PTR-ToF-MS to rapidly measure multiple yeast strains provides new insights on fermentation for brewers to modify the sensory profile and optimise quality.

Characterization of a new Saccharomyces cerevisiae isolated from banana stems and its mutant with l-leucine accumulation for awamori brewing.

We isolated a new strain of the yeast Saccharomyces cerevisiae, 35a14, from banana stems in Okinawa. This strain did not belong to any industrial yeast groups in a phylogenetic tree and produced high levels of alcohol. Furthermore, awamori, an Okinawa's traditional distilled alcoholic beverage, brewed with an l-leucine overproducing mutant derived from 35a14 showed a high concentration of isoamyl acetate.

Producción de acetato de isoamilo durante el cultivo continuo de Pichia fermentans

Pichia fermentans ITD-00165 is a yeast with a high potential to produce isoamyl acetate, but no previous works report its growth in continuous culture. A bioreactor containing a chemically defined medium allowed continuous cultures to develop three dilution rates (0.25, 0.30 y 0.35 h-1), measuring the isoamyl acetate production. Steady-state isoamyl acetate concentration was measured using an entrapping system based on a bubbling column with n-decane. Results demonstrate that the entrapping system showed a linear correlation between the isoamyl acetate concentration into the culture medium and the absorption rate into the column. Airstream for oxygen supply was used to continuously feed isoamyl alcohol to the culture to diminish the inhibitory effect of the precursor. Finally, it was demonstrated that the yeast used the precursor to produce isoamyl acetate (0.144 mg L-1).

Training with varying odor concentrations: implications for odor detection thresholds in canines.

Detection dogs are required to detect trace quantities of substances, many times in the parts per billion or parts per trillion concentration range. Frequently, detection of trace quantities is not explicitly trained but rather assumed when dogs show proficiency at higher concentrations to which they are trained. The aim of this study was to evaluate the effect of the odor concentration of the training sample on the minimum concentration dogs will subsequently detect. We expected that dogs may not spontaneously generalize to trace odor concentration when trained with higher concentrations, but when trained to a range of lower concentrations, dogs will show superior detection to lower untrained concentrations. A total of 11 dogs were randomly assigned to 2 groups and were trained to alert to isoamyl acetate at 0.01% odor dilution (v/v with mineral oil) using a 3-alternative forced choice test. Once reaching proficiency, odor detection threshold was assessed using a 2-down 1-up descending staircase procedure. Next, experimental dogs received training with systematically lower concentrations of isoamyl acetate and threshold re-assessed. Control dogs were yoked to experimental dogs in terms of training time, but only received training to the 0.01% dilution between threshold assessments. Experimental dogs showed significantly improved detection thresholds, outperforming control dogs by detecting an average dilution about 100-fold lower. Results suggest that explicitly training for lower concentrations is critical for generalization for trace odor detection.

Kinetics Modelling of Uncatalyzed Esterification of Acetic Anhydride with Isoamyl Alcohol in a Microreactor System

Uncatalyzed esterification of acetic anhydride and isoamyl alcohol has been carried out in a miniaturized intensified reactor (MIR) to develop a kinetic equation using an ideal homogenous model. The effect of reaction temperature (65℃-85℃) and residence time (7.9–180.3 min) at constant molar ratio 2:1 of isoamyl alcohol to acetic anhydride were studied. The results showed that isoamyl acetate concentration production increased from 0.80 mol/L to 2.64 mol/L with residence time from 7.9 min to 180.3 min and also increased from 1.6 mol/L to 2.0 mol/L when reaction temperature increase from 65℃ to 85 ℃. High conversion (>97%) of acetic anhydride was obtained in the absence of a catalyst in a microreactor system in a short residence time of 90 min as compared to days in a traditional batch reactor. This is because of the high surface-to-volume ratio of a microreactor system which promotes excellent proximate contact between reactants to allow efficient heat and mass transfer for esterification and effective mixing. Three different kinetic equations which are the second-order model, autocatalytic and reversible reaction were used to fit the experimental data. The latter kinetic model represented well for the esterification reaction between acetic anhydride and isoamyl alcohol with a good fit of 0.38 average standard error of regression between predicted concentration compare to experimental result. From the simulation result, hydrolysis of isoamyl acetate was found to be more favorable compared to acetic anhydride. This can be seen from the rate constant of reverse reaction of isoamyl acetate, where k3=0.008530Lmol.s which is significantly higher compare to hydrolysis of acetic anhydride, where k4=3.983×10−8Lmol.s at initial water concentration of 0.2 M. Even at different simulated initial water concentration, rate constant of hydrolysis of isoamyl acetate, k3 was always greater than the hydrolysis of acetic anhydride, k4. The parameter of initial water concentration was important to be determined in which it allows to improve the fitness of the kinetic model.

Saccharomyces bayanus Enhances Volatile Profile of Apple Brandies

Qualitative and quantitative profiles of volatiles in alcoholic beverages depend mainly on the quality of raw materials, yeasts used for fermentation, and processing technique. Saccharomyces bayanus is a yeast species which is not commonly used for the production of alcoholic beverages, but it is able to produce volatiles that add desirable aroma. Since there is little information regarding the application of that microorganism for the production of apple brandies and how it affects volatile profile of finished products, we decided to address that issue. The aim of the study was to determine the impact of S. bayanus on the profile of volatile compounds and sensory properties of apple spirits obtained from three apple cultivars (Topaz, Rubin, and Elise) in comparison to spirits obtained from fermentation carried out spontaneously or with Saccharomyces cerevisiae. Obtained brandies were analysed using gas chromatography–flame ionization detector (GC–FID), solid phase microextraction–gas chromatography–mass spectrometry (SPME–GC–MS) and sensorially. In our study, brandies produced from musts fermented by S. bayanus demonstrated the highest concentration of ethyl esters and increased concentrations of isoamyl acetate, 2-phenylethyl acetate, ethyl palmitate and hexanol. Moreover, our results support the hypothesis that non-Saccharomyces yeasts which are present during spontaneous fermentation and demonstrate higher β-glucosidase activities enhance aroma of alcoholic beverages through releasing aroma compounds from glycosidic forms, e.g., α-phellandrene, (E)-β-fanesene, (Z,E)-α-farnesene, α-farnesene, and farnesol. Considering results obtained in sensory analysis, we proved that S. bayanus is suitable for the production of apple brandies, improving their flavour. Brandies obtained from musts fermented by S. bayanus obtained the highest average range for “overall note” parameter in sensory analysis.

Irrigation effects on the volatile composition and sensory profile of Albariño wines from two different terroirs

Volatile composition plays a fundamental role in wine aroma and quality. However, the concentrations of volatiles depend on climate conditions and agricultural practices, such as irrigation. The aim of the current study was to assess the effects of irrigation on the volatile composition and sensory characteristics of wines from Vitis vinifera (L.) cultivar ‘Albarino’ in two zones of NW Spain (Rias Baixas and Ribeiro) during three consecutive years (2012, 2013, and 2014). Irrigation was scheduled by the vine grower in Rias Baixas, whereas it was fixed at 50% of the estimated crop evapotranspiration in Ribeiro. Water was applied in August, mainly, in Rias Baixas and from mid-July to mid-August in Ribeiro. Irrigation significantly altered the concentrations of several volatiles, which differed between zones and years. For instance, wines from the irrigated treatment had lower concentrations of isoamyl acetate, 2-phenylethyl acetate, and ethyl hexanoate than those from the rain-fed treatment in Rias Baixas. In contrast, irrigation increased the concentrations of ethyl hexanoate and ethyl octanoate, while reduced those of free terpenes in wines from Ribeiro. Mainly, these differences between zones were caused by the climate conditions of each region.

Non-enzymatic synthesis route for production of isoamyl acetate in a solvent-free system using miniaturized intensified reactor

Investigation on the performance of isoamyl acetate production using non-enzymatic esterification method in an intensified reactor was done in this study. Isoamyl acetate is widely being used as a food flavoring in foodstuff production as it has banana and pear like fragrance. Traditional and commercial chemical synthesis route is costly and required additional step for separation of solvents and catalyst used. Process intensification technology offers substantiated reduction of cost with improved efficiency and reduce time to market, this study uses miniaturized intensified reactor (MIR) as a new reactor to produce isoamyl acetate, and the effect of the operating parameter such as reaction temperature, reactants flow rate and acid-alcohol ratio towards concentration of isoamyl acetate produced were studied using One-Factor-At-A-Time (OFAT) method. Comparison of non-enzymatic and enzymatic esterification using enzyme Candida Antarctica Lipase B (CALB) in miniaturized intensified reactors were done to prove the hypothesis that intensified system could enhance the reaction process. Based on the outcomes of this study, it was substantiated that the described intensified system could enhance the esterification process in non-enzymatic reaction, at flow rate 40 μL min−1, acid-alcohol ratio of 0.6 and reaction temperature 50 °C.

Effect of Yeasts on the Aroma Profile of Sauvignon Blanc Varietal Wine

In this study effects of commercial yeast preparations on the aromatic profile of Sauvignon Blanc varietal wine were investigated. Grape juice was divided to 7 experimental variants and fermented spontaneously and using 6 commercial strains of Saccharomyces cerevisiae. In final wine samples, essential analytical parameters and selected aromatic compounds were analysed. The highest content of esters was found out in samples fermented by spontaneous micro‑flora; in this case, concentrations of ethyl hexanoate, ethyl octanoate and ethyl decanoate were 682 µg/L, 735 µg/L and 162 µg/L, respectively. The highest content of acetates was recorded in samples fermented by yeast Vulcaferm Sauvignon; concentrations of isoamyl acetate, 2‑phenylethyl acetate and isobutyl acetate were 7.8 mg/L, 244 µg/L and 137 µg/L, respectively. Yeast strain suitable for cold fermentation (Oenoferm Fredo) produced high amounts of ethyl esters and acetates. As far as the sensory evaluation was concerned, the best rating got the sample fermented by these yeasts; it showed a high degree of smell and flavour cleanness as well as a very good overall harmony.

Contribution of a BrazilianTorulaspora delbrueckiiisolate and a commercialSaccharomyces cerevisiaeto the aroma profile and sensory characteristics of Moscato Branco wines

Background and Aims Moscato Branco is the most important cultivar used in the production of Brazilian muscat sparkling wines and is responsible for their sensory characteristics. The aim of this work was to evaluate the effect of monoculture and co-fermentations by Torulaspora delbrueckii (TPI-4) and Saccharomyces cerevisiae (EC1118) on the physicochemical, aromatic composition and sensory characteristics of Moscato Branco wines. Methods and Results Wines inoculated with axenic and co-inoculated with S. cerevisiae and T. delbrueckii were elaborated and subjected to physicochemical, chromatographic and sensory analysis. The monoculture fermentation with T. delbrueckii, and co-fermentation with 25%EC1118/75%TPI-4 showed the lowest concentration of volatile fatty acids, considered as undesirable compounds and the highest concentration of 2-phenylethanol, acetates and ethyl esters, with fruity and flowery descriptors. Based on odour activity values, the main positive contribution of T. delbrueckii was on the concentration of isoamyl acetate, 2-phenylethanol, 2-phenylethyl acetate, ethyl hexanoate and linalyl acetate. Conclusions Wines produced by co-fermentation with 25%EC1118/75%TPI-4 obtained the highest general quality, aroma quality and flavour intensity scores in the sensory evaluation, reflecting the positive contribution of T. delbrueckii on the sensory attributes of Moscato Branco wines. Significance of the Study This work showed that co-inoculation with T. delbrueckii and S. cerevisiae improves the quality of muscat wines.

Correlation Between Sensory Descriptive Analysis and Volatile Composition of Beer Using Multivariate Analysis: The Effect of the Nonvolatile Matrix on the Sensory Perception and Volatile Fraction Behavior

ABSTRACTThe effect of carbohydrate and protein content on the volatile compound release and sensory perception of four selected volatile compounds (isoamyl acetate [banana], ethyl hexanoate [apple], myrcene [dry-hop], benzaldehyde [almond]) from a model beer solution was investigated. Sensory attributes were evaluated using a trained sensory panel, while the concentration of volatile compounds were determined by 1) solid phase microextraction (SPME), 2) solid phase dynamic extraction (SPDE) coupled to gas chromatography mass spectrometry (GC/MS), and 3) stir bar sorptive extraction (SBSE) coupled to gas chromatography flame ionization (GC/FID). In addition, sensory and analytical results were correlated by multivariate analysis. Model beer samples with low levels of proteins and high levels of carbohydrates possessed the highest concentrations of isoamyl acetate, benzaldehyde, and ethyl hexanoate. Myrcene was only influenced by carbohydrate content, with a higher concentration recovered at a lower level of carbohydrate. From sensory analysis, apple and banana aroma attributes were perceived as less intense at the low protein content (P ≤ 0.05). Dry-hop aroma was perceived as more intense in samples with low carbohydrate content (P ≤ 0.05). Multivariate analysis showed a weak correlation between the sensory and instrumental data. The results illustrate that sensory perception and volatile fraction behaviors are influenced by the nonvolatile components and also demonstrate the need for caution when correlating instrumental to sensory analysis.

Quality Comparison of Hawthorn Wines Fermented by Saccharomyces cerevisiae with and without Pulp Contact and Pectase Treatment

This study evaluated the chemical and volatile composition of hawthorn wines fermented with Saccharomyces cerevisiae A3.12 with and without pulp contact and pectase treatment during fermentation. The results indicated that the addition of pectase was in favor of pH decrease and clarification. The pectase-treated wines had significantly higher concentrations of acetic acid, ethyl octanoate, and isoamyl acetate than the non-enzyme-treated wines. Furthermore, the nonextracted wines had significantly higher concentrations of isoamyl alcohol, phenylethyl alcohol, ethyl lactate, and isoamyl acetate than the extracted wines. The first principal component separated the wine from the nonextracted juice with pectase from other samples based on the higher concentrations of isoamyl acetate (0.14 μg/g), diethyl butanedioate (0.07 μg/g), 2-phenylethyl acetate (0.23 μg/g), and acetoin (1.47 μg/g). The wine from nonextracted pulpy juice with pectase was significantly more aromatic than the others and 26.2% of the consumers were found to be willing to purchase this product.

Genetically engineered Oenococcus oeni strains to highlight the impact of estA2 and estA7 esterase genes on wine ester profile

Besides deacidifying wine, Oenococcus oeni bring significant changes in the chemical composition of wine by releasing esters by the action of their own esterases. The impact of O. oeni esterases remains relatively unexplored. Four esterase genes were identified from O. oeni genome (estA2, estA7, estC, and estB). The dual objective of this study was, first to use a genetic tool enabling the expression of esterase genes in enological conditions and, second, to investigate the impact of O. oeni esterase gene expression during winemaking on wine aromatic profile. Both estA2 and estA7 genes were successfully cloned and expressed in O. oeni and recombinant strains were inoculated in Aligoté wine to initiate malolactic fermentation (MLF). Ester profile of experimental wine was established by SPME-GC-MS. EstA2 caused significant decreases in the concentrations of isoamyl acetate, ethyl hexanoate, isobutyl acetate, and hexyl acetate, by 42.7%, 23.4%, 51.5%, and 28.9%, respectively. EstA2 has preferential hydrolytic activity toward acetate esters from higher alcohols. EstA7 has synthetic activity toward hexyl acetate with a significant 22.7% increase. This study reports the first efficient expression system enabling the production of a functional protein in O. oeni in enological conditions.

Improvement of Malvar Wine Quality by Use of Locally-Selected Saccharomyces cerevisiae Strains

Malvar grape juice offers relatively little in the way of a sensory experience. Our interest lies in the use of locally-selected yeast strains in experimental fermentations to improve the sensory characteristics of Malvar wines. Two locally-selected strains of Saccharomyces cerevisiae were used as starter cultures in vinifications and compared with spontaneous fermentations of the same cultivar musts. Wine quality was investigated by their principal oenological parameters, analysis of the volatile aroma components, and corroborated by an experienced taster panel. The most salient chemical attributes were its high concentrations of isoamyl acetate and hexyl acetate and the high acidity, which have been detected to be key constituents in setting the fruity and fresh character of Malvar wines. Winemakers of winegrowing areas where this grape variety is cultivated will have improved options to elaborate new white wines styles, using selected yeast strains that enhance its aromatic properties.

Larvicidal activity of synthesized silver nanoparticles using isoamyl acetate identified in Annona squamosa leaves against Aedes aegypti and Culex quinquefasciatus

Synthesis of silver nanoparticles has the potential to be utilized as a good, eco-friendly approach for the control of mosquito population. In the present study, synthesis of silver nanoparticles using isoamyl acetate isolated from Annona squamosa against mosquito larvae was carried out. The synthesized Ag NPs were characterized by UV, XRD, FTIR and FESEM. The FESEM analyses were clearly spherical and cluster shaped. First to fourth instar mosquito larvae were exposed to varying concentrations of isoamyl acetate and synthesized Ag NPs for 24h. The highest mortality was observed in synthesized Ag NPs against first to fourth instars of (LC50=2.50, 2.78, 3.02, 3.05μg/ml LC90=7.52, 8.34, 9.06, 9.15μg/ml) and Culex quinquefasciatus (LC50=2.75, 3.00, 3.21, 3.48μg/ml; LC90=8.25, 9.01, 9.63, 10.44μg/ml), respectively. The colloidal solution of silver nanoparticles was found to exhibit mosquito larvicidal activity against dengue and filariasis vector.

Manipulation of Conditions during Wort Collection in Production-Scale Fermentations to Regulate Volatile Ester Synthesis as an Aid to Product Matching for Multisite Brewing

Volatile esters are amongst the most important yeast-derived flavor-active compounds produced during brewery fermentation. Dissolved oxygen concentration has long been recognized as an effector for the synthesis of esters by Saccharomyces spp. Here we demonstrate the effects of oxygen exposure time at vessel filling on the synthesis of esters during fermentation using a series of laboratory-scale experiments. In control fermentations, all the yeast was pitched into 10 L of high-gravity wort. In trial fermentations, all the yeast was pitched at the start of collection and wort was added as three 3.33-L batches or five 2-L batches over 12 or 24 hr, respectively. Wort was oxygenated to 15 ppm of O2 for each experiment and identical pitching rates and temperature profiles were adopted. Compared with the controls, increasing the number of batch fills to three and five reduced the final concentration of isoamyl acetate by 15.7 and 34%, respectively, and ethyl acetate by 25 and 39%, respectively, suggesting that a relationship exists between oxygen exposure time and ester synthesis. In parallel, hydrostatic pressure was applied to each condition, resulting in a further decrease in acetate esters. These data suggest that an inverse correlation exists between vessel size relative to brew length and ester production.

Increase of fruity aroma during mixed T. delbrueckii/S. cerevisiae wine fermentation is linked to specific esters enhancement

The aim of this work was to study ester formation and the aromatic impact of Torulaspora delbrueckii when used in association with Saccharomyces cerevisiae during the alcoholic fermentation of must. In order to evaluate the influence of the inoculation procedure, sequential and simultaneous mixed cultures were carried out and compared to pure cultures of T. delbrueckii and S. cerevisiae.Our results showed that mixed inoculations allowed the increase, in comparison to S. cerevisiae pure culture, of some esters specifically produced by T. delbrueckii and significantly correlated to the maximal T. delbrueckii population reached in mixed cultures. Thus, ethyl propanoate, ethyl isobutanoate and ethyl dihydrocinnamate were considered as activity markers of T. delbrueckii. On the other hand, isobutyl acetate and isoamyl acetate concentrations were systematically increased during mixed inoculations although not correlated with the development of either species but were rather due to positive interactions between these species.Favoring T. delbrueckii development when performing sequential inoculation enhanced the concentration of esters linked to T. delbrueckii activity. On the contrary, simultaneous inoculation restricted the growth of T. delbrueckii, limiting the production of its activity markers, but involved a very important production of numerous esters due to more important positive interactions between species. These results suggest that the ester concentrations enhancement via interactions during mixed modalities was due to S. cerevisiae production in response to the presence of T. delbrueckii.Finally, sensory analyses showed that mixed inoculations between T. delbrueckii and S. cerevisiae allowed to enhance the complexity and fruity notes of wine in comparison to S. cerevisiae pure culture. Furthermore, the higher levels of ethyl propanoate, ethyl isobutanoate, ethyl dihydrocinnamate and isobutyl acetate in mixed wines were found responsible for the increase of fruitiness and complexity.

Microbiota and metabolites of aged bottled gueuze beers converge to the same composition

Gueuze beers are prepared by mixing young and old lambic beers and are bottle-refermented spontaneously for aging. The present study analyzed the microbiota and metabolites present in gueuze beers that were aged between a few months and up to 17 years. Yeasts were cultivated from all beers sampled, but bacteria could not be grown from beers older than 5 years. Lactic acid and ethyl lactate concentrations increased steadily during aging, whereas ethanol concentrations remained constant. The concentrations of isoamyl acetate and ethyl decanoate decreased during the aging process. Hence, ethyl lactate and ethyl decanoate can be considered as positive and negative gueuze beer-aging metabolite biomarkers, respectively. Nevertheless, considerable bottle-to-bottle variation in the metabolite profiles was found, which hindered the generalization of the effects seen during the aging of the gueuze beers examined, but which illustrated the unique character of the lambic beers. The present results further indicate that gueuze beers are preferably aged for less than 10 years.

Aroma-active ester profile of ale beer produced under different fermentation and nutritional conditions

A broad range of aroma-active esters produced during fermentation are vital for the complex flavour of beer. This study assessed the influence of fermentation temperature, pH, and wort nutritional supplements on the production of yeast-derived ester compounds and the overall fermentation performance. The best fermentation performance was achieved when wort was supplemented with 0.75 g/l l-leucine resulting in highest reducing sugar and FAN (free amino nitrogen) utilization and ethanol production. At optimum fermentation pH of 5, 38.27% reducing sugars and 35.28% FAN was utilized resulting in 4.07% (v/v) ethanol. Wort supplemented with zinc sulphate (0.12 g/l) resulted in 5.01% ethanol (v/v) production and 54.32% reducing sugar utilization. Increase in fermentation temperature from 18°C to room temperature (± 22.5°C) resulted in 17.03% increased ethanol production and 14.42% and 62.82% increase in total acetate ester concentration and total ethyl ester concentration, respectively. Supplementation of worth with 0.12 g/l ZnSO4 resulted in 2.46-fold increase in both isoamyl acetate and ethyl decanoate concentration, while a 7.05-fold and 1.96-fold increase in the concentration of isoamyl acetate and ethyl decanoate, respectively was obtained upon 0.75 g/l l-leucine supplementation. Wort supplemented with l-leucine (0.75 g/l) yielded the highest beer foam head stability with a rating of 2.67, while highest yeast viability was achieved when wort was supplemented with 0.12 g/l zinc sulphate. Results from this study suggest that supplementing wort with essential nutrients required for yeast growth and optimizing the fermentation conditions could be an effective way of improving fermentation performance and controlling aroma-active esters in beer.