Isoamyl Acetate Research Articles

Comparative Investigation of Aroma-Active Volatiles in ("Ruixue", "Liangzhi", "Crystal Fuji," and "Guifei") Apples by Application of Gas Chromatography-Mass Spectrometry-Olfactometry (GC-MS-O) and Two-Dimensional Gas Chromatography-Quadrupole Mass Spectrometry (GC × GC-qMS) Coupled with Sensory Molecular Science.

Aroma dramatically impacts the overall flavor profiles and consumer acceptance; therefore, it is necessary to conduct a comprehensive analysis of the aroma characteristics of apples. In this study, the aroma differences among four popular apple varieties ("Ruixue", "Liangzhi", "Crystal Fuji," and "Guifei") were compared using two extraction methods (headspace-solid phase microextraction, and solvent-assisted flavor evaporation) coupled with gas chromatography-mass spectrometry-olfactometry (GC-MS-O) and two-dimensional gas chromatography-quadrupole mass spectrometry (GC × GC-qMS). A total of 82 odorants were identified via GC-MS-O, and 143 volatiles were identified by GC× GC-qMS. Among them, 41 key aroma-active compounds (butanal, ethyl acetate, 3-methylbutanal, methyl butanoate, 2-methylpropyl acetate, ethyl 2-methylbutanoate, ethyl 3-methylbutanoate, butyl acetate, hexanal, 2-methylbutyl acetate, 1-butanol, 2-methylpropyl butanoate, 3-methylbutyl acetate, (E)-2-hexenal, butyl butanoate, butyl 2-methylbutanoate, hexyl acetate, hexyl butanoate, hexyl, 2-methylbutanoate, 1-octen-3-ol, 3-methylthiopropanol, 1,3-octanediol, linalyl acetate, and so on) with high odor activity values (OAVs) and AI value (odor activity values ≥1 or aroma intensity ≥3) were identified. Partial least-squares-discriminant analysis showed that Ruixue exhibited a high "fruity" note, Guifei and Crystal Fuji had the greatest "wood," "floral," and "sweet" notes, while Liangzhi presented a significant "green" note. This study provided flavor chemistry support for the apple quality control and production.

How Two‐Dimensional Heterocovariance Spectroscopy and Data Fusion Level out the Inadequacies of Compact Spectrometers

ABSTRACTOver the past decade, sensors and compact spectrometers have emerged as a powerful means for real‐time monitoring of chemical and biochemical processes in the field of process analytical technologies (PATs). This is largely attributed to cost‐efficiency and their robustness in near‐line applications. In comparison to more sophisticated laboratory instruments, these devices exhibit limited sensitivity and resolution. In this study, a combination of near‐infrared, low‐field 1H nuclear magnetic resonance and compact Raman spectrometers were employed for the process monitoring of the acid‐catalyzed esterification of isoamyl alcohol and acetic acid to isoamyl acetate. The resulting real‐time data were transformed and visualized for interpretation using two‐dimensional heterocovariance spectroscopy. The data were also subjected to pretreatment, concatenation, and multivariate analysis in accordance with low‐ and mid‐level data fusion. The spectral interpretation derived from heterocovariance spectroscopy provided support for the data pretreatment during data fusion. By applying these computational techniques, the inherent limitations of sensitivity and resolution associated with compact spectroscopic instruments could be overcome, thereby facilitating the interpretation of data and yielding further insights into the process under study. A comparison of the process parameters resulting from the applied methods indicated that consistent data could be obtained. This study demonstrates that heterocovariance spectroscopy and data fusion allow to enhance compact, less expensive analytical instruments for process monitoring and to acquire process knowledge. This, in turn, enables material, financial, and energy resources to be conserved.

Bioprospecting of Metschnikowia pulcherrima Strains, Isolated from a Vineyard Ecosystem, as Novel Starter Cultures for Craft Beer Production

Several studies in recent years have shown that the use of non-Saccharomyces yeasts, used both in single and in mixed fermentations with Saccharomyces cerevisiae, can help produce craft beers with distinctive compositional characteristics. The aim of this study was to evaluate the suitability of three Metschnikowia pulcherrima strains, isolated from Albanian vineyards, for use as starters in the brewing process. Because of its specific enzymatic activities (protease, β-glucosidase, and β-lyase) and its low production of hydrogen sulfide, M. pulcherrima 62 was selected as a starter culture for the production of craft beer. Specifically, the suitability of this yeast for use in sequential inoculation with S. cerevisiae S0-4 for the production of an American IPA-style beer and the main volatile compounds produced during fermentation were evaluated. The results show significant differences in the glycerol, isoamyl alcohol, and isoamyl acetate contents in beer obtained by sequential inoculum of M. pulcherrima 62 with S. cerevisiae S0-4 compared to beer obtained using S. cerevisiae S0-4 as a single starter. Therefore, these preliminary data support the candidacy of M. pulcherrima 62 as a new starter in the brewing process.

Enhancement of γ-aminobutyric acid content in Huangjiu through rice bran fermentation and its impact on the volatile organic compounds

Rice bran has high glutamic acid decarboxylase (GAD) activity and can be used to enrich and produce γ-aminobutyric acid (GABA). Glutinous rice was used as raw material to brew Huangjiu by liquefaction fermentation. Rice bran extract was added at different fermentation stages, then the content of GABA and basic physicochemical properties were tested, the changes of flavor substances and volatile organic compounds (VOCs) were observed in Huangjiu. The results showed the addition of concentrated GABA-enriched rice bran extract during the post-fermentation stage significantly increases the GABA content in Huangjiu. When the amount of rice bran used is 50 g, the GABA content in the Huangjiu can reach 592.44 mg/L after fermentation. The total sugar and pH of Huangjiu fermented with rice bran extract were higher than the control group, and the total acid and non-sugar solids were lower than the control group. Electronic tongue analysis showed that the addition of rice bran extract would affect the sourness, umami and saltiness taste of Huangjiu. Gas Chromatography-Ion Mobility Spectrometry (GC-IMS) analysis of Huangjiu made by adding rice bran extract at the post-fermentation stage showed increased isoamyl acetate, 2-heptanol, and other substances in comparison with the control group. The results of the study provide a cost-effective and rapid method for increasing the GABA content in Huangjiu. It also offers a theoretical basis and scientific guidance for the production of health-oriented Huangjiu.

Investigation of novel metabolites generated by Torulaspora delbrueckii to promote the aroma biosynthesis in Saccharomyces cerevisiae during wine fermentation

The co-fermentation of Saccharomyces cerevisiae and non-Saccharomyces has been recognized as an effective strategy for improving the quality of wine aroma. One of the most critical factors for the aroma enhancement is the yeast-produced metabolites, but the underlying mechanisms remain poorly understood. In this study, we used a cell/medium separation strategy to investigate the effects of metabolites generated by Torulaspora delbrueckii on the aroma biosynthesis in S. cerevisiae. The results demonstrated that T. delbrueckii metabolites enhanced the production of ethyl octanoate, ethyl decanoate, isoamyl acetate, and isopentanol within S. cerevisiae. Upregulation of aroma-related genes, including EEB1, SLI1, BAP3, BAT1, PDC1, and PDC5 in S. cerevisiae, was responsible for the aroma enhancement. The untargeted metabolomic analysis determined a total of 869 T. delbrueckii metabolites, in which three novel metabolites were identified to promote the aroma formation in S. cerevisiae. Specifically, 3-amino-4-methylpentanoic acid stimulated the levels of ethyl octanoate (up to 42.55%) and ethyl decanoate (up to 31.92%), while 4-methylaminobutyric acid and citraconic acid increased the production of ethyl hexanoate (up to 59.19%) and isoamyl acetate (up to 32.26%). A comprehensive understanding of the specific yeast metabolites provides a robust foundation for winemakers to purposefully modulate the aromatic characteristics of wines.

A comprehensive study on the autochthonous microbiota, volatilome, physico-chemical, and morpho-textural features of Montenegrin Njeguški cheese

The present study aims to deepen the knowledge of the microbiota, gross composition, physico-chemical and morpho-textural features, biogenic amines content and volatilome of Njeguški cheese, one of the most popular indigenous cheeses produced in Montenegro. Cheese samples were collected in duplicate from three different batches produced by three Montenegrin artisan producers. For the first time, the microbiota of Njeguški cheese was investigated using both culture-dependent techniques and metagenomic analysis. Coagulase positive staphylococci viable counts were below the detection limit of the analysis (<1 log cfu g−1). Salmonella spp., Listeria monocytogenes and staphylococcal enterotoxins were absent. However, relatively high viable counts of Enterobacteriaceae, Escherichia coli, Pseudomonadaceae and eumycetes were detected. Metataxonomic analysis revealed a core microbiome composed of Lactococcus lactis, Streptococcus thermophilus, Debaryomyces hansenii, and Kluyveromyces marxianus. Furthermore, the detection of opportunistic pathogenic yeasts such as Magnusiomyces capitatus and Wickerhamiella pararugosa, along with the variable content of biogenic amines, suggests the need for increased attention to hygienic conditions during Njeguški cheese production. Significant variability was observed in humidity (ranging from 38.37 to 45.58 %), salt content (ranging from 0.70 to 1.78 %), proteins content (ranging from 21.42 to 25.08 %), ash content (ranging from 2.97 to 4.05 %), hardness, springiness, and color among samples from different producers. Gas chromatography-mass spectrometry analysis showed a well-defined and complex volatilome profile of the Njeguški cheese, with alcohols (ethanol, isoamyl alcohol, phenetyl alcol), esters and acetates (ethyl acetate, ethyl butanoate, isoamyl acetate), ketones (acetoin, 2-butanone), and acids (acetic, butanoic, hexanoic acids) being the main chemical groups involved in aroma formation. This research will provide new insights into the still poorly explored identity of Njeguški cheese, thus serving as a first baseline for future studies aimed at protecting its tradition.

Metagenomic and Metabolomic Profiling Reveals the Differences of Flavor Quality between Hongqu Rice Wines Fermented with Gutian Qu and Wuyi Qu.

Jiuqu (starter) makes an important contribution to the formation of the flavor characteristics of Hongqu rice wine (HQW). Gutian Qu (GTQ) and Wuyi Qu (WYQ) are two kinds of Jiuqu commonly used in HQW brewing, but the comparison of the two kinds of HQW is still insufficient at present. The objective of this study was to compare the dynamic changes of amino acids (AAs), higher alcohols (HAs), bioamines (BAs), volatile flavor compounds (VFCs), and microbial communities in HQW fermentation, with GTQ and WYQ as starter. This study used an automatic amino acid analyzer, GC, HPLC, and GC-MS to detect AAs, HAs, Bas, and VFCs during fermentation; metagenomic sequencing technology was used to elucidate the microbial community and its functional characteristics. The results showed that the contents of AAs and HAs in HQW brewed with WYQ (WYW) were significantly higher than those in HQW brewed with GTQ (GTW). On the contrary, the majority of BAs in GTW were significantly higher than those in WYW. The composition of VFCs in WYW and GTW were obviously different, as most of the VFCs were notably enriched in WYW, while ethyl caproate, isoamyl acetate, ethyl heptanoate, ethyl nonanoate, 1-decanol, citronellol, phenethyl acetate, and hexanoic acid were more abundant in GTW. Burkholderia gladioli, Pantoea dispersa, Weissella cibaria, Monascus purpureus, and Saccharomyces cerevisiae were the predominant microbial populations in GTW brewing at the species level, while Sphingomonas sp., Kosakonia cowanii, Enterobacter asburiae, Leuconostoc lactis, Aspergillus niger, and Saccharomyces cerevisiae were the dominant microbial species in WYW brewing. The abundance of functional genes involved in BAs biosynthesis were much higher in GTW brewing, while the abundance of functional genes related to the metabolism of characteristic VFCs were much higher in WYW brewing. Collectively, these findings provided evidence for elucidating the effects of Jiuqu and microbial communities on HQW flavor quality, and laid a solid foundation for the improvement of HQW flavor quality.

Differences in the Determination of Volatile Organic Compounds between Chrysanthemum morifolium Ramat. and Chrysanthemum indicum L. (Wild Chrysanthemum) by HS-GC-IMS.

Chrysanthemums and wild chrysanthemums are herbs with high application value. As edible plants of the Asteraceae family, they have good antioxidant, anti-inflammatory and hepatoprotective properties. Chrysanthemums and wild chrysanthemums contain a wide variety of volatile organic compounds, and these volatile components are the main factors contributing to the flavor differences. Therefore, in this study, we investigated the volatile components of holland chrysanthemum from Bozhou, Anhui Province, Chu-chrysanthemum from Chuzhou, Anhui Province, Gong-chrysanthemums from Huangshan, Anhui Province, Huai-chrysanthemums from Jiaozuo, Henan Province, Hang-chrysanthemum from Hangzhou, Zhejiang Province, and wild chrysanthemum from Dabie Mountain by headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) coupled with principal component analysis (PCA). The results showed that Chrysanthemum and wild chrysanthemum contain alcohols, esters, hydrocarbons, ketones, aldehydes, acids, camphor, pyrazines and furans. Among them, alcohols, esters and hydrocarbons accounted for more than 15%. It was hypothesized that 2-methyl-1-propanol, 2-methylbutanol, 1-hexanol in alcohols and hexyl acetate, 3-methylbutyl acetate and ethyl 2-methylpropanoate in esters might be the main reasons for the alcoholic and sweet flavors of chrysanthemum and chrysanthemum officinale. Based on the principal component analysis, cluster analysis with the Euclidean distance and similarity analysis of fingerprints, it was found that there were significant differences in the volatile components in chrysanthemums from different origins, among which the differences between Chu-chrysanthemum and Hang-chrysanthemum were the most significant. In addition, as a genus of wild chrysanthemum with the same species, it contains a richer variety of volatile organic compounds, and the content of hydrocarbons and alcohols is significantly higher than that of chrysanthemum.

Atmospheric Degradation Mechanism of Isoamyl Acetate Initiated by OH Radicals and Cl Atoms Revealed by Quantum Chemical Calculations and Kinetic Modeling.

Isoamyl acetate is one of the volatile organic compound class molecules relevant to agricultural and industrial applications. With the growing interest in isoamyl acetate applications in industry, the atmospheric fate of isoamyl acetate must be considered. Reaction mechanisms, potential energy profiles, and rate constants of isoamyl acetate reaction with atmospheric relevant oxidant OH radicals and Cl atoms have been obtained from the quantum chemical calculations and kinetic modeling. The geometry optimizations were conducted using M06-2X/6-311++G(3df,3pd) followed by single point-energy calculations at the DLPNO-CCSD(T) method with an extrapolated complete basis set. The rate constants were calculated by solving the master equation. A hydrogen-abstraction reaction dominates the first step of isoamyl acetate degradation, while the addition-substitution reaction plays a small role in the degradation products. The kinetic study was conducted to evaluate the rate constants within a temperature range of 200-400 K. The total rate constants for the isoamyl acetate degradation reactions initiated by the OH radical and Cl atom were determined to be 6.96 × 10-12 and 1.27 × 10-10 cm3 molecule-1 s-1, respectively, under standard temperature and pressure conditions. The product degradation mechanism, ozone formation potential, and atmospheric impacts were discussed.

Identification of alarm pheromone components of the southern giant Asian hornet, Vespa soror, a major pest of honey bees.

The rise of biological invasions threatens biodiversity and food security, with the vespid family, including Vespa soror, being of particular concern. Our study focused on the alarm pheromone components of V. soror. By using gas chromatography-mass spectrometry (GC-MS) chemical analyses, electroantennograms, and field bioassays, we identified 5 compounds-2-pentanol, 3-methyl-1-butanol, 2-heptanol, 2-nonanol (2-N), and isopentyl acetate (IPA)-in hornet sting venom that elicited defensive behavior from hornets. IPA and 2-N also serve as alarm pheromone components in multiple honey bee species that are important prey for V. soror. This shared chemical signaling may allow cross-detection by each species on the other's alarm cues. While it should be advantageous for bees to detect V. soror alarm pheromone, the benefits to V. soror of using IPA and 2-N are unclear. V. soror may manipulate bee behavior, potentially distracting defenders, because they mark victim bee colonies by rubbing their abdomens, which contain their sting glands, at bee hive entrances. Our findings pose new evolutionary questions about the role of manipulation in the arms races.

Effect of Volatile Compounds Emitted by an Endophytic Yeast Isolated from the Endemic Plant Echinopsis chiloensis against Botrytis cinerea

Our research group isolated an endophyte yeast from the endemic plant Echinopsis chiloensis. This yeast, identified as Naganishia sp, produces volatile organic compounds (VOC) with antifungal activity against Botrytis cinerea. Due to the need for alternative control methods for this pathogen, the effect of VOC on B. cinerea was analyzed. On the fourth day of cultivation, in the presence of VOCs, the mycelial growth of B. cinerea stopped. VOCs inhibited 32.8% of the conidia germination and reduced sporulation by 70.6%. These compounds promoted the formation of infection cushions. VOCs caused damage to the cell wall and plasma membrane in B. cinerea. On the other hand, the volatile compounds induced oxidative stress, and led to membrane lipid peroxidation after 16 and 24 h of incubation in the presence of VOCs, because an increased level of malondialdehyde content was observed. These compounds exerted a fungistatic effect on B. cinerea. The volatile compounds emitted by Naganishia sp were identified by gas chromatography coupled with mass spectrometry as 3-methylbutyl acetate, ethylbenzene, 1-ethyl-3-methylbenzene, 2-phenylethanol, 2-heptanone and (5E)-6,10-dimethylundeca-5,9-dien-2-one. The most abundant volatile compound, 2-phenylethanol, inhibited the mycelial growth of B. cinerea with an IC50 value of 0.21 µL mL−1. The effect of this pure compound was also fungistatic. Finally, it was shown that volatile compounds decreased the severity of B. cinerea infection in tomatoes and grapes by 64.7 and 43,1%, respectively. This is the first report identifying volatile compounds emitted by a Naganishia sp. and describing their mode of action against B. cinerea.

Optimization of fermentation conditions and analysis of the changes in flavor compounds for lemon vinegar

The flavor composition is an important index to evaluate the quality of fruit vinegar, including volatile and non-volatile components. The flavor quality of fruit vinegar is related to fermentation technology. This study analyzed the acetic acid fermentation conditions and the changes in the flavor composition of lemon vinegar. After optimization, the pH, alcohol content, and inoculum were 3.0, 6%, and 10%. The statistical analysis showed significant changes in flavor components during the whole fermentation. After acetic acid fermentation, the highest organic acid changed from citric acid to acetic acid. The content of amino acids showed a decreasing trend, mainly used for the growth and metabolism of microorganisms and the precursor of aroma compounds. Terpenoids were the main aroma compounds before the fermentation, while the main aroma compounds were esters after the fermentation. Linalool, the characteristic aroma compound in lemon, was well preserved. Isoamyl acetate was the main aroma compound during the fermentation. Almost all the flavor compounds had significant changes during the lemon vinegar fermentation. This study helps to understand the changes in flavor compounds during lemon vinegar brewing and lays the foundation for further improving the quality of lemon vinegar.

Volatile aroma compound-based decoding and prediction of sweet berry aromas in dry red wine

To explore the volatile markers of typical sweet berry flavors in dry red wine, Marselan, Cabernet Sauvignon, Merlot, and Cabernet Franc wines were pretreated using solid-phase microextraction (SPME) and liquid-liquid extraction-solvent-assisted flavor evaporation (LLE-SAFE), and key odorants were analyzed using sensomics approach. Results indicated that Marselan wines exhibited intense sweet berry aromas compared to other varieties wines. Omission tests on one- and four-year-aged wines identified β-damascenone, isoamyl acetate, 2,3-butanediol, phenylethanol as sweet aroma markers, while geranyl acetone, ethyl isobutyrate, ethyl 2-methylbutyrate as berry aroma markers, which were verified by partial least squares regression. Meanwhile, optimal flavor intensity prediction models between sweet/berry aroma and volatile markers natural logarithms concentration were created with all wines. Moreover, consistent with aroma intensity, most berry markers content increased during aging while sweet markers decreased. This study completes the analytical methodology for volatile markers of wine typical aroma and provides theoretical support for wine flavor prediction.

Effects of Aging in Wood Casks on Anthocyanins Compositions, Volatile Compounds, Colorimetric Properties, and Sensory Profile of Jerez Vinegars

The Jerez (Sherry) vinegars, including Vinagre de Jerez, Reserva, and Gran Reserva, are crafted from Sherry wines and are protected under the Denomination of Origin in Spain. The aim of this study was to (i) characterize the physicochemical properties and composition; (ii) investigate the impact of the aging process on color properties, phenolics, volatile compounds, and sensorial profiles; and (iii) find a marker for tracing the authenticity of non-aged (Apto) and aged Jerez vinegars. The phenolic components were identified through LC-MS/MS, whereas the volatile compounds were examined using the GC-MS/MS technique. As the aging progressed, a decrease was observed in the levels of flavonol and phenolic acids, with anthocyanin components being undetectable in non-aged and aged samples. In the Gran Reserva variety, 2-methylbutyl acetate, acetic acid, and ethanol emerged as the predominant volatile substances. The presence of oaklactone and ethyl butanoate components served as marker substances to authenticate the Gran Reserva. Additionally, alterations in color properties were noted, marked by a decrease in yellow content and an increase in the red component depending on aging. Furthermore, novel sensory descriptors, such as vanilla, clove, woody, and nutty notes, and winy character emerged in the samples with prolonged aging.

The co-inoculation ratio of Hanseniaspora vineae-to-Saccharomyces cerevisiae correlates with aroma metabolic features in wine

AbstractHanseniaspora vineae is a non-Saccharomyces yeast used in winemaking to increase the complexity of wines. However, the fermentation rate in sequential inoculations may be challenging, particularly in industrial winemaking settings. This study aimed to assess how different co-inoculation protocols involving H. vineae and S. cerevisiae affect the fermenting performance and aroma of white and red wines. White and red wines were co-fermented with varying H. vineae-to-S. cerevisiae ratios (67%, 80%, 90%, 95%, and 98%). Results were compared to sequential and pure S. cerevisiae inoculation. Co-inoculation mitigated the inhibitory mechanisms associated with sequential inoculation, resulting in a reduction of 30 days and 6 days of fermentation for white and red wines, respectively. Moreover, the fermentation time in co-inoculation was similar to that of the controls, thereby avoiding the slowdowns typically observed in sequential inoculation. Five yeast-derived metabolic markers, two of which characterizing H. vineae metabolism, were studied to evaluate the processes. In white wines, β-phenylethyl acetate and benzyl alcohol were increased by H. vineae up to 64-fold and sevenfold, respectively, while ethyl hexanoate was fourfold higher in S. cerevisiae. In addition, 2-phenylethanol was up to twofold higher in S. cerevisiae. The results for isoamyl acetate varied depending on the co-inoculation ratio. At 67% and 80%, the H. vineae protocols showed the highest concentration, even exceeding that of S. cerevisiae pure inoculation. All compounds correlated linearly with the H. vineae-to-S. cerevisiae ratio at inoculum. The same trends were observed in red wines, but to a different extent.

Volatile Organic Compounds from Ceratocystis cacaofunesta, a Causal Agent of Ceratocystis Wilt of Cacao.

Fungi of the genus Ceratocystis are aggressive tree pathogens that cause serious diseases in several crops around the world. Ceratocystis wilt disease caused by C. cacaofunesta has been shown to be responsible for severe reductions in cacao production. In this study, headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS) was used in combination with chemometric analysis for monitoring volatile organic compounds (VOCs) released from C. cacaofunesta. Low-molecular-weight esters, alcohols, ketones, and sulphur compounds were identified in the liquid broth. Monitoring the volatile profile over five days of fungal growth revealed that the concentrations of alcohol and esters were inversely proportional. Acetate esters were responsible for the intense fruity aroma of the C. cacaofunesta culture produced within the first hours after fungal inoculation, which decreased over time, and are likely associated with the attraction of insect vectors to maintain the life cycle of the pathogen. PCA revealed that 3-methylbutyl acetate was the metabolite with the highest factor loading for the separation of the VOC samples after 4h of fungal growth, whereas ethanol and 3-methylbutan-1-ol had the highest factor loadings after 96 and 120h. 3-Methylbutan-1-ol is a phytotoxic compound that is likely associated with host cell death since C. cacaofunesta is a necrotrophic fungus. Fungal VOCs play important roles in natural habitats, regulating developmental processes and intra- and interkingdom interactions. This is the first report on the volatiles released by C. cacaofunesta.

Characterization of volatile compounds and sensory properties of spine grape (Vitis davidii Foex) brandies aged with different toasted wood chips

Aging is an important process for improving wine and brandy quality. In this study, the chemical characterization and sensory properties of spine grape brandies were compared after aging with various species of wood chips, including French oak (FO), American oak (AO), Mongolian oak (MO), Japanese blue oak (JO), chestnut, catalpa, and cherry. The results showed that high color intensity and significant concentrations of tannins and polyphenols were observed in the brandies aged with FO, AO, and chestnut chips. The volatile compounds, such as ethyl decanoate, ethyl 2-methylbutanoate, ethyl octanoate, methyl salicylate, (Z)-2-hexenol, and furfural, contributed to the floral, fruity, and roasted/smoky attributes of the brandies aged with FO, AO, and chestnut chips. The 1-butanol, 1-propanol, phenylethanol, phenylethyl acetate, isoamyl acetate, and linalool contributed to the fruity, honey, and floral attributes of the brandies aged with JO and cherry chips. These findings are extremely useful for the production of differentiated and high-quality spine grape brandies.

Functionalized ZnFe2O4@Mesoporous silica nano-support for lipase enzyme immobilization: Enhanced biocatalysis and antibacterial activity for food industry applications

Enzymes, as highly efficient biocatalysts, play a crucial role in diverse biotechnological applications. However, enzyme (re)purification and recovery challenges pose substantial obstacles, rendering them costly for industrial utilization. Addressing this, our study developed mesoporous zinc ferrite nanoparticles coated with amine-functionalized mesoporous silica structure (ZnFe2O4@MS) through the solvothermal method. These nanoparticles are an effective nano-support for immobilizing Candida rugosa Lipase (CRL), ensuring easy separability and recoverability through a magnetic field and providing a significant surface area for high mass transference capacity. Immobilizing the lipase on the nano-support (ZnFe2O4@MS/CRL) through covalent bonds on the surface and within the pores led to a notable increase in enzyme activity from 324 U/mg for free enzyme to 689 U/mg for immobilized enzyme. This indicates unchanged active sites post-immobilization, accompanied by enhanced catalytic activity. The immobilized lipases demonstrated prolonged stability at elevated temperatures, maintaining over 59% of initial catalytic activity through five cycles. Furthermore, ZnFe2O4@MS/CRL exhibited substantial antibacterial activity against Staphylococcus aureus, more than that observed in Gram-negative bacteria. The immobilized lipase was also effective in synthesizing banana flavor (isoamyl acetate) in n-hexane, achieving 64% esterification at 45 °C after 4 h. Overall, the study underscores the industrial promise of this immobilized enzyme system, emphasizing its potential for sustainable and cost-effective biotechnological processes.

Effects of unconventional non-Saccharomyces yeast fermentation on the chemical profile and bioaccessibility of watermelon wine

This study evaluated effects of watermelon fermentation using different non-Saccharomyces yeast strains (Brettanomyces lambicus, Brettanomyces bruxellensis, and Lachancea thermotolerans) on the chemical profile of the derived wines. A control product was produced using Saccharomyces cerevisiae. Analytical techniques, namely HPLC-DAD-RID and LLE-GC/MS, were used to evaluate sugars, organic acids, alcohols, phenolic compounds, amino acids, and volatile compounds profiles. Fermentation reduced the sugar (glucose and fructose) and amino acid contents and increased alcohol (ethanol and glycerol), organic acids (lactic and acetic acids), phenolics, and volatile compounds. The use of the B. bruxellensis strain resulted in an alcoholic beverage with quality parameters similar to that from S. cerevisiae but with higher concentrations of phenolics (rutin, gallic acid, caftaric acid, and caffeic acid) and important volatile compounds (isoamyl acetate). The watermelon wine had a higher content of bioaccessible phenolic compounds than the must, especially catechin, procyanidin B1, procyanidin B2 and gallic acid, due to their high bioaccessibility (>70%). The yeast type influenced the chemical profile of the beverages. B. bruxellensis is a promising tool to obtain watermelon alcoholic beverage in an industrial scale.

Chemical Characterization of Cider Produced in Hardanger—From Juice to Finished Cider

Our investigation delves into the previously uncharted territory of cider composition from Norway. This study aimed to obtain an overview of the qualitative and quantitative compositions of general chemical parameters, polyphenols (individual and total expressed as gallic acids equivalents), selected esters, and selected C6-alcohols in ciders with the PDO label Cider from Hardanger. In total, 45 juice and cider samples from the fermentation process were collected from 10 cider producers in Hardanger in 2019, 2020, and 2021. Individual sugars, acids, ethanol, and 13 individual phenols were quantified using HPLC-UV/RI. Seven ethyl esters of fatty acids, four ethyl esters of branched fatty acids, ten acetate esters, two ethyl esters of hydroxycinnamic acids, and four C6-alcohols were quantified using HS-SPME-GC-MS. For samples of single cultivars (‘Aroma’, ‘Discovery’, ‘Gravenstein’, and ‘Summerred’), the sum of the measured individual polyphenols in the samples ranges, on average, from 79 to 289 mg L−1 (the lowest for ‘Summerred’ and highest for ‘Discovery’ and ‘Gravenstein’). Chlorogenic acid was the most abundant polyphenol in all samples. Ethyl butyrate, ethyl hexanoate, ethyl octanoate, ethyl decanoate, ethyl isobutyrate, ethyl 2-methylbutyrate, isoamyl acetate, and hexanol were present at concentrations above the odour threshold and contributed to the fruity flavour of the Cider from Hardanger.