Determination of terpenes in tequila by solid phase microextraction-gas chromatography-mass spectrometry

Novel Functional Grape Juices Fortified with Free or Immobilized Lacticaseibacillus rhamnosus OLXAL-1

During the last decade, a rising interest in novel functional products containing probiotic microorganisms has been witnessed. As food processing and storage usually lead to a reduction of cell viability, freeze-dried cultures and immobilization are usually recommended in order to maintain adequate loads and deliver health benefits. In this study, freeze-dried (free and immobilized on apple pieces) Lacticaseibacillus rhamnosus OLXAL-1 cells were used to fortify grape juice. Juice storage at ambient temperature resulted in significantly higher (>7 log cfu/g) levels of immobilized L. rhamnosus cells compared to free cells after 4 days. On the other hand, refrigerated storage resulted in cell loads > 7 log cfu/g for both free and immobilized cells for up to 10 days, achieving populations > 109 cfu per share, with no spoilage noticed. The possible resistance of the novel fortified juice products to microbial spoilage (after deliberate spiking with Saccharomyces cerevisiae or Aspergillus niger) was also investigated. Significant growth limitation of both food-spoilage microorganisms was observed (both at 20 and 4 °C) when immobilized cells were contained compared to the unfortified juice. Keynote volatile compounds derived from the juice and the immobilization carrier were detected in all products by HS-SPME GC/MS analysis. PCA revealed that both the nature of the freeze-dried cells (free or immobilized), as well as storage temperature affected significantly the content of minor volatiles detected and resulted in significant differences in the total volatile concentration. Juices with freeze-dried immobilized cells were distinguished by the tasters and perceived as highly novel. Notably, all fortified juice products were accepted during the preliminary sensory evaluation.

Preliminary Evaluation of the Use of Thermally-Dried Immobilized Kefir Cells in Low Alcohol Winemaking

Low alcohol wines (≤10.5% vol) are novel products that have gradually been gaining the consumers’ and market’s interest over the last decade. Taking into account the technological properties of immobilized cell systems alongside with the commercial need for dry cultures, the aim of the present study was to assess the suitability of thermally-dried immobilized kefir cells on DCM, apples pieces, and grape skins in low alcohol wine production. Storage of thermally-dried kefir culture in various temperatures (−18, 5, and 20 °C) resulted in high viability rates for immobilized cells (up to 93% for yeasts/molds immobilized on grape skins and stored at −18 °C for 6 months). Fermentation activity was maintained after storage in all cases, while high operational stability was confirmed in repeated batch fermentations for a period of 6 months. Principal Component Analysis (PCA) revealed that the fermentation temperature rather than the state of kefir culture affected significantly volatiles detected by Head Space Solid-Phase Microextraction Gas Chromatography–Mass Spectrometry analysis. Notably, all new products were of high quality and approved by the sensory panel.

Identification of Rotundone as an Important Contributor to the Flavor of Oak-Aged Spirits

Experiments were conducted to identify a compound responsible for a spicy, woody, incense-like odor note in oak-aged spirits. The target compound was extracted from oak wood and various oak-aged spirits and analyzed by multidimensional (heart-cut) gas chromatography–mass spectrometry–olfactometry (MD–GC–MS–O), and was unambiguously identified as the sesquiterpene ketone, 5-isopropenyl-3,8-dimethyl-3,4,5,6,7,8-hexadydro-1(2H)-azulenone (rotundone). Quantitation of the trace-level target compound was done by stable isotope dilution analysis (SIDA) in a variety of oak-aged spirits, including bourbon, rye, Tennessee whiskey, scotch, rum, and tequila. The content of rotundone was found to increase as a function of years of barrel aging for 4-, 8-, and 12-year-old bourbons obtained from the same manufacturer, thus confirming its origin to be from oak. In addition, odor-activity values (OAVs) were compared for selected potent odorants, including rotundone, in the same 4-, 8-, and 12-year-old bourbons, which indicated the relative importance of rotundone in the overall flavor of oak-aged spirits.

Isotopic Characterization of 100% Agave Tequila (Silver, Aged and Extra-Aged Class) for Its Use as an Additional Parameter in the Determination of the Authenticity of the Beverage Maturation Time

Isotopic ratios of δ¹³C_VPDB and δ¹⁸O_VSMOW have been used as an additional parameter to ensure the authenticity of the aging time of 100% agave tequila. For this purpose, 120 samples were isotopically analyzed (40 silver class, 40 aged class, and 40 extra-aged classes). The samples were obtained through a stratified sampling by proportional allocation, considering tequila producers from the main different regions of Jalisco, Mexico (Valles 41%, Altos Sur 31%, Cienega 16%, and Centro 12%). The results showed that the δ¹³C_VPDB was found in an average of −12.85 ‰ for all the analyzed beverages, with no significant difference between them. Since for all the tested samples the Agave tequilana Weber blue variety was used as source of sugar to obtain alcohol, those results were foreseeable, and confirm the origin of the sugar source. Instead, the results for δ¹⁸O_VSMOW showed a positive slope linear trend for the aging time (silver class 19.52‰, aged class 20.54‰, extra-aged class 21.45‰), which is associated with the maturation process, there are oxidation reactions that add congeneric compounds to the beverage, these can be used as tracers for the authenticity of the aging time. Additionally, the experimental data showed homogeneity in the beverages regardless of the production region, evidencing the tequila industry’s high-quality standards. However, a particular case occurs with the δ¹⁸O_VSMOW data for the silver class samples, in which a clear trend is noted with the altitude of the region of origin; therefore, this information suggests that this analytical parameter could be useful to authenticate the regional origin of beverage.

Aromatic profiling of flavor active compounds in sugarcane spirits aged in tropical wooden barrels

Abstract The production of high quality spirits implies an aging period in wooden barrels, resulting in numerous physicochemical reactions between the wood and the beverage. Oak is the main wood used in the aging process of alcoholic beverages worldwide. However, in Brazil, the use of tropical wood species can be a viable option, allowing for innovation in the characteristics of spirits. This study aimed to determine the aromatic profiling of flavor active compounds in Brazilian sugarcane spirit (cachaça) after a 12-month aging period in new 225-L toasted and non-toasted barrels made from the tropical wood species cerejeira [Amburana cearensis (Fr. Allem.) A.C. Smith], castanheira (Bertholletia excelsa Humboldt & Bonpland), and cabreúva (Myrocarpus frondosus Allemão). The chemical characterization was carried out using the Gas-Chromatography/Mass Spectroscopy (GC/MS) scan mode, and the identification targeted on flavor active compounds (esters, alcohols, organic acids, phenolic compounds, and terpenes). Toasted and non-toasted cerejeira barrels intensified the contents of phenolic compounds in cachaça. The samples aged in cerejeira barrels exhibited the most complex profile, mainly related to organic acids and phenolic compounds. However, cabreúva barrels transferred significant aromatic terpenes to cachaça. This research presented a novel focus on the aromatic profiling of flavor active compounds in cachaça aged in barrels made from tropical wood species.

Freeze-Dried Immobilized Kefir Culture in Low Alcohol Winemaking

Low alcohol wines represent a rising trend in the global market. Since for ethanol removal, certain physicochemical methods that negatively affect wine quality are applied, the aim of this present study was to evaluate the efficiency of freeze-dried, immobilized kefir culture on natural supports (apple pieces, grape skins and delignified cellulosic material) in low alcohol winemaking at various temperatures (5–30 °C). Initially, genetic analysis of kefir culture was performed by Next Generation Sequencing. There was an immobilization of kefir culture on grape skins-enhanced cell survival during freeze-drying in most cases, even when no cryoprotectant was used. Simultaneous alcoholic and malolactic fermentations were performed in repeated batch fermentations for >12 months, using freeze-dried free or immobilized cells produced with no cryoprotectant, suggesting the high operational stability of the systems. Values of great industrial interest for daily ethanol productivity and malic acid conversion [up to 39.5 g/(Ld) and 67.3%, respectively] were recorded. Principal Component Analysis (PCA) showed that freeze-drying rather than the fermentation temperature affected significantly minor volatiles. All low alcohol wines produced were accepted during the preliminary sensory evaluation.

Biological activities of Agave by-products and their possible applications in food and pharmaceuticals

Agave leaves are considered a by-product of alcoholic beverage production (tequila, mezcal and bacanora) because they are discarded during the production process, despite accounting for approximately 50% of the total plant weight. These by-products constitute a potential source of Agave extracts rich in bioactive compounds, such as saponins, phenolic compounds and terpenes, and possess different biological effects, as demonstrated by in vitro and in vivo tests (e.g. antimicrobial, antifungal, antioxidant, anti-inflammatory, antihypertensive, immunomodulatory, antiparasitic and anticancer activity). Despite their positive results in biological assays, Agave extracts have not been widely evaluated in food systems and pharmaceutical areas, and these fields represent a potential route to improve the usage of Agave plants as food additives and agents for treating medical diseases. © 2017 Society of Chemical Industry.

Free Monoterpene Isomer Profiles of Vitis Vinifera L. cv. White Wines

Monoterpene compounds contribute floral and fruity characters to wine and are desired by grape growers and winemakers for many white wines. However, monoterpene isomers, especially monoterpene enantiomers, have been little explored. It is possible to identify and quantitate 17 monoterpene isomers in 148 varietal wines from eight grape varieties; Chardonnay, Gewürztraminer, Muscat, Pinot gris, Riesling, Sauvignon blanc, Torrontes, and Viognier in two vintages by Headspace solidphase microextraction multidimensional gas chromatography mass spectrometry (HS-SPME-MDGC-MS). Results obtained from general linear models and discriminant analysis showed significant differences for the isomer profiles and enantiomer fractions among the eight grape varieties and four wine styles. The high R² values from the fitted line show low variation in enantiomeric differences based on variety. These results provide an overview of the monoterpene isomers of wide varietal wines, and support that isomer profiles and enantiomer fractions could differentiate our wines by varietal and wine style.

Nerolidol production in agroinfiltrated tobacco: Impact of protein stability and membrane targeting of strawberry (Fragraria ananassa) NEROLIDOL SYNTHASE1

The sesquiterpene alcohol nerolidol, synthesized from farnesyl diphosphate (FDP), mediates plant-insect interactions across multiple trophic levels with major implications for pest management in agriculture. We compared nerolidol engineering strategies in tobacco using agroinfiltration to transiently express strawberry (Fragraria ananassa) linalool/nerolidol synthase (FaNES1) either at the endoplasmic reticulum (ER) or in the cytosol as a soluble protein. Using solid phase microextraction and gas chromatography-mass spectrometry (SPME-GCMS), we have determined that FaNES1 directed to the ER via fusion to the transmembrane domain of squalene synthase or hydroxymethylglutaryl - CoA reductase displayed significant improvements in terms of transcript levels, protein accumulation, and volatile production when compared to its cytosolic form. However, the highest levels of nerolidol production were observed when FaNES1 was fused to GFP and expressed in the cytosol. This SPME-GCMS method afforded a limit of detection and quantification of 1.54 and 5.13 pg, respectively. Nerolidol production levels, which ranged from 0.5 to 3.0 μg/g F.W., correlated more strongly to the accumulation of recombinant protein than transcript level, the former being highest in FaNES-GFP transfected plants. These results indicate that while the ER may represent an enriched source of FDP that can be exploited in metabolic engineering, protein accumulation is a better predictor of sesquiterpene production.

Investigation of a Quantitative Method for the Analysis of Chiral Monoterpenes in White Wine by HS-SPME-MDGC-MS of Different Wine Matrices

A valid quantitative method for the analysis of chiral monoterpenes in white wine using head-space solid phase micro-extraction-MDGC-MS (HS-SPME-MDGC-MS) with stable isotope dilution analysis was established. Fifteen compounds: (S)-(−)-limonene, (R)-(+)-limonene, (+)-(2R,4S)-cis-rose oxide, (−)-(2S,4R)-cis-rose oxide, (−)-(2R,4R)-trans-rose oxide, (+)-(2S,4S)-cis-rose oxide, furanoid (+)-trans-linalool oxide, furanoid (−)-cis-linalool oxide, furanoid (−)-trans-linalool oxide, furanoid (+)-cis-linalool oxide, (−)-linalool, (+)-linalool, (−)-α-terpineol, (+)-α-terpineol and (R)-(+)-β-citronellol were quantified. Two calibration curves were plotted for different wine bases, with varying residual sugar content, and three calibration curves for each wine base were investigated during a single fiber’s lifetime. This was needed as both sugar content and fiber life impacted the quantification of the chiral terpenes. The chiral monoterpene content of six Pinot Gris wines and six Riesling wines was then analyzed using the verified method. ANOVA with Tukey multiple comparisons showed significant differences for each of the detected chiral compounds in all 12 wines. PCA score plots showed a clear separation between the Riesling and Pinot Gris wines. Riesling wines had greater number of chiral terpenes in comparison to Pinot Gris wines. Beyond total terpene content it is possible that the differences in chiral terpene content may be driving the aromatic differences in white wines.

Enzymatic hydrolysis of fructans in the tequila production process

In contrast to the hydrolysis of reserve carbohydrates in most plant-derived alcoholic beverage processes carried out with enzymes, agave fructans in tequila production have traditionally been transformed to fermentable sugars through acid thermal hydrolysis. Experiments at the bench scale demonstrated that the extraction and hydrolysis of agave fructans can be carried out continuously using commercial inulinases in a countercurrent extraction process with shredded agave fibers. Difficulties in the temperature control of large extraction diffusers did not allow the scaling up of this procedure. Nevertheless, batch enzymatic hydrolysis of agave extracts obtained in diffusers operating at 60 and 90 degrees C was studied at the laboratory and industrial levels. The effects of the enzymatic process on some tequila congeners were studied, demonstrating that although a short thermal treatment is essential for the development of tequila's organoleptic characteristics, the fructan hydrolysis can be performed with enzymes without major modifications in the flavor or aroma, as determined by a plant sensory panel and corroborated by the analysis of tequila congeners.

Corn starch gel for yeast cell entrapment. A view for catalysis of wine fermentation

A new biocatalyst was prepared by immobilization of Saccharomyces cerevisiae AXAZ-1 yeast cells in the matrix of corn starch gel. This biocatalyst was used for repeated batch fermentations of glucose and grape must at various sugar concentrations (110-280 g/L) and low-temperature winemaking (5 degrees C). The biocatalyst retained its operational stability for a long period, and it was proved to be capable of producing dry and semisweet wines. The produced wines were analyzed for volatile byproducts by GC and GC-MS, and the results showed an increase in the number and amount of esters by immobilized cells. In addition, an increase in the percentages of esters and a decrease in those of alcohols with the drop of fermentation temperature were reported. The activation energy (E(a)) was lower (approximately 36%) and the reaction rate constant (k) was higher (approximately 78% at 30 degrees C and approximately 265% at 15 degrees C) in the case of immobilized cells compared to free cells, especially at low temperatures. These results show that corn starch gel may act as a promoter for the enzymes that are involved in the process or as a catalyst of the alcoholic fermentation and can explain the capability of immobilized cells for extremely low-temperature winemaking. Therefore, these results open a new way for research to find new catalysts in biotechnological processes.

Headspace solid-phase microextraction gas chromatography-mass spectrometry analysis of volatiles in orujo spirits from a defined geographical origin

A headspace solid-phase microextraction (HS-SPME) and gas chromatography-selective ion monitoring/mass spectrometry (GC-SIM/MS) method was optimized for analysis of 22 volatile compounds in orujo spirit samples from the Geographic Denomination "Orujo de Galicia/Augardente de Galicia". HS-SPME experimental conditions, such as fiber coating, extraction temperature, extraction and pre-equilibrium time, sample volume, and the presence of salt, were studied to improve the extraction process. The best results were obtained using a 65 microm Carbowax-divinylbenzene fiber during a headspace extraction at 40 degrees C with constant magnetic stirring for 15 min and after a 5 min period of pre-equilibrium time. The sample volume was 6 mL of orujo containing 25% of NaCl, placed in 12 mL glass vials equipped with a screw cap and PTFE/silicone septum. Desorption was performed directly in the gas chromatograph injector port for 5 min at 250 degrees C using the splitless mode. The proposed method is sensible (with detection limits between 0.0045 and 0.2399 mg/L), precise (with coefficients of variation in the range 0.99-8.18%), and linear over more than 1 order of magnitude. The developed method presented recoveries comprised between 76.0 and 112.4%. The applicability of the new method was demonstrated by determining the considered 22 volatile compounds in nine orujo commercial samples with quality and origin brands.

Quantifying sesquiterpene and oxygenated terpene emissions from live vegetation using solid-phase microextraction fibers

Biogenic terpenes play important roles in ecosystem functioning and atmospheric chemistry. Some of these compounds are semi-volatile and highly reactive, such as sesquiterpenes and oxygenated terpenes, and are thus difficult to quantify using traditional air sampling and analysis methods. We developed an alternative approach to quantify emissions from live branches using a flow through enclosure and sample collection on solid-phase microextraction (SPME) fibers. This method allows for collection and analysis of analytes with minimal sample transfer through tubing to reduce the potential for losses. We characterized performance characteristics for 65 microm polydimethylsiloxane-divinylbenzene (PDMS/DVB) fibers using gas chromatography followed by mass spectrometry and optimized experimental conditions and procedures for field collections followed by laboratory analysis. Using 10-45 min sampling times and linear calibration curves created from mixtures of terpenes, emissions of methyl chavicol, an oxygenated terpene, and an array of sesquiterpenes were quantified from a Ponderosa pine branch. The detection limit was 4.36 pmol/mol (ppt) for methyl chavicol and 16.6 ppt for beta-caryophyllene. Concentrations determined with SPME fibers agreed with measurements made using proton transfer reaction mass spectrometry (PTR-MS) within the estimated error of the method for well calibrated compounds. This technique can be applied for quantification of biogenic oxygenated terpene and sesquiterpene emissions from live branches in the field.