Brewing potential of Wickerhamomyces anomalus: Growth, fermentation, and aroma characteristics

The color and aroma are the significant traits of vegetables and fruits, but the metabolic and molecular mechanisms underlying anthocyanin accumulation and aroma formation remain almost unknown in fennel (Anethum foeniculum L.), which is a crucial vegetable crop and grown widely for aromatic leaves and bulbs. Here, ten major anthocyanins identified and quantified by ultra-high performance liquid chromatography coupled with quadrupole Orbitrap high-resolution mass spectrometry (UHPLC-Q-Orbitrap HRMS) were mainly responsible for the coloration of purple fennel leaf. With the application of GC-MS, it was found that the reduced volatile phenylpropanoids including isoeugenol, trans-isoeugenol, and apiol chiefly account for the characteristic aroma changes of the purple fennel. Moreover, the characteristic anthocyanin coloration and aroma formation in purple fennel were systematically studied with the integrated transcriptomics and metabolomics. The critical genes associated with the biosynthesis and regulation of anthocyanins and volatile phenylpropanoids were isolated and studied carefully in transiently transfected tobacco cells and transgenic tomato plants. Together with the results of UHPLC-Q-Orbitrap HRMS, RT-qPCR, and yeast two hybrid (Y2H), it is proved that the metabolic flux redirection of phenylpropanoid pathway primarily regulated by a functional MYB-bHLH-WD40 complex consisting of AfTT8, AfMYB7, and AfTTG1 accounts for the characteristic anthocyanin coloration and aroma formation in purple fennel leaf. The systematic understanding of the anthocyanin accumulation and aroma formation will assist in the improvement of fennel resource utilization and breeding.

Volatile metabolomics and coexpression network analyses provide insight into the formation of the characteristic cultivar aroma of oolong tea (Camellia sinensis)

As an important cash crop, tobacco (Nicotiana tabacum L.) is grown to harvest leaves which are cured at elevated temperature before sale. The quality of cured leaves impacts the economic return of growers. High-quality tobacco has high levels of aroma substances in cured leaves, derived mainly from carotenoid degradation products (CDPs). Significant difference in CDPs levels occurs between varieties of distinct genetic background and between regions with different ecological conditions. In order to have a better understanding of what are the major factors that influence the accumulation of CDPs in tobacco leaves, four tobacco varieties, K326, NC82, G28, and Gexin3, with different aroma characteristics, were grown in two typical fields in Shandong and Yunnan, two major tobacco-producing areas in northern and southern China, respectively. Transcriptomic and metabolomic analysis was conducted to identify differentially expressed genes and metabolites. The results of transcriptome analysis revealed that the number of differentially expressed genes (DEGs) between the two locations was more than three times of that among varieties, with the DEGs between locations enriched in the carotenoid biosynthetic pathway. For fresh leaves, similar group of carotenoid-related DEGs were identified and more significant difference in carotenoid contents was observed between locations than among varieties, with higher carotenoid accumulation in tobacco grown in Shandong. Significant decrease in carotenoid contents in leaves was observed during the curing process after harvest. For the same variety, the reduction in carotenoid content following curing was greater in Shandong than in Yunnan. The accumulation of CDPs in tobacco leaves after curing, however, appeared to be complex, being influenced by both environmental and genetic factors. Among the detected CDPs, acetoin, geranyl acetone, and megastigmatrienone were primarily affected by environmental factors, whereas β-ionone-5,6-epoxyde and 3-oxo-α-ionol were predominantly influenced by genetic factors. This study systematically reveals the cascade regulatory relationship among "gene expression - carotenoid accumulation - aroma formation".

Effects of mixed cultures of Saccharomyces cerevisiae Levuline FB — higher ethanol tolerance — and different Kluyveromyces strains — higher inulinase activity — on the production of ethanol from Jerusalem artichoke extract were investigated. Among the investigated strains, combination of S. cerevisiae and K. marxianus strain Y00959 with simultaneous saccharification and fermentation gave the best efficiency (76%) of bioconversion. The optimal ratio of mixed cultures was determined to be 1:1 of K. marxianus and S. cerevisiae. Central composite design (CCD) was adapted to find the optimum initial substrate concentration and inoculum size for the maximal production of ethanol from Jerusalem artichoke juice. The optimum fermentation conditions were found to be 24% (m/w) substrate concentration and 45 OD600nm ml/100 ml inoculum size of mixed culture. Use of these conditions, about 10.67% (v/v) was produced at 148 h of alcoholic fermentation given. Results of this work provide benefits of mixed culture on production of bioethanol from Jerusalem artichoke.

An aroma concentrate of the mat rush (igusa) was prepared by combining solvent extraction with the solvent-assisted flavor evaporation (SAFE) technique. An aroma extract dilution analysis (AEDA) applied to the volatile fraction revealed 51 odor-active peaks with FD factors between 4(3) and 4(7). Among the perceived odorants, twelve peaks with the higher FD factors (>or=4(6)) were proved to be the most important components of the characteristic aroma in mat rush. Eleven odorants were identified or tentatively identified from the twelve peaks as methional, (E,Z)-2,6-nonadienal, (E)-2-nonenal, (E,E)-2,4-nonadienal, (E,E,Z)-2,4,6-nonatrienal, trans-4,5-epoxy-(E)-2-decenal, 4-hydroxy-2,5-dimethyl-3(2H)-furanone, 3-hydroxy-4,5-dimethyl-2(5H)-furanone, isovaleric acid, methyl anthranirate, and vanillin. The FD factors of the odor-active peaks in dried mat rush were observed to be much higher than those in raw mat rush. This finding suggests that the drying process during manufacturing of the mat rush is one of the most important factors for the formation of the characteristic mat rush aroma.

One of the promising raw materials types for alcoholic beverages production, which have a peculiar aroma and taste, is the ashberry (red), widespread throughout the Russian Federation. The aim of the research was to develop an innovative technology for alcoholic beverages from the red ashberry based on the study of the raw materials biochemical composition transformation during its processing, maceration, fermentation, distillation, as well as its effect on the volatile components composition of distillate and the processing conditions of the finished alcoholic beverage. Fermented pulp of red ashberry, distillates and alcoholic beverage blends from ashberry were used as objects of the study. To determine the organoleptic and physico-chemical indicators in the work, standardized analysis methods and certified methods were used. The effect of various yeast races and fermentation conditions on the change in biochemical composition of the red ashberry pulp was studied. For this raw material type fermentation, recommended Siha 3 yeast race. The positive effect of the Vitamon Combi fermentation activator on the fermentation efficiency and the formation of qualitative characteristics of the fermented pulp, including its amino acid composition, is shown. It was established that the optimal conditions for fermentation is the anaerobic regimen at a temperature of no higher than 22 ºС. The effect of fractional distillation operating parameters in a direct distillation unit on the volatile components’ composition and concentration in ashberry distillate is studied. It is recommended to obtain a high-quality distillate to carry out the selection of the head fraction in the amount of 2.5% of the distilled pulp volume, and the selection of the tail fraction to start when the strength in distillate reaches 45% vol. It is shown that within 30 days of exposure in the distillate, a certain chemical equilibrium is achieved and its taste and aromatic characteristics are harmonized. The blending conditions of the alcoholic beverage are determined and the technological processing modes are established to ensure its high consumer properties. The conducted studies have allowed to develop innovative technology for a new alcoholic beverage from red ashberry.

Chinese oolong tea: An aromatic beverage produced under multiple stresses

The aim of this work is to study the ability of whey flavor precursors to form new volatile components under model conditions. The formation of new aromas is considered in the aspect of a two-stage process - enzymatic cleavage of the precursors and the subsequent Maillard reaction. The properties of whey components by their ability to form or modify aromatic descriptors at the stages of enzymatic cleavage of taste precursors are considered. It is proved that targeted enzymatic reactions with whey components lead to the formation of sweet, meat, cheese flavors at various stages of whey protein breakdown after interaction with carbohydrates. The influence of the depth of proteolysis on the subsequent formation of aroma from precursors is considered. It has been established that the breakdown products of milk sugar in whey do not play a significant role in the formation of aroma. Unlike proteolytic enzymes, the use of lactase (β-galactosidase) did not lead to a change in the aromatic characteristics of the modified serum. An increase in the concentration of lactulose, as a potential precursor of aroma in the sugar-amine reactions of serum, gives only a sweetish tint and does not significantly affect the change in aroma. The processes of aroma formation in modified whey have been consistently investigated, and the concept of flavored food foam based on it has been tested. It was shown that the addition of sodium chloride 5-10% to the lower residue after rectification of fermented milk whey significantly increases the stability of the aroma of the final product. It was found that the specific aroma of whey, limiting its use in food, can be modified by using new approaches to reactions with aroma precursors. We consider the fixation of the obtained aromas “soup mushroom”, “broth”, “cheese” on an oil basis for subsequent concentration and use in various products.

Drying methods play a crucial role in the formation of green tea aromas. This study investigated the aroma characteristics and volatile component profiles of large-leaf green tea under hot-air drying, pan-fired drying, and sun drying. The results revealed significant differences in the sensory aroma characteristics and volatile components of the large-leaf green tea among the three drying methods. The pan-fire-dried green tea (PDGT) exhibited a distinct roasted aroma, while the hot-air-dried green tea (HDGT) and sun-dried green tea (SDGT) displayed a faint scent and lasting aroma characteristics, with the SDGT additionally featuring a noticeable sun-dried odor. A total of 48 differential volatile components were identified, among which β-Ionone, (E)-β-Ionone, 2,2,6-Trimethylcyclohexanone, Dihydroactinidiolide, BenzeneacetAldehyde, 2-Pentylfuran, 1,1,6-Trimethyl-1,2-dihydronaphthalene, δ-Cadinene, β-Myrcene, Geranylacetone, o-Cymene, 6-Methyl-5-hepten-2-one, (E)-β-Ocimene, and BenzAldehyde were identified as the primary contributors to the aroma differences among the three large-leaf green teas. Additionally, 43 differential volatile compounds were found to be significantly correlated with at least one of the aroma types (floral, sweet, green, faint scent, nutty, or roasted). The findings of this study provide a theoretical foundation for understanding the formation of aroma qualities in large-leaf green tea and offer valuable insights for improving its aromatic characteristics.

This study determined the diversity and distribution of tick species infesting domestic dogs and the life cycle parameters of the dominant dog tick species. An island-wide, cross-sectional survey of tick species infesting domestic dogs was carried out, and the life cycle of the most commonly occurring dog tick, Rhipicephalus sanguineus was studied under laboratory conditions. A total of 3026 ticks were collected from 1219 dogs in all 25 districts. Eight species in five genera were identified: R. sanguineus (63.4%), R.haemaphysaloides (22.0%), Haemaphysalis bispinosa (12.5%), Haemaphysalis intermedia (0.9%), Haemaphysalis turturis (0.6%), Amblyomma integrum (0.4%), Dermacentor auratus (0.2%) and Hyalomma sp (0.1%). R. sanguineus was the dominant species in the Dry and Wet zones, while R. haemaphysaloides was the dominant species in the Intermediate Zone. Species diversity (Shannon diversity index H) was 1.135, 1.021and 0.849 in the Intermediate, Dry and Wet zones, respectively. The three-host life cycle of R. sanguineus was completed within 70-126days, and all three stages successfully fed on New Zealand white rabbits under laboratory conditions. The Reproductive Efficiency Index (REI) and Reproductive Fitness Index (RFI) were 50.8 ± 9.69 and 9.1 ± 5.01, respectively. Larger females had higher reproductive success. Of the eight species infesting domestic dogs in Sri Lanka, R. sanguineaus was the most frequently occurringtickspecies. The three-host life cycle of R. sanguineus was successfully completed within an average of98days on New Zealand white rabbits. The number of eggs laid, duration of the pre-oviposition period, incubation period and parasitic periods of all three life stages were lower than in previous records.

Fenghuang Dancong tea is a type of semi-fermented oolong tea with unique floral and fruity flavours. However, little is known about aroma formation in Fenghuang Dancong tea during production. In the present work, headspace solid phase microextraction (HS-SPME) combined with gas chromatography mass spectroscopy (GC-MS) was used to extract, detect, and analyse aroma compounds in Fenghuang Dancong tea during the six stages of its production, namely fresh leaves, withering, rocking, de-enzyming, rolling, and baking. In addition, aroma compound changes were statistically validated, and sensory implications were discussed. In total, 131 aroma compounds were extracted and identified throughout production of Fenghuang Dancong tea. The content of alcohols and esters in fresh leaves, withering, and rocking stages was higher than that in de-enzyming, rolling, and baking stages. The content of aroma compounds such as phenylethanol, nerolidol, β-Ionone, and phenylacetaldehyde increased significantly throughout production of Fenghuang Dancong tea. These aroma compounds were the major contributors to the floral and fruity aroma of Fenghuang Dancong tea, and can be thus used as markers of aroma quality of Fenghuang tea during production. In addition, hierarchical cluster analysis (HCA) and principal component analysis (PCA) indicated that aroma compounds extracted during production of Fenghuang Dancong tea clustered into four distinct categories. The findings highlighted the potential of using aroma compounds as markers for aroma quality control during production of Fenghuang Dancong tea, with rocking and de-enzyming stages being identified as the key steps for aroma formation in Fenghuang Dancong tea.

Kinetics of ethanol production from carob pods extract by immobilized S. cerevisiae cells in static and shake flask fermentation have been investigated. Shake flask fermentation proved to be a better fermentation system for the production of ethanol than static fermentation. The optimum values of ethanol concentration, ethanol productivity, ethanol yield, and fermentation efficiency were obtained at pH range 3.5-6.5 and temperature between 30-35 degrees C. A maximum ethanol concentration (65 g/L), ethanol productivity (8.3 g/Lh), ethanol yield (0.44 g/g), and fermentation efficiency (95%) was achieved at an initial sugar concentration of 200, 150, 100, and 200 g/L, respectively. The highest values of specific ethanol production rate and specific sugar uptake rate were obtained at pH 6.5, temperature 40 degrees C, and initial sugar concentration of 100 g/L. Other kinetic parameters, biomass concentration, biomass yield, and specific biomass production rate were maximum at pH 5.5, temperature 30 degrees C, and initial sugar concentration 150 g/L. Under the same fermentation conditions non-sterilized carob pod extract gave higher ethanol concentration than sterilized medium. In repeated batch fermentations, the immobilized S. cerevisiae cells in Ca-alginate beads retained their ability to produce ethanol for 5 d.

The formation mechanism of aroma quality of green and yellow teas based on GC-MS/MS metabolomics

Background and Aims. Aeration, an important operation in winemaking, cannot be controlled accurately based on dissolved oxygen for ester production in wine alcohol fermentation. The following study describes an aeration control method with oxidation-reduction potential (ORP) in alcohol fermentation and investigates its effect on ester production in fermentations with different starter cultures. Methods and Results. The proposed method is based on using ORP as a switch for aeration timing. Different aeration levels driven by ORP were performed in wine alcohol fermentation with different starter cultures including Saccharomyces cerevisiae (Sc), Pichia fermentans (Pf), Hanseniaspora uvarum (Hu), and their mixes (Pf/Sc and Hu/Sc). The accumulated aeration volume, residual sugar concentration, viable cell number, and ester concentration were analyzed. Results showed that aeration levels could be controlled effectively with an ORP value, and aeration with higher ORPs triggered faster sugar utilization in Sc and Hu/Sc fermentation. Pf and Hu survived one day less in their respective cofermentation with aeration when ORP was −100 mV or −50 mV compared to the natural ORP (−150 mV∼−105 mV in Pf/Sc and −141 mV∼−107 mV in Hu/Sc, respectively). Aeration driven by ORP changed ester profiles in cofermentations. With the aeration levels increasing, the proportion of medium-chain fatty acid ethyl esters in the concentration of total esters first increased and then decreased in Hu/Sc fermentation. When ORP was −100 mV in Pf/Sc fermentation, the proportion of higher alcohol acetates to total esters was highest (8.14%), while that of ethyl acetate to total esters was lowest (87.35%). Conclusions. Aeration driven by ORP improved wine ester profiles by increasing the proportion of medium-chain fatty acid ethyl esters or reducing that of ethyl acetate in cofermentations. Significance of the Study. The present study will allow wineries and researchers to optimize the aeration process in alcohol fermentation and develop a scientific aeration strategy to improve the wine ester profile and aroma quality.

Broad bean paste-meju was fermented by a mixture of broad bean koji and saline; koji fermentation is an essential process for the production of broad bean paste-meju. Aspergillus oryzae was the most widely used in sauce fermentation. The purpose of this study was to research the factory adaptability of the highly efficient A. oryzae PNM003 and further evaluate the effect of fermentation conditions and fermentation strains on koji. A. oryzae PNM003 was compared with the widely used strain HN 3.042 not only in the laboratory but also in factory conditions (large scale). Results showed that the koji made with the same starter in the factory had a greater amount of fungi than that in the laboratory. Bacteria and yeast levels in HN_L koji were higher than in PN_L koji. As for fungi constitution, almost only Aspergillus survived in the end through the microorganism self-purification process during koji fermentation. As for the bacterial constitution, koji was grouped by fermentation conditions instead of fermentation starter. PN koji had higher protease activity and a higher content of total acids, amino acid nitrogen, amino acids, and organic acids in the laboratory conditions. Nevertheless, in factory conditions, PN koji and HN koji had similar indexes. As for volatile flavor compounds, koji made with the two starters in the same condition was grouped together. As for the same starter, there were more flavor compounds metabolized in the factory condition than in the laboratory condition, especially esters and alcohols. The results showed PN was a highly efficient strain to ferment koji, but the advantages were expressed more remarkably in laboratory conditions. In brief, the fermented condition had a greater influence than the fermentation starter for broad bean koji.