Assessment of chemical composition and sensorial properties of ciders fermented with different non-Saccharomyces yeasts in pure and mixed fermentations

Screening of Indigenous Hanseniaspora Strains from China for Ethanol Reduction in Wine

Non-Saccharomyces yeasts have the potential to ameliorate wine ethanol levels, but such fit-for-purpose yeast strains are still lacking. Seventy-one indigenous non-Saccharomyces yeasts isolated from spontaneous fermentations of four wine regions in China (Ningxia, Xinjiang, Gansu, and Shaanxi) were screened for ethanol formation and were characterized for major metabolite profiles in synthetic grape juice fermentation to obtain non-Saccharomyces yeasts with low ethanol yields. Four Hanseniaspora strains with less volatile acidity production were primarily selected, and their ethanol yield was reduced by 22-32% compared to S. cerevisiae. These strains were further evaluated for oenological properties, namely ethanol and temperature tolerance, H2S production, and killer activities against S. cerevisiae. Strain HuC-3-2 was then subjected to Atmospheric Room Temperature Plasma (ARTP) mutagenesis, and a mutant (HuC32-2-72) with rapid growth and optimized ethanol-reducing capability was obtained. The best-performing strains were further characterized in sequential fermentations with S. cerevisiae in Merlot juice, and resulted in a 1.4% v/v decrease in ethanol yield. Comprehensive analysis of yeast populations and the production of key metabolites highlighted important carbon sinks, as well as glycerol formation, partially accounting for the ethanol reduction. In addition to ethanol amelioration, the Hanseniaspora strains also led to alterations in many metabolites, including volatile compounds and some organic acids, which can further modulate wine aroma and flavor.

Aroma Release and Consumer Perception During Cider Consumption

Flavor is an important property affecting consumer acceptance, yet little is known about the correlation between the sensory attributes, volatile compounds, and consumer preference during cider consumption. This study was the first to evaluate which sensory attributes of commercial apple ciders in China were preferred by Chinese consumers. Meanwhile, GC-MS and GC-IMS were conducted to characterize the aroma release both in orthonasal and retronasal olfactory perceptions. The sensory analyses exhibited that Chinese consumers preferred "sweet cider", and sensory attributes such as "a-tropical fruit", "f-fruity" and "t-sweet" were the most popular. A total of 63 volatile compounds were identified using GC-MS, while both the variety and concentrations of these compounds detected by GC-IMS were lower. Finally, partial least squares (PLS) analysis was used to establish two models based on sensory data, and orthonasal and retronasal volatile compounds. The two models had 32 and 29 compounds with variable importance in projection (VIP) values > 1, respectively. The results revealed that the compounds with high correlation with "t-sweet" and "f-fruity" were roughly the same in two PLS models, whereas the number of compounds contributing positively to "t-sour" and "f-fermented" changed significantly.

The Antioxidant Capacity and Flavor Diversity of Strawberry Wine Are Improved Through Fermentation with the Indigenous Non-Saccharomyces Yeasts Hanseniaspora uvarum and Kurtzmaniella quercitrusa

The production of strawberry wine is an effective strategy for addressing the significant economic losses caused by strawberry spoilage. In recent years, there has been an increase in consumer demand for quality and flavor diversity in fruit wines. Therefore, it is necessary to develop novel strawberry wine products. In this research, we assessed and analyzed the influences of fermentation with Hanseniaspora uvarum, Kurtzmaniella quercitrusa, and Saccharomyces cerevisiae under four fermentation conditions on the fermentation kinetics, organoleptic characteristics, chemical compositions, antioxidant capacities, and flavor profiles of strawberry wines. Strawberry wines fermented with the indigenous non-Saccharomyces yeasts H. uvarum and K. quercitrusa showed higher 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-Azinobis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS) free-radical-scavenging capacities and significantly different flavor profiles compared to strawberry wines fermented with S. cerevisiae. In addition, adjusting the initial soluble solids contents of strawberry juices and fermentation temperatures positively affected the quality and flavor profiles of strawberry wines fermented with the H. uvarum and K. quercitrusa strains. Under the condition of 18 °C-20 °Brix, strawberry wine fermented with K. quercitrusa presented the highest antioxidant capacity, with enhanced flavor diversity and color intensity. It is worth noting that K. quercitrusa can be an alternative yeast for producing high-quality strawberry wine with a distinct floral aroma.

Impact of co-fermentation of Saccharomyces cerevisiae and Pichia kluyveri on the metabolic characteristics of the flavor compounds in mulberry wine

This study investigated the metabolic characteristics of mulberry wine produced by co-fermentation with Saccharomyces cerevisiae (SC) and two different Pichia kluyveri (PK). Although S. cerevisiae inhibited the growth of P. kluyveri during co-fermentation, P. kluyveri showed robust growth adaptability. Classical oenological parameters were not significantly altered by co-fermentation compared to pure-fermentation. The P. kluyveri significantly modulated amino acid metabolism pathways during co-fermentation, enhancing the biosynthesis of higher alcohol acetate compounds. Furthermore, co-fermentation strategy promoted the production of volatile flavor compounds, particularly esters and alcohols, which enriched the wine with distinct floral and fruity flavors. This study provides novel insights into the metabolic mechanisms of co-fermentation with SC and PK strains and highlights the potential of P. kluyveri as a co-fermentation agent for improving the aromatic complexity of fruit wines.

Biodiversity and Winemaking Characteristics of Yeasts Isolated from Docynia delavayi (Franch.) Schneid. Wine Microbiota

The community of epibiotic yeasts significantly influences the quality of Docynia delavayi (Franch.) Schneid. wine. The yeast diversity in four different Docynia delavayi (Franch.) Schneid. wines during the brewing stage was investigated using pure culture methods and high-throughput sequencing technology. A total of 229,381,292 sequencing bases were generated, yielding 323,820 valid sequences with an average length of 708 nt and identifying 93 operational taxonomic units (OTUs) from naturally fermented samples of Docynia delavayi (Franch.) Schneid. wine for classification purposes. At the early fermentation stage, Hanseniaspora sp. was identified as the dominant species, whereas at the late fermentation stage, Hanseniaspora sp., Saccharomyces sp., and Candida californica became predominant. From these samples, a total of 109 yeast strains were isolated from Docynia delavayi (Franch.) Schneid. wine. Three specific strains-LZX-76, LZX-89, and LZX-104-were further selected based on their growth characteristics along with hydrogen sulfide production, ester production, ethanol production, and tolerance levels. Through morphological examination and molecular biology techniques, these strains were identified as Pichia fermentans and Hanseniaspora spp. Additionally, a total of 29 volatile compounds were detected through simulated fermentation processes; these included 12 esters, 6 alcohols, 2 acids, 4 aldehydes, and 5 other compounds. When compared to commercial yeasts used as starters in winemaking processes, it was observed that utilizing yeast strains LZX-76, LZX-89, and LZX-104 resulted in an increased number of volatile compounds, which enhanced the aromatic profile characteristics of Docynia delavayi (Franch.) Schneid. wine by making its aroma richer and more complex. The findings from this study hold significant potential value for both the production practices and research endeavors related to Docynia delavayi (Franch.) Schneid. wine.

Effect of hot-air drying processing on the volatile organic compounds and maillard precursors of Dictyophora Rubrovalvata based on GC-IMS, HPLC and LC-MS

The dynamic changes in volatile organic compounds (VOCs), reducing sugars, and amino acids of Dictyophora rubrovalvata (DR) at various drying temperatures were analyzed using GC-IMS, HPLC, and LC-MS. Orthogonal partial least squares discriminant analysis (OPLS-DA) combined with VOCs indicated that drying temperature of 80 °C was optimal. Variable importance in the projection (VIP) and relative odor activity value (ROAV) were employed to identify 22 key VOCs. The findings suggested that esters played a predominant role among the VOCs. Pearson correlation analysis revealed that serine (Ser), glutamine (Gln), lysine (Lys), alanine (Ala), threonine (Thr), glutamic acid (Glu), asparagine (Asn), ribose, and glucose were closely associated with the formation of esters, aldehydes, ketones, pyrimidines, and pyrazines. In conclusion, this study laid a foundational theory for elucidating the characteristics aroma substances and their production pathways, providing a valuable reference for analysing the flavor characteristics of DR.

Changes in volatile flavors during the fermentation of tomato (Solanum lycopersicum L.) juice and its storage stabilization

Flavor is a crucial indicators of the quality of fermented tomato juice; however, there has been limited research in this area. Herein, headspace solid-phase microextraction gas chromatography-mass spectrometry was used to analyze the volatile metabolites at different stages during FTJ fermentation. 131 volatile organic compounds (VOCs) were identified, with alcohols, acids, and esters as the main compounds. The content of superoxide dismutase (SOD) and lycopene (LYC) had a positive correlation with methyl salicylate, ethyl acetate, and linalyl acetate. Subsequently, the storage stability of FTJ was evaluated at temperatures of 4 °C, 25 °C, and 37 °C over a period of 45 d, revealing that the quality of FTJ decreased with increasing storage temperature. The shelf life of FTJ under different storage conditions was determined using SOD activity and LYC content as quality indicators. The final shelf life was 47 d at 37 °C, 69 d at 25 °C, and 123 d at 4 °C.

Exploring the potentials of indigenous Saccharomyces cerevisiae and Pichia kudriavzevii for enhancing flavour and aromatic characteristics in apricot wines

In this study, we investigated the oenological performance of key yeast populations previously identified from apricot wine fermentation, aiming to obtain indigenous starters suitable for apricot wine production. Twenty-one isolates were characterized physiologically, and two isolates each of Saccharomyces cerevisiae and Pichia kudriavzevii were selected for laboratory-scale fermentations. Results showed that S. cerevisiae S9 exhibited significantly higher sugar consumption than S2 and CECA strains, with the former demonstrating a fructophilic character. Mixed fermentations of P. kudriavzevii N11 and N12 resulted in lower citric acid content (decreasing by 12-25 %) and higher glycerol levels (increasing by 12-47 %) compared to pure fermentation. In the mixed fermentation, indigenous S. cerevisiae species supported the survival of P. kudriavzevii, effectively enhancing the fruity esters and terpenes content of apricot wine. This study provides technical support for screening specialized starters for apricot wine production.

Comparison of volatile compounds and sensory profiles of low-alcohol pear beverages fermented with Saccharomyces cerevisiae and different non-Saccharomyces cerevisiae

This study aimed to assess the impact of Saccharomyces cerevisiae and different non-Saccharomyces cerevisiae (Zygosaccharomyces bailii, Hanseniaspora opuntiae and Zygosaccharomyces rouxii) on the volatile compounds and sensory properties of low-alcohol pear beverages fermented from three varieties of pear juices (Korla, Laiyang and Binzhou). Results showed that all three pear juices were favorable matrices for yeasts growth. Non-Saccharomyces cerevisiae exhibited a higher capacity for acetate ester production compared to Saccharomyces cerevisiae, resulting in a significant enhancement in sensory complexity of the beverages. PCA and sensory analysis demonstrated that pear varieties exerted a stronger influence on the crucial volatile components and aroma characteristics of the fermented beverages compared to the yeast species. CA results showed different yeast strains exhibited suitability for the fermentation of specific pear juice varieties.

Untargeted metabolomics combined with chemometrics reveals distinct metabolic profiles across two sparkling cider fermentation stages

This study aimed to examine the metabolic profiles of Saccharomyces cerevisiae yeasts (WLS21 and Y41) in two phases of sparkling cider making (normal and pressure fermentation) by combining untargeted metabolomic with chemometrics. The results showed that of the 634 nonvolatile metabolites identified using LC-MS and 83 volatile metabolites identified by GC-MS, the differential metabolites were 226 and 54, respectively. Metabolic pathway and correlation analyses showed that aspartic acid, phenylalanine and tyrosine, glutamic acid and purine metabolism were associated with flavor formation. The pressure fermentation process increased apigenin, naringenin, toxifolin, pyridoxine and thiamine contents in the final cider. These findings provide useful information and new research ideas for the formation of flavor in sparkling cider and the regulation of phenolic and vitamin production by microbial stress fermentation.

Characterization of volatile profiles and markers prediction of eleven popular edible boletes using SDE-GC-MS and FT-NIR combined with chemometric analysis

Wild edible boletes mushrooms are regarded as a delicacy in many countries and regions due to their rich nutritional contents and strong aromatic compounds. This study aimed to identify 445 samples of 11 boletes species collected from Yunnan and Sichuan provinces through molecular analysis. Using simultaneous distillation-extraction (SDE) combined with gas chromatography-mass spectrometry (GC-MS), 97 volatile compounds were identified. Chemometric methods were then applied to analyze the heterogeneity of these volatile compounds among the different species. The results showed that, 22 and 21 volatile compounds were selected using variable importance in projection (VIP > 1) and relative odor activity values (ROAV > 0.1), respectively. Partial least squares discrimnatint analysis (PLS-DA) was then employed to develop pattern recognition models for 11 species, which demonstrated strong identification performance. Furthermore, correlation heat maps, volcano plots, and Fisher linear discriminant analysis identified five volatile organic compounds, including methyl (9E)-9-octadecenoate, 2, 6-dimethylpyrazine, 1-decen-3-one, furfural, and methional as markers for distinguishing 11 boletes species. Ultimately, the rapid content prediction models of partial least squares regression (PLSR) were established by combining Fourier Transform Near-Infrared Spectroscopy (FT-NIR) with the concentrations of these five marker compounds. These findings provide a methodological strategy for the effective species identification of wild edible mushrooms and the rapid prediction of their characteristic aroma compounds.

Advancements and challenges for brewing aroma-enhancement fruit wines: Microbial metabolizing and brewing techniques

Aroma, a principal determinant of consumer preference for fruit wines, has recently garnered much attention. Fruit wines brewing was concomitant with complex biochemical reactions, in which a variety of compounds jointly contribute to the aroma quality. To date, the mechanisms underlying the synthesis of aroma compounds and biological regulation methods in fruit wines have remained ambiguous, hindering the further improvement of fruit wines sensory profiles. This review provides a detailed account of the synthesis and regulatory mechanisms of typical aroma compounds and their contributions to the characteristics of wines. Additionally, Comprehensive involves between microflora and the formation of aroma compounds have been emphasized. The microflora-mediated aroma compounds evolution can be controlled by key fermentation techniques to protect and enhance. Meanwhile, the genes impacting key aroma compounds can be identified, which provide references for the rapid screening of aroma-enhanced strains as well as target formation of aroma by modifying relative genes.

Characterization and Evaluation of Taihe Black-Boned Silky Fowl Eggs Based on Physical Properties, Nutritive Values, and Flavor Profiles

Taihe black-boned silky fowl (TS) is a native chicken breed in China with more than 2000 years of history. The present study aimed to characterize and evaluate the physical, nutritional, and flavor properties of TS eggs with a comparison to two other commercial breeds. Eggs from TS (n = 60) crossbred black-boned silky fowl (CB, n = 60) and Hy-line Brown (HL, n = 60) were used for physicochemical analysis. The evaluation system was divided into four parts based on nutrient and flavor profiles: protein and amino acids, lipids and fatty acids, mineral elements, and flavor-related amino acids and volatile compounds. Results showed that TS eggs were typically associated with the lowest egg weight and the highest yolk color, as compared with CB and HL eggs. No differences were found in crude protein, crude fat, triglycerides, and cholesterol content between eggs from the different breeds, but these eggs were distinct in terms of the amino acid, fatty acid, and volatile flavor compound profiles. Moreover, the differences in amino acid and fatty acid profiles might contribute to the specific flavor of TS eggs. Evaluation results indicated that TS egg whites may be suitable as a protein source for premature infants and young children under three years old and TS egg yolks could be considered a beneficial dietary lipid source due to their potential anti-cardiovascular properties. Additionally, TS whole eggs could serve as a valuable source of selenium (Se), molybdenum (Mo), zinc (Zn), and phosphorus (P) for adults aged 18 to 65. However, TS and CB eggs showed inferior Haugh units, eggshell quality, and essential amino acid compositions for older children, adolescents, and adults. These findings provide a better insight into the health benefits of TS eggs and contribute to the breeding and nutrition regulation of TS breeds.

Effect of commercial Saccharomyces cerevisiae and non-Saccharomyces yeasts on the chemical composition and bioaccessibility of pineapple wine

Alcoholic fermentation is one of man's most efficient food preservation processes, and innovations in this area are a trend in food science and nutrition. In addition to the classic Saccharomyces yeasts, various other species may have desirable characteristics for obtaining fruit wines. This study investigated the profile of non-Saccharomyces commercial yeasts compared with S. cerevisiae regarding pineapple wine's chemical composition and bioaccessibility. The fermentation profile of the yeasts Lachancea thermotolerans, Brettanomyces bruxellensis, Brettanomyces lambicus, and S. cerevisiae was evaluated for sugar and alcohol content, and the pineapple wines obtained were analyzed for amino acids, phenolics, and organic acids by HPLC and volatile profile by GC/MS. All yeast strains were able to produce ethanol and glycerol at acceptable levels. L. thermotolerans produced higher levels of lactic acid (0.95 g/L) and higher consumption of free amino acids. B. bruxellensis produced higher levels of individual phenolics and ethanol 109 g/L. The alcoholic fermentation process improved the bioaccessibility of phenolics such as catechin (237 %), epigallocatechin gallate (81 %), procyanidin B1 (61 %) and procyanidin B2 (61 %). The yeasts differed in their volatile profiles, with Brettanomyces and Lachancea producing higher levels of compounds associated with pineapple aroma, such as ester ethyl butyrate (260-270 µg/L). These results demonstrate the importance of choosing the yeast strain for the conduction of alcoholic fermentation and that the yeasts Brettanomyces and Lachancea showed technological potential in obtaining pineapple wines. This study contributes to developing processes for obtaining fruit wines by highlighting two non-Saccharomyces yeast species with technological potential for alcoholic fermentations.

Effects of Torulaspora delbrueckii and Saccharomyces cerevisiae Co-Fermentation on the Physicochemical and Flavor Compounds of Huaniu Apple Cider

The effects of different fermentation methods utilizing Torulaspora delbrueckii 1004 and Saccharomyces cerevisiae 32169 on the physicochemical properties, organic acid content, polyphenol and flavonoid concentrations, antioxidant activity, and volatile aroma compounds of Huaniu apple cider were investigated in this study. Employing methods of single inoculation, co-inoculation, and sequential inoculation, it was found that sequential fermentation exhibited strong fermentative power in the initial stages, effectively reducing the content of soluble solids and achieving a balanced composition of malic, succinic, and citric acids while maintaining a lower titratable acidity. Sequential inoculation was observed to significantly enhance the total polyphenols and flavonoids, as well as the antioxidant capacity (p < 0.05). Specifically, in the synthesis of volatile aroma compounds, sequential inoculation significantly enhanced the richness and diversity of the Huaniu apple cider's aromas, particularly in terms of the concentration of ester compounds (p < 0.05). Principal component analysis further confirmed the superiority of sequential inoculation in terms of aroma component diversity and richness. The findings of this study suggest that sequential inoculation of fermentation with non-Saccharomyces and S. cerevisiae is an effective strategy for optimizing the flavor characteristics of Huaniu apple cider, offering valuable theoretical support and practical guidance for enhancing cider quality and fostering the development of new products.

Analysis of the key aroma components of Pu'er tea by synergistic fermentation with three beneficial microorganisms

Aroma is a key indicator of the quality and value of Pu'er tea. A total of 36 aroma components were detected,which Saccharomyces, Rhizopus, and Aspergillus niger, were in the ratios of 2:1:2, 2:2:2, and 2:3:2 inoculated to ferment Pu'er tea, comparing with natural fermentation. In addition, 12 key aroma compounds were identified by analysing ROAVs. Methoxyphenyl compounds and β-ionone were the primary contributors to the formation of aged and woody aroma when fermenting Pu'er tea naturally or using Rhizopus, while linalool and its oxides, benzyl alcohol, hexanal, and limonene were the primary contributors to the formation of floral and fruity aroma when fermenting Pu'er tea using synergistic fermentation with Saccharomyces, Rhizopus, and Aspergillus niger. This study identified the key aroma components of the Pu'er tea fermented using five methods, which revealed and demonstrated the potential application of synergistic effects of different microorganisms in the changes of aroma of Pu'er tea.

Flavor formation of tilapia byproduct hydrolysates in Maillard reaction

The Maillard reaction (MR) of tilapia byproduct protein hydrolysates was investigated for the use of byproduct protein as a food ingredient and to mask its fishy odor and bitter flavor. The flavor differences in tilapia byproduct hydrolysates before and after the MR were analyzed to explore the key flavor precursor peptides and amino acids involved in MR. The results suggested that eight key volatile substances, including 2,5-dimethylpyrazine, 2-pentylfuran, hexanal, octanal, nonanal, (E)-2-decenal, decanal, and 1-octen-3-ol contributed most to the MR products group (ROAV > 1). Ten volatile compounds, including 1-octen-3-ol, hexanal, 2-pentylfuran, 2,5-dimethylpyrazine, methyl decanoate, and 2-octylfuran, were the flavor markers that distinguished the different samples (VIP > 1). The four most consumed peptides were VAPEEHPTL, GPIGPRGPAG, KSADDIKKAF, and VWEGQNIVK. Umami peptides and bitter free amino acids (FAAs) were the key flavor precursor peptide and FAAs, respectively. Overall, the hydrolysates of tilapia byproducts with flavor improved by MR are a promising strategy for the production of flavorings.

Nonconventional yeasts and hybrids for low temperature handcrafted sparkling ciders elaboration in Patagonia

Yeasts play a crucial role in transforming apple must into cider. While Saccharomyces cerevisiae (Sc) has been traditionally associated to cider fermentations worldwide, cryotolerant species such as Saccharomyces uvarum (Su) as well as natural S. cerevisiae × S. uvarum (Sc×Su) hybrids have also been detected in ciders fermented at low temperatures. This study aimed to evaluate the ability of two Patagonian cryotolerant yeast strains (Su and Se) and their interspecific hybrids with a Sc to conduct handcrafted apple must fermentations and a second fermentation process (champenoise method). The main chemical parameters and sensory quality of the resulting sparkling beverages was also analysed. Firstly, Sc×Se and Sc×Su hybrids were evaluated in their fermentative features at laboratory scale. Hybrids were compared with their respective parental species evidencing significant differences in the physicochemical and aromatic composition of the obtained base ciders. Both Su parental strain and the hybrid Sc×Se were selected for performing pilot scale fermentations (250 L) using natural (non-sterilized) apple juice at two different temperatures: 20 °C and 13 °C. Sc parental strain was also evaluated for comparative purposes. All base ciders obtained were then subjected to a second fermentation. A high implantation capacity of both Su and the hybrid was evidenced at the lowest evaluated temperature, while commercial Sc strain was not detected at the final fermentation stage, independently from the temperature. All sparkling ciders exhibited distinct physicochemical profiles. Ciders inoculated with commercial Sc (but effectively fermented with local Sc strains) allowed the development of malolactic fermentation (MLF) in processes carried out at both temperatures. Contrarily, no MLF was observed in ciders inoculated with either Su or the hybrid. Sparkling ciders fermented with Su displayed the highest concentrations of 2-phenylethanol and 2-phenylethyl acetate, regardless of the fermentation temperature. Conversely, ciders fermented with the hybrid at 20 °C exhibited the highest concentrations of ethyl octanoate and ethyl decanoate, contributing to floral and fruity notes in the beverage. Sensory analysis conducted with untrained individuals revealed a preference for sparkling ciders produced with the hybrid strain at both 20 °C and 13 °C. The cider fermented at 20 °C exhibited floral notes, sweetness, and a full body, while ciders fermented at 13 °C displayed moderate acidity and a well-balanced profile. Conversely, a trained panel described the cider fermented at 20 °C with Su as a fruity and acidic beverage, whereas the ciders fermented at 13 °C exhibited intense bitterness and acidity. This study highlights the potential of cryotolerant Saccharomyces species and hybrids in the development of new starter cultures for producing artisanal sparkling ciders with distinctive properties.

Differential consumption of malic acid and fructose in apple musts by Pichia kudriavzevii strains

AIMS

To assess the capability of Pichia kudriavzevii strains isolated from wine, cider, and natural environments in North Patagonia to produce ciders with reduced malic acid levels.

METHODS AND RESULTS

Fermentation kinetics and malic acid consumption were assessed in synthetic media and in regional acidic apple musts. All P. kudriavzevii strains degraded malic acid and grew in synthetic media with malic acid as the sole carbon source. Among these strains, those isolated from cider exhibited higher fermentative capacity, mainly due to increased fructose utilization; however, a low capacity to consume sucrose present in the must was also observed for all strains. The NPCC1651 cider strain stood out for its malic acid consumption ability in high-malic acid Granny Smith apple must. Additionally, this strain produced high levels of glycerol as well as acceptable levels of acetic acid. On the other hand, Saccharomyces cerevisiae ÑIF8 reference strain isolated from Patagonian wine completely consumed reducing sugars and sucrose and showed an important capacity for malic acid consumption in apple must fermentations.

CONCLUSIONS

Pichia kudriavzevii NPCC1651 strain isolated from cider evidenced interesting features for the consumption of malic acid and fructose in ciders.

Exploring future applications of the apiculate yeast Hanseniaspora

As a metaphor, lemons get a bad rap; however the proverb 'if life gives you lemons, make lemonade' is often used in a motivational context. The same could be said of Hanseniaspora in winemaking. Despite its predominance in vineyards and grape must, this lemon-shaped yeast is underappreciated in terms of its contribution to the overall sensory profile of fine wine. Species belonging to this apiculate yeast are known for being common isolates not just on grape berries, but on many other fruits. They play a critical role in the early stages of a fermentation and can influence the quality of the final product. Their deliberate addition within mixed-culture fermentations shows promise in adding to the complexity of a wine and thus provide sensorial benefits. Hanseniaspora species are also key participants in the fermentations of a variety of other foodstuffs ranging from chocolate to apple cider. Outside of their role in fermentation, Hanseniaspora species have attractive biotechnological possibilities as revealed through studies on biocontrol potential, use as a whole-cell biocatalyst and important interactions with Drosophila flies. The growing amount of 'omics data on Hanseniaspora is revealing interesting features of the genus that sets it apart from the other Ascomycetes. This review collates the fields of research conducted on this apiculate yeast genus.

Selecting autochthonous lactic acid bacteria for co-inoculation in Chinese bayberry wine production: Stress response, starter cultures application and volatilomic study

This study focused on isolating and characterising autochthonous lactic acid bacteria (LAB) from spontaneously fermented Chinese bayberry (CB) and their potential application in CB wine fermentation in co-inoculation with yeast starter cultures. Numerous LAB, including Lactiplantibacillus (Lp.) plantarum (9), Limosilactobacillus (Lb.) fermentum (6), Lactococcus (Lc.) lactis (3), Enterococcus (Ec.) hirae (1), Leuconostoc (Le.) mesenteroides (1), and Weissella (Ws.) cibaria (1), were isolated and identified. The isolated strains Lp. plantarum ZFM710 and ZFM715, together with Lb. fermentum ZFM720 and ZFM722, adapted well to unfavourable fermentation environment, including ethanol, osmolality, and acidity stresses, were selected for producing CB wine by co-inoculation with Saccharomyces cerevisiae. During fermentation, the presence of LAB promoted the development of S. cerevisiae, while the population dynamics of LAB in different groups at different stages showed strain-specific differences. Fermentation trials involving LAB yielded a lower ethanol concentration except for Lp. plantarum ZFM715. Compared to the pure S. cerevisiae fermented sample, the addition of LAB led to a clear modulation in organic acid composition. Lb. fermentum strains in co-fermentation led to significant decreases in each classified group of aroma compounds, while Lp. plantarum ZFM715 significantly increased the complexity and intensity of aroma compounds, as well as the intensities of fruity and floral notes. The study selects interesting strains for the design of starter cultures for use in CB wine production, underlining the interest in the selection of autochthonous LAB in fruit wines, with the aim of improving the adaptation of bacteria to specific environmental conditions and shaping the unique traits of the finished products.

The Effect of Co-Culture with Different Pichia kluyveri and Saccharomyces cerevisiae on Volatile Compound and Characteristic Fingerprints of Mulberry Wine

In this study, changes in volatile compounds co-fermented by different Pichia kluyveri with Saccharomyces cerevisiae were analyzed using GC-IMS and compared with S. cerevisiae fermentation, to investigate the production of aroma in mulberry wine during the fermentation process. A total of 61 compounds were accurately identified, including 21 esters, 10 alcohols, 8 aldehydes, 6 ketones, and 19 other volatiles. Compared with the single strain fermentation (S. cerevisiae), the content of 2-methylpropyl acetate, allyl Isothiocyanate, ethyl crotonate, isobutyl propanoate, and butyl 2-methylbutanoate, co-fermentation groups (S. cerevisiae with different P. kluyveri) showed a significant decrease. Alcohols, aldehydes, ketones, and organic acid were lower in both the F(S-P1) and F(S-P2) groups than in the F(S) group throughout fermentation. The 2-methylpentanoic acid only was contained in the F(S) group. The co-fermentation with different P. kluyveri could also be well distinguished. The content of Benzaldehyde and 4-methylphenol in the F(S-P1) group was significantly lower than that in the F(S-P2) group. The PCA results revealed effective differentiation of mulberry wine fermented by different fermentation strains from GC-IMS. The result showed that P. kluyveri could establish a new flavor system for mulberry wine, which plays a crucial role in enhancing the flavor of fruit wine.

Analysis of aroma quality changes of large-leaf black tea in different storage years based on HS-SPME and GC-MS

The reasons for the change in volatile metabolites and aroma of black tea during storage remain unclear. Therefore, we used HS-SPME and GC-MS methods to analyze the aroma compounds of new tea (2021) versus aged tea groups (2015, 2017, and 2019). A total of 109 volatile components were identified. During storage, 36 metabolites mainly with floral and fruity aromas decreased significantly, while 18 volatile components with spicy, sour, and woody aromas increased significantly. Linalool and beta-ionone mainly contributed to sweet and floral aromas of freshly-processed and aged black tea, respectively. Isovaleric acid and hexanoic acid mainly caused sour odor of aged black tea. The monoterpene biosynthesis and secondary metabolic biosynthesis pathways might be key metabolic pathways leading to changes in the relative content of metabolites during storage of black tea. Our study provides theoretical support for fully understanding the changes in the aroma quality of black tea during storage.

Unlocking Flavor Potential Using Microbial β-Glucosidases in Food Processing

Aroma is among of the most important criteria that indicate the quality of food and beverage products. Aroma compounds can be found as free molecules or glycosides. Notably, a significant portion of aroma precursors accumulates in numerous food products as nonvolatile and flavorless glycoconjugates, termed glycosidic aroma precursors. When subjected to enzymatic hydrolysis, these seemingly inert, nonvolatile glycosides undergo transformation into fragrant volatiles or volatiles that can generate odor-active compounds during food processing. In this context, microbial β-glucosidases play a pivotal role in enhancing or compromising the development of flavors during food and beverage processing. β-glucosidases derived from bacteria and yeast can be utilized to modulate the concentration of particular aroma and taste compounds, such as bitterness, which can be decreased through hydrolysis by glycosidases. Furthermore, oral microbiota can influence flavor perception by releasing volatile compounds that can enhance or alter the perception of food products. In this review, considering the glycosidic flavor precursors present in diverse food and beverage products, we underscore the significance of glycosidases with various origins. Subsequently, we delve into emerging insights regarding the release of aroma within the human oral cavity due to the activity of oral microbial glycosidases.

Discovering the effect of co-fermentation involving Saccharomyces cerevisiae and Schizosaccharomyces pombe on the sensory quality improvement of mandarin wine based on metabolites and transcriptomic profiles

BACKGROUND

Mandarin wine has high added value, which can extend the industry chain of mandarins with excellent economic results. However, innovative fermentation methods are urgently needed to improve the typical taste and flavor characteristics of mandarin wine. In this study, the effect and underlying mechanism of co-fermentation with Saccharomyces cerevisiae and Schizosaccharomyces pombe on the characteristics of mandarin wine were investigated based on integrated metabolomic and transcriptomic analyses.

RESULTS

In comparison with fermentation with only S. cerevisiae, the mandarin wine produced from co-fermentation with S. cerevisiae and Sc. pombe had a higher pH value, lower malic acid content, and more abundant free amino acids, resulting in better sensory evaluation scores. The introduction of Sc. pombe extended the stage of alcoholic fermentation and enhanced the richness and diversity of volatile compounds, especially floral and fruity aroma compounds, including ethyl hexanoate, ethyl caprylate, ethyl enanthate, 1-heptanol, and phenylethyl alcohol. he significantly differential metabolites and varying genes were mainly found in pathways of glycolysis, pyruvate metabolism, the citrate cycle, and amino acid metabolism.

CONCLUSION

Co-fermentation with S. cerevisiae and Sc. pombe showed advantages in producing distinctive taste and flavor of mandarin wine in comparison with fermentation with only S. cerevisiae. This study can inspire new co-fermentation strategies to improve the sensory quality of mandarin wine. © 2023 Society of Chemical Industry.

Unraveling symbiotic microbial communities, metabolomics and volatilomics profiles of kombucha from diverse regions in China

Kombucha is a natural fermented beverage (mixed system). This study aimed to unravel the signatures of kombucha in China to achieve tailor-made microbial consortium. Here, biochemical parameters, microbiome, metabolite production and volatile profile were comprehensively compared and characterized across four regions (AH, HN, SD, SX), both commonalities and distinctions were highlighted. The findings revealed that yeast species yeast Starmerella, Zygosaccharomyces, Dekkera, Pichia and bacterium Komagataeibacter, Gluconobacter were the most common microbes. Additionally, the composition, distribution and stability of microbial composition in liquid phase were superior to those in biofilm. The species diversity, differences, marker and association were analyzed across four areas. Metabolite profiles revealed a total of 163 bioactive compounds (23 flavonoids, 13 phenols), and 68 differential metabolites were screened and identified. Moreover, the metabolic pathways of phenylpropanoids biosynthesis were closely linked with the highest number of metabolites, followed by flavonoid biosynthesis. Sixty-five volatile compounds (23 esters) were identified. Finally, the correlation analysis among the microbial composition and volatile and functional metabolites showed that Komagataeibacter, Gluconolactone, Zygosacchaaromycess, Starmerella and Dekkera seemed closely related to bioactive compounds, especially Komagataeibacter displayed positive correlations with 1-hexadecanol, 5-keto-D-gluconate, L-malic acid, 6-aminohexanoate, Starmerella contributed greatly to gluconolactone, thymidine, anabasine, 2-isopropylmalic acid. Additionally, Candida was related to β-damascenone and α-terpineol, and Arachnomyces and Butyricicoccus showed the consistency of associations with specific esters and alcohols. These findings provided crucial information for creating a stable synthetic microbial community structure, shedding light on fostering stable kombucha and related functional beverages.

Exploring the Bioactive Compounds in Some Apple Vinegar Samples and Their Biological Activities

Apple vinegar is highly recommended for nutrition due to its health benefits and bioactive components. However, the apple cultivar greatly influences the quality of the vinegar. In this research, our focus was on examining the impact of four different apple cultivars on the physicochemical attributes, chemical composition, as well as biological properties-including antidepressant and anti-inflammatory activities-of vinegar. Interestingly, the physicochemical properties of vinegar and the contents of acetic acid and polyphenols depend on the apple cultivars. HPLC chromatographic analysis showed that citric acid (820.62-193.63 mg/100 g) and gallic acid (285.70-54.40 µg/g) were mostly abundant in the vinegar samples. The in vivo results showed that administration of Golden Delicious apple vinegar (10 mL/kg) to adult Wistar rats reduced carrageenan-induced inflammation by 37.50%. The same vinegar sample exhibited a significant antidepressant effect by reducing the rats' immobility time by 31.07% in the forced swimming test. Due to its high acidity, Golden Delicious vinegar was found to be more effective against bacteria, particularly Bacillus subtilis and Candida albicans, resulting in a MIC value of 31.81 mg/mL. Furthermore, the antioxidant activity of various vinegar samples was found to be powerful, displaying optimal values of IC50 = 65.20 mg/mL, 85.83%, and 26.45 AAE/g in the DPPH, β-carotene decolorization and TAC assays, respectively. In conclusion, the apple cultivars used in this study impact the chemical composition and biological activities of vinegar, which may help demonstrate the importance of raw material selection for the production of vinegar.

A special drop: Characterising yeast isolates associated with fermented beverages produced by Australia's indigenous peoples

Way-a-linah, an alcoholic beverage produced from the fermented sap of Eucalyptus gunnii, and tuba, a fermented drink made from the syrup of Cocos nucifera fructifying bud, are two of several fermented beverages produced by Australian Aboriginal and Torres Strait people. Here we describe the characterisation of yeast isolates from samples associated with the fermentation of way-a-linah and tuba. Microbial isolates were obtained from two different geographical locations in Australia - the Central Plateau in Tasmania, and Erub Island in the Torres Strait. While Hanseniaspora species and Lachancea cidri were the most abundant species in Tasmania, Candida species were the most abundant in Erub Island. Isolates were screened for tolerance to stress conditions found during the production of fermented beverages and for enzyme activities relevant to the appearance, aroma and flavour of these beverages. Based on screening results, eight isolates were evaluated for their volatile profile during the fermentation of wort, apple juice and grape juice. Diverse volatile profiles were observed for beers, ciders and wines fermented with different isolates. These findings reveal the potential of these isolates to produce fermented beverages with unique aroma and flavour profiles and highlight the vast microbial diversity associated with fermented beverages produced by Australia's Indigenous peoples.

Changes in the volatile compounds and characteristic aroma during liquid-state fermentation of instant dark tea by Eurotium cristatum

Instant dark tea (IDT) was prepared by liquid-state fermentation inoculating Eurotium cristatum. The changes in the volatile compounds and characteristic aroma of IDT during fermentation were analyzed using gas chromatography-mass spectrometry by collecting fermented samples after 0, 1, 3, 5, 7, and 9 days of fermentation. Components with high odor activity (log₂^FD ≥ 5) were verified by gas chromatography-olfactometry. A total of 107 compounds showed dynamic changes during fermentation over 9 days, including 17 alcohols, 7 acids, 10 ketones, 11 esters, 8 aldehydes, 37 hydrocarbons, 4 phenols, and 13 other compounds. The variety of flavor compounds increased gradually with time within the early stage and achieved a maximum of 79 compounds on day 7 of fermentation. β-Damascenone showed the highest odor activity (log₂^FD = 9) in the day 7 sample, followed by linalool and geraniol. These results indicate that fungal fermentation is critical to the formation of these aromas of IDT.

A comparative study of the effect of bacteria and yeasts communities on inoculated and spontaneously fermented apple cider

Understanding bacteria and yeasts communities can reduce unpredictable changes of apple cider. In this study, apple juice inoculated with Saccharomyces cerevisiae WET 136 and fermented spontaneously were compared, the relationships of bacteria, yeasts, organic acids, and volatiles were analyzed. Results showed that microbial diversity affected the fermentation, organic acids and volatiles in apple ciders. In the first four spontaneous fermentation days, LAB (lactic acid bacteria) multiplied and reached 7.89 lg CFU/mL, and then triggered malolactic fermentation (MLF), leading to malic acid decreased by 3880.52 mg/L and lactic acid increased by 4787.55 mg/L. The citric, succinic and fumaric acids content was 2171.14, 701.51 and 8.06 mg/L lower than that in inoculated cider, respectively. Although the yeasts multiplied during spontaneous fermentation, it did not reach 7.50 lg CFU/mL until the 5th day, which led to a long lag period, as well as later and lower production of acetaldehyde and higher alcohols. The inoculated yeast inhibited LAB, acetic acid bacteria, Rahnella, and non-Saccharomyces. Yeasts were the key to produce citric acid, acetaldehyde and 3-methyl-1-butanol in apple cider; while bacteria were closely related to the formation of lactic acid, acetic acid and ethyl acetate. It suggested that low higher alcohols and acetaldehyde can be realized by selecting yeasts, and Leuconostoc pseudomesenteroides can work as candidate to reduce L-malic and citric acids in apple cider.

Comparative Study on the Volatile Organic Compounds and Characteristic Flavor Fingerprints of Five Varieties of Walnut Oil in Northwest China Using Using Headspace Gas Chromatography-Ion Mobility Spectrometry

Odor is an important characteristic of walnut oil; walnut oil aromas from different varieties smell differently. In order to compare the differences of volatile flavor characteristics in different varieties of walnut oil, the volatile organic compounds (VOCs) of walnut oil from five different walnut varieties in Northwest China were detected and analyzed using headspace gas chromatography–ion mobility spectrometry (HS–GC–IMS). The results showed that 41 VOCs in total were identified in walnut oil from five different varieties, including 14 aldehydes, 8 alcohols, 4 ketones, and 2 esters. Walnut oil (WO) extracted from the “Zha343” variety was most abundant in VOCs. The relative odor activity value (ROAV) analysis showed that aldehydes were the main aroma substances of walnut oil; specifically, hexanal, pentanal, and heptanal were the most abundant. Fingerprints and heat map analysis indicated that WO extracted from the “Xin2”, “185”, “Xin’guang”, and “Zha343” varieties, but not from the “Xinfeng” variety, had characteristic markers. The relative content differences of eight key VOCs in WO from five varieties can be directly compared by Kruskal–Wallis tests, among which the distribution four substances, hexanal (M), hexanal (D), pentanal (M), (E)-2-hexanal (M), presented extremely significant differences (P<0.01). According to the results of the principal component analysis (PCA), WO extracted from the “Zha343” variety was distinct from the other four varieties; in addition, WO extracted from the “Xin2” variety exhibited similarity to WO extracted from the “185” variety, and WO extracted from the “Xinfeng” variety showed similarity to WO extracted from the “Xin’guang” variety. These results reveal that there are certain differences in the VOCs extracted from five different WO varieties, making it feasible to distinguish different varieties of walnut oil or to rapidly detect walnut oil quality based on its volatile substances profile.

Sequential culture with aroma-producing yeast strains to improve the quality of Kyoho wine

Despite many non-Saccharomyces yeasts being considered spoilage microorganisms, they can increase aroma and flavor diversity in alcoholic beverages. The purpose of this study was to investigate nontraditional inoculation strategies using aroma-producing yeast strains for Kyoho wine fermentation, followed by an instrumental analysis and sensory evaluation. The winemaking process was carried out using Saccharomyces cerevisiae Gr112, Hanseniaspora uvarum Pi235, and Pichia kluyveri Pe114. Multiple inoculation strategies were explored. In instrumental analysis results, mixed culture could promote the formation of esters (5.9-folds) and glycerol (1.3-folds) and reduce the content of ethanol (-0.5% [v/v]) in wine. The sensory analysis results suggested that the three yeast strains sequential inoculation treatment was associated with the aroma attributes "floral," "red fruity," and "tropical fruity." Co-cultivation contributed to an increase in complexity and aromatic intensity, with the three-strain inoculation treatment presenting a more distinctive appearance. PRACTICAL APPLICATION: The inoculation of S. cerevisiae improved the accumulation of volatile acids and esters by inhibiting the growth of non-Saccharomyces yeast strains. Inoculation of H. uvarum and P. kluyveri would effectively solve the defect of excessive content of higher alcohols in wines produced by S. cerevisiae. The suitable inoculation strategy between non-Saccharomyces yeasts could improve the overall quality of Kyoho wine whose starter might be widely used in fermentation industry.

Quality Improvement in Apple Ciders during Simultaneous Co-Fermentation through Triple Mixed-Cultures of Saccharomyces cerevisiae, Pichia kudriavzevii, and Lactiplantibacillus plantarum

This study explored the effect of the combination of Saccharomyces yeast, non-Saccharomyces yeast (Pichia kudriavzevii), and Lactiplantibacillus plantarum during cider fermentation on physicochemical properties, antioxidant activities, flavor and aroma compounds, as well as sensory qualities. Ciders fermented with the triple mixed-cultures of these three species showed lower acid and alcohol content than those fermented with the single-culture of S. cerevisiae. The antioxidant activities were enhanced by the triple mixed-culture fermentation, giving a higher 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging rate and total antioxidant capacity; specifically, the SPL5 cider showed the highest DPPH radical scavenging rate (77.28%), while the SPL2 gave the highest total antioxidant capacity (39.57 mmol/L). Additionally, the triple mixed-culture fermentation resulted in improved flavor and aroma with a lower acidity (L-malic acid) and higher aroma compounds (Esters), when compared with the single-culture fermented ciders (Saccharomyces cerevisiae); more specifically, the SPL4 cider resulted in the highest total flavor and aroma compounds. In addition, sensory evaluation demonstrated that ciders produced using the triple mixed-cultures gained higher scores than those fermented using the single-culture of S. cerevisiae, giving better floral aroma, fruity flavor, and overall acceptability. Therefore, our results indicated that the triple mixed-cultures (S. cerevisiae, P. kudriavzevii, and L. plantarum) were found to make up some enological shortages of the single S. cerevisiae fermented cider. This study is believed to provide a potential strategy to enhance cider quality and further give a reference for new industrial development protocols for cider fermentation that have better sensory qualities with higher antioxidant properties.

Application of yeast in plant-derived aroma formation from cigar filler leaves

Introduction: There are various degrees of defects of cigar filler leaves after air drying. Methods: In order to improve the quality and plant-derived aroma content of cigar filler leaves, nine aroma-producing yeasts were applied in artificially solid-state fermentation of cigar filler leaves in this study. The differences with various yeasts application were compared by chemical composition and GC-MS analysis. Results and discussion: The results showed that 120 volatile components were identified and quantified in cigar filler leaves after fermentation, including aldehydes (25 types), alcohols (24 types), ketones (20 types), esters (11 types), hydrocarbons (12 types), acids (4 types) and other substances (23 types). Based on the analysis of odor activity value (OAV), the OVA of fruity and floral aroma components were higher. It was found that floral aroma are the representative aroma types of cigar filler leaves treated with Clavispora lusitaniae, Cyberlindera fabianii, Saccharomycosis fibuligera and Zygosaccharomyces bailii R6. After being inoculated with Hanseniaspora uvarum J1, Hanseniaspora uvarum J4 and Pichia pastoris P3, the OAV of fruity aroma in cigar filler leaves was the highest, followed by tobacco aroma and woody aroma. The correlation between volatile components of cigar filler leaves with different yeasts was revealed after PCA analysis. It was concluded that the quality of cigar filler leaves was improved, and cigar filler leaves fermented with different yeasts showed different flavor.

Sparkling Cider Paired with Italian Cheese: Sensory Analysis and Consumer Assessment

Cider is a beverage belonging to the tradition of many European rural areas. Pairing beverages and cheeses, even if it is part of an ancient tradition, is gaining more and more interest from the consumer. For this reason, in this research, we wanted to conduct a preliminary study on the combination of cider and cheese. In particular, six Italian sparkling ciders were selected, obtained through the Charmat and Champenoise method, and four types of Italian cheeses, from the Veneto region: Casatella Trevigiana, Fienil, Morlacco and Ubriaco, with very different sensory characteristics. The cider-cheese pairing test, conducted by a panel of experts, revealed how some cider parameters are reduced in intensity, such as astringency, while others are enhanced, such as fruitiness and persistence taste aroma. The hedonic test, conducted on the matching by 90 consumers, promoted some combinations while others were rejected. The sensory parameters associated with liking were fruity and taste aroma persistence, particularly expressed in some cider-cheese pairings.

A Preliminary Study of Yeast Strain Influence on Chemical and Sensory Characteristics of Apple Cider

During the fermentation of apple juice, yeast metabolism creates complex biosynthetic pathways which produce a range of compounds responsible for the organoleptic qualities of cider. In this study, basic cider quality parameters were measured to investigate the influence of six yeast strains on cider made from three apple varieties (‘Pink Lady’, ‘Sturmer’, and ‘Bulmer’s Norman’). Measurement of pH, titratable acidity, and total phenolic content revealed that yeast can influence cider attributes, albeit variety and season dependent. Descriptive sensory analysis using a trained sensory panel was conducted on cider made from ‘Pink Lady’ apples and the same six yeast strains. The sensory panel significantly differentiated the yeast strains on the attributes of ‘fresh apple’, ‘earthy’ and ‘pear’. Identifying the variety specific influence of individual yeast strains on chemical and sensory characteristics of apple cider will provide cider makers with an enhanced understanding when choosing yeast strains.

Classification of chinese fragrant rapeseed oil based on sensory evaluation and gas chromatography-olfactometry

Fragrant rapeseed oils and traditional pressed oils are increasingly popular in China owing to their sensory advantages. Many fragrant rapeseed oils are labeled by different fragrance types; however, the scientific basis for these differences is lacking. To identify the distinctive aroma and achieve fragrance classification, the sensory characteristics and aroma components of nine different fragrant rapeseed oils were analyzed via sensory evaluation and gas-chromatography-mass spectrometry-olfactometry. A total of 35 aroma compounds were found to contribute to the overall aroma. By using chemometrics methods, rapeseed oils were categorized into three fragrance styles: “strong fragrance,” “umami fragrance,” and “delicate fragrance.” In total, 10 aroma compounds were predicted to be the most effective compounds for distinguishing sensory characteristics of fragrant rapeseed oil. According to our results, this approach has excellent potential for the fragrance classification and quality control of rapeseed oil.

Comparative metabolome and transcriptome analyses of the properties of Kluyveromyces marxianus and Saccharomyces yeasts in apple cider fermentation

This study explored the application of Kluyveromyces marxianus and Saccharomyces cerevisiae (commercial and wild type) in the alcoholic fermentation of Fuji apple juice under static conditions. Metabolome analyses revealed that ethyl esters, including ethyl hexanoate, ethyl decanoate, ethyl octanoate, octanoic acid and decanoic acid, were the dominant components in ciders fermented by the Saccharomyces yeasts. In the K. marxianus ciders, ethyl acetate, hexyl acetate, propyl acetate and acetic acid were the most abundant volatiles, suggesting that the cider fermented by K. marxianus might have a fruitier smell. Transcriptome analyses were adapted to gain insight into the differential metabolite patterns between K. marxianus and S. cerevisiae during cider fermentation. GO and KEGG enrichments revealed that the metabolic pathways of glucose, organic acids and amino acids during cider fermentation were quite different between these two yeasts. The K. marxianus strain exhibited a higher rate of glycolysis and ethanol fermentation than did Saccharomyces yeasts under oxygen-limited conditions. It also reduced the metabolic flux of acetate into acetyl-CoA and then into the TCA cycle, increasing the syntheses of ethyl acetate and relevant esters, which may affect its cell growth under anaerobic conditions but enriched the taste and variety of aromas in apple cider.

Biotransformation of Hops-Derived Compounds in Beer – A Review

Besides providing bitterness to beer, hops also impart a whole range of aromas, such as herbal, spice, floral, citrus, fruity and pine to this beverage. Although hops are usually added in relatively small amounts, they have a significant impact on the sensory characteristics of the product. Raw hop aroma significantly differs from the aroma resulting from its addition to the beer. The final aroma of the beer arises from substances in the malt, hops, other additives, and yeast metabolism. The biochemical transformation of hop compounds by yeast has become more and more popular in recent years. Knowledge of this process may allow more precise control over the final sensory characteristics of the beverage. The article describes the chemical composition of hops and discusses the influence of the hopping regime on the concentration of volatile compounds in the finished product. Moreover, the article describes the biotransformation of hop-derived compounds by traditionally used Saccharomyces cerevisiae yeast, as well as less commonly used non-Saccharomyces yeast. The paper outlines the current state of knowledge on biotransformation of hop-derived hydrocarbons, terpenoids, esters, sulfur compounds and glycosidically bound aroma precursors.

Evaluation of Four Indigenous Non-Saccharomyces Yeasts Isolated from the Shangri-La Wine Region (China) for Their Fermentation Performances and Aroma Compositions in Synthetic Grape Juice Fermentation

This study investigated the fermentation performances and aroma compositions of synthetic grape juice that was fermented by four indigenous non-Saccharomyces yeast isolates that were obtained from the Shangri-La wine region (China): Meyerozyma guilliermondii (AD-58), Saccharomycopsis vini (BZL-28), Saturnispora diversa (BZL-11), and Wickerhamomyces anomalus (DR-110), in comparison to those of Saccharomyces cerevisiae (EC1118). The four indigenous non-Saccharomyces yeasts showed a lower fermentative capacity and a lower conversion rate of sugar to alcohol, but a higher yield of volatile acidity. W. anomalus (DR-110) had a greater ability to produce numerous esters and short-chain fatty acids and the representative flavors of its fermented medium were fruity and fatty. Sac. vini (BZL-28), interestingly, exhibited great capacity in the formation of many monoterpenes, particularly (Z)-β-ocimene, E-β-ocimene, linalool, citral, and geraniol and its fermented medium was characterized by a strong fruity (citrus-like) and floral flavor. M. guilliermondii (AD-58) and Sat. diversa (BZL-11) only mildly affected the aroma profiles of their resultant fermented media, since the concentrations of most of the volatiles that were produced by these two isolates were much lower than their sensory thresholds. The four indigenous non-Saccharomyces yeasts exhibited distinctive fermentation performances and aroma production behaviors. In particularly, W. anomalus (DR-110) and Sac. vini (BZL-28) have shown good potential in enhancing the aromas and complexity of wine.

Use of Non-Saccharomyces Yeast Co-Fermentation with Saccharomyces cerevisiae to Improve the Polyphenol and Volatile Aroma Compound Contents in Nanfeng Tangerine Wines

This study attempted to improve the polyphenol and volatile aroma compound contents in Nanfeng tangerine wines using non-Saccharomyces yeast and Saccharomyces cerevisiae. The effects of fermentation with pure cultures of Candida ethanolica, Hanseniaspora guilliermondii and Hanseniaspora thailandica, as well as in sequential and mixed inoculations (1:1 or 1:100 ratio) with S. cerevisiae in Nanfeng tangerine wines were evaluated. C. ethanolica was found to produce the most polyphenols (138.78 mg/L) during pure fermentation, while H. guilliermondii produced the most volatile aroma compounds (442.34 mg/L). The polyphenol content produced during sequential fermentation with S. cerevisiae and H. guilliermondii (140.24 mg/L) or C. ethanolica (140.21 mg/L) was significantly higher than other co-fermentations. Meanwhile, the volatile aroma compounds were found to be more abundant in S. cerevisiae/H. guilliermondii mixed fermentation (1:1 ratio) (588.35 mg/L) or S. cerevisiae/H. guilliermondii sequential fermentation (549.31 mg/L). Thus, S. cerevisiae/H. guilliermondii sequential fermentation could considerably boost the polyphenol and volatile aroma component contents in Nanfeng tangerine wines. The findings of this study can be used to drive strategies to increase the polyphenol content and sensory quality of tangerine wines and provide a reference for selecting the co-fermentation styles for non-Saccharomyces yeast and S. cerevisiae in fruit wine fermentation.