Development of air-blast dried non-Saccharomyces yeast starter for improving quality of Korean persimmon wine and apple cider

Impact of Co-Inoculation Patterns of Wickerhamomyces anomalus and Saccharomyces cerevisiae on Cider Quality and Aromatic Profiles

Co-inoculation with Saccharomyces cerevisiae and non-Saccharomyces yeasts is an effective method to improve the flavor of cider. Wickerhamomyces anomalus, known for its high ester production capacity, was evaluated in combination with S. cerevisiae to identify optimal mixed yeast inoculants for improved sensory characteristics. Three W. anomalus strains and three inoculation ratio attributes (1:5, 1:1, and 5:1) were tested to assess their impact on the physicochemical indices and sensory attributes of cider. All the strains used as starters developed fermentation-producing ciders with alcoholic degrees between 6.22 and 6.36 (% v/v). Co-inoculation with W. anomalus resulted in significantly higher ester, volatile acid, and higher alcohol levels compared to those of S. cerevisiae monocultures, increasing the complexity of fruity and floral aromas. Furthermore, the proportion of W. anomalus strains in the inoculations was positively correlated with increased aromatic esters and higher alcohols. The Sc-Wa (1:5) cider showed the highest contents of ethyl ethanoate and 3-methylbutan-1-ol, contributing to a nail polish-like aroma. Sc-Wa (1:1) yielded a higher aromatic diversity than did Sc-Wa (5:1), suggesting that co-inoculation with a ratio of 1:1 may provide an effective fermentation strategy for cider aroma enhancement. These findings offer valuable insights into how non-Saccharomyces yeasts can be effectively applied in cider co-fermentation, providing a foundation for their future use in industrial applications.

Evolution of fermented grain yeast communities in strong-flavored baijiu and functional validation of yeasts that produce superior-flavored substances

BACKGROUND

Baijiu is a well-known alcoholic beverage in China and the quality is determined by various microorganisms during the fermentation process. Yeast is one of the most important microorganisms in the fermentation of baijiu. It has a strong esterification capacity and also affects the aroma.

RESULTS

High-throughput sequencing results showed that the fermented grains (jiupei) during baijiu production were mainly composed of eight highly abundant yeast species. The species and abundance of yeasts changed significantly with the fermentation process. The flavor of 30 yeast strains in the jiupei was determined by a sniffing test and gas chromatography-mass spectrometry (GC-MS). The strain with the highest flavor substance content (2.34 mg L-1), named YX3205, was identified as Clavispora lusitaniae. Tolerance results showed that C. lusitaniae YX3205 can tolerate up to 15% (v v-1) ethanol. In a solid-state simulated fermentation experiment, the content of 24 flavor substances was significantly increased in the fortified group, and the total ester content reached 4240.73 μg kg-1, which was 2.8 times higher than that of the control group.

CONCLUSION

The present study demonstrated the potential of C. lusitaniae YX3205 to enhance the flavor of baijiu, thereby serving as a valuable strain for the improvement of the flavor quality of baijiu. © 2024 Society of Chemical Industry.

Improvement of volatile aromatic compound levels and sensory quality of distilled soju derived from Saccharomyces cerevisiae and Wickerhamomyces anomalus co-fermentation

Distilled soju, a Korean traditional alcoholic beverage, is produced by fermenting rice with a variety of microorganisms including molds, yeasts, and lactic acid-producing bacteria, followed by distillation. Our study sought to improve the quality of distilled soju through co-fermentation with Saccharomyces cerevisiae and Wickerhamomyces anomalus, known for producing volatile aromatic compounds during the early stages of fermentation. Analysis of volatile aromatic compounds in co-fermented distilled soju revealed a substantial increase in compounds with boiling points below 200 °C. Among them, ethyl hexanoate, isobutanol, and isoamyl alcohol were identified as the major volatile aromatic compounds based on Log2 fold change analyses of the volatile aromatic compound pattern. In sensory evaluation, co-fermented distilled soju received higher scores in terms of odor and overall preference. Therefore, incorporating W. anomalus may improve the quality of distilled soju.

Microencapsulation of epiphytic coffee yeasts by spray drying using different wall materials: Implementation in coffee medium

The storage of microorganisms in liquid form is the main drawback of commercializing epiphytic coffee yeasts. This work aimed to evaluate the fermentative performance of microencapsulated yeasts by spray drying in a coffee peel and pulp media (CPM). The yeasts, Saccharomyces cerevisiae CCMA 0543, Torulaspora delbrueckii CCMA 0684, and Meyerozyma caribbica CCMA 1738, were microencapsulated using maltodextrin DE10 (MD), high maltose (MA), and whey powder (WP) as wall materials. A Central Composite Rotational Design (CCRD) was used to investigate the effect of operating parameters on the microcapsules' cell viability, drying yield, and water activity. Yeasts reached cell viability and drying yields above 90 and 50 %, respectively. WP maintained the cell viability of the three yeasts over 90 days of storage at room temperature (25 °C) and was selected as a wall material for the three yeasts. M. caribbica showed to be more sensitive to spray drying and less resistant to storage. Some differences were found in the fermentation of the CPM medium, but the microencapsulated yeasts maintained their biotechnological characteristics. Therefore, the microencapsulation of epiphytic coffee yeasts by spray drying was promising to be used in the coffee fermentation process.

Enhancing Ethanol Tolerance via the Mutational Breeding of Pichia terricola H5 to Improve the Flavor Profiles of Wine

Although using non-Saccharomyces yeasts during alcoholic fermentation can improve the wine aroma, most of them are not ethanol tolerant; therefore, in 2017, this study screened 85 non-Saccharomyces yeasts isolated and identified from 24 vineyards in seven Chinese wine-producing regions, obtaining Pichia terricola strain H5, which displayed 8% ethanol tolerance. Strain H5 was subjected to ultraviolet (UV) irradiation and diethyl sulfate (DES) mutagenesis treatment to obtain mutant strains with different fermentation characteristics from the parental H5. Compared with strain H5, the UV-irradiated strains, UV5 and UV8, showed significantly higher ethanol tolerance and fermentation capacity. Modified aroma profiles were also evident in the fermentation samples exposed to the mutants. Increased ethyl caprate, ethyl caprylate, and ethyl dodecanoate content were apparent in the UV5 samples, providing the wine with a distinctly floral, fruity, and spicy profile. Fermentation with strain UV8 produced a high ethyl acetate concentration, causing the wine to present a highly unpleasant odor. To a certain extent, UV irradiation improved the ethanol tolerance and fermentation ability of strain H5, changing the wine aroma profile. This study provides a theoretical basis for the industrial application of non-Saccharomyces yeasts that can improve wine flavor.

Preservation of non-Saccharomyces yeasts: Current technologies and challenges

There is a recent and growing interest in the study and application of non-Saccharomyces yeasts, mainly in fermented foods. Numerous publications and patents show the importance of these yeasts. However, a fundamental issue in studying and applying them is to ensure an appropriate preservation scheme that allows to the non-Saccharomyces yeasts conserve their characteristics and fermentative capabilities by long periods of time. The main objective of this review is to present and analyze the techniques available to preserve these yeasts (by conventional and non-conventional methods), in small or large quantities for laboratory or industrial applications, respectively. Wine fermentation is one of the few industrial applications of non-Saccharomyces yeasts, but the preservation stage has been a major obstacle to achieve a wider application of these yeasts. This review considers the preservation techniques, and clearly defines parameters such as culturability, viability, vitality and robustness. Several conservation strategies published in research articles as well as patents are analyzed, and the advantages and disadvantages of each technique used are discussed. Another important issue during conservation processes is the stress to which yeasts are subjected at the time of preservation (mainly oxidative stress). There is little published information on the subject for non-Saccharomyces yeast, but it is a fundamental point to consider when designing a preservation strategy.

Genetic, Physiological, and Industrial Aspects of the Fructophilic Non-Saccharomyces Yeast Species, Starmerella bacillaris

Starmerella bacillaris (synonym Candida zemplinina) is a non-Saccharomyces yeast species, frequently found in enological ecosystems. Peculiar aspects of the genetics and metabolism of this yeast species, as well as potential industrial applications of isolated indigenous S. bacillaris strains worldwide, have recently been explored. In this review, we summarize relevant observations from studies conducted on standard laboratory and indigenous isolated S. bacillaris strains.

Isolation and Investigation of Potential Non-Saccharomyces Yeasts to Improve the Volatile Terpene Compounds in Korean Muscat Bailey A Wine

The Muscat Bailey A (MBA) grape, one of the most prominent grape cultivars in Korea, contains considerable amounts of monoterpene alcohols that have very low odor thresholds and significantly affect the perception of wine aroma. To develop a potential wine starter for Korean MBA wine, nine types of non-Saccharomyces yeasts were isolated from various Korean food materials, including nuruk, Sémillon grapes, persimmons, and Muscat Bailey A grapes, and their physiological, biochemical, and enzymatic properties were investigated and compared to the conventional wine fermentation strain, Saccharomyces cerevisiae W-3. Through API ZYM analysis, Wickerhamomyces anomalus JK04, Hanseniaspora vineae S7, Hanseniaspora uvarum S8, Candida railenensis S18, and Metschnikowia pulcherrima S36 were revealed to have β-glucosidase activity. Their activities were quantified by culturing in growth medium composed of different carbon sources: 2% glucose, 1% glucose + 1% cellobiose, and 2% cellobiose. W. anomalus JK04 and M. pulcherrima S36 showed the highest β-glucosidase activities in all growth media; thus, they were selected and utilized for MBA wine fermentation. MBA wines co-fermented with non-Saccharomyces yeasts (W. anomalus JK04 or M. pulcherrima S36) and S. cerevisiae W-3 showed significantly increased levels of linalool, citronellol, and geraniol compared to MBA wine fermented with S. cerevisiae W-3 (control). In a sensory evaluation, the flavor, taste, and overall preference scores of the co-fermented wines were higher than those for the control wine, suggesting that W. anomalus JK04 and M. pulcherrima S36 are favorable wine starters for improving Korean MBA wine quality.

Anti-obesity Effect of Fermented Persimmon Extracts via Activation of AMP-Activated Protein Kinase

There is significant cultivation of persimmon (Diospyros kaki) in East Asia, a plant whose fruit has abundant nutrients, including vitamins, polyphenols, and dietary fiber. Persimmon dietary supplements can benefit health by amelioration of diabetes, cardiovascular disease, and obesity. There are also persimmon-based beverages produced via fermentation, such as wines and vinegars, and increasing consumption of these products in East Asia. Although there is great interest in functional foods, the health effects of fermented persimmon extract (FPE) are completely unknown. We examined the effects of FPE on the metabolic parameters of mice fed a high-fat diet (HFD). Our results indicated that FPE supplementation led to an approx. 15% reduction of body weight, reduced abdominal and liver fat, and reduced serum levels of triglycerides, total cholesterol, and glucose. FPE also blocked the differentiation of murine 3T3-L1 pre-adipocyte cells into mature adipocytes. We suggest that gallic acid is a major bioactive component of FPE, and that AMP-activated protein kinase mediates the beneficial effects of FPE and gallic acid.

Basal catalase activity and high glutathione levels influence the performance of non-Saccharomyces active dry wine yeasts

Non-Saccharomyces wine yeasts are useful tools for producing wines with complex aromas or low ethanol content. Their use in wine would benefit from their production as active dry yeast (ADY) starters to be used as co-inocula alongside S. cerevisiae. Oxidative stress during biomass propagation and dehydration is a key factor in determining ADY performance, as it affects yeast vitality and viability. Several studies have analysed the response of S. cerevisiae to oxidative stress under dehydration conditions, but not so many deal with non-conventional yeasts. In this work, we analysed eight non-Saccharomyces wine yeasts under biomass production conditions and studied oxidative stress parameters and lipid composition. The results revealed wide variability among species in their technological performance during ADY production. Also, for Metschnikowia pulcherrima and Starmerella bacillaris, better performance correlates with high catalase activity and glutathione levels. Our data suggest that non-Saccharomyces wine yeasts with an enhanced oxidative stress response are better suited to grow under ADY production conditions.

Freeze-dried immobilized kefir culture in cider-making

BACKGROUND

The aim of the present study was to evaluate the fermentation efficiency of freeze-dried immobilized kefir culture on natural supports (apple pieces, delignified cellulosic material) in cider making at various temperatures (5-45 °C) in comparison with freeze-dried free cells. Freeze-dried cells were initially tested in apple juice fermentations at 30 °C, and then the freeze-dried cultures produced with no cryoprotectants were assessed in repeated batch fermentations.

RESULTS

Repeated batch fermentations lasted for longer than 5 months. High malic acid conversion rates (up to 78.5%) and ethanol productivity values (up to 37.9 g L^-1 day^-1 ) were recorded for freeze-dried immobilized cells. Polymerase chain reaction - denaturing gradient gel electrophoresis (PCR-DGGE) analysis showed that freeze-drying had no effect on the microbial diversity of kefir culture. Higher alcohols were significantly reduced at low fermentation temperatures. Application of principal component analysis (PCA) revealed that both the fermentation temperature and the nature of the freeze-dried kefir culture affected significantly the minor volatiles determined by gas chromatography/mass spectrometry (GC/MS). Notably, all ciders produced were of high quality and were accepted by the tasting panel.

CONCLUSIONS

Freeze-dried immobilized kefir culture on natural supports with no cryoprotectants was found to be suitable for simultaneous alcoholic and malolactic cider fermentation at various temperatures (5-45 °C). The high operational stability of the systems was confirmed and the results obtained are of great interest for the industrial sector as they could be exploited for cider, low-alcohol cider, or 'soft' cider production. © 2020 Society of Chemical Industry.