Fermentation

13 pages, 3278 KiB

Open AccessArticle

Alterations in Yeast Species Composition of Uninoculated Wine Ferments by the Addition of Sulphur Dioxide

by Kathleen Cuijvers, Steven Van Den Heuvel, Cristian Varela, Mark Rullo, Mark Solomon, Simon Schmidt and Anthony Borneman

Fermentation 2020, 6(2), 62; https://doi.org/10.3390/fermentation6020062 - 23 Jun 2020

Cited by 8 | Viewed by 3534

Abstract

Uninoculated wine fermentations are conducted by a consortium of wine yeast and bacteria that establish themselves either from the grape surface or from the winery environment. Of the additives that are commonly used by winemakers, sulphur dioxide (SO₂) represents the main [...] Read more.

Uninoculated wine fermentations are conducted by a consortium of wine yeast and bacteria that establish themselves either from the grape surface or from the winery environment. Of the additives that are commonly used by winemakers, sulphur dioxide (SO₂) represents the main antimicrobial preservative and its use can have drastic effects on the microbial composition of the fermentation. To investigate the effect of SO₂ on the resident yeast community of uninoculated ferments, Chardonnay grape juice from 2018 and 2019 was treated with a variety of SO₂ concentrations ranging up to 100 mg/L and was then allowed to undergo fermentation, with the yeast community structure being assessed via high-throughput meta-barcoding (phylotyping). While the addition of SO₂ was shown to select against the presence of many species of non-Saccharomyces yeasts, there was a clear and increasing selection for the species Hanseniaspora osmophila as concentrations of SO₂ rose above 40 mg/L in fermentations from both vintages. Chemical analysis of the wines resulting from these treatments showed significant increases in acetate esters, and specifically the desirable aroma compound 2-phenylethyl acetate, that accompanied the increase in abundance of H. osmophila. The ability to modulate the yeast community structure of an uninoculated ferment and the resulting chemical composition of the final wine, as demonstrated in this study, represents an important tool for winemakers to begin to be able to influence the organoleptic profile of uninoculated wines. Full article

(This article belongs to the Special Issue Enological Repercussions of Non-Saccharomyces Species 2.0)

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21 pages, 3135 KiB

Open AccessArticle

Evaluation of Media Components and Process Parameters in a Sensitive and Robust Fed-Batch Syngas Fermentation System with Clostridium ljungdahlii

by Alba Infantes, Michaela Kugel and Anke Neumann

Fermentation 2020, 6(2), 61; https://doi.org/10.3390/fermentation6020061 - 18 Jun 2020

Cited by 22 | Viewed by 4417

Abstract

The fermentation of synthesis gas, or syngas, by acetogenic bacteria can help in transitioning from a fossil-fuel-based to a renewable bioeconomy. The main fermentation products of Clostridium ljungdahlii, one of such microorganisms, are acetate and ethanol. A sensitive, robust and reproducible system [...] Read more.

The fermentation of synthesis gas, or syngas, by acetogenic bacteria can help in transitioning from a fossil-fuel-based to a renewable bioeconomy. The main fermentation products of Clostridium ljungdahlii, one of such microorganisms, are acetate and ethanol. A sensitive, robust and reproducible system was established for C. ljungdahlii syngas fermentation, and several process parameters and medium components (pH, gas flow, cysteine and yeast extract) were investigated to assess its impact on the fermentation outcomes, as well as real time gas consumption. Moreover, a closed carbon balance could be achieved with the data obtained. This system is a valuable tool to detect changes in the behavior of the culture. It can be applied for the screening of strains, gas compositions or media components, for a better understanding of the physiology and metabolic regulation of acetogenic bacteria. Here, it was shown that neither yeast extract nor cysteine was a limiting factor for cell growth since their supplementation did not have a noticeable impact on product formation or overall gas consumption. By combining the lowering of both the pH and the gas flow after 24 h, the highest ethanol to acetate ratio was achieved, but with the caveat of lower productivity. Full article

(This article belongs to the Special Issue Microbial Production of Added-value Products from Renewable Resources 2.0)

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15 pages, 1111 KiB

Open AccessArticle

Sequential Non-Saccharomyces and Saccharomyces cerevisiae Fermentations to Reduce the Alcohol Content in Wine

by Margarita García, Braulio Esteve-Zarzoso, Juan Mariano Cabellos and Teresa Arroyo

Fermentation 2020, 6(2), 60; https://doi.org/10.3390/fermentation6020060 - 10 Jun 2020

Cited by 32 | Viewed by 5828

Abstract

Over the last decades, the average alcohol content of wine has increased due to climate change and consumer preferences for particular wine styles that resulted in increased grape sugar levels at harvest. Therefore, alcohol reduction is a current challenge in the winemaking industry. [...] Read more.

Over the last decades, the average alcohol content of wine has increased due to climate change and consumer preferences for particular wine styles that resulted in increased grape sugar levels at harvest. Therefore, alcohol reduction is a current challenge in the winemaking industry. Among several strategies under study, the use of non-conventional yeasts in combination with Saccharomyces cerevisiae plays an important role for lowering ethanol production in wines nowadays. In the present work, 33 native non-Saccharomyces strains were assayed in sequential culture with a S. cerevisiae wine strain to determine their potential for reducing the alcohol content in Malvar white wines. Four of the non-Saccharomyces strains (Wickerhamomyces anomalus 21A-5C, Meyerozyma guilliermondii CLI 1217, and two Metschnikowia pulcherrima (CLI 68 and CLI 460)) studied in sequential combination with S. cerevisiae CLI 889 were best able to produce dry wines with decreased alcohol proportion in comparison with one that was inoculated only with S. cerevisiae. These sequential fermentations produced wines with between 0.8% (v/v) and 1.3% (v/v) lower ethanol concentrations in Malvar wines, showing significant differences compared with the control. In addition, these combinations provided favorable oenological characteristics to wines such as high glycerol proportion, volatile higher alcohols, and esters with fruity and sweet character. Full article

(This article belongs to the Special Issue Enological Repercussions of Non-Saccharomyces Species 2.0)

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12 pages, 1165 KiB

Open AccessArticle

Production, Characterization, and Industrial Application of Pectinase Enzyme Isolated from Fungal Strains

by Sudeep KC, Jitendra Upadhyaya, Dev Raj Joshi, Binod Lekhak, Dhiraj Kumar Chaudhary, Bhoj Raj Pant, Tirtha Raj Bajgai, Rajiv Dhital, Santosh Khanal, Niranjan Koirala and Vijaya Raghavan

Fermentation 2020, 6(2), 59; https://doi.org/10.3390/fermentation6020059 - 9 Jun 2020

Cited by 93 | Viewed by 22910

Abstract

Pectinases are the group of enzymes that catalyze the degradation of pectic substances. It has wide applications in food industries for the production and clarification of wines and juices. The aim of this study was to isolate, screen and characterize pectinase from fungi [...] Read more.

Pectinases are the group of enzymes that catalyze the degradation of pectic substances. It has wide applications in food industries for the production and clarification of wines and juices. The aim of this study was to isolate, screen and characterize pectinase from fungi isolated from various soil samples and evaluate its application in juice clarification. Fungal strains were isolated and screened primarily using 1% citruspectin incorporated potato dextrose agar (PDA) and secondarily using pectinase screening agar medium (PSAM) for pectinolytic organisms. The enzyme was produced by submerged state fermentation and assayed using the dinitro salicylic acid (DNS) method. From 20 different soil samples, 55 fungal isolates were screened primarily and, among them, only 14 isolates were subjected for secondary screening. Out of 14, only four strains showed the highest pectinolytic activity. Among four strains, Aspergillus spp. Gm showed the highest enzyme production at a 48-h incubation period, 1% substrate concentration, and 30 °C temperature. The thermal stability assessment resulted that the activity of pectinase enzyme declines by 50% within 10 min of heating at 60 °C. The optimum temperature, pH, and substrate concentration for the activity of enzyme was 30 °C (75.4 U/mL), 5.8 (72.3 U/mL), and 0.5% (112.0 U/mL), respectively. Furthermore, the yield of the orange juice, the total soluble solid (TSS), and clarity (% transmittance) was increased as the concentration of the pectinase increased, indicating its potential use in juice processing. Overall, the strain Aspergillus spp. Gm was identified as a potent strain for pectinase production in commercial scale. Full article

(This article belongs to the Special Issue Industrial Fermentation)

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11 pages, 1318 KiB

Open AccessArticle

Global View of Biofuel Butanol and Economics of Its Production by Fermentation from Sweet Sorghum Bagasse, Food Waste, and Yellow Top Presscake: Application of Novel Technologies

by N. Qureshi, X. Lin, S. Liu, B. C. Saha, A. P. Mariano, J. Polaina, T. C. Ezeji, A. Friedl, I. S. Maddox, K. T. Klasson, B. S. Dien and V. Singh

Fermentation 2020, 6(2), 58; https://doi.org/10.3390/fermentation6020058 - 3 Jun 2020

Cited by 31 | Viewed by 6449

Abstract

Worldwide, there are various feedstocks such as straws, corn stover, sugarcane bagasse, sweet sorghum bagasse (SSB), grasses, leaves, whey permeate, household organic waste, and food waste (FW) that can be converted to valuable biofuels such as butanol. For the present studies, an economic [...] Read more.

Worldwide, there are various feedstocks such as straws, corn stover, sugarcane bagasse, sweet sorghum bagasse (SSB), grasses, leaves, whey permeate, household organic waste, and food waste (FW) that can be converted to valuable biofuels such as butanol. For the present studies, an economic analysis was performed to compare butanol production from three feedstocks (SSB; FW; and yellow top presscake, YTP or YT) using a standard process and an advanced integrated process design. The total plant capacity was set at 170,000–171,000 metric tons of total acetone butanol ethanol (ABE) per year (99,300 tons of just butanol per year). Butanol production from SSB typically requires pretreatment, separate hydrolysis, fermentation, and product recovery (SHFR). An advanced process was developed in which the last three steps were combined into a single unit operation for simultaneous saccharification, fermentation, and recovery (SSFR). For the SHFR and SSFR plants, the total capital investments were estimated as $213.72 × 10⁶ and $198.16 × 10⁶, respectively. It was further estimated that the minimum butanol selling price (using SSB as a feedstock) for the two processes were $1.14/kg and $1.05/kg. Therefore, SSFR lowered the production cost markedly compared to that of the base case. Butanol made using FW had an estimated minimum selling price of only $0.42/kg. This low selling price is because the FW to butanol process does not require pretreatment, hydrolysis, and cellulolytic enzymes. For this plant, the total capital investment was projected to be $107.26 × 10⁶. The butanol selling price using YTP as a feedstock was at $0.73/kg and $0.79/kg with total capital investments for SSFR and SHFR of $122.58 × 10⁶ and $132.21 × 10⁶, respectively. In the Results and Discussion section, the availability of different feedstocks in various countries such as Brazil, the European Union, New Zealand, Denmark, and the United States are discussed. Additionally, the use of various microbial strains and product recovery technologies are also discussed. Full article

(This article belongs to the Special Issue Ethanol and Value-Added Co-Products 2.0)

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15 pages, 3017 KiB

Open AccessReview

Homologous Recombination: A GRAS Yeast Genome Editing Tool

by Beatrice Bernardi and Jürgen Wendland

Fermentation 2020, 6(2), 57; https://doi.org/10.3390/fermentation6020057 - 1 Jun 2020

Cited by 14 | Viewed by 7142

Abstract

The fermentation industry is known to be very conservative, relying on traditional yeast management. Yet, in the modern fast-paced world, change comes about in facets such as climate change altering the quality and quantity of harvests, changes due to government regulations e.g., the [...] Read more.

The fermentation industry is known to be very conservative, relying on traditional yeast management. Yet, in the modern fast-paced world, change comes about in facets such as climate change altering the quality and quantity of harvests, changes due to government regulations e.g., the use of pesticides or SO₂, the need to become more sustainable, and of course by changes in consumer preferences. As a silent companion of the fermentation industry, the wine yeast Saccharomyces cerevisiae has followed mankind through millennia, changing from a Kulturfolger, into a domesticated species for the production of bread, beer, and wine and further on into a platform strain for the production of biofuels, enzymes, flavors, or pharmaceuticals. This success story is based on the ‘awesome power of yeast genetics’. Central to this is the very efficient homologous recombination (HR) machinery of S. cerevisiae that allows highly-specific genome edits. This microsurgery tool is so reliable that yeast has put a generally recognized as safe (GRAS) label onto itself and entrusted to itself the life-changing decision of mating type-switching. Later, yeast became its own genome editor, interpreted as domestication events, to adapt to harsh fermentation conditions. In biotechnology, yeast HR has been used with tremendous success over the last 40 years. Here we discuss several types of yeast genome edits then focus on HR and its inherent potential for evolving novel wine yeast strains and styles relevant for changing markets. Full article

(This article belongs to the Special Issue Industrial Fermentation)

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12 pages, 1582 KiB

Open AccessArticle

Beer Aroma and Quality Traits Assessment Using Artificial Intelligence

by Claudia Gonzalez Viejo and Sigfredo Fuentes

Fermentation 2020, 6(2), 56; https://doi.org/10.3390/fermentation6020056 - 28 May 2020

Cited by 26 | Viewed by 6494

Abstract

Increasing beer quality demands from consumers have put pressure on brewers to target specific steps within the beer-making process to modify beer styles and quality traits. However, this demands more robust methodologies to assess the final aroma profiles and physicochemical characteristics of beers. [...] Read more.

Increasing beer quality demands from consumers have put pressure on brewers to target specific steps within the beer-making process to modify beer styles and quality traits. However, this demands more robust methodologies to assess the final aroma profiles and physicochemical characteristics of beers. This research shows the construction of artificial intelligence (AI) models based on aroma profiles, chemometrics, and chemical fingerprinting using near-infrared spectroscopy (NIR) obtained from 20 commercial beers used as targets. Results showed that machine learning models obtained using NIR from beers as inputs were accurate and robust in the prediction of six important aromas for beer (Model 1; R = 0.91; b = 0.87) and chemometrics (Model 2; R = 0.93; b = 0.90). Additionally, two more accurate models were obtained from robotics (RoboBEER) to obtain the same aroma profiles (Model 3; R = 0.99; b = 1.00) and chemometrics (Model 4; R = 0.98; b = 1.00). Low-cost robotics and sensors coupled with computer vision and machine learning modeling could help brewers in the decision-making process to target specific consumer preferences and to secure higher consumer demands. Full article

(This article belongs to the Special Issue Industrial Fermentation)

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17 pages, 1976 KiB

Open AccessCommunication

PTR-ToF-MS for the Online Monitoring of Alcoholic Fermentation in Wine: Assessment of VOCs Variability Associated with Different Combinations of Saccharomyces/Non-Saccharomyces as a Case-Study

by Carmen Berbegal, Iuliia Khomenko, Pasquale Russo, Giuseppe Spano, Mariagiovanna Fragasso, Franco Biasioli and Vittorio Capozzi

Fermentation 2020, 6(2), 55; https://doi.org/10.3390/fermentation6020055 - 26 May 2020

Cited by 43 | Viewed by 4844

Abstract

The management of the alcoholic fermentation (AF) in wine is crucial to shaping product quality. Numerous variables (e.g., grape varieties, yeast species/strains, technological parameters) can affect the performances of this fermentative bioprocess. The fact that these variables are often interdependent, with a high [...] Read more.

The management of the alcoholic fermentation (AF) in wine is crucial to shaping product quality. Numerous variables (e.g., grape varieties, yeast species/strains, technological parameters) can affect the performances of this fermentative bioprocess. The fact that these variables are often interdependent, with a high degree of interaction, leads to a huge ‘oenological space’ associated with AF that scientists and professionals have explored to obtain the desired quality standards in wine and to promote innovation. This challenge explains the high interest in approaches tested to monitor this bioprocess including those using volatile organic compounds (VOCs) as target molecules. Among direct injection mass spectrometry approaches, no study has proposed an untargeted online investigation of the diversity of volatiles associated with the wine headspace. This communication proposed the first application of proton-transfer reaction-mass spectrometry coupled to a time-of-flight mass analyzer (PTR-ToF-MS) to follow the progress of AF and evaluate the impact of the different variables of wine quality. As a case study, the assessment of VOC variability associated with different combinations of Saccharomyces/non-Saccharomyces was selected. The different combinations of microbial resources in wine are among the main factors susceptible to influencing the content of VOCs associated with the wine headspaces. In particular, this investigation explored the effect of multiple combinations of two Saccharomyces strains and two non-Saccharomyces strains (belonging to the species Metschnikowia pulcherrima and Torulaspora delbrueckii) on the content of VOCs in wine, inoculated both in commercial grape juice and fresh grape must. The results demonstrated the possible exploitation of non-invasive PTR-ToF-MS monitoring to explore, using VOCs as biomarkers, (i) the huge number of variables influencing AF in wine, and (ii) applications of single/mixed starter cultures in wine. Reported preliminary findings underlined the presence of different behaviors on grape juice and on must, respectively, and confirmed differences among the single yeast strains ‘volatomes’. It was one of the first studies to include the simultaneous inoculation on two non-Saccharomyces species together with a S. cerevisiae strain in terms of VOC contribution. Among the other outcomes, evidence suggests that the addition of M. pulcherrima to the coupled S. cerevisiae/T. delbrueckii can modify the global release of volatiles as a function of the characteristics of the fermented matrix. Full article

(This article belongs to the Special Issue Yeast Biotechnology 3.0)

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16 pages, 4839 KiB

Open AccessReview

Non-Saccharomyces Yeasts and Organic Wines Fermentation: Implications on Human Health

by Alice Vilela

Fermentation 2020, 6(2), 54; https://doi.org/10.3390/fermentation6020054 - 25 May 2020

Cited by 16 | Viewed by 5862

Abstract

A relevant trend in winemaking is to reduce the use of chemical compounds in both the vineyard and winery. In organic productions, synthetic chemical fertilizers, pesticides, and genetically modified organisms must be avoided, aiming to achieve the production of a “safer wine”. Safety [...] Read more.

A relevant trend in winemaking is to reduce the use of chemical compounds in both the vineyard and winery. In organic productions, synthetic chemical fertilizers, pesticides, and genetically modified organisms must be avoided, aiming to achieve the production of a “safer wine”. Safety represents a big threat all over the world, being one of the most important goals to be achieved in both Western society and developing countries. An occurrence in wine safety results in the recovery of a broad variety of harmful compounds for human health such as amines, carbamate, and mycotoxins. The perceived increase in sensory complexity and superiority of successful uninoculated wine fermentations, as well as a thrust from consumers looking for a more “natural” or “organic” wine, produced with fewer additives, and perceived health attributes has led to more investigations into the use of non-Saccharomyces yeasts in winemaking, namely in organic wines. However, the use of copper and sulfur-based molecules as an alternative to chemical pesticides, in organic vineyards, seems to affect the composition of grape microbiota; high copper residues can be present in grape must and wine. This review aims to provide an overview of organic wine safety, when using indigenous and/or non-Saccharomyces yeasts to perform fermentation, with a special focus on some metabolites of microbial origin, namely, ochratoxin A (OTA) and other mycotoxins, biogenic amines (BAs), and ethyl carbamate (EC). These health hazards present an increased awareness of the effects on health and well-being by wine consumers, who also enjoy wines where terroir is perceived and is a characteristic of a given geographical area. In this regard, vineyard yeast biota, namely non-Saccharomyces wine-yeasts, can strongly contribute to the uniqueness of the wines derived from each specific region. Full article

(This article belongs to the Special Issue Enological Repercussions of Non-Saccharomyces Species 2.0)

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26 pages, 410 KiB

Open AccessReview

Gluten-Free Brewing: Issues and Perspectives

by Nazarena Cela, Nicola Condelli, Marisa C. Caruso, Giuseppe Perretti, Maria Di Cairano, Roberta Tolve and Fernanda Galgano

Fermentation 2020, 6(2), 53; https://doi.org/10.3390/fermentation6020053 - 20 May 2020

Cited by 45 | Viewed by 10245

Abstract

Celiac disease (CD) is an immune-mediated gluten-sensitive enteropathy. Currently, it affects around 1% of world population, but it is constantly growing. Celiac patients have to follow a strict gluten-free (GF) diet. Beer is one of the most consumed beverages worldwide, but it is [...] Read more.

Celiac disease (CD) is an immune-mediated gluten-sensitive enteropathy. Currently, it affects around 1% of world population, but it is constantly growing. Celiac patients have to follow a strict gluten-free (GF) diet. Beer is one of the most consumed beverages worldwide, but it is not safe for people with CD. It has a gluten content usually above the safe threshold (20 ppm), determined by the official method for hydrolyzed foods (R5-competitive-ELISA). The demand on the market for GF beers is increasingly growing. This review aims to provide a comprehensive overview of different strategies to produce GF beer, highlighting strengths and weaknesses of each approach and taking into account technological and sensory issues. GF cereals or pseudocereals have poor brewing attitudes (if used as main raw material) and give the beer unusual flavour. Instead, enzymatic treatments allow traditional brewing process followed by gluten content reduction. A survey on 185 GF-producing breweries (both industrial and craft) from all over the world have been considered to assess which approach is most used. Beers brewed with GF cereals and pseudocereals (used in well-balanced proportions) are more common than gluten-removed (GR) beers, obtained by enzymatic treatment. Full article

(This article belongs to the Special Issue Fermentation and Bioactive Metabolites 2.0)

15 pages, 3151 KiB

Open AccessArticle

Harnessing the Residual Nutrients in Anaerobic Digestate for Ethanol Fermentation and Digestate Remediation Using Saccharomyces cerevisiae

by Victor Chinomso Ujor, Christopher Chukwudi Okonkwo, Brennen Bradley Rush, Grace Ellen McCrea and Thaddeus Chukwuemeka Ezeji

Fermentation 2020, 6(2), 52; https://doi.org/10.3390/fermentation6020052 - 18 May 2020

Cited by 10 | Viewed by 3709

Abstract

This study evaluated the feasibility of concomitant nutrient removal, cleaner water recovery, and improved ethanol production via glucose fermentation in the liquid fraction of anaerobic digestate (ADE) by Saccharomyces cerevisiae. The 25%, 50%, and 100% (v/v) ADE supported the growth of S. [...] Read more.

This study evaluated the feasibility of concomitant nutrient removal, cleaner water recovery, and improved ethanol production via glucose fermentation in the liquid fraction of anaerobic digestate (ADE) by Saccharomyces cerevisiae. The 25%, 50%, and 100% (v/v) ADE supported the growth of S. cerevisiae, glucose utilization (~100 g/L) and ethanol production (up to 50.4 ± 6.4 g/L). After a 144 h fermentation in the 50% ADE, the concentrations of ammonia, total nitrogen, phosphate, and total phosphorus decreased 1000-, 104.43-, 1.94-, and 2.20-fold, respectively. Notably, only 0.40 ± 0.61 mg/L ammonia was detected in the 50% ADE post-fermentation. Similarly, the concentrations of aluminum, copper, magnesium, manganese, molybdenum, potassium, sodium, iron, sulfur, zinc, chloride, and sulfate decreased significantly in the ADE. Further analysis suggests that the nitrogen (ammonia and protein), phosphate, and the metal contents of the digestate work in tandem to promote growth and ethanol production. Among these, ammonia and protein appear to exert considerable effects on S. cerevisiae. These results represent a significant first step towards repurposing ADE as a resource in bio-production of fuels and chemicals, whilst generating effluent that is economically treatable by conventional wastewater treatment technologies. Full article

(This article belongs to the Special Issue Biofuel Fermentation from Renewable Biomass)

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22 pages, 2323 KiB

Open AccessArticle

Fermentative Microbes of Khadi, a Traditional Alcoholic Beverage of Botswana

by Koketso Motlhanka, Kebaneilwe Lebani, Teun Boekhout and Nerve Zhou

Fermentation 2020, 6(2), 51; https://doi.org/10.3390/fermentation6020051 - 11 May 2020

Cited by 14 | Viewed by 5777

Abstract

Khadi is a popular traditional alcoholic beverage in rural households in Botswana. The product is produced by fermentation of ripened sun-dried Grewia flava (Malvaceae) fruits supplemented with brown table sugar. Despite its popularity, its growing consumer acceptance, its potential nutritional value, and its [...] Read more.

Khadi is a popular traditional alcoholic beverage in rural households in Botswana. The product is produced by fermentation of ripened sun-dried Grewia flava (Malvaceae) fruits supplemented with brown table sugar. Despite its popularity, its growing consumer acceptance, its potential nutritional value, and its contribution to the socio-economic lifestyle of Botswana, the production process remains non-standardized. Non-standardized production processes lead to discrepancies in product quality and safety as well as varying shelf life. Identification of unknown fermentative microorganisms of khadi is an important step towards standardization of its brewing process for entrance into commercial markets. The aim of this study was to isolate and identify bacteria and yeasts responsible for fermentation of khadi. Yeasts and bacteria harbored in 18 khadi samples from 18 brewers in central and northern Botswana were investigated using classic culture-dependent techniques and DNA sequencing methods. Additionally, we used the same techniques to investigate the presence of bacteria and yeasts on six batches of ripened-dried G. flava fruits used for production of the sampled brews. Our results revealed that Saccharomyces cerevisiae closely related to a commercial baker’s yeast strain sold locally was the most predominant yeast species in khadi suggesting a possible non-spontaneous brewing process. However, we also detected diverse non-Saccharomyces yeasts, which are not available commercially in retail shops in Botswana. This suggests that spontaneous fermentation is partially responsible for fermentation of khadi. This study, presenting the first microbiological characterization of a prominent traditional alcoholic beverage in Botswana, is vital for development of starter cultures for the production of a consistent product towards the commercialization of khadi. Full article

(This article belongs to the Special Issue Non-Saccharomyces Yeasts as Aroma Enhancers in Fermented Products)

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18 pages, 1147 KiB

Open AccessArticle

Aromatic Potential of Diverse Non-Conventional Yeast Species for Winemaking and Brewing

by Amparo Gamero, Annereinou Dijkstra, Bart Smit and Catrienus de Jong

Fermentation 2020, 6(2), 50; https://doi.org/10.3390/fermentation6020050 - 11 May 2020

Cited by 14 | Viewed by 4010

Abstract

Traditionally, Saccharomyces species are those used to conduct industrial alcoholic fermentations. Recently, an increasing interest has arisen with respect to the potential of so-called non-conventional yeasts to improve wine and beer aroma profiles, keeping the particular terroir of each region or for the [...] Read more.

Traditionally, Saccharomyces species are those used to conduct industrial alcoholic fermentations. Recently, an increasing interest has arisen with respect to the potential of so-called non-conventional yeasts to improve wine and beer aroma profiles, keeping the particular terroir of each region or for the development of craft beers. In this study, the potential of diverse non-conventional yeasts to improve aroma in winemaking and brewing was investigated, testing several pure and mixed culture combinations. In addition, a comparison between microscale and labscale was carried out in order to assess the value of microwine and microbeer as screening tools. The results indicated that non-Saccharomyces yeasts were good candidates to enhance or diversify aroma profiles in alcoholic beverages, especially regarding acetate ester yield and fruity aromas. However, mixed cultures with Saccharomyces spp. are normally required to achieve a successful fermentation. The adjustment of pithing ratios is crucial for this purpose. Microscale is presented as an effective and efficient screening tool to compare different culture combinations, although scaling-up will always be necessary in order to get results closer to real winemaking or brewing processes. Full article

(This article belongs to the Special Issue Non-Saccharomyces Yeasts as Aroma Enhancers in Fermented Products)

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9 pages, 1307 KiB

Open AccessArticle

Assessing the Oenological Potential of Nakazawaea ishiwadae, Candida railenensis and Debaryomyces hansenii Strains in Mixed-Culture Grape Must Fermentation with Saccharomyces cerevisiae

by Niel van Wyk, Isak S. Pretorius and Christian von Wallbrunn

Fermentation 2020, 6(2), 49; https://doi.org/10.3390/fermentation6020049 - 7 May 2020

Cited by 19 | Viewed by 4405

Abstract

Recently, there has been a growing interest in the role of non-Saccharomyces yeast (NSY) as a coculturing partner with Saccharomyces cerevisiae during grape must fermentation. We investigated three new strains, namely Nakazawaea ishiwadae, Candida railenensis and Debaryomyces hansenii, for their [...] Read more.

Recently, there has been a growing interest in the role of non-Saccharomyces yeast (NSY) as a coculturing partner with Saccharomyces cerevisiae during grape must fermentation. We investigated three new strains, namely Nakazawaea ishiwadae, Candida railenensis and Debaryomyces hansenii, for their oenological potential in mixed-culture micro-vinifications with S. cerevisiae Vin13 using Muscaris grape must. None of the NSY strains impeded the fermentation performance as all the mixed-culture experiments finished at the same time. Coculturing with N. ishiwadae yielded significantly higher concentrations of ethyl and acetate esters in the final wine product. Apart from higher acetic acid levels, wines produced with C. railenensis and D. hansenii yielded much lower esters concentrations. The concentrations of certain terpenes and norisoprenoids were also significantly modulated in the mixed-culture fermentations. This study reveals the rarely reported species of N. ishiwadae as a promising coculturing partner for increasing aroma-active compounds in a wine. Full article

(This article belongs to the Special Issue Non-Saccharomyces Yeasts as Aroma Enhancers in Fermented Products)

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16 pages, 1256 KiB

Open AccessArticle

Impact of Genotype, Environment, and Malting Conditions on the Antioxidant Activity and Phenolic Content in US Malting Barley

by Bing Zhou, Zhao Jin, Paul Schwarz and Yin Li

Fermentation 2020, 6(2), 48; https://doi.org/10.3390/fermentation6020048 - 29 Apr 2020

Cited by 6 | Viewed by 3659

Abstract

The phenolic content and antioxidant potential of malting barley are important in brewing. The objective of our study was to investigate the effects of barley genotype, growing environment, and malting conditions on the total phenolic content and antioxidant activities of malting barley grown [...] Read more.

The phenolic content and antioxidant potential of malting barley are important in brewing. The objective of our study was to investigate the effects of barley genotype, growing environment, and malting conditions on the total phenolic content and antioxidant activities of malting barley grown in North America. Eight barley cultivars grown at three locations over three years were used. For the malting study, a single barley cultivar, separated into different kernel size fractions, was germinated for various periods of time and then processed by kilning or freeze-drying. Total phenolic content (TPC) and some of the antioxidant activities, including DPPH, ABTS, and superoxide anion radical scavenging activities, reducing power, and iron (II) chelating activity, were significantly impacted by the barley genotype, growth environment, and their interactions. The TPC and most antioxidant activities were also influenced by malting conditions and were generally higher in the malted barleys of the thin kernel size fraction, four-day germination, and in samples processed by kilning, when compared to the plumper kernel size fractions, one and two days of germination, and freeze-dried samples, respectively. There were interactions between malting parameters, and stepwise regression analysis was used to suggest the contribution of each parameter to the TPC and antioxidant activities. Full article

(This article belongs to the Special Issue Fermentation and Bioactive Metabolites 2.0)

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4 pages, 177 KiB

Open AccessEditorial

Food Wastes: Feedstock for Value-Added Products

by Diomi Mamma

Fermentation 2020, 6(2), 47; https://doi.org/10.3390/fermentation6020047 - 27 Apr 2020

Cited by 5 | Viewed by 2610

Abstract

Food is a precious commodity, and its production can be resource-intensive [...] Full article

(This article belongs to the Special Issue Food Wastes: Feedstock for Value-Added Products)

12 pages, 2454 KiB

Open AccessArticle

Selenastrum Capricornutum a New Strain of Algae for Biodiesel Production

by Annarita Pugliese, Lorenzo Biondi, Pietro Bartocci and Francesco Fantozzi

Fermentation 2020, 6(2), 46; https://doi.org/10.3390/fermentation6020046 - 26 Apr 2020

Cited by 24 | Viewed by 5719

Abstract

The increasing global demand for biofuels for energy security and to reduce the effects of climate change has created an opportunity to explore new sources of biomass, of which, microalgae is the most promising one. The Laboratory of the Biomass Research Centre (CRB, [...] Read more.

The increasing global demand for biofuels for energy security and to reduce the effects of climate change has created an opportunity to explore new sources of biomass, of which, microalgae is the most promising one. The Laboratory of the Biomass Research Centre (CRB, University of Perugia) is equipped with a photobioreactor that is used to cultivate microalgae under batch conditions. Tests were carried out a temperature of 22 °C and a Photosynthetic Photon Flux Density of 140 µE·m⁻²·s⁻¹. Cultures were characterized in terms of biomass produced and lipid fraction distribution. The novelty of this paper is the measure of the fuel properties of Selenastrum capricornutum, a new strain for biodiesel production. In particular, after the microalgae have been collected and oil has been extracted, this has been transesterified using a methanol/NaOH solution. The resulting biodiesel has been analyzed with a high-resolution gas chromatograph to determine the concentration of the different methylesters. Full article

(This article belongs to the Special Issue Cultivation and Downstream Processing of Algal Biomass)

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15 pages, 1933 KiB

Open AccessArticle

Evaluation of the Growth Kinetics of Lactobacillus Plantarum ATCC 8014 on a Medium Based on Hydrolyzed Bovine Blood Plasma at Laboratory and Bench-Scale Levels and Its Application as a Starter Culture in a Meat Product

by Pedro José Barragán, Óscar J. Sánchez and Juan C. Henao-Rojas

Fermentation 2020, 6(2), 45; https://doi.org/10.3390/fermentation6020045 - 26 Apr 2020

Cited by 7 | Viewed by 3425

Abstract

Lactobacilli are used in food because of their beneficial effect on human health and their biopreservative activity in matured meat products. The objective of this work was to study the growth kinetics of Lactobacillus plantarum ATCC 8014 by submerged fermentation at laboratory and [...] Read more.

Lactobacilli are used in food because of their beneficial effect on human health and their biopreservative activity in matured meat products. The objective of this work was to study the growth kinetics of Lactobacillus plantarum ATCC 8014 by submerged fermentation at laboratory and bench scales, using a culture medium based on bovine blood plasma (BBP) with hydrolyzed proteins, and to evaluate the maturational effects and sensory properties conferred by the obtained biomass on a matured meat product (pepperoni). At bench scale, it was found that the maximum viable biomass concentration of L. plantarum was 9.58 log CFU/mL, which was higher than what was found in the MRS culture medium (9.53 log CFU/mL). The mathematical model proposed appropriately described the L. plantarum growth kinetics and carbohydrate dynamics during fermentation at laboratory and bench scales in hydrolyzed BBP medium. The application of viable L. plantarum biomass propagated on this medium did not show statistically significant differences during pepperoni maturation compared to the product made with the commercial starter culture. The sensory panel found no differences in the evaluated sensory attributes between these two products. The L. plantarum biomass obtained on this medium can be used successfully in maturation processes in different meat matrices. Full article

(This article belongs to the Special Issue Industrial Fermentation)

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15 pages, 1186 KiB

Open AccessArticle

Physicochemical, Microbiological and Functional Properties of Camelina Meal Fermented in Solid-State Using Food Grade Aspergillus Fungi

by Oladapo Oluwaseye Olukomaiya, W. Chrishanthi Fernando, Ram Mereddy, Xiuhua Li and Yasmina Sultanbawa

Fermentation 2020, 6(2), 44; https://doi.org/10.3390/fermentation6020044 - 24 Apr 2020

Cited by 11 | Viewed by 4756

Abstract

Camelina meal (CAM) was fermented in solid-state using food grade Aspergillus fungi (A. sojae, A. ficuum and their co-cultures), and the physicochemical composition, microbiological and functional properties were investigated. SSF increased the starch contents but reduced (p < 0.05) the [...] Read more.

Camelina meal (CAM) was fermented in solid-state using food grade Aspergillus fungi (A. sojae, A. ficuum and their co-cultures), and the physicochemical composition, microbiological and functional properties were investigated. SSF increased the starch contents but reduced (p < 0.05) the contents of soluble carbohydrate. The microbiological counts of the fermented meals were higher (p < 0.05) than that of the unfermented CAM. Phytic acid content reduced (p < 0.05) in the fermented meals. SSF reduced the protein molecular weight and colour attributes of CAM. The fermented camelina meals had increased (p < 0.05) bulk density and swelling capacity but reduced (p < 0.05) water absorption capacity. Thus, the study indicated that SSF with A. sojae, A. ficuum and their co-cultures influenced the physicochemical, microbiological and functional properties of CAM. There is potential for the development of value-added novel food and feed products from solid-state fermented camelina meal. Full article

(This article belongs to the Special Issue Solid State Fermentations)

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11 pages, 1673 KiB

Open AccessArticle

Selection of Saccharomyces cerevisiae Starter Strain for Merwah Wine

by Nadine Feghali, Angela Bianco, Giacomo Zara, Edouard Tabet, Chantal Ghanem and Marilena Budroni

Fermentation 2020, 6(2), 43; https://doi.org/10.3390/fermentation6020043 - 22 Apr 2020

Cited by 10 | Viewed by 3910

Abstract

In order to select Saccharomyces cerevisiae starter strains for ‘‘Merwah’’ wine production, three strains (M.6.16, M.10.16, and M.4.17) previously isolated from ‘‘Merwah’’ must and characterized at the lab scale were tested in pilot-scale fermentation in a Lebanese winery during the 2019 vintage. The [...] Read more.

In order to select Saccharomyces cerevisiae starter strains for ‘‘Merwah’’ wine production, three strains (M.6.16, M.10.16, and M.4.17) previously isolated from ‘‘Merwah’’ must and characterized at the lab scale were tested in pilot-scale fermentation in a Lebanese winery during the 2019 vintage. The three inoculated musts were compared to that obtained with a spontaneous fermentation. During the fermentations, must samples were taken to evaluate the dominance of the inoculated strains, and at the end of fermentation, the obtained wines were subjected to chemical and sensorial characterization. Molecular monitoring by interdelta analysis revealed that only M.4.17 was able to complete the fermentation and dominate over the wild yeasts. Based on the analysis of principal technological parameters (i.e., residual sugar, fermentative vigor, sulfur production, and acetic acid) and sensorial analysis of the wines obtained, M.4.17 was selected as an adequate starter for the production of typical ‘‘Merwah’’ wine. Full article

(This article belongs to the Special Issue Brewing & Distilling 2.0)

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18 pages, 1234 KiB

Open AccessReview

Valorising Agro-industrial Wastes within the Circular Bioeconomy Concept: the Case of Defatted Rice Bran with Emphasis on Bioconversion Strategies

by Maria Alexandri, José Pablo López-Gómez, Agata Olszewska-Widdrat and Joachim Venus

Fermentation 2020, 6(2), 42; https://doi.org/10.3390/fermentation6020042 - 22 Apr 2020

Cited by 36 | Viewed by 10678

Abstract

The numerous environmental problems caused by the extensive use of fossil resources have led to the formation of the circular bioeconomy concept. Renewable resources will constitute the cornerstone of this new, sustainable model, with biomass presenting a huge potential for the production of [...] Read more.

The numerous environmental problems caused by the extensive use of fossil resources have led to the formation of the circular bioeconomy concept. Renewable resources will constitute the cornerstone of this new, sustainable model, with biomass presenting a huge potential for the production of fuels and chemicals. In this context, waste and by-product streams from the food industry will be treated not as “wastes” but as resources. Rice production generates various by-product streams which currently are highly unexploited, leading to environmental problems especially in the countries that are the main producers. The main by-product streams include the straw, the husks, and the rice bran. Among these streams, rice bran finds applications in the food industry and cosmetics, mainly due to its high oil content. The high demand for rice bran oil generates huge amounts of defatted rice bran (DRB), the main by-product of the oil extraction process. The sustainable utilisation of this by-product has been a topic of research, either as a food additive or via its bioconversion into value-added products and chemicals. This review describes all the processes involved in the efficient bioconversion of DRB into biotechnological products. The detailed description of the production process, yields and productivities, as well as strains used for the production of bioethanol, lactic acid and biobutanol, among others, are discussed. Full article

(This article belongs to the Special Issue Biorefineries)

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12 pages, 364 KiB

Open AccessArticle

Unusual Non-Saccharomyces Yeasts Isolated from Unripened Grapes without Antifungal Treatments

by José Juan Mateo, Patricia Garcerà and Sergi Maicas

Fermentation 2020, 6(2), 41; https://doi.org/10.3390/fermentation6020041 - 21 Apr 2020

Cited by 4 | Viewed by 3404

Abstract

There a lot of studies including the use of non-Saccharomyces yeasts in the process of wine fermentation. The attention is focused on the first steps of fermentation. However, the processes and changes that the non-Saccharomyces yeast populations may have suffered during [...] Read more.

There a lot of studies including the use of non-Saccharomyces yeasts in the process of wine fermentation. The attention is focused on the first steps of fermentation. However, the processes and changes that the non-Saccharomyces yeast populations may have suffered during the different stages of grape berry ripening, caused by several environmental factors, including antifungal treatments, have not been considered in depth. In our study, we have monitored the population dynamics of non-Saccharomyces yeasts during the ripening process, both with biochemical identification systems (API 20C AUX and API ID 32C), molecular techniques (RFLP-PCR) and enzymatic analyses. Some unusual non-Saccharomyces yeasts have been identified (Metschnikowia pulcherrima, Aureobasidium pullulans, Cryptococcus sp. and Rhodotorula mucilaginosa). These yeasts could be affected by antifungal treatments used in wineries, and this fact could explain the novelty involved in their isolation and identification. These yeasts can be a novel source for novel biotechnological uses to be explored in future work. Full article

(This article belongs to the Special Issue Non-Saccharomyces Yeasts as Aroma Enhancers in Fermented Products)

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11 pages, 1140 KiB

Open AccessArticle

Dual Extraction of Crustacean and Fungal Chitosan from a Single Mucor circinelloides Fermentation

by Yun Nian Tan, Pei Pei Lee and Wei Ning Chen

Fermentation 2020, 6(2), 40; https://doi.org/10.3390/fermentation6020040 - 12 Apr 2020

Cited by 33 | Viewed by 5196

Abstract

Mucor circinelloides is a fungus that has been reported to produce ethanol, oil, protein, phosphate and glucosamine, depending on the available nutrients and cultivation conditions. Due to its ability to produce extracellular proteases, it is able to ferment polypeptides and amino acids broken [...] Read more.

Mucor circinelloides is a fungus that has been reported to produce ethanol, oil, protein, phosphate and glucosamine, depending on the available nutrients and cultivation conditions. Due to its ability to produce extracellular proteases, it is able to ferment polypeptides and amino acids broken down from various protein sources. In this study, we attempted to culture the Mucor circinelloides on waste substrates to deproteinize prawn shells for the extraction of chitin and subsequently extract chitosan from its fungal cell wall in a concurrent fermentation. The physio-chemical properties of the extracted crustacean chitin and fungal chitosan were determined by Fourier Transform Infrared Spectroscopy (FTIR) and Elemental Analysis (EA). We found that Mucor circinelloides grown on okara and coffee waste behaved as an excellent protease producer and successfully extracted chitin from prawn shells with a degree of deacetylation of 69.94% and 68.82%, respectively, comparable to commercial chitin (70.46%). The fungal chitosan extracted from the fermentation of Mucor circinelloides on red grape pomace substrate showed a degree of deacetylation of 61.05%, comparable to commercial chitosan (64.00%). Our results suggested feasibility of extracting chitosan from seafood waste-streams using cost-effective microbial fermentation. Full article

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11 pages, 1706 KiB

Open AccessArticle

Bioethanol Production from Food Waste Applying the Multienzyme System Produced On-Site by Fusarium oxysporum F3 and Mixed Microbial Cultures

by George Prasoulas, Aggelos Gentikis, Aikaterini Konti, Styliani Kalantzi, Dimitris Kekos and Diomi Mamma

Fermentation 2020, 6(2), 39; https://doi.org/10.3390/fermentation6020039 - 26 Mar 2020

Cited by 63 | Viewed by 8380

Abstract

Waste management and production of clean and affordable energy are two main challenges that our societies face. Food waste (FW), in particular, can be used as a feedstock for the production of ethanol because of its composition which is rich in cellulose, hemicellulose [...] Read more.

Waste management and production of clean and affordable energy are two main challenges that our societies face. Food waste (FW), in particular, can be used as a feedstock for the production of ethanol because of its composition which is rich in cellulose, hemicellulose and starch. However, the cost of the necessary enzymes used to convert FW to ethanol remains an obstacle. The on-site production of the necessary enzymes could be a possible solution. In the present study, the multienzyme production by the fungus Fusarium oxysporum F3 under solid state cultivation using different agroindustrial residues was explored. Maximum amylase, glucoamylase, endoglucanase, b-glucosidase, cellobiohydrolase, xylanase, b-xylosidase and total cellulase titers on wheat bran (WB) were 17.8, 0.1, 65.2, 27.4, 3.5, 221.5, 0.7, 0.052 and 1.5 U/g WB respectively. F. oxysporum was used for the hydrolysis of FW and the subsequent ethanol production. To boost ethanol production, mixed F. oxysporum and S. cerevisiae cultures were also used. Bioethanol production by F. oxysporum monoculture reached 16.3 g/L (productivity 0.17 g/L/h), while that of the mixed culture was 20.6 g/L (productivity 1.0 g/L/h). Supplementation of the mixed culture with glucoamylase resulted in 30.3 g/L ethanol with a volumetric productivity of 1.4 g/L/h. Full article

(This article belongs to the Special Issue Food Wastes: Feedstock for Value-Added Products)

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Fermentation, Volume 6, Issue 2 (June 2020) – 24 articles

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