Fermentation

14 pages, 2526 KiB

Open AccessReview

How to Deal with Uninvited Guests in Wine: Copper and Copper-containing Oxidases

by Harald Claus

Fermentation 2020, 6(1), 38; https://doi.org/10.3390/fermentation6010038 - 24 Mar 2020

Cited by 15 | Viewed by 4256

Copper is one of the most frequently occurring heavy metals in must and wine. It is introduced by pesticides, brass fittings, and as copper sulphate for treatment of reductive off-flavors. At higher concentrations, copper has harmful effects on the wine. It contributes to [...] Read more.

Copper is one of the most frequently occurring heavy metals in must and wine. It is introduced by pesticides, brass fittings, and as copper sulphate for treatment of reductive off-flavors. At higher concentrations, copper has harmful effects on the wine. It contributes to the oxidation of wine ingredients, browning reactions, cloudiness, inhibition of microorganisms, and wine fermentation. Last but not least, there is also a danger to the consumer. At present, some physicochemical methods exist to reduce the copper content in must and wine, but they all have their shortcomings. A possible solution is the biosorption of metals by yeasts or lactobacilli. Copper can also reach must and wine in the form of copper-containing phenol oxidases (grape tyrosinase, Botrytis cinerea laccases). Similar to free copper, they oxidize phenolic wine compounds, and thus lead to considerable changes in color and nutritional value, making the product ultimately unsaleable. All measurements for enzyme inactivation such as heat treatment, and addition of sulphites or bentonite are either problematic or not effective enough. The application of oenological tannins could offer a way out but needs further research. Full article

(This article belongs to the Special Issue Wine Fermentation 2.0)

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11 pages, 440 KiB

Open AccessArticle

Production of Lactic Acid from Seaweed Hydrolysates via Lactic Acid Bacteria Fermentation

by Hong-Ting Victor Lin, Mei-Ying Huang, Te-Yu Kao, Wen-Jung Lu, Hsuan-Ju Lin and Chorng-Liang Pan

Fermentation 2020, 6(1), 37; https://doi.org/10.3390/fermentation6010037 - 24 Mar 2020

Cited by 47 | Viewed by 10641

Abstract

Biodegradable polylactic acid material is manufactured from lactic acid, mainly produced by microbial fermentation. The high production cost of lactic acid still remains the major limitation for its application, indicating that the cost of carbon sources for the production of lactic acid has [...] Read more.

Biodegradable polylactic acid material is manufactured from lactic acid, mainly produced by microbial fermentation. The high production cost of lactic acid still remains the major limitation for its application, indicating that the cost of carbon sources for the production of lactic acid has to be minimized. In addition, a lack of source availability of food crop and lignocellulosic biomass has encouraged researchers and industries to explore new feedstocks for microbial lactic acid fermentation. Seaweeds have attracted considerable attention as a carbon source for microbial fermentation owing to their non-terrestrial origin, fast growth, and photoautotrophic nature. The proximate compositions study of red, brown, and green seaweeds indicated that Gracilaria sp. has the highest carbohydrate content. The conditions were optimized for the saccharification of the seaweeds, and the results indicated that Gracilaria sp. yielded the highest reducing sugar content. Optimal lactic acid fermentation parameters, such as cell inoculum, agitation, and temperature, were determined to be 6% (v/v), 0 rpm, and 30 °C, respectively. Gracilaria sp. hydrolysates fermented by lactic acid bacteria at optimal conditions yielded a final lactic acid concentration of 19.32 g/L. Full article

(This article belongs to the Special Issue Lactic Acid Fermentation and the Colours of Biotechnology 2.0)

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25 pages, 2138 KiB

Open AccessReview

Changes Occurring in Spontaneous Maize Fermentation: An Overview

by Clemencia Chaves-López, Chiara Rossi, Francesca Maggio, Antonello Paparella and Annalisa Serio

Fermentation 2020, 6(1), 36; https://doi.org/10.3390/fermentation6010036 - 23 Mar 2020

Cited by 56 | Viewed by 12665

Abstract

Maize and its derived fermented products, as with other cereals, are fundamental for human nutrition in many countries of the world. Mixed cultures, principally constituted by lactic acid bacteria (LAB) and yeasts, are responsible for maize fermentation, thus increasing its nutritional value and [...] Read more.

Maize and its derived fermented products, as with other cereals, are fundamental for human nutrition in many countries of the world. Mixed cultures, principally constituted by lactic acid bacteria (LAB) and yeasts, are responsible for maize fermentation, thus increasing its nutritional value and extending the products’ shelf-life. Other microorganisms involved, such as molds, acetic acid bacteria, and Bacillus spp. can contribute to the final product characteristics. This review gives an overview of the impact of the activities of this complex microbiota on maize product development and attributes. In particular, starting from amylolytic activity, which is able to increase sugar availability and influence the microbial succession and production of exopolysaccharides, vitamins, and antimicrobial compounds, which improve the nutritional value. Further activities are also considered with positive effects on the safety profile, such as phytates detoxification and mycotoxins reduction. Full article

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

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14 pages, 670 KiB

Open AccessArticle

Influence of Nutrient Supplementation on Torulaspora Delbrueckii Wine Fermentation Aroma

by Debora Mecca, Santiago Benito, Beata Beisert, Silvia Brezina, Stefanie Fritsch, Heike Semmler and Doris Rauhut

Fermentation 2020, 6(1), 35; https://doi.org/10.3390/fermentation6010035 - 22 Mar 2020

Cited by 13 | Viewed by 4430

Abstract

This study was performed with the aim of characterizing the fermentative performance of three commercial strains of Torulaspora delbrueckii and their impact on the production of volatile and non-volatile compounds. Laboratory-scale single culture fermentations were performed using a commercial white grape juice. The [...] Read more.

This study was performed with the aim of characterizing the fermentative performance of three commercial strains of Torulaspora delbrueckii and their impact on the production of volatile and non-volatile compounds. Laboratory-scale single culture fermentations were performed using a commercial white grape juice. The addition of commercial nutrient products enabled us to test the yeasts under two different nutrient conditions. The addition of nutrients promoted fermentation intensity from 9% to 20 % with significant differences (p < 0.05) among the strains tested. The strain diversity together with the nutrient availability influenced the production of volatile compounds. Full article

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

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15 pages, 1353 KiB

Open AccessArticle

Steam Explosion Pretreatment of Sludge for Pharmaceutical Removal and Heavy Metal Release to Improve Biodegradability and Biogas Production

by Abolfazl Lotfi Aski, Alimohammad Borghei, Ali Zenouzi, Nariman Ashrafi and Mohammad J. Taherzadeh

Fermentation 2020, 6(1), 34; https://doi.org/10.3390/fermentation6010034 - 20 Mar 2020

Cited by 7 | Viewed by 3294

Abstract

Steam explosion pretreatment was developed and evaluated to remove pharmaceuticals and heavy metals from wastewater sludge and to improve its biodegradability and methane yield. Effects of pressure (5–15 bar) and duration (1–15 min) during the pretreatment were examined, and the pretreatment efficiency was [...] Read more.

Steam explosion pretreatment was developed and evaluated to remove pharmaceuticals and heavy metals from wastewater sludge and to improve its biodegradability and methane yield. Effects of pressure (5–15 bar) and duration (1–15 min) during the pretreatment were examined, and the pretreatment efficiency was evaluated based on the solubilization degree, the capillary suction time (CST) test and anaerobic digestion. The removal efficiency of ibuprofen, acetaminophen, and amoxicillin was 65%, 69%, and 66% and 70%, 66%, and 70% in primary sludge (PS) and waste-activated sludge (WAS), respectively. The highest percent release efficiency of heavy metals, i.e., lead, cadmium, and silver, for PS and WAS was 78%, 70%, and 79% and 79%, 80%, and 75%, respectively. The highest methane yield was obtained after pretreatment at 10 bar for 15 min and at 15 bar for 10 min, with respective yields of 380 and 358 mL CH₄/g volatile solids (VS) for the PS and 315 and 334 mL CH₄/g VS for the WAS. The results of methane production indicated that the decreased concentrations of pharmaceuticals and heavy metals resulted in increased biodegradability of PS and WAS. Full article

(This article belongs to the Special Issue Biorefineries)

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12 pages, 940 KiB

Open AccessReview

The Xylose Metabolizing Yeast Spathaspora passalidarum is a Promising Genetic Treasure for Improving Bioethanol Production

by Khaled A. Selim, Saadia M. Easa and Ahmed I. El-Diwany

Fermentation 2020, 6(1), 33; https://doi.org/10.3390/fermentation6010033 - 18 Mar 2020

Cited by 30 | Viewed by 7005

Abstract

Currently, the fermentation technology for recycling agriculture waste for generation of alternative renewable biofuels is getting more and more attention because of the environmental merits of biofuels for decreasing the rapid rise of greenhouse gas effects compared to petrochemical, keeping in mind the [...] Read more.

Currently, the fermentation technology for recycling agriculture waste for generation of alternative renewable biofuels is getting more and more attention because of the environmental merits of biofuels for decreasing the rapid rise of greenhouse gas effects compared to petrochemical, keeping in mind the increase of petrol cost and the exhaustion of limited petroleum resources. One of widely used biofuels is bioethanol, and the use of yeasts for commercial fermentation of cellulosic and hemicellulosic agricultural biomasses is one of the growing biotechnological trends for bioethanol production. Effective fermentation and assimilation of xylose, the major pentose sugar element of plant cell walls and the second most abundant carbohydrate, is a bottleneck step towards a robust biofuel production from agricultural waste materials. Hence, several attempts were implemented to engineer the conventional Saccharomyces cerevisiae yeast to transport and ferment xylose because naturally it does not use xylose, using genetic materials of Pichia stipitis, the pioneer native xylose fermenting yeast. Recently, the nonconventional yeast Spathaspora passalidarum appeared as a founder member of a new small group of yeasts that, like Pichia stipitis, can utilize and ferment xylose. Therefore, the understanding of the molecular mechanisms regulating the xylose assimilation in such pentose fermenting yeasts will enable us to eliminate the obstacles in the biofuels pipeline, and to develop industrial strains by means of genetic engineering to increase the availability of renewable biofuel products from agricultural biomass. In this review, we will highlight the recent advances in the field of native xylose metabolizing yeasts, with special emphasis on S. passalidarum for improving bioethanol production. Full article

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

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14 pages, 2403 KiB

Open AccessArticle

Suitability of the Lebanese “Ace Spur” Apple Variety for Cider Production Using Hanseniaspora sp. Yeast

by Marina Al Daccache, Mohamed Koubaa, Richard G. Maroun, Dominique Salameh, Nicolas Louka and Eugène Vorobiev

Fermentation 2020, 6(1), 32; https://doi.org/10.3390/fermentation6010032 - 08 Mar 2020

Cited by 6 | Viewed by 4061

Abstract

In the present research work, the physicochemical and fermentative properties of the “Ace spur” apple variety, obtained from a Lebanese farm, and the “Kermerrien” variety, obtained from a French cider industry, were investigated. The pomological properties were first determined for both varieties showing [...] Read more.

In the present research work, the physicochemical and fermentative properties of the “Ace spur” apple variety, obtained from a Lebanese farm, and the “Kermerrien” variety, obtained from a French cider industry, were investigated. The pomological properties were first determined for both varieties showing significant differences in the shapes and sizes. Sugar content, titratable acidity, soluble solids, and pH values were then determined. The potential of the “Ace spur” apple juice was then evaluated using the yeast strain Hanseniaspora sp., a major yeast found during the spontaneous fermentation of apples. “Ace spur” apples contained more sugars while the “Kermerrien” cultivar had a highest malic acid and polyphenol concentrations. After 100 h of fermentation, the ethanol percentage (v/v) was around 4% in both ciders. Results obtained in this work revealed the chemical potential of the Lebanese apple juice to produce cider. Full article

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

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27 pages, 1162 KiB

Open AccessReview

Production of Oligosaccharides from Agrofood Wastes

by María Emilia Cano, Alberto García-Martin, Pablo Comendador Morales, Mateusz Wojtusik, Victoria E. Santos, José Kovensky and Miguel Ladero

Fermentation 2020, 6(1), 31; https://doi.org/10.3390/fermentation6010031 - 08 Mar 2020

Cited by 45 | Viewed by 7472

Abstract

The development of biorefinery processes to platform chemicals for most lignocellulosic substrates, results in side processes to intermediates such as oligosaccharides. Agrofood wastes are most amenable to produce such intermediates, in particular, cellooligo-saccharides (COS), pectooligosaccharides (POS), xylooligosaccharides (XOS) and other less abundant oligomers [...] Read more.

The development of biorefinery processes to platform chemicals for most lignocellulosic substrates, results in side processes to intermediates such as oligosaccharides. Agrofood wastes are most amenable to produce such intermediates, in particular, cellooligo-saccharides (COS), pectooligosaccharides (POS), xylooligosaccharides (XOS) and other less abundant oligomers containing mannose, arabinose, galactose and several sugar acids. These compounds show a remarkable bioactivity as prebiotics, elicitors in plants, food complements, healthy coadyuvants in certain therapies and more. They are medium to high added-value compounds with an increasing impact in the pharmaceutical, nutraceutical, cosmetic and food industries. This review is focused on the main production processes: autohydrolysis, acid and basic catalysis and enzymatic saccharification. Autohydrolysis of food residues at 160–190 °C leads to oligomer yields in the 0.06–0.3 g/g dry solid range, while acid hydrolysis of pectin (80–120 °C) or cellulose (45–180 °C) yields up to 0.7 g/g dry polymer. Enzymatic hydrolysis at 40–50 °C of pure polysaccharides results in 0.06–0.35 g/g dry solid (DS), with values in the range 0.08–0.2 g/g DS for original food residues. Full article

(This article belongs to the Special Issue Fermentation Process in Biorefinery)

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20 pages, 957 KiB

Open AccessReview

Review on Non-Dairy Probiotics and Their Use in Non-Dairy Based Products

by Maria Aspri, Photis Papademas and Dimitrios Tsaltas

Fermentation 2020, 6(1), 30; https://doi.org/10.3390/fermentation6010030 - 26 Feb 2020

Cited by 100 | Viewed by 14568

Abstract

Consumer demands for foods promoting health while preventing diseases have led to development of functional foods that contain probiotic bacteria. Fermented dairy products are good substrates for probiotic delivery, but the large number of lactose intolerant people, their high fat and cholesterol content [...] Read more.

Consumer demands for foods promoting health while preventing diseases have led to development of functional foods that contain probiotic bacteria. Fermented dairy products are good substrates for probiotic delivery, but the large number of lactose intolerant people, their high fat and cholesterol content and also due to the growing vegetarianism the consumers are seeking for alternatives. Therefore, researches have been widely studied the feasibility of probiotic bacteria in non-dairy products such as fruits, vegetables, and cereals. This review describes the application of probiotic cultures in non-dairy food products. Full article

(This article belongs to the Special Issue Probiotics and Prebiotics: New Knowledge)

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10 pages, 769 KiB

Open AccessArticle

Non-Conventional Yeasts as Sources of Ene-Reductases for the Bioreduction of Chalcones

by Sara Filippucci, Giorgia Tasselli, Fatima-Zohra Kenza Labbani, Benedetta Turchetti, Maria Rita Cramarossa, Pietro Buzzini and Luca Forti

Fermentation 2020, 6(1), 29; https://doi.org/10.3390/fermentation6010029 - 21 Feb 2020

Cited by 9 | Viewed by 3428

Abstract

Thirteen Non-Conventional Yeasts (NCYs) have been investigated for their ability to reduce activated C=C bonds of chalcones to obtain the corresponding dihydrochalcones. A possible correlation between bioreducing capacity of the NCYs and the substrate structure was estimated. Generally, whole-cells of the NCYs were [...] Read more.

Thirteen Non-Conventional Yeasts (NCYs) have been investigated for their ability to reduce activated C=C bonds of chalcones to obtain the corresponding dihydrochalcones. A possible correlation between bioreducing capacity of the NCYs and the substrate structure was estimated. Generally, whole-cells of the NCYs were able to hydrogenate the C=C double bond occurring in (E)-1,3-diphenylprop-2-en-1-one, while worthy bioconversion yields were obtained when the substrate exhibited the presence of a deactivating electron-withdrawing Cl substituent on the B-ring. On the contrary, no conversion was generally found, with a few exceptions, in the presence of an activating electron-donating substituent OH. The bioreduction aptitude of the NCYs was apparently correlated to the logP value: Compounds characterized by a higher logP exhibited a superior aptitude to be reduced by the NCYs than compounds with a lower logP value. Full article

(This article belongs to the Special Issue Biocatalysis and Fermentation—Enzyme Production and Whole Cell Biocatalysis)

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9 pages, 1525 KiB

Open AccessArticle

Yeast Nanometric Scale Oscillations Highlights Fibronectin Induced Changes in C. albicans

by Anne-Céline Kohler, Leonardo Venturelli, Abhilash Kannan, Dominique Sanglard, Giovanni Dietler, Ronnie Willaert and Sandor Kasas

Fermentation 2020, 6(1), 28; https://doi.org/10.3390/fermentation6010028 - 21 Feb 2020

Cited by 13 | Viewed by 4066

Abstract

Yeast resistance to antifungal drugs is a major public health issue. Fungal adhesion onto the host mucosal surface is still a partially unknown phenomenon that is modulated by several actors among which fibronectin plays an important role. Targeting the yeast adhesion onto the [...] Read more.

Yeast resistance to antifungal drugs is a major public health issue. Fungal adhesion onto the host mucosal surface is still a partially unknown phenomenon that is modulated by several actors among which fibronectin plays an important role. Targeting the yeast adhesion onto the mucosal surface could lead to potentially highly efficient treatments. In this work, we explored the effect of fibronectin on the nanomotion pattern of different Candida albicans strains by atomic force microscopy (AFM)-based nanomotion detection and correlated the cellular oscillations to the yeast adhesion onto epithelial cells. Preliminary results demonstrate that strongly adhering strains reduce their nanomotion activity upon fibronectin exposure whereas low adhering Candida remain unaffected. These results open novel avenues to explore cellular reactions upon exposure to stimulating agents and possibly to monitor in a rapid and simple manner adhesive properties of C. albicans. Full article

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

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17 pages, 2151 KiB

Open AccessArticle

Optimization of β-galactosidase Production by Batch Cultures of Lactobacillus leichmannii 313 (ATCC 7830™)

by Yongjin Deng, Min Xu, Dawei Ji and Dominic Agyei

Fermentation 2020, 6(1), 27; https://doi.org/10.3390/fermentation6010027 - 15 Feb 2020

Cited by 16 | Viewed by 10142

Abstract

The endoenzyme β-galactosidase (β-d-galactoside galactohydrolase; EC 3.2.1.23) has been used at industrial scales for the preparation of lactose-free milk and for the conversion of lactose to galacto-oligosaccharides (GOS) prebiotics. In this study, using Plackett–Burman (PB) design and the response surface methodology [...] Read more.

The endoenzyme β-galactosidase (β-d-galactoside galactohydrolase; EC 3.2.1.23) has been used at industrial scales for the preparation of lactose-free milk and for the conversion of lactose to galacto-oligosaccharides (GOS) prebiotics. In this study, using Plackett–Burman (PB) design and the response surface methodology (RSM), the batch growth conditions for the production of β-galactosidase in DeMan-Rogosa-Sharpe (MRS) media have been studied and optimized for Lactobacillus leichmannii 313 (ATCC 7830™) for the first time. The incubation temperature (30 < T < 55 °C), starting pH (5.5 < pH < 7.5), and carbon source (glucose, lactose, galactose, fructose, and sucrose) were selected as the significant variables for optimization. The maximum crude β-galactosidase production (measured by specific activity) was 4.5 U/mg proteins and was obtained after 12 h of fermentation. The results of the PB design and further optimization by RSM showed that the initial pH of 7.0 and 15.29 g/L of lactose were the levels that gave the optimum observed and predicted β-galactosidase activities of 23.13 U/mg and 23.40 U/mg, respectively. Through RSM optimization, β-galactosidase production increased significantly (over five-fold) in optimized medium (23.13 U/mg), compared with unoptimized medium (4.5 U/mg). Moreover, the crude enzyme obtained was able to hydrolyze lactose and also produce galacto-oligosaccharides. Because its ability to produce β-galactosidase was significantly improved through optimization by RSM, L. leichmannii 313 can serve as a potential source of β-galactosidase for food applications at an industrial scale. Full article

(This article belongs to the Special Issue Biocatalysis and Fermentation—Enzyme Production and Whole Cell Biocatalysis)

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15 pages, 2752 KiB

Open AccessArticle

Robotic Cell Printing for Constructing Living Yeast Cell Microarrays in Microfluidic Chips

by Charlotte Yvanoff, Stefania Torino and Ronnie G. Willaert

Fermentation 2020, 6(1), 26; https://doi.org/10.3390/fermentation6010026 - 14 Feb 2020

Cited by 4 | Viewed by 4001

Abstract

Living cell microarrays in microfluidic chips allow the non-invasive multiplexed molecular analysis of single cells. Here, we developed a simple and affordable perfusion microfluidic chip containing a living yeast cell array composed of a population of cell variants (green fluorescent protein (GFP)-tagged Saccharomyces [...] Read more.

Living cell microarrays in microfluidic chips allow the non-invasive multiplexed molecular analysis of single cells. Here, we developed a simple and affordable perfusion microfluidic chip containing a living yeast cell array composed of a population of cell variants (green fluorescent protein (GFP)-tagged Saccharomyces cerevisiae clones). We combined mechanical patterning in 102 microwells and robotic piezoelectric cell dispensing in the microwells to construct the cell arrays. Robotic yeast cell dispensing of a yeast collection from a multiwell plate to the microfluidic chip microwells was optimized. The developed microfluidic chip and procedure were validated by observing the growth of GFP-tagged yeast clones that are linked to the cell cycle by time-lapse fluorescence microscopy over a few generations. The developed microfluidic technology has the potential to be easily upscaled to a high-density cell array allowing us to perform dynamic proteomics and localizomics experiments. Full article

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

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15 pages, 712 KiB

Open AccessArticle

Isolation and Selection of Non-Saccharomyces Yeasts Being Capable of Degrading Citric acid and Evaluation Its Effect on Kiwifruit Wine Fermentation

by Wu Zhong, Tuo Chen, Hong Yang and Erhu Li

Fermentation 2020, 6(1), 25; https://doi.org/10.3390/fermentation6010025 - 13 Feb 2020

Cited by 28 | Viewed by 4334

Abstract

High citric acid content in kiwifruit wine would lead to bad sensory experience and quality deterioration. It is opportune and crucial to develop an appropriate and feasible method to degrade citric acid for kiwifruit wine. The non-Saccharomyces yeasts confirmed to have the [...] Read more.

High citric acid content in kiwifruit wine would lead to bad sensory experience and quality deterioration. It is opportune and crucial to develop an appropriate and feasible method to degrade citric acid for kiwifruit wine. The non-Saccharomyces yeasts confirmed to have the ability to degrade citric acid were screened and used in kiwifruit wine fermentation in the study. A representative number of 23 yeasts with a strong citric acid degradation ability was identified by molecular approaches. JT-1-3, identified to be Pichia fermentans, was preferred for high citric acid degradation and strong stress resistance in association with RV002 (commercial Saccharomyces cerevisiae). Then it was pure-cultured in kiwifruit juice, and the results indicated that citric, malic and tartaric acids declined significantly from 12.30, 3.09 and 0.61 g/L to 11.00, 2.02 and 0.41 g/L after fermentation, respectively, resulting in the significant decrease in total acid in kiwifruit wine. The analytical profiles for amino acids and volatile compounds showed that Pichia fermentans JT-1-3 could improve amino acids’ proportion and increase the volatile compounds of alcohols, esters and phenols. This work indicated that JT-1-3 has great potential to be applied for fruit wine with high level citric acid. Full article

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10 pages, 427 KiB

Open AccessReview

Assessment of Pomegranate Juice as an Alternative “Substrate” for Probiotic Delivery. Recent Advances and Prospects

by Stavros Kazakos, Ioanna Mantzourani and Stavros Plessas

Fermentation 2020, 6(1), 24; https://doi.org/10.3390/fermentation6010024 - 12 Feb 2020

Cited by 7 | Viewed by 6188

Abstract

The probiotic products in the market are mostly milk-based products, such as yoghurts, cheese and fermented milk. However, lately, there has been an increasing demand for non-dairy probiotic products due to various reasons such as allergies, lactose intolerance, high cholesterol content and consumers [...] Read more.

The probiotic products in the market are mostly milk-based products, such as yoghurts, cheese and fermented milk. However, lately, there has been an increasing demand for non-dairy probiotic products due to various reasons such as allergies, lactose intolerance, high cholesterol content and consumers turning to more natural foods. Fruit juices are considered as an appropriate new substrate for probiotic delivery. From these, pomegranate (Punica granatum L.) is gaining more attention in recent years. Pomegranate is a fruit known since ancient times for its therapeutic qualities, such as antioxidant, anti-inflammatory, antibacterial, antiviral and antitumor properties, among others. Pomegranate juice contains a range of bioactive compounds such as phytochemicals, like polyphenols, ellagitannins, anthocyanins and punicalagins. The fermentation of the juice with probiotic strains seems to provide beverages of high nutritional values and accepted organoleptic quality. Therefore, the aim of this comprehensive review is to present an overview of the innovative in vitro and in vivo assays that have taken place regarding fermentation of pomegranate juice by probiotic bacteria. In addition, various drawbacks are underlined and solutions are proposed and discussed regarding the feasibility of pomegranate juice as an alternative substrate for probiotic delivery. Full article

(This article belongs to the Special Issue Probiotics and Prebiotics: New Knowledge)

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21 pages, 1262 KiB

Open AccessReview

Multi-Product Lactic Acid Bacteria Fermentations: A Review

by José Aníbal Mora-Villalobos, Jéssica Montero-Zamora, Natalia Barboza, Carolina Rojas-Garbanzo, Jessie Usaga, Mauricio Redondo-Solano, Linda Schroedter, Agata Olszewska-Widdrat and José Pablo López-Gómez

Fermentation 2020, 6(1), 23; https://doi.org/10.3390/fermentation6010023 - 10 Feb 2020

Cited by 109 | Viewed by 25184

Abstract

Industrial biotechnology is a continuously expanding field focused on the application of microorganisms to produce chemicals using renewable sources as substrates. Currently, an increasing interest in new versatile processes, able to utilize a variety of substrates to obtain diverse products, can be observed. [...] Read more.

Industrial biotechnology is a continuously expanding field focused on the application of microorganisms to produce chemicals using renewable sources as substrates. Currently, an increasing interest in new versatile processes, able to utilize a variety of substrates to obtain diverse products, can be observed. A robust microbial strain is critical in the creation of such processes. Lactic acid bacteria (LAB) are used to produce a wide variety of chemicals with high commercial interest. Lactic acid (LA) is the most predominant industrial product obtained from LAB fermentations, and its production is forecasted to rise as the result of the increasing demand of polylactic acid. Hence, the creation of new ways to revalorize LA production processes is of high interest and could further enhance its economic value. Therefore, this review explores some co-products of LA fermentations, derived from LAB, with special focus on bacteriocins, lipoteichoic acid, and probiotics. Finally, a multi-product process involving LA and the other compounds of interest is proposed. Full article

(This article belongs to the Special Issue Lactic Acid Fermentation and the Colours of Biotechnology 2.0)

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19 pages, 1394 KiB

Open AccessReview

Modulating Wine Pleasantness Throughout Wine-Yeast Co-Inoculation or Sequential Inoculation

by Alice Vilela

Fermentation 2020, 6(1), 22; https://doi.org/10.3390/fermentation6010022 - 09 Feb 2020

Cited by 19 | Viewed by 9008

Abstract

Wine sensory experience includes flavor, aroma, color, and (for some) even acoustic traits, which impact consumer acceptance. The quality of the wine can be negatively impacted by the presence of off-flavors and aromas, or dubious colors, or sediments present in the bottle or [...] Read more.

Wine sensory experience includes flavor, aroma, color, and (for some) even acoustic traits, which impact consumer acceptance. The quality of the wine can be negatively impacted by the presence of off-flavors and aromas, or dubious colors, or sediments present in the bottle or glass, after pouring (coloring matter that precipitates or calcium bitartrate crystals). Flavor profiles of wines are the result of a vast number of variations in vineyard and winery production, including grape selection, winemaker’s knowledge and technique, and tools used to produce wines with a specific flavor. Wine color, besides being provided by the grape varieties, can also be manipulated during the winemaking. One of the most important “tools” for modulating flavor and color in wines is the choice of the yeasts. During alcoholic fermentation, the wine yeasts extract and metabolize compounds from the grape must by modifying grape-derived molecules, producing flavor-active compounds, and promoting the formation of stable pigments by the production and release of fermentative metabolites that affect the formation of vitisin A and B type pyranoanthocyanins. This review covers the role of Saccharomyces and non-Saccharomyces yeasts, as well as lactic acid bacteria, on the perceived flavor and color of wines and the choice that winemakers can make by choosing to perform co-inoculation or sequential inoculation, a choice that will help them to achieve the best performance in enhancing these wine sensory qualities, avoiding spoilage and the production of defective flavor or color compounds. Full article

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

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9 pages, 256 KiB

Open AccessArticle

β-Glucan Degradation During Malting of Different Purpose Barley Varieties

by Kristina Habschied, Alojzije Lalić, Daniela Horvat, Krešimir Mastanjević, Jasmina Lukinac, Marko Jukić and Vinko Krstanović

Fermentation 2020, 6(1), 21; https://doi.org/10.3390/fermentation6010021 - 06 Feb 2020

Cited by 14 | Viewed by 4832

Abstract

The aim of this study was to investigate the possibility of predicting the concentration of β-glucan from starting barley and malt, as well as malt and wort for different types and purpose of barley groups. The strength of the correlation between types and [...] Read more.

The aim of this study was to investigate the possibility of predicting the concentration of β-glucan from starting barley and malt, as well as malt and wort for different types and purpose of barley groups. The strength of the correlation between types and purpose of barley groups was determined between the values of β-glucans and other indicators of cytolytic degradation. Statistically significant correlations were obtained for β-glucans in barley-malt (r = 0.9717) and barley-wort (r = 0.9998) for brewing (B w-tr) and brewing/feed winter two-row (B/Fe w-tr) varieties, and for brewing/brewing feed/feed spring varieties (B/B-Fe/Fe w-tr) between barley and Δm (Δm = β-glucan difference between barley and malt) (r = 0.8779). For the dual-purpose varieties (B/Fe w-tr), a strong correlation for β-glucans was found between malt and wort (r = 0.8188), malt and Δm* (Δm* = % of degraded β-glucan in malt in regard to the starting β-glucan in barley) (r = −0.9099), as well as Δm and Δm* (r = 0.9951). The results indicate that the starting concentration of β-glucan in barley and malt can be used as predictors of their concentration in wort only in brewing and dual-purpose (brewing-feed) varieties. Full article

9 pages, 1765 KiB

Open AccessCommunication

Adaptive Evolution of Industrial Brewer’s Yeast Strains towards a Snowflake Phenotype

by Yeseren Kayacan, Thijs Van Mieghem, Filip Delvaux, Freddy R. Delvaux and Ronnie Willaert

Fermentation 2020, 6(1), 20; https://doi.org/10.3390/fermentation6010020 - 05 Feb 2020

Cited by 7 | Viewed by 4736

Abstract

Flocculation or cell aggregation is a well-appreciated characteristic of industrial brewer’s strains, since it allows removal of the cells from the beer in a cost-efficient and environmentally-friendly manner. However, many industrial strains are non-flocculent and genetic interference to increase the flocculation characteristics are [...] Read more.

Flocculation or cell aggregation is a well-appreciated characteristic of industrial brewer’s strains, since it allows removal of the cells from the beer in a cost-efficient and environmentally-friendly manner. However, many industrial strains are non-flocculent and genetic interference to increase the flocculation characteristics are not appreciated by the consumers. We applied adaptive laboratory evolution (ALE) to three non-flocculent, industrial Saccharomyces cerevisiae brewer’s strains using small continuous bioreactors (ministats) to obtain an aggregative phenotype, i.e., the “snowflake” phenotype. These aggregates could increase yeast sedimentation considerably. We evaluated the performance of these evolved strains and their produced flavor during lab scale beer fermentations. The small aggregates did not result in a premature sedimentation during the fermentation and did not result in major flavor changes of the produced beer. These results show that ALE could be used to increase the sedimentation behavior of non-flocculent brewer’s strains. Full article

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

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12 pages, 2252 KiB

Open AccessArticle

Cheese Whey Fermentation by Its Native Microbiota: Proteolysis and Bioactive Peptides Release with ACE-Inhibitory Activity

by Miguel A. Mazorra-Manzano, Glen R. Robles-Porchas, Daniel A. González-Velázquez, María J. Torres-Llanez, Marcel Martínez-Porchas, Celia O. García-Sifuentes, Aarón F. González-Córdova and Belinda Vallejo-Córdoba

Fermentation 2020, 6(1), 19; https://doi.org/10.3390/fermentation6010019 - 31 Jan 2020

Cited by 48 | Viewed by 7962

Abstract

Cheese whey contains about 20% of the total milk protein and has high nutritional and technological value, as well as attractive biological properties. Whey protein represents an important source of bioactive peptides with beneficial effects on health (e.g., antioxidant, antidiabetic, antihypertensive, etc.). Microbiota [...] Read more.

Cheese whey contains about 20% of the total milk protein and has high nutritional and technological value, as well as attractive biological properties. Whey protein represents an important source of bioactive peptides with beneficial effects on health (e.g., antioxidant, antidiabetic, antihypertensive, etc.). Microbiota in cheese whey can hydrolyze proteins and generate bioactive peptides through a fermentation process. The objective of this study was to evaluate the effect of temperature on the fermentation of cheese whey by its native microbiota, and the action of microbial proteolytic activity on whey proteins to release peptides with inhibitory activity of the angiotensin-converting enzyme (ACE). Whey proteins hydrolysis occurred at all incubation temperatures evaluated (32–50 °C), with the major proteolytic effect within the range of 35–42 °C. Minor whey proteins (i.e., Lf, bovine serum albumin (BSA), and IgG) were more susceptible to degradation, while β-lactoglobulin and α-lactalbumin showed major resistance to microbial proteolytic action. Alfa-amino groups increased from 36 to 360–456 µg Gly/mL after 120 h of fermentation. A higher lactic acid production (11.32–13.55 g/L) and lower pH (3.3–3.5) were also observed in the same temperature range (32–42 °C). In addition, ACE-inhibitory activity increased from 22% (unfermented whey) to 60–70% after 120 h of fermentation. These results suggest that the fermentation of cheese whey by its native microbiota represents an attractive process to give value to whey for the production of whey-based beverages or functional foods with potential antihypertensive properties. Full article

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16 pages, 2802 KiB

Open AccessArticle

Antioxidant Properties of Fermented Green Coffee Beans with Wickerhamomyces anomalus (Strain KNU18Y3)

by Mesfin Haile and Won Hee Kang

Fermentation 2020, 6(1), 18; https://doi.org/10.3390/fermentation6010018 - 28 Jan 2020

Cited by 11 | Viewed by 5581

Abstract

A few yeast species have been tested frequently to improve the tastes, flavors, and other important quality parameters of coffee. However, continuing evaluations of different yeast species for fermenting green coffee beans will have a significant positive contribution to the coffee industry. This [...] Read more.

A few yeast species have been tested frequently to improve the tastes, flavors, and other important quality parameters of coffee. However, continuing evaluations of different yeast species for fermenting green coffee beans will have a significant positive contribution to the coffee industry. This experiment was conducted to evaluate the antioxidant properties, total phenol content (TPC), total flavonoid content (TFC), total tannin content (TTC), and the consumer acceptability of fermented green coffee beans with Wickerhamomyces anomalu. The coffee beans were roasted at different roasting conditions (light, medium, and dark). There was no significant (p > 0.05) difference between the yeast-fermented and non-fermented coffee with regard to the oxygen radical absorbance capacity (ORAC) values in medium and dark roasted coffee. Similarly, the superoxide dismutase-like (SOD)-like activity did not significantly differ in all roasting conditions. However, the SOD-like activity was significantly different (p < 0.05), particularly within light roasted and medium roasted, and between light roasted and dark roasted in both the control and fermented coffee extracts. The 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay and ferric reducing antioxidant power (FRAP) were improved in fermented coffee beans. There was a significant (p ≤ 0.05) difference between the yeast-fermented and non-fermented coffee with respect to the TPC and TFC in all roasting types and the TTC in the light and dark roasting conditions. The fermentation of green coffee beans with W. anomalus increased the TPC and TFC. However, the TTC was lower in the fermented coffee beans compared to the non-fermented coffee beans in medium and dark roasted coffee. In general, fermentation of green coffee beans with W. anomalus has the potential to improve the functionality of coffee beans. Full article

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

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13 pages, 1825 KiB

Open AccessArticle

Co-Existence of Inoculated Yeast and Lactic Acid Bacteria and Their Impact on the Aroma Profile and Sensory Traits of Tempranillo Red Wine

by Pedro Miguel Izquierdo-Cañas, María Ríos-Carrasco, Esteban García-Romero, Adela Mena-Morales, José María Heras-Manso and Gustavo Cordero-Bueso

Fermentation 2020, 6(1), 17; https://doi.org/10.3390/fermentation6010017 - 25 Jan 2020

Cited by 11 | Viewed by 4645

Abstract

This study investigates the effects of simultaneous inoculation of a selected Saccharomyces cerevisiae yeast strain with two different commercial strains of wine bacteria Oenococcus oeni at the beginning of the alcoholic fermentation on the kinetics of malolactic fermentation (MLF), wine chemical composition, and [...] Read more.

This study investigates the effects of simultaneous inoculation of a selected Saccharomyces cerevisiae yeast strain with two different commercial strains of wine bacteria Oenococcus oeni at the beginning of the alcoholic fermentation on the kinetics of malolactic fermentation (MLF), wine chemical composition, and organoleptic characteristics in comparison with spontaneous MLF in Tempranillo grape must from Castilla-La Mancha (Spain). Evolution of MLF was assessed by the periodic analysis of L-malic acid through the enzymatic method, and most common physiochemical parameters and sensory traits were evaluated using a standardized sensory analysis. The samples were analyzed by GC/MS in SCAN mode using a Trace GC gas chromatograph and a DSQII quadrupole mass analyzer. Co-inoculation reduced the overall fermentation time by up to 2 weeks leading to a lower increase in volatile acidity. The fermentation-derived wine volatiles profile was distinct between the co-inoculated wines and spontaneous MLF and was influenced by the selected wine bacteria used in co-inoculation. Co-inoculation allows MLF to develop under reductive conditions and results in wines with very few lactic and buttery flavors, which is related to the impact of specific compounds like 2,3-butanedione. This compound has been also confirmed as being dependent on the wine bacteria used. Full article

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

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11 pages, 652 KiB

Open AccessReview

Production of the Polysaccharide Curdlan by Agrobacterium species on Processing Coproducts and Plant Lignocellulosic Hydrolysates

by Thomas P. West

Fermentation 2020, 6(1), 16; https://doi.org/10.3390/fermentation6010016 - 24 Jan 2020

Cited by 23 | Viewed by 3808

Abstract

This review examines the production of the biopolymer curdlan, synthesized by Agrobacterium species (sp.), on processing coproducts and plant lignocellulosic hydrolysates. Curdlan is a β-(1→3)-D-glucan that has various food, non-food and biomedical applications. A number of carbon sources support bacterial curdlan production upon [...] Read more.

This review examines the production of the biopolymer curdlan, synthesized by Agrobacterium species (sp.), on processing coproducts and plant lignocellulosic hydrolysates. Curdlan is a β-(1→3)-D-glucan that has various food, non-food and biomedical applications. A number of carbon sources support bacterial curdlan production upon depletion of nitrogen in the culture medium. The influence of culture medium pH is critical to the synthesis of curdlan. The biosynthesis of the β-(1→3)-D-glucan is likely controlled by a regulatory protein that controls the genes involved in the bacterial production of curdlan. Curdlan overproducer mutant strains have been isolated from Agrobacterium sp. ATCC 31749 and ATCC 31750 by chemical mutagenesis and different selection procedures. Several processing coproducts of crops have been utilized to support the production of curdlan. Of the processing coproducts investigated, cassava starch waste hydrolysate as a carbon source or wheat bran as a nitrogen source supported the highest curdlan production by ATCC 31749 grown at 30 °C. To a lesser extent, plant biomass hydrolysates have been explored as possible substrates for curdlan production by ATCC 31749. Prairie cordgrass hydrolysates have been shown to support curdlan production by ATCC 31749 although a curdlan overproducer mutant strain, derived from ATCC 31749, was shown to support nearly double the level of ATCC 31749 curdlan production under the same growth conditions. Full article

(This article belongs to the Special Issue Biorefineries)

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20 pages, 1060 KiB

Open AccessArticle

Modifications of Phenolic Compounds, Biogenic Amines, and Volatile Compounds in Cabernet Gernishct Wine through Malolactic Fermentation by Lactobacillus plantarum and Oenococcus oeni

by Shao-Yang Wang, Hai-Zhen Zhu, Yi-Bin Lan, Ruo-Jin Liu, Ya-Ran Liu, Bo-Lin Zhang and Bao-Qing Zhu

Fermentation 2020, 6(1), 15; https://doi.org/10.3390/fermentation6010015 - 20 Jan 2020

Cited by 16 | Viewed by 3681

Abstract

Malolactic fermentation is a vital red wine-making process to enhance the sensory quality. The objective of this study is to elucidate the starter cultures’ role in modifying phenolic compounds, biogenic amines, and volatile compounds after red wine malolactic fermentation. We initiated the malolactic [...] Read more.

Malolactic fermentation is a vital red wine-making process to enhance the sensory quality. The objective of this study is to elucidate the starter cultures’ role in modifying phenolic compounds, biogenic amines, and volatile compounds after red wine malolactic fermentation. We initiated the malolactic fermentation in Cabernet Gernishct wine by using two Oenococcus oeni and two Lactobacillus plantarum strains. Results showed that after malolactic fermentation, wines experienced a content decrease of total flavanols and total flavonols, accompanied by the accumulation of phenolic acids. The Lactobacillus plantarum strains, compared to Oenococcus oeni, exhibited a prevention against the accumulation of biogenic amines. The malolactic fermentation increased the total esters and modified the aromatic features compared to the unfermented wine. The Lactobacillus plantarum strains retained more aromas than the Oenococcus oeni strains did. Principal component analysis revealed that different strains could distinctly alter the wine characteristics being investigated in this study. These indicated that Lactobacillus plantarum could serve as a better alternative starter for conducting red wine malolactic fermentation. Full article

(This article belongs to the Special Issue Wine Fermentation 2.0)

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19 pages, 1906 KiB

Open AccessArticle

Saccharomyces arboricola and Its Hybrids’ Propensity for Sake Production: Interspecific Hybrids Reveal Increased Fermentation Abilities and a Mosaic Metabolic Profile

by Matthew J. Winans, Yuki Yamamoto, Yuki Fujimaru, Yuki Kusaba, Jennifer E. G. Gallagher and Hiroshi Kitagaki

Fermentation 2020, 6(1), 14; https://doi.org/10.3390/fermentation6010014 - 20 Jan 2020

Cited by 7 | Viewed by 5334

Abstract

The use of interspecific hybrids during the industrial fermentation process has been well established, positioning the frontier of advancement in brewing to capitalize on the potential of Saccharomyces hybridization. Interspecific yeast hybrids used in modern monoculture inoculations benefit from a wide range of [...] Read more.

The use of interspecific hybrids during the industrial fermentation process has been well established, positioning the frontier of advancement in brewing to capitalize on the potential of Saccharomyces hybridization. Interspecific yeast hybrids used in modern monoculture inoculations benefit from a wide range of volatile metabolites that broaden the organoleptic complexity. This is the first report of sake brewing by Saccharomyces arboricola and its hybrids. S. arboricola x S. cerevisiae direct-mating generated cryotolerant interspecific hybrids which increased yields of ethanol and ethyl hexanoate compared to parental strains, important flavor attributes of fine Japanese ginjo sake rice wine. Hierarchical clustering heatmapping with principal component analysis for metabolic profiling was used in finding low levels of endogenous amino/organic acids clustered S. arboricola apart from the S. cerevisiae industrial strains. In sake fermentations, hybrid strains showed a mosaic profile of parental strains, while metabolic analysis suggested S. arboricola had a lower amino acid net uptake than S. cerevisiae. Additionally, this research found an increase in ethanolic fermentation from pyruvate and increased sulfur metabolism. Together, these results suggest S. arboricola is poised for in-depth metabolomic exploration in sake fermentation. Full article

(This article belongs to the Special Issue Wine Fermentation 2.0)

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4 pages, 184 KiB

Open AccessEditorial

Modern Technologies and Their Influence in Fermentation Quality

by Santiago Benito

Fermentation 2020, 6(1), 13; https://doi.org/10.3390/fermentation6010013 - 19 Jan 2020

Cited by 1 | Viewed by 3265

Abstract

Since the beginning of enology and fermentation research, wine quality has been parametrized from a chemical and sensory point of view [...] Full article

(This article belongs to the Special Issue Modern Technologies and Their Influence in Fermentation Quality)

7 pages, 1519 KiB

Open AccessArticle

Microbiological and Metagenomic Analysis to Assess the Effect of Container Material on the Microbiota of Feta Cheese during Ripening

by Evgenia D. Spyrelli, Anastasios Stamatiou, Chrysoula C. Tassou, George-John E. Nychas and Agapi I. Doulgeraki

Fermentation 2020, 6(1), 12; https://doi.org/10.3390/fermentation6010012 - 18 Jan 2020

Cited by 21 | Viewed by 4719

Abstract

The aim of the present study was to assess the influence of ripening container’s material on the bacterial diversity of Feta cheese PDO (Protected Designation of Origin). The microbiota of fresh and mature cheese produced in plastic and stainless steel container was monitored [...] Read more.

The aim of the present study was to assess the influence of ripening container’s material on the bacterial diversity of Feta cheese PDO (Protected Designation of Origin). The microbiota of fresh and mature cheese produced in plastic and stainless steel container was monitored by microbial enumeration and 16s rRNA gene sequencing. According to the obtained results, lactic acid bacteria (LAB) was the dominant microbiota of fresh and mature cheese. Metagenomics data revealed that fresh cheese was dominated by Lactococcus followed by members of Enterobacteriaceae family and Pseudomonas. Similarly, Lactococcus was the most abundant genus detected in mature cheese (54 days and 120 days), regardless of the container’s material. In both fresh and mature cheese, species of Pseudomonas, Streptococcus, Acinetobacter, Lactobacillus, Flavobacterium, and Carnobacterium were detected. The abundance of Enterobacteriaceae, Moraxellaceae and Pseudomonadaceae in mature cheese ripened in stainless steel container seems to be numerically reduced after 120 days of storage compared to the cheese ripened in plastic container but not significant differences were observed (p > 0.05). In conclusion, metagenomic analysis suggests that ripening container’s material does not affect the microbial community responsible for the ripening of feta cheese PDO. Full article

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3 pages, 215 KiB

Open AccessEditorial

Acknowledgement to Reviewers of Fermentation in 2019

by Fermentation Editorial Office

Fermentation 2020, 6(1), 11; https://doi.org/10.3390/fermentation6010011 - 17 Jan 2020

Viewed by 1585

Abstract

Full article

15 pages, 5574 KiB

Open AccessArticle

Bacterial Flow Cytometry and Imaging as Potential Process Monitoring Tools for Industrial Biotechnology

by Sumana Kadamalakunte Narayana, Sanjaya Mallick, Henrik Siegumfeldt and Frans van den Berg

Fermentation 2020, 6(1), 10; https://doi.org/10.3390/fermentation6010010 - 17 Jan 2020

Cited by 10 | Viewed by 4487

Abstract

Minimizing process variations by early identification of deviations is one approach to make industrial production processes robust. Cell morphology is a direct representation of the physiological state and an important factor for the cell’s survival in harsh environments as encountered during industrial processing. [...] Read more.

Minimizing process variations by early identification of deviations is one approach to make industrial production processes robust. Cell morphology is a direct representation of the physiological state and an important factor for the cell’s survival in harsh environments as encountered during industrial processing. The adverse effects of fluctuating process parameters on cells were studied using flow cytometry and imaging. Results showed that altered pH caused a shift in cell size distribution from a heterogeneous mix of elongated and short cells to a homogenous population of short cells. Staining based on membrane integrity revealed a dynamics in the pattern of cluster formation during fermentation. Contradictory findings from forward scatter and imaging highlight the need for use of complementary techniques that provide visual confirmation to interpret changes. An atline flow cytometry or imaging capable of identifying subtle population deviations serves as a powerful monitoring tool for industrial biotechnology. Full article

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11 pages, 1393 KiB

Open AccessArticle

Characterization of Old Wine Yeasts Kept for Decades under a Zero-Emission Maintenance Regime

by Katrin Matti, Beatrice Bernardi, Silvia Brezina, Heike Semmler, Christian von Wallbrunn, Doris Rauhut and Jürgen Wendland

Fermentation 2020, 6(1), 9; https://doi.org/10.3390/fermentation6010009 - 11 Jan 2020

Cited by 4 | Viewed by 4795

Abstract

All laboratories dealing with microbes have to develop a strain maintenance regime. While lyophilization based on freeze-drying may be feasible for large stock centers, laboratories around the world rely on cryopreservation and freezing of stocks at −80 °C. Keeping stocks at these low [...] Read more.

All laboratories dealing with microbes have to develop a strain maintenance regime. While lyophilization based on freeze-drying may be feasible for large stock centers, laboratories around the world rely on cryopreservation and freezing of stocks at −80 °C. Keeping stocks at these low temperatures requires investments of several thousand kW/h per year. We have kept yeast stocks for several decades at room temperature on agar slants in glass reagent tubes covered with vaspar and sealed with cotton plugs. They were part of the Geisenheim Yeast Breeding Center stock collection that was started in the 19th century, well before −80 °C refrigeration technology was invented. Of these stocks, 60 tubes were analyzed and around one-third of them could be regrown. The strains were typed by sequencing of rDNA PCR fragments. Based on BlastN analyses, twelve of the strains could be assigned to Saccharomyces cerevisiae, two to S. kudriavzevii, and the others to Meyerozyma and Candida. The strains were used in white wine fermentations and compared to standard wine yeasts Uvaferm/GHM (Geisenheim) and Lalvin EC1118. Even with added nitrogen, the strains exhibited diverse fermentation curves. Post-fermentation aroma analyses and the determination of residual sugar and organic acid concentrations indicated that some strains harbor interesting flavor characteristics, surpassing current standard yeast strains. Thus, old strain collections bear treasures for direct use either in wine fermentations or for incorporation in yeast breeding programs aimed at improving modern wine yeasts. Furthermore, this provides evidence that low-cost/long-term culture maintenance at zero-emission levels is feasible. Full article

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

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