Editor’s Choice Articles

Editor’s Choice articles are based on recommendations by the scientific editors of MDPI journals from around the world. Editors select a small number of articles recently published in the journal that they believe will be particularly interesting to readers, or important in the respective research area. The aim is to provide a snapshot of some of the most exciting work published in the various research areas of the journal.

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19 pages, 1871 KiB  
Article
Starmerella bacillaris Strains Used in Sequential Alcoholic Fermentation with Saccharomyces cerevisiae Improves Protein Stability in White Wines
by Luiza de Paula Dias Moreira, Chiara Nadai, Vinícius da Silva Duarte, Edward John Brearley-Smith, Matteo Marangon, Simone Vincenzi, Alessio Giacomini and Viviana Corich
Fermentation 2022, 8(6), 252; https://doi.org/10.3390/fermentation8060252 - 27 May 2022
Cited by 5 | Viewed by 3041
Abstract
Haze can appear in white wines as a result of the denaturation and subsequent aggregation of grape pathogenesis-related (PR) proteins. Yeast cell-wall polysaccharides, particularly mannoproteins, represent a promising strategy to reduce the incidence of this phenomenon. The aim of this study was to [...] Read more.
Haze can appear in white wines as a result of the denaturation and subsequent aggregation of grape pathogenesis-related (PR) proteins. Yeast cell-wall polysaccharides, particularly mannoproteins, represent a promising strategy to reduce the incidence of this phenomenon. The aim of this study was to evaluate the effects of 13 Starmerella bacillaris strains, in sequential fermentation with Saccharomyces cerevisiae, on wine protein stability of three white wines (Sauvignon blanc, Pinot grigio, and Manzoni bianco). The resulting wines were characterized in terms of their chemical composition, content of PR proteins and polysaccharides, and heat stability. In addition, the mannoprotein fraction was purified from six wines, five produced with S. bacillaris and one with S. cerevisiae EC1118 used as control. Generally, wines produced with S. bacillaris strains were more heat-stable, despite generally containing higher amounts of PR proteins. The increased heat stability of Starmerella wines was attributed to the stabilizing effect resulting from their higher concentrations of both total polysaccharides and mannoprotein fractions. In particular, for the most heat unstable wine (Manzoni bianco), the low MW mannoprotein fraction resulted to be the most involved in wine stability. The ability to produce wines with different heat stability was demonstrated to be strain-dependent and was more evident in the most unstable wines. By reducing fining waste, the use of S. bacillaris as an enological starter can be proposed as a new tool to manage wine protein stability for a more sustainable winemaking. Full article
(This article belongs to the Section Microbial Metabolism, Physiology & Genetics)
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14 pages, 1258 KiB  
Article
Designing a Waste-Based Culture Medium for the Production of Plant Growth Promoting Microorganisms Based on Cladodes Juice from Opuntia ficus-indica Pruning
by Rosaria Alessandra Magarelli, Mario Trupo, Alfredo Ambrico, Vincenzo Larocca, Maria Martino, Salvatore Palazzo, Roberto Balducchi, Vesa Joutsjoki, Anne Pihlanto and Annamaria Bevivino
Fermentation 2022, 8(5), 225; https://doi.org/10.3390/fermentation8050225 - 14 May 2022
Cited by 8 | Viewed by 3642
Abstract
The production of beneficial microorganisms is the first step to obtain a commercial-based product for application in agriculture. In this study, prickly pear (Opuntia ficus-indica) pruning waste was evaluated as a raw material for the production of large amounts of Plant [...] Read more.
The production of beneficial microorganisms is the first step to obtain a commercial-based product for application in agriculture. In this study, prickly pear (Opuntia ficus-indica) pruning waste was evaluated as a raw material for the production of large amounts of Plant Growth Promoting Microorganisms (PGPMs) reducing the number of generated wastes. Specifically, five PGPMs constituting a synthetic microbial consortium with complementing plant growth-promoting traits were grown on a laboratory scale and, subsequently, on a pilot scale using a 21-L bioreactor. Primarily, the physical-chemical characterization of the culture medium obtained from the juice of Opuntia cladodes was carried out, revealing the presence of sugars and organic acids with different molar ratios. Compared to conventional media, the waste medium did not show significant differences in bacterial growth efficiency. Instead, the survival rates of the bacteria grown in cladodes juice media, after air-drying on zeolite or freeze-drying, were significantly higher than those observed when they were grown in conventional media. The present work is the first conducted on a pilot-scale that maximizes the production of PGPMs in submerged fermentation using cladodes juice from Opuntia, reducing both economic and environmental impacts associated with the generation of wastes. Full article
(This article belongs to the Collection Food Waste Valorization)
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14 pages, 3084 KiB  
Article
pH Auto-Sustain-Based Fermentation Supports Efficient Gamma-Aminobutyric Acid Production by Lactobacillus brevis CD0817
by Mengya Jia, Yisong Zhu, Lingqin Wang, Tianyi Sun, Hao Pan and Haixing Li
Fermentation 2022, 8(5), 208; https://doi.org/10.3390/fermentation8050208 - 03 May 2022
Cited by 17 | Viewed by 2275
Abstract
Gamma-aminobutyric acid (GABA) plays a role in several physiological functions. GABA production by lactic acid bacteria has attracted considerable interest; however, there is need to improve production. This study aimed to develop a pH auto-sustain (PAS)-based GABA fermentation process for Lactobacillus brevis CD0817, [...] Read more.
Gamma-aminobutyric acid (GABA) plays a role in several physiological functions. GABA production by lactic acid bacteria has attracted considerable interest; however, there is need to improve production. This study aimed to develop a pH auto-sustain (PAS)-based GABA fermentation process for Lactobacillus brevis CD0817, with L-glutamic acid (solubility ~6.0 g/L and isoelectric point 3.22) as the substrate. Firstly, we determined the optimum levels of vital factors affecting GABA synthesis using Erlenmeyer flask experiments. The results showed that optimal levels of sugar, yeast extract, Tween-80, manganese ion, and temperature were 5.0 g/L, 35.0 g/L, 1.0 g/L, 16.0 mg/L, and 30.0 °C, respectively. The added L-glutamic acid (650 g per liter of medium) mostly existed in the form of solid powder was slowly released to supply the substrate and acidity essential for GABA production with the progress of fermentation. Based on the optimizations, the PAS-based GABA fermentation was performed using a 10 L fermenter. The PAS-based strategy promoted GABA synthesis by the strain of up to 321.9 ± 6.7 g/L after 48 h, with a productivity of 6.71 g/L/h and a substrate molar conversion rate of 99.6%. The findings suggest that the PAS-based fermentation is a promising method for GABA production by lactic acid bacteria. Full article
(This article belongs to the Section Microbial Metabolism, Physiology & Genetics)
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19 pages, 959 KiB  
Article
Recombinant Protein Production in E. coli Using the phoA Expression System
by Thomas Gundinger, Stefan Kittler, Sabine Kubicek, Julian Kopp and Oliver Spadiut
Fermentation 2022, 8(4), 181; https://doi.org/10.3390/fermentation8040181 - 11 Apr 2022
Cited by 7 | Viewed by 4614
Abstract
Auto-inducible promoter systems have been reported to increase soluble product formation in the periplasm of E. coli compared to inducer-dependent systems. In this study, we investigated the phosphate (PO4)-sensitive phoA expression system (pAT) for the production of a recombinant model antigen-binding [...] Read more.
Auto-inducible promoter systems have been reported to increase soluble product formation in the periplasm of E. coli compared to inducer-dependent systems. In this study, we investigated the phosphate (PO4)-sensitive phoA expression system (pAT) for the production of a recombinant model antigen-binding fragment (Fab) in the periplasm of E. coli in detail. We explored the impact of non-limiting and limiting PO4 conditions on strain physiology as well as Fab productivity. We compared different methods for extracellular PO4 detection, identifying automated colorimetric measurement to be most suitable for at-line PO4 monitoring. We showed that PO4 limitation boosts phoA-based gene expression, however, the product was already formed at non-limiting PO4 conditions, indicating leaky expression. Furthermore, cultivation under PO4 limitation caused physiological changes ultimately resulting in a metabolic breakdown at PO4 starvation. Finally, we give recommendations for process optimization with the phoA expression system. In summary, our study provides very detailed information on the E. coli phoA expression system, thus extending the existing knowledge of this system, and underlines its high potential for the successful production of periplasmic products in E. coli. Full article
(This article belongs to the Section Fermentation Process Design)
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24 pages, 2987 KiB  
Article
Towards a Complete Exploitation of Brewers’ Spent Grain from a Circular Economy Perspective
by Chiara Allegretti, Emanuela Bellinetto, Paola D’Arrigo, Gianmarco Griffini, Stefano Marzorati, Letizia Anna Maria Rossato, Eleonora Ruffini, Luca Schiavi, Stefano Serra, Alberto Strini, Davide Tessaro and Stefano Turri
Fermentation 2022, 8(4), 151; https://doi.org/10.3390/fermentation8040151 - 29 Mar 2022
Cited by 14 | Viewed by 4049
Abstract
In the present work, brewers’ spent grain (BSG), which represents the major by-product of the brewing industry, was recovered from a regional brewery and fractionated in order to obtain a complete valorization. In particular, the whole process was divided in two main parts. [...] Read more.
In the present work, brewers’ spent grain (BSG), which represents the major by-product of the brewing industry, was recovered from a regional brewery and fractionated in order to obtain a complete valorization. In particular, the whole process was divided in two main parts. A first pretreatment with hot water in an autoclave allowed the separation of a solution containing the soluble proteins and sugars, which accounted for 25% of the total starting biomass. This first step allowed the preparation of a medium that was successfully employed as a valuable growing medium for different microbial fermentations, leading to valuable fungal biomass as well as triglycerides with a high content of linear or branched fatty acids, depending on the microorganism used. The solid water-insoluble residue was then submitted to a lignocellulose deep eutectic solvent-mediated fractionation, which allowed the recovery of two important main fractions: BSG cellulose and BSG lignin. The latter product was tested as potential precursor for the development of cement water reducers with encouraging results. This combination of treatments of the waste biomass appeared to be a promising sustainable strategy for the development of the full exploitation of BSG from a circular economy perspective. Full article
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22 pages, 22962 KiB  
Article
Applying AI Tools for Modeling, Predicting and Managing the White Wine Fermentation Process
by Adrian Florea, Anca Sipos and Melisa-Cristina Stoisor
Fermentation 2022, 8(4), 137; https://doi.org/10.3390/fermentation8040137 - 22 Mar 2022
Cited by 3 | Viewed by 3538
Abstract
This paper reveals two of the challenges faced by Romania and proposes a sustainable and simple solution for its wine industry. First, substantial areas with vineyards that may produce qualitative wine, and second, the very low digitalization rate of industrial sectors. More precisely, [...] Read more.
This paper reveals two of the challenges faced by Romania and proposes a sustainable and simple solution for its wine industry. First, substantial areas with vineyards that may produce qualitative wine, and second, the very low digitalization rate of industrial sectors. More precisely, this work proposes a solution for digitalizing the fermentation process of white wine, allowing it to be adapted for other control techniques (i.e., knowledge-based systems, intelligent control). Our method consists of implementing a pre-trained multi-layer perceptron neural network, using genetic algorithms capable of predicting the concentration of alcohol and the amount of substrate at a certain point in time that starts from the initial configuration of the fermentation process. The purpose of predicting these process features is to obtain information about status variables so that the process can be automatically driven. The main advantage of our application is to help experts reduce the time needed for making the relevant measurements and to increase the lifecycles of sensors in bioreactors. After comprehensive simulations using experimental data obtained from previous fermentation processes, we concluded that a configuration that is close to the optimal one, for which the prediction accuracy is high, is a neural network (NN) having an input layer with neurons for temperature, time, initial substrate concentration, and the biomass concentration, a hidden layer with 10 neurons, and an output layer with 2 neurons representing the alcohol and substrate concentration, respectively. The best results were obtained with a pre-trained NN, using a genetic algorithm (GA) with a population of 50 individuals for 20 generations, a crossover probability of 0.9, and a probability of mutation of 0.5 that uniformly decreases depending on the generations, based on a beta coefficient of 0.3 and an elitist selection method. In the case of a data set with a larger number of variables, which also contains data regarding pH and CO2, the prediction accuracy is even higher, leading to the conclusion that a larger data set positively influences the performance of the neural network. Furthermore, methods based on artificial intelligence applications like neural networks, along with various heuristic optimization methods such as genetic algorithms, are essential if hardware sensors cannot be used, or if direct measurements cannot be made. Full article
(This article belongs to the Special Issue Machine Learning in Fermented Food and Beverages)
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20 pages, 1876 KiB  
Article
Sustainable and Eco-Friendly Conversions of Olive Mill Wastewater-Based Media by Pleurotus pulmonarius Cultures
by Ilias Diamantis, Eirini-Maria Melanouri, Marianna Dedousi, Ioanna Panagopoulou, Seraphim Papanikolaou, Nikolaos G. Stoforos and Panagiota Diamantopoulou
Fermentation 2022, 8(3), 129; https://doi.org/10.3390/fermentation8030129 - 16 Mar 2022
Cited by 10 | Viewed by 2451
Abstract
Pleurotus pulmonarius mushroom was cultivated on liquid cultures with olive mill wastewaters (OMWs) of initial phenolic compound concentrations of 0 (control), 1, 2 and 3 g/L and glucose at initial concentrations of 40 and 60 g/L. The ability of the fungus to grow [...] Read more.
Pleurotus pulmonarius mushroom was cultivated on liquid cultures with olive mill wastewaters (OMWs) of initial phenolic compound concentrations of 0 (control), 1, 2 and 3 g/L and glucose at initial concentrations of 40 and 60 g/L. The ability of the fungus to grow on media containing toxic compounds enriched with glucose was assessed through biomass production, glucose consumption, polysaccharide (IPS) accumulation and total cellular lipids biosynthesis, while the total phenolic compounds (TPC) and antioxidant component monitoring were also assessed during a 43-day fermentation. An analysis of the total simple sugar composition of IPS and the total fatty acid composition of lipids was performed. The phenolic reduction and media decolorization were also monitored. Results showed that the addition of glucose in OMW-based media had a positive effect on biomass, IPS and lipid production and increased the unsaturated fatty acids and TPC concentration. The maximum recorded values were the following: biomass 32.76 g/L, IPS 4.38 g/L (14.70%, w/w in dry weight), lipids 2.85 g/L (11.69%, w/w in dry weight). The mycelial lipids were unsaturated and dominated by linoleic acid, whereas IPS were composed mainly of glucose. Significant phenolic compound reduction (87–95%) and color removal (70–85%) occurred. Results strongly suggest the potentiality of P. pulmonarius utilization in the OMW treatment. Full article
(This article belongs to the Special Issue Organic Waste Valorization into Added-Value Products)
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11 pages, 912 KiB  
Article
Single Cell Protein Production through Multi Food-Waste Substrate Fermentation
by Alessia Tropea, Antonio Ferracane, Ambrogina Albergamo, Angela Giorgia Potortì, Vincenzo Lo Turco and Giuseppa Di Bella
Fermentation 2022, 8(3), 91; https://doi.org/10.3390/fermentation8030091 - 23 Feb 2022
Cited by 28 | Viewed by 9104
Abstract
Today, food valorization represents an important challenge to environmental sustainability. Food waste can be used as a substrate for single cell protein production suitable for animal feed. In this study, animal and agricultural food waste, represented by fish, pineapple, banana, apple, and citrus [...] Read more.
Today, food valorization represents an important challenge to environmental sustainability. Food waste can be used as a substrate for single cell protein production suitable for animal feed. In this study, animal and agricultural food waste, represented by fish, pineapple, banana, apple, and citrus peels, have been used simultaneously as a fermentation substrate for single cell protein production by Saccharomyces cerevisiae, to evaluate the possibility of using a multi complex substrate for a simultaneous biovalorization of different food waste. The fermentation process was implemented by the supplementation of a hydrolytic enzyme and nutrient to allow the best yeast growing conditions. At the end of the process, the final substrate was enriched in protein, reaching up to 40.19% of protein, making the multisubstrate useful for animal feed. The substrate was also investigated for crude lipid, ash, lignin, soluble and insoluble sugar. The substrate composition at the end of the fermentation process was represented by 14.46% of crude lipid, 1.08% ash, 6.29% lignin. Conversely, the soluble and insoluble sugars dropped down from 20.5% to 6.10% and 19.15% to 2.14%, respectively, at the end of the process. Full article
(This article belongs to the Collection Food Waste Valorization)
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10 pages, 4511 KiB  
Article
Effects of Mulberry Branch and Leaves Silage on Microbial Community, Rumen Fermentation Characteristics, and Milk Yield in Lactating Dairy Cows
by Yan Li, Jiaqi Wang, Jie Mei, Lingxia Huang and Hongyun Liu
Fermentation 2022, 8(2), 86; https://doi.org/10.3390/fermentation8020086 - 18 Feb 2022
Cited by 7 | Viewed by 2767
Abstract
This study investigated the effects of mulberry branch and leaves (MBL) silage on milk yield, ruminal fermentation, and bacteria composition in dairy cows. Thirty-six mid-lactation cows were selected and randomly allocated into three groups. The control group (C) was fed on a total [...] Read more.
This study investigated the effects of mulberry branch and leaves (MBL) silage on milk yield, ruminal fermentation, and bacteria composition in dairy cows. Thirty-six mid-lactation cows were selected and randomly allocated into three groups. The control group (C) was fed on a total mixed ratio (TMR) diet, while the experimental groups were fed on TMR supplemented with 5% (L) and 10% (H) MBL silage. The experiment lasted for eight weeks, including two weeks of adaption. The results showed that Group H had an increased milk yield, milk fat content (p < 0.05), and 4% feed conversion ratio (p = 0.10). In addition, rumen propionic acid was significantly increased (p < 0.05), while acetate/propionate was significantly decreased (p < 0.05) in the high MBL silage group. The microbiome analysis showed that Bacteroides, Firmicutes, and Proteobacteria were the predominant phyla. Compared with Group C, the abundance of Bacteroides was significantly decreased (p < 0.01), while the Firmicutes and Proteobacteria were increased but not significantly different in Groups L and H. Prevotella was significantly decreased (p < 0.05) in the MBL silage groups, and Succinivibrionaceae_UCG-001 was increased in Group H. The correlation analysis showed that eight bacterial species belonging to Firmicutes were positively correlated with propionic acid. However, four bacterial species belonging to the Bacteroides group were negatively correlated with propionic acid. In conclusion, feed supplementation with about 5–10% of MBL silage could modulate the rumen microbiota and fermentation, and increase the abundance of fiber-digesting, propionic acid synthesis and milk fat-related microorganisms, thus improving milk yield in dairy cows. Full article
(This article belongs to the Section Microbial Metabolism, Physiology & Genetics)
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18 pages, 4605 KiB  
Article
Production of Fumaric Acid by Rhizopus arrhizus NRRL 1526: A Simple Production Medium and the Kinetic Modelling of the Bioprocess
by Victor Martin-Dominguez, Paula I. Aleman Cabrera, Laslo Eidt, Ulf Pruesse, Anja Kuenz, Miguel Ladero and Victoria E. Santos
Fermentation 2022, 8(2), 64; https://doi.org/10.3390/fermentation8020064 - 30 Jan 2022
Cited by 6 | Viewed by 4437
Abstract
Fumaric acid is a promising monomer to obtain biomass-based polyesters and polyamides, and it is mainly produced by fungi of the Rhizopus genus in medium to high titters. The use of glucose, a main component of starchy and cellulosic food waste, as carbon [...] Read more.
Fumaric acid is a promising monomer to obtain biomass-based polyesters and polyamides, and it is mainly produced by fungi of the Rhizopus genus in medium to high titters. The use of glucose, a main component of starchy and cellulosic food waste, as carbon source, together with a low-nitrogen source concentration, is a promising route to reduce process costs. In this work, the effects of nitrogen and carbonate sources on Rhizopus arrhizus NRRL 1526 morphology and fumaric acid productivity were analysed, simplifying the traditional production broth composition. Moreover, a non-structured, non-segregated kinetic model was proposed and fitted to concentration data of all relevant components obtained in batches performed in triplicate with the selected production broth at 34 °C and 200 rpm in an orbital shaker. Full article
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14 pages, 3196 KiB  
Article
Effect of Lactobacillus plantarum Inoculation on Chemical Composition, Fermentation, and Bacterial Community Composition of Ensiled Sweet Corn Whole Plant or Stover
by Zhi-Yuan Ma, Emilio Ungerfeld, Zhu Ouyang, Xiao-Ling Zhou, Xue-Feng Han, Yan-Qin Zeng and Zhi-Liang Tan
Fermentation 2022, 8(1), 24; https://doi.org/10.3390/fermentation8010024 - 10 Jan 2022
Cited by 3 | Viewed by 2317
Abstract
Sweet corn is a feed resource with a high content of water-soluble carbohydrates (WSC) available for ruminant production. This study was conducted to investigate the effect of inoculation with Lactobacillus plantarum on fermentation and nutritional quality of sweet corn silage. Sweet corn whole [...] Read more.
Sweet corn is a feed resource with a high content of water-soluble carbohydrates (WSC) available for ruminant production. This study was conducted to investigate the effect of inoculation with Lactobacillus plantarum on fermentation and nutritional quality of sweet corn silage. Sweet corn whole plant (WP) and sweet corn stover (CS) were ensiled in mini silos with or without inoculation of L. plantarum. Proximate composition and fermentation variables, and composition of the bacterial community, were evaluated before ensiling and at the end of the first, second, and third month after ensiling. There was fiber degradation in CS silage after three months of ensilage, but not in WP silage. Inoculation of WP silage, but not of CS silage, with L. plantarum, increased starch content. The relative abundance of genus Lactobacillus was increased by inoculation with L. plantarum by 14.2% and 82.2% in WP and CS silage, respectively. Inoculation with L. plantarum was not necessary to achieve adequate fermentation of either WP or CS silage, as the abundance of native lactic acid bacteria in both materials seemed suitable for adequate fermentation. That said, increased starch content in WP resulting from inoculation with L. plantarum can increase the nutritive value of WP for ruminants. Full article
(This article belongs to the Special Issue Silage Fermentation)
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13 pages, 2261 KiB  
Article
Supplemental Aspergillus Lipase and Protease Preparations Display Powerful Bifidogenic Effects and Modulate the Gut Microbiota Community of Rats
by Yongshou Yang, Thanutchaporn Kumrungsee, Norihisa Kato, Shinji Fukuda, Manabu Kuroda and Shotaro Yamaguchi
Fermentation 2021, 7(4), 294; https://doi.org/10.3390/fermentation7040294 - 01 Dec 2021
Cited by 6 | Viewed by 3701
Abstract
Aspergillus-derived protease and lipase, which are involved in the production of Aspergillus-fermented foods, are consumed as digestive enzyme supplements. A marked bifidogenic effect of supplemental Aspergillus protease preparation (AP) in rats fed with a high-fat diet was identified. This study was [...] Read more.
Aspergillus-derived protease and lipase, which are involved in the production of Aspergillus-fermented foods, are consumed as digestive enzyme supplements. A marked bifidogenic effect of supplemental Aspergillus protease preparation (AP) in rats fed with a high-fat diet was identified. This study was conducted to examine whether the consumption of Aspergillus-derived lipase exerts similar bifidogenic effect. Rats were fed diets supplemented with either an Aspergillus-derived lipase preparation (AL) or AP at 0.1% for two weeks. 16S rRNA gene sequencing analysis indicated that supplemental AL and AP markedly influenced cecal microbial community. At the phylum level, treatment with AL and AP resulted in a lower relative abundance of Firmicutes and Bacteroidetes, but a higher relative abundance of Actinobacteria and Proteobacteria than the control rats (p < 0.05). At the genus level, AL and AP remarkedly elevated the relative abundances of Bifidobacterium, Collinsella, and Enterococcus, but significantly reduced those of Oscillospira, Dorea, and Coprobacillus (p < 0.05). These modulations were similar to those reported by several studies with typical prebiotic oligosaccharides. Notably, the bifidogenic effect of AL was much greater than that of AP. Our results show that the two different Aspergillus-derived preparations, AL and AP, have strong bifidogenic effects and can change the microbiota’s composition. Full article
(This article belongs to the Special Issue Fermented Foods and Microbes Related to Health)
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21 pages, 1236 KiB  
Article
Wine Saccharomyces Yeasts for Beer Fermentation
by Vanesa Postigo, Margarita García, Juan Mariano Cabellos and Teresa Arroyo
Fermentation 2021, 7(4), 290; https://doi.org/10.3390/fermentation7040290 - 30 Nov 2021
Cited by 13 | Viewed by 5361
Abstract
Multiple studies in recent years have shown the potential of Saccharomyces wild yeasts to produce craft beers with new flavour profiles and other desirable properties. Yeasts isolated from food (wine, bread, kombucha…) have shown potential promise for application in brewing. The aim of [...] Read more.
Multiple studies in recent years have shown the potential of Saccharomyces wild yeasts to produce craft beers with new flavour profiles and other desirable properties. Yeasts isolated from food (wine, bread, kombucha…) have shown potential promise for application in brewing. The aim of this study is to evaluate the ability of 141 Saccharomyces yeast strains isolated from the Madrilenian agriculture (from grapes, must, wine, vineyard, and cellars) to produce a novel ale beer. Fermentation activity of the strains was compared against the commercial strain Saccharomyces cerevisiae Safale S-04. In addition to the other aspects such as melatonin production, thirty-three volatile compounds belonging to higher alcohols, esters, aldehydes/cetones, acids, lactones and phenolic groups, were analysed by GC for selection of the strains. Ten strains were finally chosen, among which the most relevant was the strain G 520 showing a higher production of esters, higher alcohols and acids compared with S-04. The apparent attenuation for this strain was lower than commercial strain, which translates into more residual sugars. Furthermore, G 520 was more capable of producing significantly higher amounts of melatonin studied by HPLC, as well as showing a higher antioxidant capacity. Consumer study showed that G 520 strain could be used to produce a potential beer that has a place in the current market. Full article
(This article belongs to the Special Issue Advances in Wine Fermentation)
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15 pages, 1113 KiB  
Article
Use of Lachancea thermotolerans for Biological vs. Chemical Acidification at Pilot-Scale in White Wines from Warm Areas
by Cristian Vaquero, Pedro Miguel Izquierdo-Cañas, Adela Mena-Morales, L. Marchante-Cuevas, José María Heras and Antonio Morata
Fermentation 2021, 7(3), 193; https://doi.org/10.3390/fermentation7030193 - 15 Sep 2021
Cited by 16 | Viewed by 2860
Abstract
Climate change is affecting vineyards, resulting in grapes with a low acidity a high pH and sugar at harvest time. The most common procedure so far to improve the acidity and reduce the final pH of wines is to use tartaric acid, but [...] Read more.
Climate change is affecting vineyards, resulting in grapes with a low acidity a high pH and sugar at harvest time. The most common procedure so far to improve the acidity and reduce the final pH of wines is to use tartaric acid, but wine can also be acidified microbiologically using Lachancea thermotolerans yeasts, a natural bio-tool that acidifies gradually during the first stage/days of fermentation. Two strains of L. thermotolerans were compared with one Saccharomyces cerevisiae at a pilot-scale under similar fermentation conditions and in duplicate. A sequential inoculation was performed on the third day for the non-Saccharomyces, producing only about 1 g/L of lactic acid, which was suitable for comparison with the Saccharomyces, to which 1.5 g/L of tartaric acid had been added to lower the final pH. The three fermentations ended with a total acidity without significant differences. A significant and normal feature of the L. thermotolerans yeasts is their higher propane-1,2,3-triol production, which was observed in the Laktia yeast, and the acetic acid was <0.3 g/L. The amount of volatile metabolites was generally higher for non-Saccharomyces and the increase was seen in carbonyl compounds, organic acids, lactones, fumaric compounds, and phenols. Finally, the sensory analysis showed that there were hardly any significant differences, even though the non-Saccharomyces had a higher quantity of volatile metabolites, which could lead to a good acceptance of the product, since biological acidification was used, generating a more natural product. Full article
(This article belongs to the Special Issue Enological Repercussions of Non-Saccharomyces Species 3.0)
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20 pages, 7495 KiB  
Article
Mixed-Culture Metagenomics of the Microbes Making Sour Beer
by Renan Eugênio Araujo Piraine, Fábio Pereira Leivas Leite and Matthew L. Bochman
Fermentation 2021, 7(3), 174; https://doi.org/10.3390/fermentation7030174 - 30 Aug 2021
Cited by 9 | Viewed by 3844
Abstract
Mixed microbial cultures create sour beers but many brewers do not know which microbes comprise their cultures. The objective of this work was to use deep sequencing to identify microorganisms in sour beers brewed by spontaneous and non-spontaneous methods. Twenty samples were received [...] Read more.
Mixed microbial cultures create sour beers but many brewers do not know which microbes comprise their cultures. The objective of this work was to use deep sequencing to identify microorganisms in sour beers brewed by spontaneous and non-spontaneous methods. Twenty samples were received from brewers, which were processed for microbiome analysis by next generation sequencing. For bacteria, primers were used to amplify the V3-V4 region of the 16S rRNA gene; fungal DNA detection was performed using primers to amplify the entire internal transcribed spacer region. The sequencing results were then used for taxonomy assignment, sample composition, and diversity analyses, as well as nucleotide BLAST searching. We identified 60 genera and 140 species of bacteria, of which the most prevalent were Lactobacillus acetotolerans, Pediococcus damnosus, and Ralstonia picketti/mannitolilytica. In fungal identification, 19 genera and 26 species were found, among which the most common yeasts were Brettanomyces bruxellensis and Saccharomyces cerevisiae. In some cases, genetic material from more than 60 microorganisms was found in a single sample. In conclusion, we were able to determine the microbiomes of various mixed cultures used to produce beer, providing useful information to better understand the sour beer fermentation process and brewing techniques. Full article
(This article belongs to the Special Issue Mixed Culture Fermentation)
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14 pages, 1804 KiB  
Article
Digital Smoke Taint Detection in Pinot Grigio Wines Using an E-Nose and Machine Learning Algorithms Following Treatment with Activated Carbon and a Cleaving Enzyme
by Vasiliki Summerson, Claudia Gonzalez Viejo, Damir D. Torrico, Alexis Pang and Sigfredo Fuentes
Fermentation 2021, 7(3), 119; https://doi.org/10.3390/fermentation7030119 - 16 Jul 2021
Cited by 14 | Viewed by 2768
Abstract
The incidence and intensity of bushfires is increasing due to climate change, resulting in a greater risk of smoke taint development in wine. In this study, smoke-tainted and non-smoke-tainted wines were subjected to treatments using activated carbon with/without the addition of a cleaving [...] Read more.
The incidence and intensity of bushfires is increasing due to climate change, resulting in a greater risk of smoke taint development in wine. In this study, smoke-tainted and non-smoke-tainted wines were subjected to treatments using activated carbon with/without the addition of a cleaving enzyme treatment to hydrolyze glycoconjugates. Chemical measurements and volatile aroma compounds were assessed for each treatment, with the two smoke taint amelioration treatments exhibiting lower mean values for volatile aroma compounds exhibiting positive ‘fruit’ aromas. Furthermore, a low-cost electronic nose (e-nose) was used to assess the wines. A machine learning model based on artificial neural networks (ANN) was developed using the e-nose outputs from the unsmoked control wine, unsmoked wine with activated carbon treatment, unsmoked wine with a cleaving enzyme plus activated carbon treatment, and smoke-tainted control wine samples as inputs to classify the wines according to the smoke taint amelioration treatment. The model displayed a high overall accuracy of 98% in classifying the e-nose readings, illustrating it may be a rapid, cost-effective tool for winemakers to assess the effectiveness of smoke taint amelioration treatment by activated carbon with/without the use of a cleaving enzyme. Furthermore, the use of a cleaving enzyme coupled with activated carbon was found to be effective in ameliorating smoke taint in wine and may help delay the resurgence of smoke aromas in wine following the aging and hydrolysis of glycoconjugates. Full article
(This article belongs to the Special Issue Implementation of Digital Technologies on Beverage Fermentation)
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18 pages, 4078 KiB  
Article
Smart Detection of Faults in Beers Using Near-Infrared Spectroscopy, a Low-Cost Electronic Nose and Artificial Intelligence
by Claudia Gonzalez Viejo, Sigfredo Fuentes and Carmen Hernandez-Brenes
Fermentation 2021, 7(3), 117; https://doi.org/10.3390/fermentation7030117 - 15 Jul 2021
Cited by 20 | Viewed by 3906
Abstract
Early detection of beer faults is an important assessment in the brewing process to secure a high-quality product and consumer acceptability. This study proposed an integrated AI system for smart detection of beer faults based on the comparison of near-infrared spectroscopy (NIR) and [...] Read more.
Early detection of beer faults is an important assessment in the brewing process to secure a high-quality product and consumer acceptability. This study proposed an integrated AI system for smart detection of beer faults based on the comparison of near-infrared spectroscopy (NIR) and a newly developed electronic nose (e-nose) using machine learning modelling. For these purposes, a commercial larger beer was used as a base prototype, which was spiked with 18 common beer faults plus the control aroma. The 19 aroma profiles were used as targets for classification ma-chine learning (ML) modelling. Six different ML models were developed; Model 1 (M1) and M2 were developed using the NIR absorbance values (100 inputs from 1596–2396 nm) and e-nose (nine sensor readings) as inputs, respectively, to classify the samples into control, low and high concentration of faults. Model 3 (M3) and M4 were based on NIR and M5 and M6 based on the e-nose readings as inputs with 19 aroma profiles as targets for all models. A customized code tested 17 artificial neural network (ANN) algorithms automatically testing performance and neu-ron trimming. Results showed that the Bayesian regularization algorithm was the most adequate for classification rendering precisions of M1 = 95.6%, M2 = 95.3%, M3 = 98.9%, M4 = 98.3%, M5 = 96.8%, and M6 = 96.2% without statistical signs of under- or overfitting. The proposed system can be added to robotic pourers and the brewing process at low cost, which can benefit craft and larger brewing companies. Full article
(This article belongs to the Special Issue Implementation of Digital Technologies on Beverage Fermentation)
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19 pages, 746 KiB  
Article
Bacteriocinogenic Bacillus spp. Isolated from Korean Fermented Cabbage (Kimchi)—Beneficial or Hazardous?
by Joanna Ivy Irorita Fugaban, Jorge Enrique Vazquez Bucheli, Wilhelm Heinrich Holzapfel and Svetoslav Dimitrov Todorov
Fermentation 2021, 7(2), 56; https://doi.org/10.3390/fermentation7020056 - 07 Apr 2021
Cited by 10 | Viewed by 3075
Abstract
Bacillus velezensis ST03 and ST32, Bacillus amyloliquefaciens ST06 and ST109, and Bacillus subtilis ST08 were isolated from artisanal-produced kimchi and were identified based on 16S rRNA partial sequencing. DNA obtained from the investigated bacilli generated positive results for lichenicidin, iturin, subtilosin, and surfactin [...] Read more.
Bacillus velezensis ST03 and ST32, Bacillus amyloliquefaciens ST06 and ST109, and Bacillus subtilis ST08 were isolated from artisanal-produced kimchi and were identified based on 16S rRNA partial sequencing. DNA obtained from the investigated bacilli generated positive results for lichenicidin, iturin, subtilosin, and surfactin on a strain-specific basis. The strains were found to produce antimicrobial metabolites with activity levels ranging between 800 and 1600 AU/mL on a strain-specific basis, as determined against Listeria monocytogenes ATCC15313. Moreover, all tested strains in this study were still active after treatment with proteolytic enzymes, even with reduced inhibition zones compared to the controls, pointing to additional antimicrobial activity possibly related to a non-proteinaceous molecular structure. Most probably these strains may express surfactin as an additional factor in their complex antimicrobial activity. B. amyloliquefaciens ST09 and B. velezensis ST03 and ST32 were characterized as positive for β-hemolysis. B. subtilis ST08 was shown to be positive for hblC and nheC and B. amyloliquefaciens ST109 for nheB. B. amyloliquefaciens ST109 generated positive results for gelatinase activity. The ability of the studied Bacillus strains to metabolize different carbohydrate sources was done based on the API50CHB test, while the enzyme production profile was recorded by the APIZym kit. All studied strains were positive producers for biogenic amines production. Studied Bacillus spp. strains were resistant to some of the evaluated antibiotics, tested according to recommendations of CLSI and EFSA. Full article
(This article belongs to the Special Issue Fermented Foods and Microbes Related to Health)
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17 pages, 767 KiB  
Review
Biodiversity of Oenological Lactic Acid Bacteria: Species- and Strain-Dependent Plus/Minus Effects on Wine Quality and Safety
by Vittorio Capozzi, Maria Tufariello, Nicola De Simone, Mariagiovanna Fragasso and Francesco Grieco
Fermentation 2021, 7(1), 24; https://doi.org/10.3390/fermentation7010024 - 17 Feb 2021
Cited by 28 | Viewed by 5741
Abstract
Winemaking depends on several elaborate biochemical processes that see as protagonist either yeasts or lactic acid bacteria (LAB) of oenological interest. In particular, LAB have a fundamental role in determining the quality chemical and aromatic properties of wine. They are essential not only [...] Read more.
Winemaking depends on several elaborate biochemical processes that see as protagonist either yeasts or lactic acid bacteria (LAB) of oenological interest. In particular, LAB have a fundamental role in determining the quality chemical and aromatic properties of wine. They are essential not only for malic acid conversion, but also for producing several desired by-products due to their important enzymatic activities that can release volatile aromatic compounds during malolactic fermentation (e.g., esters, carbonyl compounds, thiols, monoterpenes). In addition, LAB in oenology can act as bioprotectors and reduce the content of undesired compounds. On the other hand, LAB can affect wine consumers’ health, as they can produce harmful compounds such as biogenic amines and ethyl carbamate under certain conditions during fermentation. Several of these positive and negative properties are species- and strain-dependent characteristics. This review focuses on these aspects, summarising the current state of knowledge on LAB’s oenological diversity, and highlighting their influence on the final product’s quality and safety. All our reported information is of high interest in searching new candidate strains to design starter cultures, microbial resources for traditional/typical products, and green solutions in winemaking. Due to the continuous interest in LAB as oenological bioresources, we also underline the importance of inoculation timing. The considerable variability among LAB species/strains associated with spontaneous consortia and the continuous advances in the characterisation of new species/strains of interest for applications in the wine sector suggest that the exploitation of biodiversity belonging to this heterogeneous group of bacteria is still rising. Full article
(This article belongs to the Special Issue Lactic Acid Fermentation and the Colours of Biotechnology 2.0)
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11 pages, 1739 KiB  
Article
Predicting Fermentation Rates in Ale, Lager and Whisky
by Struan J. Reid, Maria Josey, Andrew J. MacIntosh, Dawn L. Maskell and R. Alex Speers
Fermentation 2021, 7(1), 13; https://doi.org/10.3390/fermentation7010013 - 14 Jan 2021
Cited by 5 | Viewed by 4660
Abstract
Recently there has been an increased interest in characterising the rates of alcoholic fermentations. Sigmoidal models have been used to predict changes such as the rate of density decline. In this study, three published sigmoidal models were assessed and fit to industrial fermentation [...] Read more.
Recently there has been an increased interest in characterising the rates of alcoholic fermentations. Sigmoidal models have been used to predict changes such as the rate of density decline. In this study, three published sigmoidal models were assessed and fit to industrial fermentation data. The first is the four-parameter logistic model described in the ASBC Yeast-14 method. The second model is a nested form of the four-parameter logistic function, adding an extra parameter, creating the 5-parameter logistic equation., where an additional parameter was added to allow for asymmetry. The final model is a three-parameter logistic equation which describes the change in the Apparent Degree of Fermentation with time. The three models were compared by fitting them to industrial data from Australian and Canadian lagers, American and Scottish ales and Scotch Whisky fermentations. The model fits were then compared to one another with a technique developed by Akaike and a nested F-test. The Akaike information criterion compares the models and accounts for both the goodness of fit, and the number of parameters in the model. Finally, consideration was given to the establishment of prediction bands (that enclose the area that one can be 99% sure contains the true datapoints). Calculation of these bands was “challenging” but successful as the industrial fermentation data was heteroscedastic. Full article
(This article belongs to the Special Issue Brewing & Distilling 2.0)
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15 pages, 4452 KiB  
Review
An Overview of CRISPR-Based Technologies in Wine Yeasts to Improve Wine Flavor and Safety
by Alice Vilela
Fermentation 2021, 7(1), 5; https://doi.org/10.3390/fermentation7010005 - 02 Jan 2021
Cited by 15 | Viewed by 7273
Abstract
Modern industrial winemaking is based on the use of specific starters of wine strains. Commercial wine strains present several advantages over natural isolates, and it is their use that guarantees the stability and reproducibility of industrial winemaking technologies. For the highly competitive wine [...] Read more.
Modern industrial winemaking is based on the use of specific starters of wine strains. Commercial wine strains present several advantages over natural isolates, and it is their use that guarantees the stability and reproducibility of industrial winemaking technologies. For the highly competitive wine market with new demands for improved wine quality and wine safety, it has become increasingly critical to develop new yeast strains. In the last decades, new possibilities arose for creating upgraded wine yeasts in the laboratory, resulting in the development of strains with better fermentation abilities, able to improve the sensory quality of wines and produce wines targeted to specific consumers, considering their health and nutrition requirements. However, only two genetically modified (GM) wine yeast strains are officially registered and approved for commercial use. Compared with traditional genetic engineering methods, CRISPR/Cas9 is described as efficient, versatile, cheap, easy-to-use, and able to target multiple sites. This genetic engineering technique has been applied to Saccharomyces cerevisiae since 2013. In this review, we aimed to overview the use of CRISPR/Cas9 editing technique in wine yeasts to combine develop phenotypes able to increase flavor compounds in wine without the development of off-flavors and aiding in the creation of “safer wines.” Full article
(This article belongs to the Special Issue Yeast Biotechnology 4.0)
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