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Fermentation, Volume 8, Issue 8 (August 2022) – 72 articles

Cover Story (view full-size image): Forage is mainly administered in a Total Mixed Ration (TMR) for livestock as hay or silage. However, during the preservation processes several sugar losses occur. The inclusion of liquid feeds could reduce the losses and could represent an energy source. The study aimed to evaluate the in vitro fermentation characteristics of different liquid feeds, using bovine and buffalo rumen liquor as inocula. As a result, several differences were observed between the two species, for instance, organic matter degradability, gas, and volatile fatty acids production. The liquid feeds showed different fermentation patterns in relation to their ingredients and chemical composition. Supplementing liquid feed to a TMR appears to improve fermentation parameters and could be an energy source for both ruminant species. View this paper
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Article
Characterization of Saccharomyces Strains Isolated from “Kéknyelű” Grape Must and Their Potential for Wine Production
Fermentation 2022, 8(8), 416; https://doi.org/10.3390/fermentation8080416 - 22 Aug 2022
Viewed by 473
Abstract
Novel wine yeast strains have the potential to satisfy customer demand for new sensorial experiences and to ensure that wine producers have strains that can produce wine as efficiently as possible. In this respect, hybrid yeast strains have recently been the subject of [...] Read more.
Novel wine yeast strains have the potential to satisfy customer demand for new sensorial experiences and to ensure that wine producers have strains that can produce wine as efficiently as possible. In this respect, hybrid yeast strains have recently been the subject of intense research, as they are able to combine the favourable characteristics of both parental strains. In this study, two Saccharomyces “Kéknyelű” grape juice isolates were identified by species-specific PCR and PCR-RFLP methods and investigated with respect to their wine fermentation potential. Physiological characterization of the isolated strains was performed and included assessment of ethanol, sulphur dioxide, temperature and glucose (osmotic stress) tolerance, killer-toxin production, glucose fermentation ability at 16 °C and 24 °C, and laboratory-scale fermentation using sterile “Kéknyelű” must. Volatile components of the final product were studied by gas chromatography (GC) and mass spectrometry (MS). One isolate was identified as a S. cerevisiae × S. kudriavzevii hybrid and the other was S. cerevisiae. Both strains were characterized by high ethanol, sulphur dioxide and glucose tolerance, and the S. cerevisiae strain exhibited the killer phenotype. The hybrid isolate showed good glucose fermentation ability and achieved the lowest residual sugar content in wine. The ester production of the hybrid strain was high compared to the control S. cerevisiae starter strain, and this contributed to the fruity aroma of the wine. Both strains have good oenological characteristics, but only the hybrid yeast has the potential for use in wine fermentation. Full article
(This article belongs to the Special Issue Wine Microbiology)
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Article
Evaluation of Gas Production, Fermentation Parameters, and Nutrient Degradability in Different Proportions of Sorghum Straw and Ammoniated Wheat Straw
Fermentation 2022, 8(8), 415; https://doi.org/10.3390/fermentation8080415 - 22 Aug 2022
Viewed by 361
Abstract
The purpose of this study was to investigate the optimum proportion of sorghum straw and ammoniated wheat straw in vitro and in vivo to apply in ruminant diets. One-factor and two-factor experimental designs were used in the in vitro tests, with different ratios [...] Read more.
The purpose of this study was to investigate the optimum proportion of sorghum straw and ammoniated wheat straw in vitro and in vivo to apply in ruminant diets. One-factor and two-factor experimental designs were used in the in vitro tests, with different ratios of sorghum straw to ammoniated wheat straw (S:AWS) of 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, and 8:2 to measure the in vitro total gas production, CH4 production, in vitro dry matter degradability (IVDMD), in vitro organic matter degradability (IVOMD) and in vitro fermentation parameters. Additionally, the nylon bag technique was used to determine the dynamic degradation of these different ratios of mixed feedstuffs for incubating in sheep rumen for 6 h, 12 h, 24 h, and 48 h. The results show that IVDMD, IVOMD, and the molar ratio of propionate were the highest when the ratio of S:AWS was 8:2 (p < 0.05) in vitro; however, this ratio released much more CH4 (p < 0.05). In addition, the degradability of DM, OM, CP, and ash and the effective degradability of DM and CP were the highest when the ratio of S:AWS was 8:2 cultured in sheep rumen for 48 h (p < 0.05). In the in vitro and in situ nylon bag tests, IVDMD, IVOMD, rumen nutrient degradability, and effective degradability of DM and CP increased with the increase in the sorghum straw proportion. In conclusion, the higher the proportion of sorghum straw, the higher the nutrient degradability in vivo and in vitro, but also the higher the emissions of CH4. Therefore, when the ratio of S:AWS is 8:2, ruminants can effectively utilize nutrients in feed. Full article
(This article belongs to the Special Issue In Vitro Fermentation)
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Article
Genomic and Transcriptional Characteristics of Strain Rum-meliibacillus sp. TYF-LIM-RU47 with an Aptitude of Directly Producing Acetoin from Lignocellulose
Fermentation 2022, 8(8), 414; https://doi.org/10.3390/fermentation8080414 - 22 Aug 2022
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Abstract
Rummeliibacillus sp. TYF-LIM-RU47, isolated from the fermentation substrate of grain vinegar, could produce acetoin using a variety of carbon sources, including pentose, hexose and lignocellulose. The draft genome of TYF-LIM-RU47 was constructed and the genomic information revealed that TYF-LIM-RU47 contains genes related to [...] Read more.
Rummeliibacillus sp. TYF-LIM-RU47, isolated from the fermentation substrate of grain vinegar, could produce acetoin using a variety of carbon sources, including pentose, hexose and lignocellulose. The draft genome of TYF-LIM-RU47 was constructed and the genomic information revealed that TYF-LIM-RU47 contains genes related to starch and sucrose metabolism, pyruvate metabolism, the oxidative phosphorylation metabolic pathway and lignocellulosic metabolism. The acetoin anabolic pathway of TYF-LIM-RU47 has been deduced from the sequencing results, and acetoin is produced from α-acetolactate via decarboxylation and diacetyl reductase catalytic steps. The results of quantitative real-time PCR tests showed that the synthesis and degradation of acetoin had a dynamic balance in acetoin metabolism, and the transcription of the α-acetolactate synthase gene might exist to the extent of feedback regulation. This study can help researchers to better understand the bioinformation of thermophilic-lignocellulosic bacteria and the mechanisms of the acetoin biosynthesis pathway. Full article
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Article
The Impact of Indigenous Non-Saccharomyces Yeasts Inoculated Fermentations on ‘Semillon’ Icewine
Fermentation 2022, 8(8), 413; https://doi.org/10.3390/fermentation8080413 - 21 Aug 2022
Viewed by 392
Abstract
The emerging low acidity in icewine grapes is becoming a major problem in producing quality icewine. Using non-Saccharomyces cerevisiae yeasts in fermentation can improve wine’s organoleptic characteristics and aromatic quality. This study evaluated two indigenous non-Saccharomyces cerevisiae yeasts, Lachancea thermotolerans (LT-2) [...] Read more.
The emerging low acidity in icewine grapes is becoming a major problem in producing quality icewine. Using non-Saccharomyces cerevisiae yeasts in fermentation can improve wine’s organoleptic characteristics and aromatic quality. This study evaluated two indigenous non-Saccharomyces cerevisiae yeasts, Lachancea thermotolerans (LT-2) and Torulaspora delbrueckii (TD-3), for their ability to improve the acidity and quality of ‘Semillon’ icewine. Five different inoculation schemes were implemented, including a single inoculation of S. cerevisiae (SC), L. thermotolerans (LT), and T. delbrueckii (TD); the sequential inoculation of L. thermotolerans, followed by S. cerevisiae after 6 days (L-S); and the sequential inoculation of L. thermotolerans, followed by T. delbrueckii after 6 days (L-D). The results showed that, during sequential fermentation (L-S and L-D), the presence of S. cerevisiae or T. delbrueckii slightly restrained the growth of L. thermotolerans. Single or sequential inoculation with L. thermotolerans and T. delbrueckii significantly reduced the amount of volatile acidity and increased the glycerol content. Furthermore, fermentations involving L. thermotolerans produced relevant amounts of lactic acid (2.04–2.2 g/L) without excessive deacidification of the icewines. Additionally, sequential fermentations increased the concentration of terpenes, C13-norisoprenoid compounds, and phenethyl compounds. A sensory analysis also revealed that sequentially fermented icewines (L-S and L-D) had more fruity and floral odors and aroma intensity. This study highlights the potential application of L. thermotolerans and T. delbrueckii in sequential fermentation to improve the icewine quality. Full article
(This article belongs to the Special Issue Enological Repercussions of Non-saccharomyces Species 4.0)
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Article
Effects of Adding Ethanol Extract of Propolis on the Fermentation Quality, Aerobic Stability, Fatty Acid Profile, and In Vitro Digestibility of Alfalfa Silages
Fermentation 2022, 8(8), 412; https://doi.org/10.3390/fermentation8080412 - 21 Aug 2022
Viewed by 378
Abstract
This study was planned to determine the effects of ethanol extract of propolis on the fermentation quality, fatty acid profile, aerobic stability, and in vitro digestibility of alfalfa silages. The ethanol extract of propolis was added to alfalfa at levels of 1000 mg/kg [...] Read more.
This study was planned to determine the effects of ethanol extract of propolis on the fermentation quality, fatty acid profile, aerobic stability, and in vitro digestibility of alfalfa silages. The ethanol extract of propolis was added to alfalfa at levels of 1000 mg/kg (PROP1), 2000 mg/kg (PROP2), and 3000 mg/kg (PROP3); propolis was not added to the control (CON) group. After the propolis was added, the pH value of the alfalfa silage declined, and the crude protein content was effectively preserved (p < 0.05). Adding propolis to alfalfa silages caused crude fiber, neutral detergent fiber, and acid detergent fiber (p < 0.05) to decrease. The ethanol extract of propolis significantly improved the lactic acid content and reduced the NH3-N content (p < 0.05). Propolis significantly improved the unsaturated fatty acid content (p < 0.05) and reduced the saturated fatty acid content (p < 0.05). In addition, propolis significantly improved the relative feed value, the digestibility of the organic matter, and the in vitro metabolic energy content (p < 0.05). These results show that the ethanol extract of propolis improves the silage quality of last cutting alfalfa silages, and has potential as an antimicrobial silage additive. Full article
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Article
Statistical Optimization for Cost-Effective Production of Yeast-Bacterium Cell-Bound Lipases Using Blended Oily Wastes and Their Potential Applications in Biodiesel Synthesis and Wastewater Bioremediation
Fermentation 2022, 8(8), 411; https://doi.org/10.3390/fermentation8080411 - 20 Aug 2022
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Abstract
Oily wastes have been widely used to produce lipases, but there is insufficient knowledge on their use to efficiently produce cell-bound lipases (CBLs). This research aimed to optimize yeast–bacterium CBLs production using blended oily wastes by statistical optimization and their potential applications in [...] Read more.
Oily wastes have been widely used to produce lipases, but there is insufficient knowledge on their use to efficiently produce cell-bound lipases (CBLs). This research aimed to optimize yeast–bacterium CBLs production using blended oily wastes by statistical optimization and their potential applications in biodiesel production and wastewater bioremediation. The co-culture of Magnusiomyces spicifer AW2 and Staphylococcus hominis AUP19 produced CBLs as high as 4709 U/L with cell biomass of 23.4 g/L in a two-fold diluted palm oil mill effluent (POME) added by 2.08% (v/v) waste frying oil, 1.72.0% (w/v) ammonium sulfate, 0.1% (w/v) Gum Arabic as an emulsifier (initial pH at 7.0) within 24 h. The CBLs were successfully applied as whole-cell biocatalysts to produce biodiesel through esterification and transesterification with 76% and 87% yields, respectively. Direct application of CBLs for bioremediation of heat-treated various POME concentrations achieved 73.3% oil and grease removal and 73.6% COD removal within 3 days. This study has shown that the blended oily wastes medium was suitable for low-cost production of yeast–bacterium CBLs and their potential applications in solvent-free biodiesel production and wastewater bioremediation. These strategies may greatly contribute to economical green biofuel production and waste biotreatment. Full article
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Article
Pseudo-Lager—Brewing with Lutra® Kveik Yeast
Fermentation 2022, 8(8), 410; https://doi.org/10.3390/fermentation8080410 - 19 Aug 2022
Viewed by 342
Abstract
Brewers commonly produce ales since the ale yeast is more resilient, ferments quicker and requires higher temperatures, which are easier to ensure as opposed to lager and pilsner, which require lower temperatures and longer lagering time. However, Kveik yeasts are also resilient, ferment [...] Read more.
Brewers commonly produce ales since the ale yeast is more resilient, ferments quicker and requires higher temperatures, which are easier to ensure as opposed to lager and pilsner, which require lower temperatures and longer lagering time. However, Kveik yeasts are also resilient, ferment at fairly high temperatures (up to 35 °C), and can provide light, lager-like beers, but more quickly, in shorter lagering time, and with reduced off flavors. Diacetyl rest is not needed. The intention of this paper was to assess the possibility of producing pseudo-lager by using Lutra® Kveik. A batch (120 L) was divided into six fermenting vessels and inoculated with Lutra® yeast. To test its possibility to result in lager-like beer at higher temperature, we conducted fermentation at two temperatures (21 and 35 °C). Fermentation subjected to 21 °C lasted for 9 days, while at 35 °C, fermentation was finished in 2 days. After fermentation, both beers were stored in cold temperatures (4 °C) and then kegged, carbonized, and analyzed (pH, ethanol, polyphenols, color, bitterness, clarity). Alongside the sensory evaluation, a GC-MS analysis was also conducted in order to determine if there are any difference between the samples. Full article
(This article belongs to the Special Issue Brewing Yeast and Fermentation)
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Article
Critical Optimized Conditions for Gamma-Aminobutyric Acid (GABA)-Producing Tetragenococcus Halophilus Strain KBC from a Commercial Soy Sauce Moromi in Batch Fermentation
Fermentation 2022, 8(8), 409; https://doi.org/10.3390/fermentation8080409 - 19 Aug 2022
Viewed by 411
Abstract
Gamma-aminobutyric acid (GABA) has several health-promoting qualities, leading to a growing demand for natural GABA production via microbial fermentation. The GABA-producing abilities of the new Tetragenococcus halophilus (THSK) isolated from a commercial soy sauce moromi were proven in this investigation. Under aerobic conditions, [...] Read more.
Gamma-aminobutyric acid (GABA) has several health-promoting qualities, leading to a growing demand for natural GABA production via microbial fermentation. The GABA-producing abilities of the new Tetragenococcus halophilus (THSK) isolated from a commercial soy sauce moromi were proven in this investigation. Under aerobic conditions, the isolate produced 293.43 mg/L of GABA after 5 days of cultivation, compared to 217.13 mg/L under anaerobic conditions. Critical parameters such as pH, monosodium glutamate (MSG), and sodium chloride (NaCl) concentrations were examined to improve GABA yield. MSG had the most significant impact on GABA and GABA synthesis was not suppressed even at high NaCl concentrations. Data showed that a pH of 8, MSG content of 5 g/L, and 20% NaCl were the best culture conditions. The ultimate yield was improved to 653.101 mg/L, a 2.22-fold increase (293.43 mg/L). This design shows that the bacteria THSK has industrial GABA production capability and can be incorporated into functional food. Full article
(This article belongs to the Special Issue High Quality Functional Food: Potential of Probiotics)
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Communication
Apple Pomace Modulates the Microbiota and Increases the Propionate Ratio in an In Vitro Piglet Gastrointestinal Model
Fermentation 2022, 8(8), 408; https://doi.org/10.3390/fermentation8080408 - 19 Aug 2022
Viewed by 312
Abstract
Apple pomace (AP) contains biomolecules that induce changes in intestinal fermentation of monogastrics with positive expected health effects. The weaning of piglets can induce economic losses due to intestinal disturbances; new weaning strategies are, thus, welcome. The purpose of this study was to [...] Read more.
Apple pomace (AP) contains biomolecules that induce changes in intestinal fermentation of monogastrics with positive expected health effects. The weaning of piglets can induce economic losses due to intestinal disturbances; new weaning strategies are, thus, welcome. The purpose of this study was to test the effect of AP on fermentation products by using baby-SPIME, an in vitro multi-compartment model dedicated to piglet weaning. A comparison was done on short chain fatty acid (SCFA) ratio and the microbiota induced in bioreactors between a control culture medium vs. an AP culture medium. The results of 2 preliminary runs showed that AP medium increased the molar ratio of propionate (p = 0.021) and decreased the molar ratio of butyrate (p = 0.009). Moreover, this medium increased the cumulative relative abundance of Prevotella sp. and Akkermansia sp. in bioreactors. AP could promote an ecosystem enriched with bacteria known as next-generation probiotics (NGP)—likely influencing the energy metabolism of piglets by their fermentation metabolites. AP could be used as a dietary strategy to influence bacterial changes in the intestine by stimulating the growth of bacteria identified as NGP. Full article
(This article belongs to the Special Issue In Vitro Fermentation)
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Article
Selection of Yeast and Lactic Acid Bacteria Strains, Isolated from Spontaneous Raw Milk Fermentation, for the Production of a Potential Probiotic Fermented Milk
Fermentation 2022, 8(8), 407; https://doi.org/10.3390/fermentation8080407 - 19 Aug 2022
Viewed by 466
Abstract
Probiotic milk is a class of fermented milk that possesses health-promoting effects, not only due to the lactic acid bacteria (LAB) presence but potentially also to yeast activity. Hence, the aim of this work was to isolate and select yeasts from spontaneous milk [...] Read more.
Probiotic milk is a class of fermented milk that possesses health-promoting effects, not only due to the lactic acid bacteria (LAB) presence but potentially also to yeast activity. Hence, the aim of this work was to isolate and select yeasts from spontaneous milk fermentations to be used as inoculum, together with LAB, for manufacturing a potentially probiotic acidic low-alcohol fermented milk. Six yeast species were detected from the spontaneous milk fermentation. A screening of 13 yeast strains and 14 previously isolated LAB strains, based on the resistance to bile salts and to acidic conditions, was carried out. The best performing strains were successively tested for in vitro gastrointestinal tolerance. A strain of Kluyveromyces marxianus and a strain of Lactococcus lactis were selected for the manufacturing of two different fermented milk. The values of the main technological and microbiological parameters (pH, organic acids, ethanol, and microbial concentrations) of the experimental milk were in the range of those reported for this category of products. The evaluation of microorganism survival in fermented milk samples subjected to simulated gastrointestinal conditions highlighted a high resistance of both strains. In conclusion, the selected microbial starter culture enabled the setting up of potential probiotic fermented milk. Full article
(This article belongs to the Special Issue High Quality Functional Food: Potential of Probiotics)
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Article
Responses of Fermentation Characteristics and Microbial Communities to Vitamin B12 Supplementation in In Vitro Ruminal Cultures
Fermentation 2022, 8(8), 406; https://doi.org/10.3390/fermentation8080406 - 19 Aug 2022
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Abstract
Vitamin B12, an important cofactor involved in propionate formation, is synthesized exclusively by bacteria and archaebacteria. Humans need to intake vitamin B12 through food, and dairy products are generally the best source of vitamin B12. In the present [...] Read more.
Vitamin B12, an important cofactor involved in propionate formation, is synthesized exclusively by bacteria and archaebacteria. Humans need to intake vitamin B12 through food, and dairy products are generally the best source of vitamin B12. In the present study, the effects of vitamin B12 supplementation in diets on in vitro ruminal fermentation characteristics and microbial communities were investigated to provide a reference for increasing the vitamin B12 content in milk by dietary supplementation. A completely randomized design was carried out using the in vitro rumen culture technique, and 5 vitamin B12 dose levels (0, 0.5, 1.0, 2.0, and 4 mg/g of dry matter) were used. The results showed that vitamin B12 supplementation in diets decreased acetate: propionate ratio and butyrate concentration. The change in the acetate: propionate ratio can be attributed to the increased relative abundances of the Proteobacteria phylum and the Negativicutes class, both of which are involved in propionate metabolism. The decrease in butyrate concentration can likely be attributed to a reduction in relative abundance of species belonging to the Clostridia class, which are known as the predominant butyrate producers in the mammalian intestine. In addition, vitamin B12 supplementation in diets reduced the CH4 production by altering the species composition of the archaeal community. In conclusion, dietary supplementation of vitamin B12 resulted in rumen perturbation. In vivo studies should be conducted cautiously when evaluating the effects of vitamin B12 supplementation on the synthesis and absorption of it, as well as its content in milk. Full article
(This article belongs to the Special Issue In Vitro Fermentation)
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Article
Differences between Yaks and Qaidam Cattle in Digestibilities of Nutrients and Ruminal Concentration of Volatile Fatty Acids Are not Dependent on Feed Level
Fermentation 2022, 8(8), 405; https://doi.org/10.3390/fermentation8080405 - 19 Aug 2022
Viewed by 292
Abstract
The Qinghai–Tibetan Plateau (QTP) is characterized by highly fluctuating seasonal pastures. Yaks (Bos grunniens) graze at higher altitudes than Qaidam cattle (Bos taurus), but the two bovine species co-graze in their overlapping ranges. We hypothesized that yaks would digest [...] Read more.
The Qinghai–Tibetan Plateau (QTP) is characterized by highly fluctuating seasonal pastures. Yaks (Bos grunniens) graze at higher altitudes than Qaidam cattle (Bos taurus), but the two bovine species co-graze in their overlapping ranges. We hypothesized that yaks would digest nutrients to a greater extent and utilize energy more efficiently than cattle at low dietary intakes, but the difference between bovine species would not be apparent at high intakes. To test this hypothesis, six yaks (203 ± 6.0 kg) and six Qaidam cattle (214 ± 9.0 kg), all 3.5-year-old castrated males, were used in two concurrent 4 × 4 Latin square designs with two extra steers of each species in each period. The digestibilities of dry matter, organic matter, crude protein, ether extract, neutral and acid detergent fiber were greater (p < 0.05) in yaks than in cattle and decreased linearly (p < 0.05) when feed level (FL) increased. The average daily gain (ADG), the ratios of digestible energy (DE) to gross energy and metabolizable energy (ME) to DE, and ruminal total volatile fatty acids and ammonia-N concentrations were greater (p < 0.001) in yaks than in cattle and increased linearly (p < 0.001) when FL increased. Based on the regression equations of ADG on ME intake, the daily ME requirement for maintenance in yaks was 0.53 MJ BW−0.75 d−1, which was lesser (p < 0.05) than the 0.62 MJ BW−0.75 d−1 in cattle. We concluded that: (1) when differences between breeds emerged, the differences existed for all FLs; (2) maintenance energy requirement was lesser and ADG was greater in yaks than in cattle; (3) the digestibilities of nutrients were greater in yaks than in cattle when consuming only oat hay pellets. These findings indicate that yaks adapt to fluctuating dietary intakes in harsh environments by having a low energy requirement and high digestibility of nutrients, independent of the FL. Full article
(This article belongs to the Section Industrial Fermentation)
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Article
Fermented Milk Product Enriched with γ-PGA, Peptides and GABA by Novel Co-Fermentation with Bacillus subtilis and Lactiplantibacillus plantarum
Fermentation 2022, 8(8), 404; https://doi.org/10.3390/fermentation8080404 - 19 Aug 2022
Viewed by 332
Abstract
Milk was co-fermented with Bacillus subtilis HA and Lactiplantibacillus plantarum EJ2014 to produce a dairy ingredient enriched with poly-γ-glutamic acid (γ-PGA) and γ-aminobutyric acid (GABA). The first fermentation of milk with B. subtilis HA resulted in a viscous broth with pH 6.56, 0.26% [...] Read more.
Milk was co-fermented with Bacillus subtilis HA and Lactiplantibacillus plantarum EJ2014 to produce a dairy ingredient enriched with poly-γ-glutamic acid (γ-PGA) and γ-aminobutyric acid (GABA). The first fermentation of milk with B. subtilis HA resulted in a viscous broth with pH 6.56, 0.26% acidity, 1.40 mg/g tyrosine equivalent, and 17.21 U/g protease activity. The viable cell counts of B. subtilis indicated 8.74 log CFU/mL, and the consistency index of the alkaline fermented milk was 1.82 Pa·sn. In addition, 4.65% mucilage was produced with 35.93% γ-PGA content. The milk co-fermented by L. plantarum indicated 1.34% acidity and pH 4.91. The viable bacterial counts of B. subtilis decreased to 4.44 log CFU/mL, whereas those of L. plantarum increased to 9.42 log CFU/mL. Monosodium glutamate (MSG) as a precursor was effectively converted into γ-PGA by B. subtilis, and then residual MSG was completely converted into GABA by L. plantarum with a yield of 26.15 mg/g. Furthermore, the co-fermented milk produced volatiles, including hexanoic acid, 2,3-butanediol, and acetoin, which may be responsible for its aged cheese-like aroma. Full article
(This article belongs to the Special Issue Recent Trends in Lactobacillus and Fermented Food)
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Article
Transcriptomic Analysis of Staphylococcus equorum KM1031, Isolated from the High-Salt Fermented Seafood Jeotgal, under Salt Stress
Fermentation 2022, 8(8), 403; https://doi.org/10.3390/fermentation8080403 - 19 Aug 2022
Viewed by 285
Abstract
Staphylococcus equorum is a potential starter for Korean high-salt fermented foods because of its salt tolerance and enzymatic activities that contribute to enhanced sensory properties of the food products. However, the mechanisms of salt tolerance of S. equorum are not fully understood. Here, [...] Read more.
Staphylococcus equorum is a potential starter for Korean high-salt fermented foods because of its salt tolerance and enzymatic activities that contribute to enhanced sensory properties of the food products. However, the mechanisms of salt tolerance of S. equorum are not fully understood. Here, RNA sequencing was performed on S. equorum strain KM1031 exposed to 7% NaCl (w/v) for 2 and 4 h to determine global gene expression changes. Salt pressure for 2 and 4 h resulted in significant differential expression of 4.8% (106/2209) and 6.1% (134/2209) of S. equorum KM1031 genes, respectively. Twenty-five core genes were differentially expressed on salt treatment for both 2 and 4 h, seven of which were related to osmoprotectant uptake and synthesis. We analyzed the genome of strain KM1031 and identified osmoprotectant uptake (Opu) systems, potassium importers, sodium exporters, and the glycine betaine synthesis system. The RNA sequencing results indicated that the OpuD system and glycine betaine synthesis might play the main roles in the salt tolerance of strain KM1031. Finally, the results of RNA sequencing were validated by quantitative real-time PCR of likely salt stress-related genes. This transcriptomic analysis provides evidence regarding the osmotic stress responses of S. equorum strain KM1031. Full article
(This article belongs to the Special Issue Microbial Metabolism in Fermentation Process)
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Article
Nutraceutical Enrichment of Animal Feed by Filamentous Fungi Fermentation
Fermentation 2022, 8(8), 402; https://doi.org/10.3390/fermentation8080402 - 19 Aug 2022
Viewed by 419
Abstract
There is an urgent need for improvements in animal production, particularly for ruminants, such that more sustainable and efficient processes are developed for obtaining more nutritious and efficient feeds. Filamentous fungi can add value to residual plant biomass, and may also have the [...] Read more.
There is an urgent need for improvements in animal production, particularly for ruminants, such that more sustainable and efficient processes are developed for obtaining more nutritious and efficient feeds. Filamentous fungi can add value to residual plant biomass, and may also have the potential to produce metabolites and enrich plant biomasses used in animal nutrition, converting them into nutraceutical sources. Thus, in this work, filamentous fungal fermentation of ruminant feed biomasses commonly used in Brazil was performed, and the enrichment for bioactive metabolites was tested. For this, Fistulina hepatica, Ganoderma lucidum, Pleurotus pulmonarius, Panus lecomtei, and Aspergillus terreus were grown for 28 days on different substrates: starchy grains- (sorghum, oat, and corn), fibrous substrates (coast-cross, rice husk, and moringa plant) and protein-rich substrates (cottonseed cake and pigeon pea plant). Fermented substrates were evaluated for laccase activity, crude protein, β-glucan, and lovastatin content. The highest growth rate was observed for G. lucidum in oat substrate (OT-01) (0.708 ± 0.035 cm/day) and F. hepatica in oat + coast-cross + pigeon pea treatment (OT-10) (0.607 ± 0.012 cm/day). High laccase activity was observed for P. lecomtei grown in starchy grain + moringa + pigeon pea substrate, reaching an activity of 416.8 ± 20.28 U/g. A. terreus growth in ST-09 (sorghum + pigeon pea) showed higher protein (15.3 ± 0.46%), β-glucan (503.56 ± 8.6 mg/g) and lovastatin (1.10 ± 0.17 mg/g) content compared to untreated substrates. These results demonstrate that filamentous fungi are an alternative for nutraceutical enrichment of ruminant feed biomasses. To the best of our knowledge, this is the first report in which P. lecomtei and F. hepatica are evaluated for their ability to be cultivated in ruminant feed substrates from Brazil. Full article
(This article belongs to the Special Issue Biotransformation of Plant Materials by Molds and Higher Fungi)
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Article
Investigating the Relation between Skin Cell Wall Composition and Phenolic Extractability in Cabernet Sauvignon Wines
Fermentation 2022, 8(8), 401; https://doi.org/10.3390/fermentation8080401 - 18 Aug 2022
Viewed by 324
Abstract
In this study, phenolic extractability of Cabernet Sauvignon grapes from two California regions (Sonoma County and Central Coast) and its relation with skin cell wall composition was investigated. Phenolic grape composition, wine phenolic content as well as berry and pomace cell wall composition [...] Read more.
In this study, phenolic extractability of Cabernet Sauvignon grapes from two California regions (Sonoma County and Central Coast) and its relation with skin cell wall composition was investigated. Phenolic grape composition, wine phenolic content as well as berry and pomace cell wall composition of three sites per region were determined. Grape cell wall material (CWM) composition, and thus pomace CWM composition, was impacted by the growing region. The process of fermentation modified CWM composition, solubilizing some of the compounds such as pectin and polysaccharides making pomace CWM composition from different sites more similar in the case of Sonoma County and more different for the samples grown in the Central Coast. Growing region had a significant impact on grape phenolics, particularly on flavan−3-ols and polymeric phenols, whereas polymeric pigments and anthocyanin contents were more similar among samples. Wines made from Sonoma County grapes showed higher anthocyanin and polymeric phenol content when compared to wines made from Central Coast grapes. Comparing wine to grape phenolic composition suggests a large difference in extractability based on region. Of all the CWM components analyzed, only lignin and the amount of cell wall isolated were found to have a significant impact on phenolic extractability. Full article
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Article
Cultivation of Lactic Acid Bacteria and Evaluation of the Antimicrobial Potential of Partially Purified Bacteriocin-like Inhibitory Substances against Cariogenic and Food Pathogens
Fermentation 2022, 8(8), 400; https://doi.org/10.3390/fermentation8080400 - 18 Aug 2022
Viewed by 365
Abstract
One of the major challenges in the pharmaceutical industry is the search for new antimicrobial compounds that can replace antibiotics. Lactic acid bacteria (LAB) can produce bacteriocin-like inhibitory substances (BLIS) that have a bacteriostatic or bactericidal effect against different bacterial genera, including those [...] Read more.
One of the major challenges in the pharmaceutical industry is the search for new antimicrobial compounds that can replace antibiotics. Lactic acid bacteria (LAB) can produce bacteriocin-like inhibitory substances (BLIS) that have a bacteriostatic or bactericidal effect against different bacterial genera, including those responsible for dental caries. Among the pathological processes of microbial etiology, the dental caries stands out, whose main pathogenic agent is the species Streptococcus mutans, present in about 80–90% of the oral cavity. In this context, this study aimed to produce and semi-purify BLIS from Lactobacillus plantarum ST16 Pa, Bifidobacteriumlactis BL 04, Lactococcus lactis CECT-4434 and Lactobacillus lactis 27 as well as to assess their antimicrobial potential against important dental caries causing pathogens like S. mutans UA159, Listeria innocua 2711, Carnobacterium maltaromaticum CECT 4020, Staphylococcus aureus CECT 239, and Escherichia coli ATCC 25922. While BLIS from L. plantarum ST16 Pa and L. lactis CECT-4434 were able to inhibit the growth only of S. mutans UA159, that which was produced by B. lactis BL 04 did so against all bioindicator strains; therefore, this suggests that its application could be important in the control of cariogenic microorganisms. Full article
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Article
Anaerobic Co-Digestion of Sugarcane Leaves, Cow Dung and Food Waste: Focus on Methane Yield and Synergistic Effects
Fermentation 2022, 8(8), 399; https://doi.org/10.3390/fermentation8080399 - 17 Aug 2022
Viewed by 425
Abstract
Anaerobic co-digestion (AcoD) of food waste (FW) and lignocellulose waste is a promising technology for methane production. This work investigated the methane generation from AcoD of FW, sugarcane leaves (SLs), and cow dung (CD) under mesophilic conditions in a batch test. As for [...] Read more.
Anaerobic co-digestion (AcoD) of food waste (FW) and lignocellulose waste is a promising technology for methane production. This work investigated the methane generation from AcoD of FW, sugarcane leaves (SLs), and cow dung (CD) under mesophilic conditions in a batch test. As for AcoD of two feedstocks (SL and FW or CD and FW), introduction of SL and CD (25%, volatile solid (VS) basis) showed slight improvement in methane production from FW. In contrast, positive synergistic effect (synergy index = 1.03–1.14 > 1) was observed in all the AcoD reactors of the three feedstocks (SL, CD, and FW). The optimum mixing ratio of FW:SL:CD (VS basis) was 85:11.25:3.75 with a synergy index of 1.07, achieving a methane yield rate and methane content of 297.16 mL/g VS and 73.26%, respectively. This group cumulative methane production was an improvement of 110.45 and 444.72% higher than mono-digestion of SL and CD. The biodegradability, soluble chemical oxygen demand (SCOD), and VS removal rate were 56.44, 44.55 and 55.38%, respectively. The optimum results indicated that AcoD of FW, SL, and CD have higher potentials for energy recovery and provided forceful scientific evidence for their energy utilization. Full article
(This article belongs to the Special Issue Biomass Waste as a Renewable Source of Biogas Production)
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Article
Selection and Optimization of Medium Components for the Efficient Production of L-Asparaginase by Leucosporidium scottii L115—A Psychrotolerant Yeast
Fermentation 2022, 8(8), 398; https://doi.org/10.3390/fermentation8080398 - 17 Aug 2022
Viewed by 371
Abstract
This study reports the production of L-asparaginase (ASNase), an enzyme mainly used for the treatment of acute lymphoblastic leukemia, by Leucosporidiumscottii L115, a psychrotolerant yeast isolated from the Antarctic ecosystem. Focus was given to select the most appropriate medium components able to [...] Read more.
This study reports the production of L-asparaginase (ASNase), an enzyme mainly used for the treatment of acute lymphoblastic leukemia, by Leucosporidiumscottii L115, a psychrotolerant yeast isolated from the Antarctic ecosystem. Focus was given to select the most appropriate medium components able to maximize the enzyme production by this yeast, as a first step for the development of a new process to produce ASNase. By combining knowledge in bioprocesses, statistical analysis and modeling, the medium composition that most favored enzyme production was established, which consisted of using a mixture of sucrose (28.34 g L−1) and glycerol (15.61 g L−1) as carbon sources, supplemented with proline (6.15 g L−1) and the following salts (g L−1): KCl, 0.52; MgSO4·7H2O, 0.52; CuNO3·3H2O, 0.001; ZnSO4·7H2O, 0.001; and FeSO4·7H2O, 0.001. By using this medium, enzyme production of 2850 U L−1 (productivity of 23.75 U L−1 h−1) was obtained, which represented a 28-fold increase in enzyme production per gram of cells (178 U gdcw−1) when compared to the control (non-optimized medium), and a 50-fold increase when compared to a reference medium used for ASNase production. Full article
(This article belongs to the Special Issue Production of Pharmaceuticals and Nutraceuticals by Fermentation)
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Article
Influence of Animal/Plant Activated Biochar Properties on Methane Production from Corn Stalk by Anaerobic Fermentation
Fermentation 2022, 8(8), 397; https://doi.org/10.3390/fermentation8080397 - 16 Aug 2022
Viewed by 332
Abstract
Activated biochar (ABC) was prepared from typical plant/animal biochar (pig bone biochar/corn stalk biochar) by optimizing the gas production characteristics of anaerobic fermentation. The effects of the physical and chemical properties (specific surface area, surface functional group and conductivity) of ABC on the [...] Read more.
Activated biochar (ABC) was prepared from typical plant/animal biochar (pig bone biochar/corn stalk biochar) by optimizing the gas production characteristics of anaerobic fermentation. The effects of the physical and chemical properties (specific surface area, surface functional group and conductivity) of ABC on the gas production characteristics of anaerobic fermentation were investigated. The results showed that the effect of pig-bone activated biochar (PABC) on anaerobic fermentation gas production characteristics was better than that of corn-stalk activated biochar (CABC). The peak period of gas production or methane production was up to 4 days earlier than that of the control group, and the cumulative methane production was up to 68% higher; this can shorten the fermentation period for up to 7 days, and the effect of stabilizing pH is better. In addition, the surface functional groups are not the dominant factors affecting the gas production characteristics, but the effects of conductivity and specific surface area cannot be neglected. For most experimental groups, when the specific surface area of PABC is more than 90 m2/g and the specific surface area of CABC is more than 100 m2/g. Methane production increases with the specific surface area increases and the controllable range of CBAC is relatively wider than that of PBAC. When the conductivity of CABC is more than 650 μS/cm and the conductivity of PABC is more than 1000 μS/cm, the conductivity has a positive correlation with methane production. Full article
(This article belongs to the Section Industrial Fermentation)
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Article
Biohydrogen and Methane Production from Sugarcane Leaves Pretreated by Deep Eutectic Solvents and Enzymatic Hydrolysis by Cellulolytic Consortia
Fermentation 2022, 8(8), 396; https://doi.org/10.3390/fermentation8080396 - 16 Aug 2022
Cited by 1 | Viewed by 462
Abstract
This study determined the optimal conditions for the deep eutectic solvent (DES) pretreatment of sugarcane leaves and the best fermentation mode for hydrogen and methane production from DES-pretreated sugarcane leaves. Choline chloride (ChCl):monoethanolamine (MEA) is the most effective solvent for removing lignin from [...] Read more.
This study determined the optimal conditions for the deep eutectic solvent (DES) pretreatment of sugarcane leaves and the best fermentation mode for hydrogen and methane production from DES-pretreated sugarcane leaves. Choline chloride (ChCl):monoethanolamine (MEA) is the most effective solvent for removing lignin from sugarcane leaves. The optimum conditions were a ChCl: MEA molar ratio of 1:6, 120 °C, 3 h, and substrate-to-DES solution ratio of 1:12. Under these conditions, 86.37 ± 0.36% lignin removal and 73.98 ± 0.42% hemicellulose removal were achieved, whereas 84.13 ± 0.77% cellulose was recovered. At a substrate loading of 4 g volatile solids (VS), the simultaneous saccharification and fermentation (SSF) and separate hydrolysis and fermentation (SHF) processes yielded maximum hydrogen productions of 3187 ± 202 and 2135 ± 315 mL H2/L, respectively. In the second stage, methane was produced using the hydrogenic effluent. SSF produced 5923 ± 251 mL CH4/L, whereas SHF produced 3583 ± 128 mL CH4/L. In a one-stage methane production process, a maximum methane production of 4067 ± 320 mL CH4/L with a substrate loading of 4 g VS was achieved from the SSF process. SSF proved to be more efficient than SHF for producing hydrogen from DES-pretreated sugarcane leaves in a two-stage hydrogen and methane production process as well as a one-stage methane production process. Full article
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Article
Comparative Evaluation of Secreted Plant Carotenoid Cleavage Dioxygenase 1 (CCD1) Enzymes in Saccharomyces cerevisiae
Fermentation 2022, 8(8), 395; https://doi.org/10.3390/fermentation8080395 - 15 Aug 2022
Viewed by 362
Abstract
Enabling technologies in synthetic biology now present the opportunity to engineer wine yeast for enhanced novel aromas. In doing so, improved wine products will increase the desirability of wine for the consumer and add value to the winemaker. The action of the enzyme [...] Read more.
Enabling technologies in synthetic biology now present the opportunity to engineer wine yeast for enhanced novel aromas. In doing so, improved wine products will increase the desirability of wine for the consumer and add value to the winemaker. The action of the enzyme carotenoid cleavage dioxygenase 1 (CCD1) on β-carotene to produce β-ionone is of interest to improve the aroma and flavour of the wine. Engineering the yeast, Saccharomyces cerevisiae, to produce higher concentrations of CCD1 in grape-must presents an opportunity to increase the levels of this volatile organic compound, thus enhancing the organoleptic properties of wine. To this end, four phylogenetically diverse plant CCD1 genes were synthesised with a secretion signal peptide and transformed into S. cerevisiae. The relative ability of each enzyme secreted into the yeast supernatant to cleave the deep orange C40 β-carotene was determined by spectrophotometry; furthermore, the by-product of such cleavage, the highly aromatic C13 β-ionone, was assessed by head-space solid-phase micro-extraction, with analysis and detection by GCMS. Reduction in β-carotene levels and release of β-ionone from the supernatant were validated by LCMS detection of CCD1. These experiments demonstrated that expression in yeast of the CCD1s derived from Petunia hybrida and Vitis vinifera and their subsequent secretion into the medium provided superior efficacy in both β-carotene reduction and β-ionone liberation. We anticipate this knowledge being of benefit to future winemakers in producing a vinous product with enhanced organoleptic properties. Full article
(This article belongs to the Special Issue Wine Microbiology)
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Article
Rumen Metaproteomics Highlight the Unique Contributions of Microbe-Derived Extracellular and Intracellular Proteins for In Vitro Ruminal Fermentation
Fermentation 2022, 8(8), 394; https://doi.org/10.3390/fermentation8080394 - 15 Aug 2022
Viewed by 351
Abstract
Rumen microorganisms can be used in in vitro anaerobic fermentation to encourage the sustainable exploitation of agricultural wastes. However, the understanding of active microbiota under in vitro ruminal fermentation conditions is still insufficient. To investigate how rumen microbes actively participate in the fermentation [...] Read more.
Rumen microorganisms can be used in in vitro anaerobic fermentation to encourage the sustainable exploitation of agricultural wastes. However, the understanding of active microbiota under in vitro ruminal fermentation conditions is still insufficient. To investigate how rumen microbes actively participate in the fermentation process in vitro, we resolved the metaproteome generated from ruminal fermentation broth after seven days of in vitro incubation. Herein, the sample-specific database for metaproteomic analysis was constructed according to the metagenomic data of in vitro ruminal fermentation. Based on the sample-specific database, we found in the metaproteome that Bacteroidetes and Firmicutes_A were the most active in protein expression, and over 50% of these proteins were assigned to gene categories involved in energy conversion and basic structures. On the other hand, a variety of bacteria-derived extracellular proteins, which contained carbohydrate-active enzyme domains, were found in the extracellular proteome of fermentation broth. Additionally, the bacterial intracellular/surface moonlighting proteins (ISMPs) and proteins of outer membrane vesicles were detected in the extracellular proteome, and these ISMPs were involved in maintaining microbial population size through potential adherence to substrates. The metaproteomic characterizations of microbial intracellular/extracellular proteins provide new insights into the ability of the rumen microbiome to maintain in vitro ruminal fermentation. Full article
(This article belongs to the Special Issue In Vitro Fermentation)
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Review
Research Progress on the Construction of Artificial Pathways for the Biosynthesis of Adipic Acid by Engineered Microbes
Fermentation 2022, 8(8), 393; https://doi.org/10.3390/fermentation8080393 - 15 Aug 2022
Viewed by 363
Abstract
Adipic acid is an important bulk chemical used in the nylon industry, as well as in food, plasticizers and pharmaceutical fields. It is thus considered one of the most important 12 platform chemicals. The current production of adipic acid relies on non-renewable petrochemical [...] Read more.
Adipic acid is an important bulk chemical used in the nylon industry, as well as in food, plasticizers and pharmaceutical fields. It is thus considered one of the most important 12 platform chemicals. The current production of adipic acid relies on non-renewable petrochemical resources and emits large amounts of greenhouse gases. The bio-production of adipic acid from renewable resources via engineered microorganisms is regarded as a green and potential method to replace chemical conversion, and has attracted attention all over the world. Herein we review the current status of research on several artificial pathways for the biosynthesis of adipic acid, especially the reverse degradation pathway, which is a full biosynthetic method and has achieved the highest titer of adipic acid so far. Other artificial pathways including the fatty acid degradation pathway, the muconic acid conversion pathway, the polyketide pathway, the α-ketopimelate pathway and the lysine degradation pathway are also discussed. In addition, the challenges in the bio-production of adipic acid via these artificial pathways are analyzed and the prospects are presented with the intention of providing some significant points for the promotion of adipic acid biosynthesis. Full article
(This article belongs to the Special Issue Carboxylic Acid Production 2.0)
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Article
The Implications of Composite Dark Purple Rice Malt on Phenolic Acid Profiles, 4-Vinyl Guaiacol Reduction and Enhancing the Antioxidation of Beer
Fermentation 2022, 8(8), 392; https://doi.org/10.3390/fermentation8080392 - 15 Aug 2022
Viewed by 300
Abstract
This study highlights the dynamics of phenolic acids, antioxidation, and 4-vinylguaiacol in beer produced with dark purple rice malt, also known as Riceberry rice malt, as an adjunct and base malt. Riceberry rice malt substituted barley malt at 40% (w/w [...] Read more.
This study highlights the dynamics of phenolic acids, antioxidation, and 4-vinylguaiacol in beer produced with dark purple rice malt, also known as Riceberry rice malt, as an adjunct and base malt. Riceberry rice malt substituted barley malt at 40% (w/w), 60% (w/w), 80% (w/w), and 100% (w/w) with 100% (w/w) barley malt as the control. Two types of ale beer were produced with two yeasts, designated as POF and POF+. The wort produced with the Riceberry rice malt had higher anthocyanin and vanillic acids relative to all barley malt wort. Fermentation and beer maturation reduced phenolic acids and antioxidant activity in all treatment. Nevertheless, beer produced from 40% (w/w)–80% (w/w) Riceberry rice malt maintained higher p-coumaric acid, vanillic acid, anthocyanin, and antioxidant activity in beers with lower 4-vinylguaiacol relative to all barley malt beer, which also had higher ferulic acid and sinapic acid contents. The beers made from POF+ yeast contained more 4-vinylguaiacol contents than those found in beers made from POF yeasts. This study suggests that Riceberry rice malt or POF yeast are suitable raw materials for phenolic acid off-flavour reduction and the stabilisation of antioxidant activity in beer. Full article
(This article belongs to the Special Issue Brewing Yeast and Fermentation)
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Article
Nutritional Evaluation of Sea Buckthorn “Hippophae rhamnoides” Berries and the Pharmaceutical Potential of the Fermented Juice
Fermentation 2022, 8(8), 391; https://doi.org/10.3390/fermentation8080391 - 14 Aug 2022
Viewed by 478
Abstract
Sea buckthorn is a temperate bush plant native to Asian and European countries, explored across the world in traditional medicine to treat various diseases due to the presence of an exceptionally high content of phenolics, flavonoids and antioxidants. In addition to the evaluation [...] Read more.
Sea buckthorn is a temperate bush plant native to Asian and European countries, explored across the world in traditional medicine to treat various diseases due to the presence of an exceptionally high content of phenolics, flavonoids and antioxidants. In addition to the evaluation of nutrients and active compounds, the focus of the present work was to assess the optimal levels for L. plantarum RM1 growth by applying response surface methodology (RSM), and to determine the impact of juice fermentation on antioxidant, anti-hypertension and anticancer activity, as well as on organoleptic properties. Sea buckthorn berries were shown to contain good fiber content (6.55%, 25 DV%), high quality of protein (3.12%, 6.24 DV%) containing: histidine, valine, threonine, leucine and lysine (with AAS 24.32, 23.66, 23.09, 23.05 and 21.71%, respectively), and 4.45% sugar that provides only 79 calories. Potassium was shown to be the abundant mineral content (793.43%, 22.66 DV), followed by copper and phosphorus (21.81 and 11.07 DV%, respectively). Sea buckthorn juice exhibited a rich phenolic, flavonoid and carotenoid content (283.58, 118.42 and 6.5 mg/g, respectively), in addition to a high content of vitamin C (322.33 mg/g). The HPLC profile indicated that benzoic acid is the dominant phenolic compound in sea buckthorn berries (3825.90 mg/kg). Antioxidant potentials (DPPH and ABTS) of sea buckthorn showed higher inhibition than ascorbic acid. Antimicrobial potentials were most pronounced against Escherichia coli BA12296 (17.46 mm). The probiotic growth was 8.5 log cfu/mL, with juice concentration, inoculum size and temperature as the main contributors to probiotic growth with a 95% confidence level. Fermentation of sea buckthorn juice with L. plantarum RM1 enhanced the functional phenolic and flavonoid content, as well as antioxidant and antimicrobial activities. The fermentation with L. plantarum RM1 enhanced the anti-hypertension and anticancer properties of the sea buckthorn juice and gained consumers’ sensorial overall acceptance. Full article
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Article
Insights into the Microbiological and Physicochemical Properties of Bio-Frozen Yoghurt Made with Probiotic Strains in Combination with Jerusalem Artichoke Tubers Powder
Fermentation 2022, 8(8), 390; https://doi.org/10.3390/fermentation8080390 - 14 Aug 2022
Cited by 1 | Viewed by 438
Abstract
Frozen yoghurt is a refreshing and nutritious dessert, with or without the flavour that combines the texture of ice cream and yoghurt. Several previous studies have been conducted on Jerusalem artichoke tubers due to their components, which contain inulin compounds and other nutrients [...] Read more.
Frozen yoghurt is a refreshing and nutritious dessert, with or without the flavour that combines the texture of ice cream and yoghurt. Several previous studies have been conducted on Jerusalem artichoke tubers due to their components, which contain inulin compounds and other nutrients with beneficial properties of fresh yoghurt. However, limited studies explored the potential benefits of the addition of Jerusalem artichoke tuber powder as a fat replacer on the physicochemical properties and survival of probiotics in frozen yoghurt. In this respect, the aim of this study was to determine the effect of Jerusalem artichoke tuber powder (JATP) (0, 5, 10, 15, and 20% w/w) of the fat source used in the mix as a fat, and sugar replacer in frozen yoghurt production. The microbiological, physicochemical, textural, and sensory properties of frozen yoghurt were investigated. Samples with JATP contained viable counts of bifidobacterium bifidum BGN4 and Lactobacillus casei Lc-01 of 7 log cfu/g during 90 days of storage, as compared to the control sample. The highest viability of probiotics was obtained in the sample formulated with 10% JATP. The formulation of frozen yoghurt with JATP increased the acidity and enhanced the overrun. Compared with the control sample, the incorporation of JATP into frozen yoghurt increased the melting resistance, overrun, and viscosity of the frozen yoghurt. The addition of JATP up to 10% significantly increased sensory attributes. Collectively, the study concluded that the enrichment of frozen yoghurt with JATP up to 20% will provide consumers with health benefits and could be introduced to markets as functional frozen yoghurt. Full article
(This article belongs to the Special Issue Dairy Fermentation)
Article
A Comparative Study on the Debittering of Kinnow (Citrus reticulate L.) Peels: Microbial, Chemical, and Ultrasound-Assisted Microbial Treatment
Fermentation 2022, 8(8), 389; https://doi.org/10.3390/fermentation8080389 - 14 Aug 2022
Viewed by 412
Abstract
Kinnow mandarin (Citrus reticulate L.) peels are a storehouse of well-known bioactive compounds, viz., polyphenols, flavonoids, carotenoids, limonoids, and tocopherol, which exhibit an effective antioxidant capacity. However, naringin is the most predominant bitter flavanone compound found in Kinnow peels that causes their [...] Read more.
Kinnow mandarin (Citrus reticulate L.) peels are a storehouse of well-known bioactive compounds, viz., polyphenols, flavonoids, carotenoids, limonoids, and tocopherol, which exhibit an effective antioxidant capacity. However, naringin is the most predominant bitter flavanone compound found in Kinnow peels that causes their bitterness. It prohibits the effective utilization of peels in food-based products. In the present study, a novel approach for the debittering of Kinnow peels has been established to tackle this problem. A comparative evaluation of the different debittering methods (chemical, microbial, and ultrasound-assisted microbial treatments) used on Kinnow peel naringin and bioactive compounds was conducted. Among the chemical and microbial method; solid-state fermentation with A. niger led to greater extraction of naringin content (7.08 mg/g) from kinnow peels. Moreover, the numerical process optimization of ultrasound-assisted microbial debittering was performed by the Box–Behnken design (BBD) of a response surface methodology to maximize naringin hydrolysis. Among all three debittering methods, ultrasound-assisted microbial debittering led to a greater hydrolysis of naringin content and reduced processing time. The optimum conditions were ultrasound temperature (40 °C), time (30 min), and A. niger koji extract (1.45%) for the maximum extraction rate of naringin (11.91 mg/g). These debittered Kinnow peels can be utilized as raw material to develop therapeutic food products having a high phytochemical composition without any off-flavors or bitterness. Full article
(This article belongs to the Special Issue The Role of Antioxidant Compounds in Fermented Foods)
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Article
Biodiversity and Oenological Property Analysis of Non-Saccharomyces Yeasts Isolated from Korla Fragrant Pears (Pyrus sinkiangensis Yu)
Fermentation 2022, 8(8), 388; https://doi.org/10.3390/fermentation8080388 - 14 Aug 2022
Viewed by 437
Abstract
Oenological yeasts play a critical role in the winemaking process. In this study, the biodiversity of the non-Saccharomyces yeast was analyzed and monitored using high-throughput sequencing and culture-dependent approaches. Oenological and fermentation characteristics of these native yeasts were further investigated. A total [...] Read more.
Oenological yeasts play a critical role in the winemaking process. In this study, the biodiversity of the non-Saccharomyces yeast was analyzed and monitored using high-throughput sequencing and culture-dependent approaches. Oenological and fermentation characteristics of these native yeasts were further investigated. A total of 241 fungus species and 5 species of culturable non-Saccharomyces yeasts were detected using high-throughput sequencing and culture-dependent approaches, respectively. Five strains of aroma-producing yeasts (K4, K14, K19, K21, and K26) were isolated, and their growth characteristics, carbon source utilization, hydrogen sulfide production performance, and β-glucosidase activity were different. The oenological condition tolerances of most strains were lower than that of commercial S. cerevisiae X16. The co-inoculum of these strains and S. cerevisiae X16 regulated the volatile aroma characteristics of the fermented Korla fragrant pear (KFP) fruit wine, enriching and complicating the aroma flavor. Thus, the combined inoculation of these indigenous wine yeasts and S. cerevisiae has some application potential in the production of KFP wine. Full article
(This article belongs to the Special Issue Enological Repercussions of Non-saccharomyces Species 4.0)
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Article
Nitrification upon Nitrogen Starvation and Recovery: Effect of Stress Period, Substrate Concentration and pH on Ammonia Oxidizers’ Performance
Fermentation 2022, 8(8), 387; https://doi.org/10.3390/fermentation8080387 - 13 Aug 2022
Viewed by 364
Abstract
Nitrification has been widely applied in wastewater treatment, however gaining more insight into the nitrifiers’ physiology and stress response is necessary for the optimization of nutrient removal and design of advanced processes. Since nitrification initiates with ammonia oxidation performed by ammonia-oxidizing bacteria (AOB), [...] Read more.
Nitrification has been widely applied in wastewater treatment, however gaining more insight into the nitrifiers’ physiology and stress response is necessary for the optimization of nutrient removal and design of advanced processes. Since nitrification initiates with ammonia oxidation performed by ammonia-oxidizing bacteria (AOB), the purpose of this study was to investigate the effects of short-term ammonia starvation on nitrogen uptake and transformation efficiency, as well as the performance of starved nitrifiers under various initial substrate concentrations and pH values. Ammonium deprivation for 3 days resulted in fast ammonium/ammonia accumulation upon nitrogen availability, with a maximum uptake rate of 3.87 mmol gprotein−1 min−1. Furthermore, a delay in the production of nitrate was observed with increasing starvation periods, resulting in slower recovery and lower nitrification rate compared to non-starved cells. The maximum accumulation capacity observed was 8.51% (w/w) independently of the external nitrogen concentration, at a range of 250–750 mg N L−1, while pH significantly affected ammonia oxidizers’ response, with alkaline values enhancing nitrogen uptake. In total, ammonia accumulation after short-term starvation might serve as an important strategy that helps AOB restore their activity, while concurrently it could be applied in wastewater treatment for effective nitrogen removal and subsequent biomass utilization. Full article
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