Fermented Samples Research Articles

Effect of Isolated Cultures Fermentation on the Microbial Loads of Fermented African Oil Bean Seed (<i>Pentachletra macrophylla</i>) Products

The study explores the effect of isolated culture from traditionally fermented African oil bean seed on the microbial loads of pure and mixed cultures fermented “Ukana” (Ugba, African oil bean seed dessert). The isolates were morphologically and biochemically characterized. Their results as indicated in this study compared favorably to standard. Their characteristics resemble that of Bacillus substillis and Lactobacillus fermentum. These identified isolates were used as pure and mixed cultures to ferment African oil bean seed at 24 h, 48 h, 72 h and 96 h. The result obtained indicated that total coliform and Staphylococcus aureus count increased across the fermentation period when AOBS was traditionally fermented but kept decreasing as the fermentation period progressed in pure and mixed cultures fermented samples. The range of the total fungal count (TFC) varied from 5.1 x 104 Cfu/ml to 1.0 x 103 Cfu/ml. Moreover, the number of Lactic acid bacteria recorded in this study outweighed the fungi count. The result also showed that the colony count of Lactic acid bacteria at 96 h fermentation period supersedes that of coliform, staphylococcus and fungi whereas the total coliform was higher in traditionally fermented AOBS. This result according to literature could be attributed to the production of bacitracin and organic acids, especially bacteriocins which can inhibit the proliferation of pathogenic organisms. Bacillus substillis and Lactobacillus fermemtum isolated in this research are desirable probiotics with enormous health functions.

Whole genome sequencing of the poly-γ-glutamic acid-producing novel Bacillus subtilis Tamang strain, isolated from spontaneously fermented kinema

Kinema, a traditional fermented soybean food from the Himalayas, is well-liked for its sticky texture and flavourful umami taste. Among 175 bacterial strains from spontaneously fermented kinema samples, Bacillus subtilis Tamang strain stood out for its high stickiness and viscosity. The strain’s Poly-γ-glutamic acid (γ-PGA) contains various groups of glutamic acid and has a molecular weight of 660 kDa. It demonstrates the ability to solubilize iron, preserve ferritin in Caco-2 cells, and exhibit antibacterial properties. The genome of B. subtilis Tamang is devoid of plasmid elements but does feature nine insert elements. Noteworthy is the presence of unique secondary metabolites with potential antimicrobial effects, such as amyloliquecidin GF610, bogorol A, and thermoactinoamide A. A total of 132 carbohydrate-active enzymes (CAZy) were identified, hinting at possible prebiotic characteristics. The genome analysis revealed genes responsible for γ-PGA production via the capBCA complex. Furthermore, genes associated with fibrinolytic activity, taste enhancement, biopeptides, immunomodulators, and vitamins like B12 and K2 were found, along with probiotics and various health benefits. The genetic material for L-asparaginase production, known for its anti-cancer properties, was also detected, as well as CRISPR-Cas systems. The absence of virulence factors and antimicrobial resistance genes confirms the safety of consuming B. subtilis Tamang as a food-grade bacterium.

Effect of fermentation on color characteristics and metabolite profiles of purple potato flour

The effect of fermentation on color characteristics and metabolite profiles of purple potato flour (PPF) were evaluated. The results showed that fermentation had a significant effect on the color attributes of samples. The bioactive compounds in PPF were identified using untargeted ultra-performance liquid chromatography with quadrupole time-of-flight mass spectrometry (UPLC-QTOF/MS). There were 63 compounds found in unfermented PPF (UF), while fermented samples showed more abundant compounds, including 69 compounds in naturally fermented PPF and 73 compounds in lactobacillus fermented PPF. The quantitative results showed that bioactive compounds with larger molecular weight decreased, but small molecules with high bioavailability increased after fermentation. The levels of caffeic acid, ferulic acid, and kaempferol in amylolytic L. plantarum CGMCC 14177 fermented PPF (ALF) were more than 3 times higher than those in UF. Foodomics analysis indicated that natural fermentation and lactobacillus fermentation had obvious differences in the conversion effect of metabolites in PPF. Based on orthogonal partial least squares discriminant analysis, 17 key bioactive compounds affected by fermentation were screened. L. plantarum CGMCC 15358 and CGMCC 14177 showed similar conversion effects on bioactive compounds, and their marker metabolites were trihydroxyoctadecenoic acid isomer 2, caffeic acid, 12,15-octadecadienoic acid methyl ester, and lactic acid.

Contribution of Microbiota to Bioactivity Exerted by Bee Bread.

Bee-collected pollen (BCP) and bee bread (BB) are honey bee products known for their beneficial biological properties. The main goal of this study was to investigate BB microbiota and its contribution to bioactivity exerted by BB. The microbiota of BB samples collected at different maturation stages was investigated via culture-independent (Next Generation Sequencing, NGS) and culture-dependent methods. Microbial communities dynamically fluctuate during BB maturation, ending in a stable microbial community structure in mature BB. Bee bread bacterial isolates were tested for phenotypes and genes implicated in the production and secretion of enzymes as well as antibacterial activity. Out of 309 bacterial isolates, 41 secreted hemicellulases, 13 cellulases, 39 amylases, 132 proteinases, 85 Coomassie brilliant blue G or R dye-degrading enzymes and 72 Malachite Green dye-degrading enzymes. Furthermore, out of 309 bacterial isolates, 42 exhibited antibacterial activity against Staphylococcus aureus, 34 against Pseudomonas aeruginosa, 47 against Salmonella enterica ser. Typhimurium and 43 against Klebsiella pneumoniae. Artificially fermented samples exerted higher antibacterial activity compared to fresh BCP, strongly indicating that BB microbiota contribute to BB antibacterial activity. Our findings suggest that BB microbiota is an underexplored source of novel antimicrobial agents and enzymes that could lead to new applications in medicine and the food industry.

Selective Elucidation of Living Microbial Communities in Fermented Grains of Chinese Baijiu: Development of a Technique Integrating Propidium Monoazide Probe Pretreatment and Amplicon Sequencing.

The fermentation process of Chinese Baijiu's fermented grains involves the intricate succession and metabolism of microbial communities, collectively shaping the Baijiu's quality. Understanding the composition and succession of these living microbial communities within fermented grains is crucial for comprehending fermentation and flavor formation mechanisms. However, conducting high-throughput analysis of living microbial communities within the complex microbial system of fermented grains poses significant challenges. Thus, this study addressed this challenge by devising a high-throughput analysis framework using light-flavor Baijiu as a model. This framework combined propidium monoazide (PMA) pretreatment technology with amplicon sequencing techniques. Optimal PMA treatment parameters, including a concentration of 50 μM and incubation in darkness for 5 min followed by an exposure incubation period of 5 min, were identified. Utilizing this protocol, viable microorganism biomass ranging from 8.71 × 106 to 1.47 × 108 copies/μL was successfully detected in fermented grain samples. Subsequent amplicon sequencing analysis revealed distinct microbial community structures between untreated and PMA-treated groups, with notable differences in relative abundance compositions, particularly in dominant species such as Lactobacillus, Bacillus, Pediococcus, Saccharomycopsis, Issatchenkia and Pichia, as identified by LEfSe analysis. The results of this study confirmed the efficacy of PMA-amplicon sequencing technology for analyzing living microbial communities in fermented grains and furnished a methodological framework for investigating living microbial communities in diverse traditional fermented foods. This technical framework holds considerable significance for advancing our understanding of the fermentation mechanisms intrinsic to traditional fermented foods.

Effect of Germination and Fermentation on the Nutrient Contents, Functional and Antioxidant Activities of Pigeon Pea (Cajanus cajan) Flour

Effect of germination and fermentation on the nutrient contents, functional and antioxidant activities of pigeon pea (Cajanus cajan) flour were investigated. The pigeon pea seeds were sorted, cleaned and processed into germinated, fermented and raw flours. The flour samples obtained were analyzed for proximate composition, mineral contents, antinutrient contents, functional properties and antioxidant/free radical scavenging properties using standard methods. The results of the proximate composition showed that the moisture content within the range of 9.62±0.02-9.96±0.01, crude protein content 16.63±0.01-24.17±0.01, crude fibre content 1.41±0.01-2.59±0.01, lipid 4.33±0.01-5.61±0.01, ash content 1.62±0.01-2.17±0.01, carbohydrate 56.80±0.02 - 62.47±0.01 and energy values 366.91 - 374.40kcal/100g. The result of elemental mineral analysis showed magnesium as the major mineral element in the sample (91.32±0.02 to 123.75±0.04mg/g), calcium (96.02 ± 0.02 - 110.14 ± 0.003mg/g), phosphorus (39.11 ± 0.02 - 46.12 ± 0.03mg/g), sodium (8.63 ± 0.02 - 12.61 ± 0.001mg/g), Iron (3.08 ± 0.02 - 4.11 ± 0.001mg/g) and zinc (2.04 ± 0.01 - 3.17mg/g) respectively. The result of the functional properties showed optimal gelatinization temperature ranged from 73.610C - 89.410C, emulsion capacity, 11.88 - 43.42%, foam stability,28.22 to 65.81%, foaming capacity,15.83 to 21.11%, bulk density,0.53 - 0.71g/ml, water absorption capacity, 1.11 and 1.51ml/g while oil absorption capacity,0.84 - 1.14ml/g. The sensory properties of the moi-moi from the processed flours showed that the colour test, (6.33 -7.53), flavour (7.63 to 7.75), taste (5.13 to 5.53), mouth-feel (7.25 to 7.36), overall acceptability (6.93±0.04 - 8.83±0.04). The results of the phenolic content ranged from 20.13mg\GAE, 53.43mg\GAE and 42.64mg\GAE for raw processed, malted and fermented samples respectively. The results of the 1,1-diphenyl-2-picrylhydrazyl (DPPH) antioxidant activity of ethanolic extracts showed IC50values of 0.810, 1.177 and 1.014mg\ml for the raw, malted and fermented seed extracts respectively. The moisture, crude protein and fibre contents was significantly increased (p>0.05) during germination and fermentation whereas lipid, carbohydrate, ash and energy values were significantly (p<0.05) decreased by the processing techniques. Germination increased the emulsion capacity, foaming capacity whereas fermentation reduced the foaming capacity of pigeon pea flour. Malting and fermentation significantly (p>0.05) increased the % scavenging properties of pigeon pea extract though that of germination was higher. Malting and fermentation significantly (p<0.05) decreased the sensory properties of moi-moi produced. Based on the result obtained, regular consumption of pigeon pea will be a proactive measure against heart diseases and other related disorders in the human body.

Effect of Solid-State Fermentation on Phytochemical and Proximate Composition of Millet Bran Meal

The majority of a fish farm's overall operating expenses involve costs related to feeds. Commercial feeds are often too expensive for fish farmers. Consequently, farmers do use agricultural by-products and locally available fish feed ingredients to improve pond productivity and minimise cost. This study was aimed at evaluating the effects of solid-state fermentation on phytochemical components and proximate composition of millet bran meal for possible incorporation in fish feed production. Millet bran was collected in three different bowls, ground to powder, and then sieved and fermented using a solid-state fermentation procedure. Each sample was fermented (wet at 10% moisture and kept in a container at ambient temperature) for 24 hours (1 day), 96 hours (4 days), and 168 hours (7 days). Afterwards, the fermented samples were sun-dried for 94 hours (4 days approximately). Quantitative phytochemical screening was carried out on the samples which were analysed for proximate composition. The results revealed that fermenting millet bran for seven days (168hrs) using solid-state fermentation method reduced the alkaloid content from 14.69±1.24 to 10.12±0.16, phytate from 5.73±1.32 to 3.25±0.73, tannins from 6.62±0.53 to 4.62±0.84, oxalate from 17.78±1.65 to 13.82±0.53. However, it increases flavonoids from 11.95±1.82 to 13.08±1.35 and phenols from 23.78±1.65 to 31.71±0.62. The study also elucidates an increase in crude protein from 9.23±0.64 to 19.77±0.53 and a reduction in crude fibre from 7.41±0.52 to 6.02±1.14. This study demonstrates that solid-state fermented millet bran meal can be incorporated as an essential part of feed production.

Shotgun metagenomic analysis of microbiota dynamics during long-term backslopping fermentation of traditional fermented milk in a controlled laboratory environment

Traditional fermented milks are produced through an inoculation process that involves the deliberate introduction of microorganisms that have been adapted and perpetuated across successive generations. However, the changes in the microbiota of traditional fermented milk during long-term inoculation fermentation in a laboratory environment remain unclear. In this study, we collected 5 samples of traditional fermented milk samples from 5 different counties in Tibet (3 kurut products) and Xinjiang (2 tarag products) of China, which served as starter cultures for a 9-mo continuous inoculation fermentation experiment. We analyzed the inter- and intra-population variations in the microbial communities of the collected samples, representing their macrodiversity and microdiversity, using shotgun metagenomic sequencing. Across all samples, we obtained a total of 186 high-quality metagenomic-assembled genomes, including 7 genera and 13 species with a relative abundance of more than 1%. The majority of these genomes were annotated as Lactobacillus helveticus (60.46%), Enterococcus durans (9.52%), and Limosilactobacillus fermentum (6.23%). We observed significant differences in species composition and abundance among the 5 initial inoculants. During the long-term inoculation fermentation, we found an overall increasing trend in species diversity, composition, and abundances of carbohydrate metabolism module-encoding genes in the fermented milk bacterial metagenome, while the fermented milk virome exhibited a relatively narrow range of variation. Lactobacillus helveticus, a dominant species in traditional fermented milk, displayed high stability during the long-term inoculation fermentation. Our study provides valuable insights for the industrial production of traditional fermented milk.

Changes in the Composition of Olive Pomace after Fermentation: A Preliminary Study

Because olive pomace (the main by-product of olive oil production) is phytotoxic, new applications must be investigated to minimize its negative environmental impact. In this work, olive pomace was fermented for 4 and 32 days at room temperature, having in view its valorization as a novel food, thereby creating opportunities for the food industry and addressing a challenge of the olive oil sector. The chemical and microbiological modifications that occurred along the fermentation were followed. The results showed no significant differences (p > 0.05) in total protein between the control and the fermented samples; however, the latter exhibited higher levels of essential amino acids. The major nonessential and essential amino acids were glutamic acid and leucine in all samples. There was a significant increase in the total fat of the 32-day sample and the main fatty acid was oleic acid in all samples. There were considerable reductions in total vitamin E, phenolics, and antioxidant activity values post-fermentation. Hydroxytyrosol replaced oleacein as the main phenolic in the 32-day sample. A sharp increase in total microorganisms occurred (2.20 × 102 to 3.00 × 104–2.01 × 107 colony forming units/mL) but no pathogenic microorganisms were detected. Overall, olive pomace fermentation creates novel products for the food industry with a balanced nutritional composition.

Gelatinization and fermentation synergy: investigating the protein digestibility, mineral bioaccessibility and microstructural transformations of black mash beans through Saccharomyces cerevisiae and Lactobacillus spp

ABSTRACT This study explored the nutritional qualities of black mash bean flour impacted by fermentation, gelatinization and their combination. Protease activity, in vitro protein digestibility (IVPD), and protein solubility were evaluated for both fermented and unfermented black mash bean flour samples. Interestingly, when compared to fermented samples and gelatinized mash bean flour (GMBF), raw mash bean flour (RMBF) showed the highest protein solubility. Due to enzymatic activity and protein hydrolysis, fermentation with Lactobacillus E14 and Saccharomyces cerevisiae MK-157 enhanced protein solubility. Prolonged fermentation timeframes were positively correlated with protease activity and IVPD, suggesting the degradation of complex proteins. The highest levels of IVPD (90.12%) and protease activity (5546.78 U/g) were detected in GMBF fermented by S. cerevisiae MK-157, indicating the impact of fermentation on protein breakdown. The Lactobacillus E14-fermented RMBF exhibited 5521.45 U/g of protease activity and 87.54% IVPD. The mineral content of the fermented samples was substantially greater than that of the unfermented GMBF. The increased calcium, magnesium, potassium, sodium, iron, zinc, and copper levels for the GMBF fermented by S. cerevisiae MK-157 indicated that fermentation facilitated the release of minerals from chelated compounds. Microscopic examination revealed higher protein quantities in the fermented flour as well as hydrolyzed and broken starch granules embedded in the protein matrix. Large mash bean proteins were shown to be proteolyzed during fermentation into smaller peptides by SDS PAGE. Storage proteins were extensively broken down during fermentation with S. cerevisiae MK-157, whereas Lactobacillus E14 displayed a more focused pattern of hydrolysis. The nutritional profile of black mash bean flour was improved by fermentation with Lactobacillus E14 and S. cerevisiae MK-157.

Physicochemical, functional, and antinutritional properties of fermented Bambara groundnut and sorghum flours at different times

This study investigated the effect of fermentation at different times (24 and 48 h) on the proximate composition, physicochemical, antinutritional, and functional properties of fermented Bambara groundnut and sorghum flours. The results showed that fermentation improved the crude protein and crude fibre of the flours, with a decrease in crude fat and ash content. An increase in the mineral contents (potassium, magnesium, phosphorus, zinc, and iron), water absorption capacity, and foam stability were also observed. The oil absorption capacity of the fermented flour samples decreased after 24 h of fermentation, with an increase thereafter. A decrease in foam, emulsification capacity, and antinutritional factors were observed. The redness and yellowness values increased with an increase in fermentation time, while the lightness and total change in colour decreased. In conclusion, this study shows that fermented Bambara groundnut and sorghum flours could be useful ingredients or serve as an alternative for commercial and industrial purposes. Subsequent use of fermented Bambara groundnut and sorghum flours may also help mitigate nutritional issues, particularly in developing nations.

Submerged fermentation of lentil protein isolate and its impact on protein functionality, nutrition, and volatile profiles.

Fermentation of pulses as a clean processing technique has been reported to have a favorable impact on the functional and nutritional quality of the starting materials. Compared to commonly fermented pulses such as peas and chickpeas, limited information is available on the effect of fermentation on lentils, especially when using a high protein isolate (>80% protein) as compared to seeds or flours. Therefore, in the present work, lentil protein isolate was used as a feedstock for submerged fermentation with Aspergillus niger, Aspergillus oryzae, or Lactobacillus plantarum. After 48h, the samples showed increased protein content with enhanced solubility and oil-holding capacity. Controlled fermentation, as opposed to spontaneous fermentation, maintained the high foaming capacity; however, all fermented samples had lower foam and emulsion stabilizing properties and reduced water-holding capacity compared to the control. The fermented proteins were also less digestible, possibly due to an increase in phenolics and saponins. New volatile compounds were identified in fermented samples that show promise for improved sensory attributes. Significant differences were observed in specific quality attributes depending on the microbial strain used. Further research is required to better understand the fermentative metabolism of microbial communities when provided high-protein lentil ingredients as growth substrates. PRACTICAL APPLICATION: Fermented lentil protein isolate has promising flavor profiles that may improve its sensory properties for food application.

Intermolecular interactions between malvidin-3-O-glucoside and caffeic acid: Structural and thermodynamic characterization and its effect on real wine color quality

The copigmentation effect between malvidin-3-O-glucoside and caffeic acid was comprehensive inquiry on the model wine solution, theoretical simulation and real wine. Thermodynamic parameters were determined by UV/Visible spectroscopy and Isothermal titration calorimetry (ITC). Theoretical data were obtained employing a dispersion-corrected density functional approach. The effects in real wines were investigated by adding the caffeic acid during different fermentation periods. Results shown that the copigmentation reaction between caffeic acid and malvidin-3-O-glucoside is a spontaneous exothermic reaction driven by hydrogen bonding and dispersions forces. Computations show that the polyhydroxyl sugar moiety and phenolic hydroxyl groups are the key active sites. The addition of caffeic acid in post-alcohol fermentation samples evidences an improving color characteristics in the wine.

Effect of selective fermentation on nutritional parameters and techno-functional characteristics of fermented millet-based probiotic dairy product

The primary goal of this study was to assess the effect of selective fermentation on the nutritional and techno-functional characteristics of fermented millet-skim milk-based product. The product was made with HHB-311 biofortified pearl millet (PM) flour, skim milk powder, and isolated cultures (either alone or in combination) of Limosilactobacillus fermentum MS005 (LF) and Lactobacillus rhamnosus GG 347 (LGG). To optimize fermentation time, time intervals 8, 16, and 24 h were explored, while the temperature was kept 37 °C. Results of protein digestibility showed that LF (16 h) and LGG (24 h) fermented samples had significantly higher (P < 0.05) protein digestibility of 90.75 ± 1.6% and 93.76 ± 3.4%, respectively, than that of control (62.60 ± 2.6%). Further, 16 h fermentation with LF showed enhanced iron (39%) and zinc (14%) bioavailability. The results suggested that LF with 16 h fermentation is most suitable for making millet-based fermented products with superior techno-functional attributes and micronutrient bioavailability.

Effects of Lactobacillus plantarum fermentation on the structure, physicochemical properties, and digestibility of foxtail millet starches

This study investigated the effects of Lactobacillus plantarum fermentation on the structural, physicochemical, and digestive properties of foxtail millet starches. The fermented starch granules formed a structure with honeycomb-like dents, uneven pores, and reduced particle size. As the fermentation time extended, the amylose content of waxy (0.88 %) and non-waxy (33.71 %) foxtail millet starches decreased to the minimum value at 24 h (0.59 % and 29.19 %, respectively), and then increased to 0.85 % and 31.87 % at 72 h, respectively. Both native and fermented foxtail millet starches exhibited an A-type crystal structure. Compared with native samples, the fermented samples performed enhanced proportion of short-branched chain, crystallinity, and short-range ordered degree. After fermentation for 24 h, the solubility, adsorption capacity, and pasting viscosity of foxtail millet starches improved, whereas the swelling power, pasting temperature, breakdown, setback, and degree of retrogradation reduced. Additionally, fermentation increased the transition temperatures, enthalpy, and digestibility. Overall, Lactobacillus plantarum fermentation is considered a competent choice to regulate the characteristics of foxtail millet starch.

Microbiome dynamics and environment driving factors throughout pit fermentation of Jiang-flavor Baijiu: A multi-omics study

Pit fermentation process has a significant impact on Baijiu production. However, the dynamics patterns and environmental driving mechanisms in Jiang-flavor Baijiu pit fermentation remain unclear. Here, we present a multi-omics study on 180 Jiang-flavor Baijiu fermentation samples across the pit fermentation process. We revealed and validated the dynamics and metabolic functions of the core species employing both culture-independent (i.e., metagenomics and metatranscriptomics) and culture-dependent tools. Our findings delineate the fermentation into three distinct stages, each characterized by a unique microbial community, functional profile, and accumulation of flavor compounds. In stage I, Bacillus subtilis, Pichia kudriavzevii, and Saccharomyces cerevisiae were the most abundant species, while Acetilactobacillus jinshanensis, S. cerevisiae, P. kudriavzevii, Schizosaccharomyces pombe, and Zygosaccharomyces bailii had the highest transcriptional activity. In stage II, A. jinshanensis emerged as the most abundant and metabolically active species in stage II, reaching a proportion of 45.69% ± 20.21%, and maintained a leading role in stage III with a proportion of 65.75% ± 6.56%, a period marked by minimal microbial diversity and significant accumulation of key flavor substances, notably esters and acids. In addition, A. jinshanensis was isolated and its core acid-producing microbial status confirmed based on culture-dependent tools. Structural equation modeling indicated that A. jinshanensis plays crucial roles in the heterogeneous succession of alcohol-producing microorganisms, with spatial differences in acidity being a key factor. This work not only provides a robust analytical framework for understanding the Baijiu fermentation microbiome but also lays the groundwork for technological innovation in the fermentation industry.

Fermentation Analytical Technology (FAT): Monitoring industrial E. coli fermentations using absolute quantitative 1H NMR spectroscopy

BackgroundTo perform fast, reproducible, and absolute quantitative measurements in an automated manner has become of paramount importance when monitoring industrial processes, including fermentations. Due to its numerous advantages – including its inherent quantitative nature – Proton Nuclear Magnetic Resonance (1H NMR) spectroscopy provides an ideal tool for the time-resolved monitoring of fermentations. However, analytical conditions, including non-automated sample preparation and long relaxation times (T1) of some metabolites, can significantly lengthen the experimental time and make implementation in an industrial set up unfeasible. ResultsWe present a high throughput method based on Standard Operating Procedures (SOPs) and 1H NMR, which lays the foundation for what we call Fermentation Analytical Technology (FAT). Our method was developed for the accurate absolute quantification of metabolites produced during Escherichia coli industrial fermentations. The method includes: (1) a stopped flow system for non-invasive sample collection followed by sample quenching, (2) automatic robot-assisted sample preparation, (3) fast 1H NMR measurements, (4) metabolites quantification using multivariate curve resolution (MCR), and (5) metabolites absolute quantitation using a novel correction factor (k) to compensate for the short recycle delay (D1) employed in the 1H NMR measurements. The quantification performance was tested using two sample types: buffer solutions of chemical standards and real fermentation samples. Five metabolites – glucose, acetate, alanine, phenylalanine and betaine – were quantified. Absolute quantitation ranged between 0.64 and 3.40 mM in pure buffer, and 0.71–7.76 mM in real samples. SignificanceThe proposed method is generic and can be straight forward implemented to other types of fermentations, such as lactic acid, ethanol and acetic acid fermentations. It provides a high throughput automated solution for monitoring fermentation processes and for quality control through absolute quantification of key metabolites in fermentation broth. It can be easily implemented in an at-line industrial setting, facilitating the optimization of the manufacturing process towards higher yields and more efficient and sustainable use of resources.

Towards controlled and simple design of non-enzymatic amperometric sensor for glycerol determination in yeast fermentation medium

Glycerol is a widely used signaling bioanalyte in biotechnology. Glycerol can serve as a substrate or product of many metabolic processes in cells. Therefore, quantification of glycerol in fermentation samples with inexpensive, reliable, and rapid sensing systems is of great importance. In this work, an amperometric assay based on one-step designed electroplated functional Pd layers with controlled design was proposed for a rapid and selective measurement of glycerol in yeast fermentation medium. A novel assay utilizing electroplated Pd-sensing layers allows the quantification of glycerol in yeast fermentation medium in the presence of interfering species with RSD below 3% and recoveries ranged from 99 to 103%. The assay requires minimal sample preparation, viz. adjusting of sample pH to 12. The time taken to complete the electrochemical analysis was 3 min. Remarkably, during investigations, it was revealed that sensitivity and selectivity of glycerol determination on Pd sensors were significantly affected by its adsorption and did not depend on the surface structure of sensing layers. This study is expected to contribute to both fundamental and practical research fields related to a preliminary choice of functional sensing layers for specific biotechnology and life science applications in the future.Graphical

Optimising the recovery of phenolic compounds and antioxidant activity from orange peels through solid-state fermentation

It is widely recognised that orange peels contain a considerable quantity of phenolics, primarily in the form of glycosides. The process of fermentation holds potential as a viable method for extracting phenolic compounds and facilitating their biotransformation into novel metabolites. The aim of this study was to assess the enhanced release of phenolic compounds through the process of solid-state fermentation of orange peels using microorganisms. Following a 6-day incubation period, the methanol extract obtained from the sample fermented with starter Banh men exhibited the highest concentration of total phenolic compounds (17.57 ± 0.34 mg GAE/g DW) and demonstrated the most significant DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity (55.03%). The Reverse Phase High Performance Liquid Chromatography (RP-HPLC) analysis revealed that the predominant phenolic compounds in all fermented samples were flavonoid aglycones, specifically naringenin, hesperetin, and nobiletin. Conversely, in the unfermented orange peels, the major compound observed was the glycoside derivative hesperidin.

QUALITY ASSESSMENT OF FERMENTED MEAT PRODUCT AFTER NATURAL EXTRACTS OF BLACKCURRANT (RIBES NIGRUM) AND KAMCHATKA HONEYSUCKLE (LONICERA CAERULEA VAR. KAMTSCHATICA) ADDITION

The aim of this work was to analyse the effect of blackcurrant (Ribes nigrum) and kamchatka honeysuckle (Lonicera caerulea var. Kamtschatica) extracts on the physico-chemical properties, microbiological and sensory quality of fermented meat product. Analyses were performed after 5, 15, 30 and 45 days of ageing. The addition of blackcurrant and kamchatka honeysuckle extracts in quantities of 3 and 5 ml.kg-¹ did not adversely affect the ageing process of fermented meat product samples determined based on pH. After 45 days of ageing period, we found higher malondialdehyde (MDA) values in all experimental groups (except for the experimental group with the addition of 3 ml blackcurrant extract). The addition of the extracts in the tested quantities did not cause demonstrable differences in the intensity values of brightness (L*), red (a*) and yellow (b*) colour throughout the ageing period. Microbial examination indicates that the addition of blackcurrant and kamchatka honeysuckle extracts did not inhibit the growth of starter culture. Bacteria of the genus Lactobacillus and Staphylococcus predominated in all experimental groups. Family Enterobacteriaceae was not detected after 45 days of ageing and storage. Moulds were detected only after 5 days of ageing and in the experimental groups with the addition of blackcurrant extracts. The counts of yeasts gradually increased with increasing ageing time in all experimental groups. Sensory analysis revealed a beneficial effect of kamchatka honeysuckle extract in the amount of 3 ml.kg-1 after 30 days of fermented sausages ageing. On the other hand, blackcurrant extract in higher amount (5 ml.kg-1) had a beneficial effect on sensory quality after 30th day. Traditional kamchatka honeysuckle aroma was probably transferred into the samples of meat product and caused lower sensory scores. Due to the known functional properties of black currant and kamchatka honeysuckle, we recommend carrying out their further analyses on the quality of fermented meat products.