Special Issue "Microbial Metabolic Pathways and the “Fermented Plant Foods ‒ Human Health” Axis"

A special issue of Foods (ISSN 2304-8158). This special issue belongs to the section "Food Microbiology".

Deadline for manuscript submissions: closed (15 November 2020).

Special Issue Editors

Prof. Dr. Raffaella Di Cagno
Website
Guest Editor
Faculty of Sciences and Technology, Libera Università di Bolzano, 39100 Bolzano, Italy
Interests: [i] molecular microbiology and biotechnology of vegetable/fruit, sourdough, and cheese lactic acid bacteria; [ii] synthesis of biogenic compounds by lactic acid bacteria; [iii] transcriptomics and phenomics of lactic acid bacteria in response to plant niche environments; [iv] phenolics; phytochemicals
Prof. Dr. Marco Gobbetti
Website
Guest Editor
Faculty of Sciences and Technology, Libera Università di Bolzano, 39100 Bolzano, Italy
Interests: [i] molecular microbiology and biotechnology of sourdough, cheese, and vegetable/fruit lactic acid bacteria; [ii] proteomics and transcriptomic of lactic acid bacteria in response to environmental stresses and quorum sensing; [iii] synthesis of biogenic compounds by lactic acid bacteria; [iv] overall microbial metabolic networking and human intestinal microbiome in response to diseases and food intolerance
Dr. Pasquale Filannino
Website
Guest Editor
Department of Soil, Plant and Food Science, University of Bari Aldo Moro, 70126 Bari, Italy
Interests: lactic acid bacteria; yeasts; fermentation; metabolomics; functional foods and beverages; bioactive compounds; phenolics; phytochemicals; novel foods; food technology
Special Issues and Collections in MDPI journals

Special Issue Information

Dear Colleagues,

The journal Foods (ISSN 2304-8158) is currently running a Special Issue entitled “Microbial Metabolic Pathways and the 'Fermented Plant Foods‒human health' Axis”, for which we are serving as Guest Editors. The Special Issue aims to build a solid platform to discuss the multitude of microbial metabolic pathways that may potentially affect the health-promoting properties of plant-based foods during fermentative processes. Fermentations may lead to significant changes in the health-promoting features of fruit- and vegetable-based foods and beverages. Lactic acid fermentation is the most widespread and represents an established biotechnological tool. Nevertheless, the functionality of the most representative microbial groups (e.g., yeasts, acetic acid bacteria, and lactic acid bacteria) involved in plant fermentations deserves to be further exploited to increase the level of bioactive compounds or to decrease that of antinutritional factors during fermentation. The exploitation of microbial metabolic pathways along the “fermented plant foods‒human health” axis is strictly linked to food products innovation, which is approaching novel formulations based on natural ingredients or food industry by-products as functional ingredients.

We would like to invite you to contribute with high-quality original research and review papers addressing the most innovative and relevant findings on the functional exploitation of microbial metabolic pathways during fruit and vegetable fermentation.

Prof. Dr. Raffaella Di Cagno
Prof. Dr. Marco Gobbetti
Dr. Pasquale Filannino
Guest Editors

Manuscript Submission Information

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Keywords

  • fermentation
  • microbes
  • fruits
  • vegetables
  • phenolic compounds
  • metabolism
  • novel foods
  • bioactivity
  • phytochemicals

Published Papers (9 papers)

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Research

Open AccessArticle
Degradation of Wheat Germ Agglutinin during Sourdough Fermentation
Foods 2021, 10(2), 340; https://doi.org/10.3390/foods10020340 - 05 Feb 2021
Viewed by 356
Abstract
Non Celiac Wheat Sensitivity (NCWS) is an intolerance to wheat products and individuals with NCWS often adhere to a gluten free diet. However, gluten free diets are often associated with a reduced sensory and nutritional quality. Wheat Germ Agglutinin (WGA) is one of [...] Read more.
Non Celiac Wheat Sensitivity (NCWS) is an intolerance to wheat products and individuals with NCWS often adhere to a gluten free diet. However, gluten free diets are often associated with a reduced sensory and nutritional quality. Wheat Germ Agglutinin (WGA) is one of the wheat components linked to NCWS. This study explored the fate of WGA during sourdough fermentation. To assess the role of thiol-exchange reactions and proteolysis, sourdoughs were fermented with Fructilactobacillus sanfranciscensis DSM20451, F. sanfranciscensis DSM20451ΔgshR, which lacks glutathione reductase activity, or Latilactobacillus sakei TMW1.22, with or without addition of fungal protease. The conversion of WGA was determined by size exclusion chromatography of fluorescence-labeled WGA, and by enzyme-linked immunosorbent assay (ELISA). Commercial whole wheat flour contained 6.6 ± 0.7 μg WGA/g. After fermentation with L. sakei TMW1.22 and F. sanfranciscensis DSM20451, the WGA content was reduced (p < 0.05) to 2.7 ± 0.4 and 4.3 ± 0.3 μg WGA/g, respectively, while the WGA content remained unchanged in chemically acidified controls or in doughs fermented with F. sanfranciscensis DSM20451ΔgshR. Protease addition did not affect the WGA content. In conclusion, the fate of WGA during sourdough fermentation relates to thiol-exchange reactions but not to proteolytic degradation. Full article
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Open AccessArticle
Functional Exploitation of Carob, Oat Flour, and Whey Permeate as Substrates for a Novel Kefir-Like Fermented Beverage: An Optimized Formulation
Foods 2021, 10(2), 294; https://doi.org/10.3390/foods10020294 - 01 Feb 2021
Viewed by 429
Abstract
This study investigated the fortification of a carob-based kefir-like beverage (KLB) with whey permeate (WP) and oat flour (OF). The response surface method was used to show the effect of WP and OF concentrations on lactic acid bacteria and yeast cell densities, pH, [...] Read more.
This study investigated the fortification of a carob-based kefir-like beverage (KLB) with whey permeate (WP) and oat flour (OF). The response surface method was used to show the effect of WP and OF concentrations on lactic acid bacteria and yeast cell densities, pH, total titratable acidity (TTA), total phenolics content (TCP), DPPH radical scavenging activity, and overall acceptability (OA) in KLB. The statistical design provided thirteen formulations where OF concentration varied from 3% to 5% and WP from 10% to 15%. The enrichment of carob pods decoction with WP and OF had a positive effect on biomass production. Overall fermentation was shown to increase TPC of KLB. Furthermore, OF supplementation led to the higher levels of TPC and antiradical activity. WP negatively affected OA at linear and quadratic levels, whereas no effect of OF was observed at the linear level. The optimum point was found by using WP at 11.51% and OF at 4.77%. Optimized KLB resulted in an enrichment of bioavailable phenolics derivatives and highly digestible proteins. Full article
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Open AccessArticle
Volatilome and Bioaccessible Phenolics Profiles in Lab-Scale Fermented Bee Pollen
Foods 2021, 10(2), 286; https://doi.org/10.3390/foods10020286 - 31 Jan 2021
Viewed by 346
Abstract
Bee-collected pollen (BCP) is currently receiving increasing attention as a dietary supplement for humans. In order to increase the accessibility of nutrients for intestinal absorption, several biotechnological solutions have been proposed for BCP processing, with fermentation as one of the most attractive. The [...] Read more.
Bee-collected pollen (BCP) is currently receiving increasing attention as a dietary supplement for humans. In order to increase the accessibility of nutrients for intestinal absorption, several biotechnological solutions have been proposed for BCP processing, with fermentation as one of the most attractive. The present study used an integrated metabolomic approach to investigate how the use of starter cultures may affect the volatilome and the profile of bioaccessible phenolics of fermented BCP. BCP fermented with selected microbial starters (Started-BCP) was compared to spontaneously fermented BCP (Unstarted-BCP) and to unprocessed raw BCP (Raw-BCP). Fermentation significantly increased the amount of volatile compounds (VOC) in both Unstarted- and Started-BCP, as well as modifying the relative proportions among the chemical groups. Volatile free fatty acids were the predominant VOC in Unstarted-BCP. Started-BCP was differentiated by the highest levels of esters and alcohols, although volatile free fatty acids were always prevailing. The profile of the VOC was dependent on the type of fermentation, which was attributable to the selected Apilactobacillus kunkeei and Hanseniaspora uvarum strains used as starters, or to the variety of yeasts and bacteria naturally associated to the BCP. Started-BCP and, to a lesser extent, Unstarted-BCP resulted in increased bioaccessible phenolics, which included microbial derivatives of phenolic acids metabolism. Full article
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Open AccessArticle
Nutritional and Functional Advantages of the Use of Fermented Black Chickpea Flour for Semolina-Pasta Fortification
Foods 2021, 10(1), 182; https://doi.org/10.3390/foods10010182 - 18 Jan 2021
Viewed by 422
Abstract
Pasta represents a dominant portion of the diet worldwide and its functionalization with high nutritional value ingredients, such as legumes, is the most ideal solution to shape consumers behavior towards healthier food choices. Aiming at improving the nutritional quality of semolina pasta, semi-liquid [...] Read more.
Pasta represents a dominant portion of the diet worldwide and its functionalization with high nutritional value ingredients, such as legumes, is the most ideal solution to shape consumers behavior towards healthier food choices. Aiming at improving the nutritional quality of semolina pasta, semi-liquid dough of a Mediterranean black chickpea flour, fermented with Lactiplantibacillus plantarum T0A10, was used at a substitution level of 15% to manufacture fortified pasta. Fermentation with the selected starter enabled the release of 20% of bound phenolic compounds, and the conversion of free compounds into more active forms (dihydrocaffeic and phloretic acid) in the dough. Fermented dough also had higher resistant starch (up to 60% compared to the control) and total free amino acids (almost 3 g/kg) contents, whereas antinutritional factors (raffinose, condensed tannins, trypsin inhibitors and saponins) significantly decreased. The impact of black chickpea addition on pasta nutritional, technological and sensory features, was also assessed. Compared to traditional (semolina) pasta, fortified pasta had lower starch hydrolysis rate (ca. 18%) and higher in vitro protein digestibility (up to 38%). Moreover, fortified cooked pasta, showing scavenging activity against DPPH and ABTS radicals and intense inhibition of linoleic acid peroxidation, was appreciated for its peculiar organoleptic profile. Therefore, fermentation technology appears to be a promising tool to enhance the quality of pasta and promote the use of local chickpea cultivars while preventing their genetic erosion. Full article
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Open AccessArticle
Role of Lactic Acid Bacteria Phospho-β-Glucosidases during the Fermentation of Cereal by-Products
Foods 2021, 10(1), 97; https://doi.org/10.3390/foods10010097 - 05 Jan 2021
Viewed by 485
Abstract
Bioprocessing using lactic acid bacteria (LAB) is a powerful means to exploit plant-derived by-products as a food ingredient. LAB have the capability to metabolize a large variety of carbohydrates, but such metabolism only relies on few metabolic routes, conferring on them a high [...] Read more.
Bioprocessing using lactic acid bacteria (LAB) is a powerful means to exploit plant-derived by-products as a food ingredient. LAB have the capability to metabolize a large variety of carbohydrates, but such metabolism only relies on few metabolic routes, conferring on them a high fermentation potential. One example of these pathways is that involving phospho-β-glucosidase genes, which are present in high redundancy within LAB genomes. This enzymatic activity undertakes an ambivalent role during fermentation of plant-based foods related to the release of a wide range of phenolic compounds, from their β-D-glycosylated precursors and the degradation of β-glucopyranosyl derived carbohydrates. We proposed a novel phenomic approach to characterize the metabolism drift of Lactiplantibacillus plantarum and Leuconostoc pseudomesenteroides caused by a lignocellulosic by-product, such as the brewers’ spent grain (BSG), in contrast to Rich De Man, Rogosa and Sharpe (MRS) broth. We observed an increased metabolic activity for gentiobiose, cellobiose and β-glucoside conjugates of phenolic compounds during BSG fermentation. Gene expression analysis confirmed the importance of cellobiose metabolism while a release of lignin-derived aglycones was found during BSG fermentation. We provided a comprehensive view of the important role exerted by LAB 6-phospho-β-glucosidases as well the major metabolic routes undertaken during plant-based fermentations. Further challenges will consider a controlled characterization of pbg gene expression correlated to the metabolism of β-glucosides with different aglycone moieties. Full article
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Open AccessArticle
Fermentation by Probiotic Lactobacillus gasseri Strains Enhances the Carotenoid and Fibre Contents of Carrot Juice
Foods 2020, 9(12), 1803; https://doi.org/10.3390/foods9121803 - 04 Dec 2020
Viewed by 498
Abstract
Carrot juice (straight, 8.5 Brix and concentrated, 15.2 Brix) was fermented by lactic acid bacteria (Lactobacillus gasseri strain DSM 20604 or DSM 20077). Fermentation enhanced the nutritional profile of carrot juice. There was a greater sugar reduction (27%) in fermented straight carrot [...] Read more.
Carrot juice (straight, 8.5 Brix and concentrated, 15.2 Brix) was fermented by lactic acid bacteria (Lactobacillus gasseri strain DSM 20604 or DSM 20077). Fermentation enhanced the nutritional profile of carrot juice. There was a greater sugar reduction (27%) in fermented straight carrot juices than in the fermented concentrated juices (15%). The sugar reduction was independent of the strain used for fermentation. The two L. gasseri strains synthesised fructosyltransferase enzymes during fermentation of carrot juice samples that enabled conversion of simple sugars primarily into polysaccharides. The level of conversion to polysaccharides was dependent on the L. gasseri strain and juice concentration. Fermentation of carrot juice by L. gasseri enables the production of a nutritionally-enhanced beverage with reduced calorie and prebiotic potential. An additional benefit is the increased carotenoid content observed in straight and concentrated juices fermented by Lactobacillus gasseri DSM 20077 and the concentrated juice fermented by Lactobacillus gasseri DSM 20604. Full article
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Open AccessArticle
Leuconostoc citreum TR116 as a Microbial Cell Factory to Functionalise High-Protein Faba Bean Ingredients for Bakery Applications
Foods 2020, 9(11), 1706; https://doi.org/10.3390/foods9111706 - 20 Nov 2020
Viewed by 652
Abstract
Grain legumes, such as faba beans, have been investigated as promising ingredients to enhance the nutritional value of wheat bread. However, a detrimental effect on technological bread quality was often reported. Furthermore, considerable amounts of antinutritional compounds present in faba beans are a [...] Read more.
Grain legumes, such as faba beans, have been investigated as promising ingredients to enhance the nutritional value of wheat bread. However, a detrimental effect on technological bread quality was often reported. Furthermore, considerable amounts of antinutritional compounds present in faba beans are a subject of concern. Sourdough-like fermentation can positively affect baking performance and nutritional attributes of faba bean flours. The multifunctional lactic acid bacteria strain Leuconostoc citreum TR116 was employed to ferment two faba bean flours with different protein contents (dehulled flour (DF); high-protein flour (PR)). The strain’s fermentation profile (growth, acidification, carbohydrate metabolism and antifungal phenolic acids) was monitored in both substrates. The fermentates were applied in regular wheat bread by replacing 15% of wheat flour. Water absorption, gluten aggregation behaviour, bread quality characteristics and in vitro starch digestibility were compared to formulations containing unfermented DF and PR and to a control wheat bread. Similar microbial growth, carbohydrate consumption as well as production of lactic and acetic acid were observed in both faba bean ingredients. A less pronounced pH drop as well as a slightly higher amount of antifungal phenolic acids were measured in the PR fermentate. Fermentation caused a striking improvement of the ingredients’ baking performance. GlutoPeak measurements allowed for an association of this observation with an improved gluten aggregation. Given its higher potential to improve protein quality in cereal products, the PR fermentate seemed generally more promising as functional ingredient due to its positive impact on bread quality and only moderately increased starch digestibility in bread. Full article
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Open AccessArticle
Living the Sweet Life: How Liquorilactobacillus hordei TMW 1.1822 Changes Its Behavior in the Presence of Sucrose in Comparison to Glucose
Foods 2020, 9(9), 1150; https://doi.org/10.3390/foods9091150 - 21 Aug 2020
Cited by 1 | Viewed by 730
Abstract
Liquorilactobacillus (L.) hordei (formerly Lactobacillus hordei) is one of the dominating lactic acid bacteria within the water kefir consortium, being highly adapted to survive in this environment, while producing high molecular weight dextrans from sucrose. In this work, we extensively [...] Read more.
Liquorilactobacillus (L.) hordei (formerly Lactobacillus hordei) is one of the dominating lactic acid bacteria within the water kefir consortium, being highly adapted to survive in this environment, while producing high molecular weight dextrans from sucrose. In this work, we extensively studied the physiological response of L. hordei TMW 1.1822 to sucrose compared to glucose, applying label-free, quantitative proteomics of cell lysates and exoproteomes. This revealed the differential expression of 53 proteins within cellular proteomes, mostly associated with carbohydrate uptake and metabolism. Supported by growth experiments, this suggests that L. hordei TMW 1.1822 favors fructose over other sugars. The dextransucrase was expressed irrespectively of the present carbon source, while it was significantly more released in the presence of sucrose (log2FC = 3.09), being among the most abundant proteins within exoproteomes of sucrose-treated cells. Still, L. hordei TMW 1.1822 expressed other sucrose active enzymes, predictively competing with the dextransucrase reaction. While osmolysis appeared to be unlikely, sucrose led to increased release of a multitude of cytoplasmic proteins, suggesting that biofilm formation in L. hordei is not only composed of a polysaccharide matrix but is also of proteinaceous nature. Therefore, our study highlights the intrinsic adaptation of water kefir-borne L. hordei to sucrose-rich habitats and provides fundamental knowledge for its use as a starter culture in plant-based food fermentations with in situ dextran formation. Full article
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Open AccessArticle
Sourdough Fermentation Degrades Wheat Alpha-Amylase/Trypsin Inhibitor (ATI) and Reduces Pro-Inflammatory Activity
Foods 2020, 9(7), 943; https://doi.org/10.3390/foods9070943 - 16 Jul 2020
Cited by 7 | Viewed by 1664
Abstract
The ingestion of gluten-containing foods can cause wheat-related disorders in up to 15% of wheat consuming populations. Besides the role of gluten, α-amylase/trypsin inhibitors (ATI) have recently been identified as inducers of an innate immune response via toll-like receptor 4 in celiac disease [...] Read more.
The ingestion of gluten-containing foods can cause wheat-related disorders in up to 15% of wheat consuming populations. Besides the role of gluten, α-amylase/trypsin inhibitors (ATI) have recently been identified as inducers of an innate immune response via toll-like receptor 4 in celiac disease and non-celiac wheat sensitivity. ATI are involved in plant self-defense against insects and possibly in grain development. Notably, they are largely resistant to gastrointestinal proteases and heat, and their inflammatory activity affects not only the intestine, but also peripheral organs. The aim of this study was to understand the changes of ATI throughout the sourdough and yeast-fermented bread-making processes. ATI tetramers were isolated, fluorescein-labelled, and added to a mini-dough bread-making system. When the pH decreased below 4.0 in sourdough fermentation, the ATI tetramers were degraded due to the activation of aspartic proteases, whilst in yeast fermentation, ATI tetramers remained intact. The amylase inhibitory activity after sourdough fermentation decreased significantly, while the concentration of free thiol groups increased. The glutathione reductase activity of Fructilactobacillus sanfranciscensis did not contribute to the reduction of ATI tetramers. Compared to the unfermented wheat, sourdough fermentation was able to decrease the release of pro-inflammatory cytokines monocyte chemoattractant protein-1 (MCP-1) and tumor necrosis factor alpha (TNF-α) in quantitative ATI extracts added to the human monocytic cell line THP-1. The current data suggest that sourdough fermentation can degrade ATI structure and bioactivity, and point to strategies to improve product development for wheat sensitivity patients. Full article
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