Special Issue "Food Wastes: Feedstock for Value-Added Products 2.0"

A special issue of Fermentation (ISSN 2311-5637). This special issue belongs to the section "Industrial Fermentation".

Deadline for manuscript submissions: closed (31 January 2021).

Special Issue Editor

Prof. Dr. Diomi Mamma
E-Mail Website
Guest Editor
Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens, Athens, Greece
Interests: biochemical engineering; fermentation biotechnology; bioreactor design; valorization of agro-industrial wastes and food wastes for biofuels; kinetic modeling; halogenated hydrocarbons degradation; mass transfer phenomena; hydrolytic enzymes (purification, characterization); bio-scouring of cotton fabrics; growth of microalgae
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Special Issue Information

Dear Colleagues,

Food waste (FW) is a global problem that has moved up the public and political agenda in recent years. It will grow in importance, especially given the need to feed the growing global population. Food is a precious commodity, and its production can be resource-intensive. According to the Food and Agriculture Organization of the United Nations (FAO), food loss (FL) is defined as “the decrease in quantity or quality of food”. Food waste is part of food loss, and refers to discarding or alternative (non-food) use of food that is safe and nutritious for human consumption along the entire food supply chain, from primary production to end-household consumer level. The European Project FUSIONS defines FW as ‘‘any food, and inedible parts of food, removed from (lost to or diverted from) the food supply chain to be recovered or disposed of (including composted, crops plowed in/not harvested, anaerobic digestion, bio-energy production, co-generation, incineration, disposal to sewer, landfill or discarded to sea)”. According to the FAO, nearly 1.3 billion tons of food products per year are lost along the food supply chain, and in the next 25 years the amount of food waste is projected to increase exponentially.

Currently, most food wastes are recycled, mainly as animal feed and compost. The remaining quantities are incinerated and disposed of in landfills, causing serious emissions of methane (CH4), which is 23 times more potent than carbon dioxide (CO2) as a greenhouse gas and significantly contributes to climate change. The social impacts of FL and FW may be ascribed with ethical and moral dimensions within the general concept of global food security. Economic impacts are due to the costs related to food wastage and their effects on farmers and consumer incomes.

The EU waste framework directive 2008/98/EC defines the EU waste management hierarchy as follows: (a) prevention, (b) preparing for reuse, (c) recycling, (d) other recovery (e.g., energy recovery), and (e) disposal. Similarly, the Environmental Protection Agency defines the following hierarchy in relation to FW management: (a) source reduction; (b) feed hungry people; (c) feed animals; (d) industrial uses; (e) composting, incineration, or landfilling.

Preventing the overproduction and oversupply of food are the first steps to be taken in reducing FW generation. FW is rich in a spectrum of organic components including carbohydrates, proteins, oils and fats, and organic acids. FW can be converted into a spectrum of bio-commodity chemicals and bio-energy by employing bioprocesses. The implementation of the biorefinery concept could be an essential part of the successful valorization of FW. Producing a spectrum of bio-based products, FW biorefinery can complement fossil-based refinery to a certain extent and address the major drivers for bioeconomy, namely, climate, resource security, and ecosystem services.

In continuation, this Special Issue 2.0 compiles both recent innovative research results as well as review papers on food waste valorization for the production of value-added products.

Prof. Dr. Diomi Mamma
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Fermentation is an international peer-reviewed open access quarterly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • food waste
  • value-added products
  • bioeconomy
  • biorefinery
  • integrated bioprocesses
  • bioenergy
  • bio-hydrogen
  • biomethane
  • biohythane
  • biobased products
  • platform chemicals
  • biofuels
  • bioethanol
  • butanol
  • bio-diesel
  • microbial fuel cell (MFC)
  • enzymes
  • biopolymers
  • organic acids

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Published Papers (7 papers)

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Research

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Article
Residual Brewing Yeast as Substrate for Co-Production of Cell Biomass and Biofilm Using Candida maltosa SM4
Fermentation 2021, 7(2), 84; https://0-doi-org.brum.beds.ac.uk/10.3390/fermentation7020084 - 30 May 2021
Viewed by 1063
Abstract
Candida maltosa was cultivated in the liquid phase of residual brewing yeast, a major brewery residue, to produce biomass and biofilm. Using response surface methodology, the effect of two variables at two different levels was investigated. The independent variables were agitation speed (at [...] Read more.
Candida maltosa was cultivated in the liquid phase of residual brewing yeast, a major brewery residue, to produce biomass and biofilm. Using response surface methodology, the effect of two variables at two different levels was investigated. The independent variables were agitation speed (at 100 and 200 rpm), and aeration (at 1 and 3 L min−1). Aeration was identified to be important for the production of both biomass and biofilm, while agitation was the only factor significantly affecting biofilm production. The maximal production of biofilm (2.33 g L−1) was achieved for agitation of 200 rpm and aeration of 1 L min−1, while the maximum for biomass (16.97 g L−1) was reached for 100 rpm agitation and 3 L min−1 air flow. A logistic model applied to predict the growth of C. maltosa in the exponential phase and the biofilm production, showed a high degree of agreement between the prediction and the actual biomass measured experimentally. The produced biofilms were further characterized using Fourier-transform infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Thermogravimetric Analysis (TGA). FTIR allowed the identification of methyl, carbonyl ester and sulfate groups, and revealed the presence of uronic acid moieties and glycosidic bonds. Water-retention ability up to relatively high temperatures was revealed by TGA, and that makes the produced biofilm suitable for production of hydrogels. SEM also gave indications on the hydrogel-forming potential of the biofilm. Full article
(This article belongs to the Special Issue Food Wastes: Feedstock for Value-Added Products 2.0)
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Article
Exopolysaccharides Production by Cultivating a Bacterial Isolate from the Hypersaline Environment of Salar de Uyuni (Bolivia) in Pretreatment Liquids of Steam-Exploded Quinoa Stalks and Enzymatic Hydrolysates of Curupaú Sawdust
Fermentation 2021, 7(1), 33; https://0-doi-org.brum.beds.ac.uk/10.3390/fermentation7010033 - 28 Feb 2021
Cited by 2 | Viewed by 962
Abstract
The halotolerant bacterial strain BU-4, isolated from a hypersaline environment, was identified as an exopolysaccharide (EPS) producer. Pretreatment liquids of steam-exploded quinoa stalks and enzymatic hydrolysates of Curupaú sawdust were evaluated as carbon sources for EPS production with the BU-4 strain, and the [...] Read more.
The halotolerant bacterial strain BU-4, isolated from a hypersaline environment, was identified as an exopolysaccharide (EPS) producer. Pretreatment liquids of steam-exploded quinoa stalks and enzymatic hydrolysates of Curupaú sawdust were evaluated as carbon sources for EPS production with the BU-4 strain, and the produced EPS was characterized using FTIR, TGA, and SEM. Cultivation was performed at 30 °C for 48 h, and the cells were separated from the culture broth by centrifugation. EPS was isolated from the cell pellets by ethanol precipitation, and purified by trichloroacetic acid treatment, followed by centrifugation, dialysis, and freeze-drying. EPS production from quinoa stalks- and Curupaú sawdust-based substrates was 2.73 and 0.89 g L−1, respectively, while 2.34 g L−1 was produced when cultivation was performed on glucose. FTIR analysis of the EPS revealed signals typical for polysaccharides, as well as ester carbonyl groups and sulfate groups. High thermal stability, water retention capacity and gel-forming ability were inferred from SEM and TGA. The capability of the halotolerant isolate for producing EPS from pretreatment liquids and hydrolysates was demonstrated, and characterization of the EPS revealed their broad application potential. The study shows a way for producing value-added products from waste materials using a bacterium from a unique Bolivian ecosystem. Full article
(This article belongs to the Special Issue Food Wastes: Feedstock for Value-Added Products 2.0)
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Article
Ethanol Production from Olive Stones through Liquid Hot Water Pre-Treatment, Enzymatic Hydrolysis and Fermentation. Influence of Enzyme Loading, and Pre-Treatment Temperature and Time
Fermentation 2021, 7(1), 25; https://0-doi-org.brum.beds.ac.uk/10.3390/fermentation7010025 - 17 Feb 2021
Cited by 2 | Viewed by 966
Abstract
Olive table industry, olive mills and olive pomace oil extraction industries annually generate huge amounts of olive stones. One of their potential applications is the production of bioethanol by fractionation of their lignocellulose constituents and subsequent fermentation of the released sugars using yeasts. [...] Read more.
Olive table industry, olive mills and olive pomace oil extraction industries annually generate huge amounts of olive stones. One of their potential applications is the production of bioethanol by fractionation of their lignocellulose constituents and subsequent fermentation of the released sugars using yeasts. In this work, we studied the influence of temperature (175–225 °C) and residence time (0–5 min) in the liquid hot-water pre-treatment of olive stones as well as the initial enzyme loading (different mixtures of cellulases, hemicellulases and β–glucosidases) in the later enzymatic hydrolysis on the release of fermentable sugars. The Chrastil’s model was applied to the d-glucose data to relate the severity of pre-treatment to enzyme diffusion through the pre-treated cellulose. Finally, the hydrolysate obtained under the most suitable conditions (225 °C and 0 min for pre-treatment; 24 CE initial enzyme concentration) was fermented into ethanol using the yeast Pachysolen tannophilus ATCC 32691. Considering the overall process, 6.4 dm3 ethanol per 100 kg olive stones were produced. Full article
(This article belongs to the Special Issue Food Wastes: Feedstock for Value-Added Products 2.0)
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Article
β-Glucosidase Activity of Lactiplantibacillus plantarum UNQLp 11 in Different Malolactic Fermentations Conditions: Effect of pH and Ethanol Content
Fermentation 2021, 7(1), 22; https://0-doi-org.brum.beds.ac.uk/10.3390/fermentation7010022 - 14 Feb 2021
Cited by 1 | Viewed by 791
Abstract
Lactiplantibacillus plantarum strain UNQLp 11 is a lactic acid bacterium with the potential to carry out malolactic fermentation (MLF) in red wines. Recently, the complete genome of UNQLp 11 was sequenced and this strain possesses four loci of the enzyme β-glucosidase. In order [...] Read more.
Lactiplantibacillus plantarum strain UNQLp 11 is a lactic acid bacterium with the potential to carry out malolactic fermentation (MLF) in red wines. Recently, the complete genome of UNQLp 11 was sequenced and this strain possesses four loci of the enzyme β-glucosidase. In order to demonstrate that these glucosidase enzymes could be functional under harsh wine conditions, we evaluated the hydrolysis of p-nitrophenyl-β-D-glucopyranoside (p-NPG) in synthetic wine with different ethanol contents (0%, 12%, and 14% v/v) and at different pH values (3.2, 3.5, and 3.8). Then, the hydrolysis of precursor n-octyl β-D-glucopyranoside was analyzed in sterile Pinot Noir wine (containing 14.5% v/v of ethanol, at different pH values) by headspace sorptive extraction gas chromatography-mass spectrometry (HSSE-GC/MS). The hydrolysis of p-NPG showed that β-glucosidase activity is very susceptible to low pH but induced in the presence of high ethanol content. Furthermore, UNQLp 11 was able to release the glycosilated precursor n-octyl, during MLF to a greater extent than a commercial enzyme. In conclusion, UNQLp 11 could improve the aromatic profile of the wine by the release of volatile precursors during MLF. Full article
(This article belongs to the Special Issue Food Wastes: Feedstock for Value-Added Products 2.0)
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Article
Influence of the Heating Method on the Efficiency of Biomethane Production from Expired Food Products
Fermentation 2021, 7(1), 12; https://0-doi-org.brum.beds.ac.uk/10.3390/fermentation7010012 - 13 Jan 2021
Cited by 1 | Viewed by 668
Abstract
The aim of the study was to determine the effect of heating with microwave electromagnetic radiation (EMR) on the efficiency of the methane fermentation (MF) of expired food products (EFP). The research was inspired by the positive effect of EMR on the production [...] Read more.
The aim of the study was to determine the effect of heating with microwave electromagnetic radiation (EMR) on the efficiency of the methane fermentation (MF) of expired food products (EFP). The research was inspired by the positive effect of EMR on the production of biogas and methane from different organic substrates. The experiment was carried out on a laboratory scale in fully mixed, semi-continuous anaerobic reactors. The technological conditions were as follows: temperature, 35 ± 1 °C; organic load rate (OLR), 2.0 kgVS·m−3∙d−1; and hydraulic retention time (HRT), 40 days. The source of the EMR was a magnetron (electric power, 300 W). There was no statistically significant influence of the use of EMR on the achieved technological effects of MF. The efficiency of biogas production was 710 ± 35 dm3·kgVS−1 in the variant with EMR and 679 ± 26 dm3·kgVS−1 in the variant with convection heating (CH). The methane contents were 63.5 ± 2.4% (EMR) and 62.4 ± 4.0% (CH), and the cumulative methane production after 40 days was 271.2 and 288.6 dm3CH4, respectively. Full article
(This article belongs to the Special Issue Food Wastes: Feedstock for Value-Added Products 2.0)
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Article
Nitrogen Sources Effect on Lactobacillus reuteri Growth and Performance Cultivated in Date Palm (Phoenix dactylifera L.) By-Products
Fermentation 2020, 6(3), 64; https://0-doi-org.brum.beds.ac.uk/10.3390/fermentation6030064 - 30 Jun 2020
Cited by 4 | Viewed by 1138
Abstract
Lactic acid bacteria (LAB) are fastidious microorganisms that have specific nutritional requirements. The de Man, Rogosa, and Sharpe (MRS) is an expensive standard growth medium for LAB to produce lactic acid, and the industry is always looking for an alternative low-cost medium. The [...] Read more.
Lactic acid bacteria (LAB) are fastidious microorganisms that have specific nutritional requirements. The de Man, Rogosa, and Sharpe (MRS) is an expensive standard growth medium for LAB to produce lactic acid, and the industry is always looking for an alternative low-cost medium. The date palm (Phoenix dactylifera L.) is naturally full of essential nutrients that lead to stimulate or promote the growth of Lactobacillus spp. The date fruit industries generate a large amount of unwanted date by-product. Thus, the objective of this study was to examine the effect of different nitrogen sources on the growth of Lactobacillus reuteri grown in a date base medium. In this study, date palm fruit was pressed, and the fiber was blended with distilled water, centrifuged, and the supernatant was autoclaved to obtain date palm extract (DPE). The date palm medium (DPM) was formed by mixing the DPE with buffer solution. The DPM was then supplemented with different concentrations of different nitrogen sources. Lactobacilli MRS was used as a standard growth medium. Three different L. reuteri strains were individually inoculated into batches of MRS and DPMs at an initial inoculum 2.5 Log CFU/mL, and then incubated at 37 °C for 18 h. Bacterial growth was monitored by measuring the optical density readings (O.D 610 nm) for up to 18 h. At the end of the incubation period, final populations of each individual strain were verified by enumeration of the MRS agar. Our results showed that the bacterial population in DPM (control; without nitrogen), reached 3.55 ± 0.5 Log CFU/mL. However, the bacterial populations that reached 7.03 ± 0.1 Log CFU/mL in the DPM medium were supplemented with 0.8% phytone peptone, compared to the MRS 7.90 ± 0.24 Log CFU/mL. Our findings thus suggest that date by-products could be used as a low-cost alternative for the LAB growth medium. Full article
(This article belongs to the Special Issue Food Wastes: Feedstock for Value-Added Products 2.0)
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Review

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Review
Sweet Dreams (Are Made of This): A Review and Perspectives on Aspartic Acid Production
Fermentation 2021, 7(2), 49; https://0-doi-org.brum.beds.ac.uk/10.3390/fermentation7020049 - 29 Mar 2021
Viewed by 730
Abstract
Aspartic acid, or “aspartate,” is a non-essential, four carbon amino acid produced and used by the body in two enantiomeric forms: L-aspartic acid and D-aspartic acid. The L-configuration of amino acids is the dominant form used in protein synthesis; thus, L-aspartic acid is [...] Read more.
Aspartic acid, or “aspartate,” is a non-essential, four carbon amino acid produced and used by the body in two enantiomeric forms: L-aspartic acid and D-aspartic acid. The L-configuration of amino acids is the dominant form used in protein synthesis; thus, L-aspartic acid is by far the more common configuration. However, D-aspartic acid is one of only two known D-amino acids biosynthesized by eukaryotes. While L-aspartic acid is used in protein biosynthesis and neurotransmission, D-aspartic acid is associated with neurogenesis and the endocrine system. Aspartic acid production and use has been growing in recent years. The purpose of this article is to discuss various perspectives on aspartic acid, including its industrial utility, global markets, production and manufacturing, optimization, challenges, and future outlook. As such, this review will provide a thorough background on this key biochemical. Full article
(This article belongs to the Special Issue Food Wastes: Feedstock for Value-Added Products 2.0)
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