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Fermentation
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Food Wastes: Feedstock for Value-Added Products: 3rd Edition
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Food Wastes: Feedstock for Value-Added Products: 3rd Edition

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

Deadline for manuscript submissions: closed (31 March 2022) | Viewed by 40205

Special Issue Editor

Dr. Diomi Mamma

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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
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Food waste (FW) is a global problem that has received increasing public and political attention 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) feeding hungry people; (c) feeding animals; (d) industrial uses; (e) composting, incineration, or landfilling.

Preventing the overproduction and oversupply of food is the first step 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 the bioeconomy, namely climate, resource security, and ecosystem services.

In continuation, this Special Issue 3.0 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 submissions that pass pre-check are 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 monthly 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 2600 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 (11 papers)

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Research

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11 pages, 1816 KiB  
Article
Effect of Sea Salt and Taro Waste on Fungal Mortierella alpina Cultivation for Arachidonic Acid-Rich Lipid Production
by Yen-Hui Chen, Chang-Chng Ong and Ting-Yao Lin
Fermentation 2022, 8(2), 81; https://doi.org/10.3390/fermentation8020081 - 16 Feb 2022
Cited by 4 | Viewed by 1974
Abstract
Arachidonic acid (ARA), an important polyunsaturated fatty acid (PUFA), acts as a precursor for eicosanoid hormones, such as prostaglandins, leukotrienes and other biological substances in human and animal bodies. Mortierella alpina is considered to be a potential strain for ARA production. Using agricultural [...] Read more.
Arachidonic acid (ARA), an important polyunsaturated fatty acid (PUFA), acts as a precursor for eicosanoid hormones, such as prostaglandins, leukotrienes and other biological substances in human and animal bodies. Mortierella alpina is considered to be a potential strain for ARA production. Using agricultural waste as a substrate for microbial fermentation could achieve biorefinery concepts, and sea water utilization of the cultivation process could help to conserve fresh water resources. The objectives of this study were to find a potential M. alpina strain for ARA production, to investigate the tolerance of salinity and to evaluate the feasibility of the taro waste hydrolysate for M. alpina cultivation. The result showed that M. alpina FU30797 had the highest lipid content (25.97%) and ARA ratio (34.60%) among three strains. Furthermore, there was no significant difference between 0 and 10 g/L of sea salt solution on the biomass concentration and lipid content of M. alpina FU30797. The acidic hydrolysate and enzymatic hydrolysate of taro peel waste (TPW) were both utilized as culture substrates by M. alpina FU30797; however, the substrate up-take rate and lipid content in the TPW enzymatic hydrolysate cultivation were 292.33 mg/L-h and 30.68%, respectively, which are higher than those in acidic hydrolysate cultivation, and the ARA ratio was 33.05% in the enzymatic hydrolysate cultivation. From fed-batch cultivation in the bioreactor, the lipid content and ARA ratio reached 36.97% and 46.04%, respectively. In summary, the results from this project could potentially provide useful information for developing the PUFA-ARA bioprocess by using M. alpina. Full article
(This article belongs to the Special Issue Food Wastes: Feedstock for Value-Added Products: 3rd Edition)
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22 pages, 2320 KiB  
Article
Production of Exopolysaccharides by Cultivation of Halotolerant Bacillus atrophaeus BU4 in Glucose- and Xylose-Based Synthetic Media and in Hydrolysates of Quinoa Stalks
by Diego Chambi, Jenny Lundqvist, Erik Nygren, Luis Romero-Soto, Katherine Marin, András Gorzsás, Mattias Hedenström, Markus Carlborg, Markus Broström, Ola Sundman, Cristhian Carrasco, Leif J. Jönsson and Carlos Martín
Fermentation 2022, 8(2), 79; https://doi.org/10.3390/fermentation8020079 - 14 Feb 2022
Cited by 4 | Viewed by 3603
Abstract
A halotolerant, exopolysaccharide-producing bacterium isolated from the Salar de Uyuni salt flat in Bolivia was identified as Bacillus atrophaeus using next-generation sequencing. Comparisons indicate that the genome most likely (p-value: 0.0024) belongs to a subspecies previously not represented in the database. [...] Read more.
A halotolerant, exopolysaccharide-producing bacterium isolated from the Salar de Uyuni salt flat in Bolivia was identified as Bacillus atrophaeus using next-generation sequencing. Comparisons indicate that the genome most likely (p-value: 0.0024) belongs to a subspecies previously not represented in the database. The growth of the bacterial strain and its ability to produce exopolysaccharides (EPS) in synthetic media with glucose or xylose as carbon sources, and in hydrolysates of quinoa stalks, was investigated. The strain grew well in all synthetic media, but the growth in glucose was better than that in xylose. Sugar consumption was better when initial concentrations were low. The growth was good in enzymatically produced cellulosic hydrolysates but was inhibited in hemicellulosic hydrolysates produced using hydrothermal pretreatment. The EPS yields were up to 0.064 g/g on initial glucose and 0.047 g/g on initial xylose, and was higher in media with relatively low sugar concentrations. The EPS was isolated and purified by a sequential procedure including centrifugation, cold ethanol precipitation, trichloroacetic acid treatment, dialysis, and freeze-drying. Glucose and mannose were the main sugars identified in hydrolyzed EPS. The EPS was characterized by size-exclusion chromatography, Fourier-transform infrared (FTIR) spectroscopy, heteronuclear single-quantum coherence nuclear magnetic resonance (HSQC NMR) spectroscopy, scanning electron microscopy, X-ray diffraction, and thermogravimetric analysis. No major differences were elucidated between EPS resulting from cultivations in glucose- or-xylose-based synthetic media, while some divergences with regard to molecular-weight averages and FTIR and HSQC NMR spectra were detected for EPS from hydrolysate-based media. Full article
(This article belongs to the Special Issue Food Wastes: Feedstock for Value-Added Products: 3rd Edition)
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14 pages, 1632 KiB  
Article
Valorization of Fruit Peels into Biovanillin and Statistical Optimization of Process Using Enterobacter hormaechei through Solid-State Fermentation
by Tahir Mehmood, Sibtain Ahmed, Rida Waseem, Shagufta Saeed, Waqas Ahmed, Muhammad Irfan and Azmat Ullah
Fermentation 2022, 8(2), 40; https://doi.org/10.3390/fermentation8020040 - 20 Jan 2022
Cited by 9 | Viewed by 3394
Abstract
Vanillin is a secondary metabolite of plants and the major organoleptic aroma component of natural vanilla. Nowadays, the chemical synthesis method used for vanillin production has been rejected by the United States and European legislation, while plant-derived vanillin is expensive. The current study [...] Read more.
Vanillin is a secondary metabolite of plants and the major organoleptic aroma component of natural vanilla. Nowadays, the chemical synthesis method used for vanillin production has been rejected by the United States and European legislation, while plant-derived vanillin is expensive. The current study demonstrates vanillin production via solid-state fermentation (SSF) by Enterobacter hormaechei using different ferulic acid-rich fruit peels as substrates. From different ferulic acid-rich fruit peels (pomegranate, banana, and orange) screened Punica granatum (pomegranate) peels yielded maximum biovanillin (0.09 mg/g) after 24 h. Different bioprocess parameters, including moisture content, inoculum size, pH, and temperature, were optimized using central composite design (CCD) of the response surface methodology (RSM). The maximum biovanillin yield (0.462 mg/g) from Punica granatum peels was achieved at 60% moisture content, 2 mL inoculum size, 6.5 pH, and 32 °C temperature. An F-value of 12.94 and a p-value of 0.00 were recorded by the variance analysis indicated the proposed model’s significance. The coefficient of determination (R2) confirmed the model’s goodness of fit, having a value of 91.89%, which indicated the model’s accuracy. The optimally produced biovanillin was extracted and confirmed using FTIR. Further purity analysis was done by HPLC and the biovanillin was reported to be 99.2% pure. The results demonstrated that microbial conversion of ferulic acid-rich fruit peels to biovanillin offers a cost-effective approach for the industrial production of biovanillin. Full article
(This article belongs to the Special Issue Food Wastes: Feedstock for Value-Added Products: 3rd Edition)
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13 pages, 1438 KiB  
Article
Volatile Fatty Acids (VFA) Production from Wastewaters with High Salinity—Influence of pH, Salinity and Reactor Configuration
by Maria Salomé Duarte, João V. Oliveira, Carla Pereira, Miguel Carvalho, Daniela P. Mesquita and Maria Madalena Alves
Fermentation 2021, 7(4), 303; https://doi.org/10.3390/fermentation7040303 - 09 Dec 2021
Cited by 7 | Viewed by 3969
Abstract
The hydrocarbon-based economy is moving at a large pace to a decarbonized sustainable bioeconomy based on biorefining all types of secondary carbohydrate-based raw materials. In this work, 50 g L−1 in COD of a mixture of food waste, brine and wastewater derived [...] Read more.
The hydrocarbon-based economy is moving at a large pace to a decarbonized sustainable bioeconomy based on biorefining all types of secondary carbohydrate-based raw materials. In this work, 50 g L−1 in COD of a mixture of food waste, brine and wastewater derived from a biodiesel production facility were used to produce organic acids, important building-blocks for a biobased industry. High salinity (12–18 g L−1), different reactors configuration operated in batch mode, and different initial pH were tested. In experiment I, a batch stirred reactor (BSR) at atmospheric pressure and a granular sludge bed column (GSBC) were tested with an initial pH of 5. In the end of the experiment, the acidification yield (ηa) was similar in both reactors (22–24%, w/w); nevertheless, lactic acid was in lower concentrations in BSR (6.3 g L−1 in COD), when compared to GSBC (8.0 g L−1 in COD), and valeric was the dominant acid, reaching 17.3% (w/w) in the BSR. In experiment II, the BSR and a pressurized batch stirred reactor (PBSR, operated at 6 bar) were tested with initial pH 7. The ηa and the VFA concentration were higher in the BSR (46%, 22.8 g L−1 in COD) than in the PBSR (41%, 20.3 g/L in COD), and longer chain acids were more predominant in BSR (24.4% butyric, 6.7% valeric, and 6.2% caproic acids) than in PBSR (23.2%, 6.2%, and 4.2%, respectively). The results show that initial pH of 7 allows achieving higher ηa, and the BSR presents the most suitable reactor among tested configurations to produce VFA from wastes/wastewaters with high salinity. Full article
(This article belongs to the Special Issue Food Wastes: Feedstock for Value-Added Products: 3rd Edition)
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18 pages, 2575 KiB  
Article
Submerged Fermentation of Animal Fat By-Products by Oleaginous Filamentous Fungi for the Production of Unsaturated Single Cell Oil
by Sushil S. Gaykawad, Sreerekha S. Ramanand, Johanna Blomqvist, Boris Zimmermann, Volha Shapaval, Achim Kohler, Marije Oostindjer and Catherine Boccadoro
Fermentation 2021, 7(4), 300; https://doi.org/10.3390/fermentation7040300 - 09 Dec 2021
Cited by 4 | Viewed by 3076
Abstract
Animal waste fats were explored as a fermentation substrate for the production of high-value unsaturated single cell oil (SCO) using oleaginous fungi, Mucor circinelloides and Mortierella alpina. Both strains showed good growth and lipid accumulation when using animal fat as a single [...] Read more.
Animal waste fats were explored as a fermentation substrate for the production of high-value unsaturated single cell oil (SCO) using oleaginous fungi, Mucor circinelloides and Mortierella alpina. Both strains showed good growth and lipid accumulation when using animal fat as a single carbon source. The biomass concentration of 16.7 ± 2.2 gDCW/L and lipid content of 54.1%wt (of dry cell weight) were obtained for Mucor circinelloides in shake flask experiments, surpassing the biomass yield achieved in batch and fed-batch fermentation. In contrast, Mortierella alpina gave the highest biomass concentration (8.3 ± 0.3 gDCW/L) and lipid content (55.8%wt) in fed-batch fermentation. Fat grown Mortierella alpina was able to produce arachidonic acid (ARA), and the highest ARA content of 23.8%wt (of total lipid weight) was in fed-batch fermentation. Gamma-linolenic acid (GLA) was produced by both fungal strains. At the end of fed-batch fermentation, the GLA yields obtained for Mucor circinelloides and Mortierella alpina were 4.51%wt and 2.77%wt (of total lipid weight), respectively. This study demonstrates the production of unsaturated SCO-rich fungal biomass from animal fat by fermentation. Full article
(This article belongs to the Special Issue Food Wastes: Feedstock for Value-Added Products: 3rd Edition)
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19 pages, 3478 KiB  
Article
Production of Pigments by Filamentous Fungi Cultured on Agro-Industrial by-Products Using Submerged and Solid-State Fermentation Methods
by Tumisi Beiri Jeremiah Molelekoa, Thierry Regnier, Laura Suzanne da Silva and Wilma Augustyn
Fermentation 2021, 7(4), 295; https://doi.org/10.3390/fermentation7040295 - 02 Dec 2021
Cited by 12 | Viewed by 3761
Abstract
The food and pharmaceutical industries are searching for natural colour alternatives as required by consumers. Over the last decades, fungi have emerged as producers of natural pigments. In this paper, five filamentous fungi; Penicillium multicolour, P. canescens, P. herquie, Talaromyces verruculosus [...] Read more.
The food and pharmaceutical industries are searching for natural colour alternatives as required by consumers. Over the last decades, fungi have emerged as producers of natural pigments. In this paper, five filamentous fungi; Penicillium multicolour, P. canescens, P. herquie, Talaromyces verruculosus and Fusarium solani isolated from soil and producing orange, green, yellow, red and brown pigments, respectively, when cultured on a mixture of green waste and whey were tested. The culture media with varying pH (4.0, 7.0 and 9.0) were incubated at 25 °C for 14 days under submerged and solid-state fermentation conditions. Optimal conditions for pigment production were recorded at pH 7.0 and 9.0 while lower biomass and pigment intensities were observed at pH 4.0. The mycelial biomass and pigment intensities were significantly higher for solid-state fermentation (0.06–2.50 g/L and 3.78–4.00 AU) compared to submerged fermentation (0.220–0.470 g/L and 0.295–3.466 AU). The pigment intensities were corroborated by lower L* values with increasing pH. The λmax values for the pigments were all in the UV region. Finally, this study demonstrated the feasibility of pigment production using green waste:whey cocktails (3:2). For higher biomass and intense pigment production, solid-state fermentation may be a possible strategy for scaling up in manufacturing industries. Full article
(This article belongs to the Special Issue Food Wastes: Feedstock for Value-Added Products: 3rd Edition)
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11 pages, 4187 KiB  
Article
Use of Apple Pomace as Substrate for Production of Lactiplantibacillus plantarum Malolactic Starter Cultures
by Victoria Cerdeira, Natalia S. Brizuela, Sebastián M. E. Bravo, Bárbara M. Bravo-Ferrada, Danay Valdés La Hens, Adriana C. Caballero, Liliana C. Semorile and E. Elizabeth Tymczyszyn
Fermentation 2021, 7(4), 244; https://doi.org/10.3390/fermentation7040244 - 29 Oct 2021
Viewed by 1765
Abstract
The by-products of the food industry are an economic alternative as a source of nutrients to obtain biomass. At the same time, theiruse could solve the environmental problem related to their disposal, which is highly polluting due to their elevated biochemical oxygen demand. [...] Read more.
The by-products of the food industry are an economic alternative as a source of nutrients to obtain biomass. At the same time, theiruse could solve the environmental problem related to their disposal, which is highly polluting due to their elevated biochemical oxygen demand. In this work, we seek to optimize the production of cellular biomass of two native Patagonian strains of Lactiplantibacillus plantarum (UNQLp 11 and UNQLp155), selected for its oenological and technological properties, using apple pomace (AP), a residue from the juice and cider industry. The supplementation of AP with yeast extract, salts, and Tween 80 (sAP), proved to maintain the growth of the Lpb. plantarum strains, similar to the commercial medium used to grow LAB (De Man, Rogosa, Sharpe, MRS). Cultures grown in sAP medium showed good tolerance to wine conditions (high ethanol content and low pH), demonstrated by its ability to consume L-malic acid. The subsequent inoculation of these cultures in sterile wines (Merlot and Pinot noir) was carried out at laboratory scale, evaluating cell viability and L-malic acid consumption for 21 days at 21 °C. Cultures grown in sAP media showed a similar performance to MRS media. Thus, sAP media proved to be a suitable substrate to grow oenological Lpb. plantarum strains where cultures (with high size inoculums) were able to drive malolactic fermentation, with an L-malic acid consumption higher than 90%. Full article
(This article belongs to the Special Issue Food Wastes: Feedstock for Value-Added Products: 3rd Edition)
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12 pages, 1532 KiB  
Article
Optimization of Carotenoids Production from Camelina sativa Meal Hydrolysate by Rhodosporidium toruloides
by Stefano Bertacchi, Chiara Cantù, Danilo Porro and Paola Branduardi
Fermentation 2021, 7(4), 208; https://doi.org/10.3390/fermentation7040208 - 25 Sep 2021
Cited by 5 | Viewed by 2659
Abstract
Several compounds on the market derive from petrochemical synthesis, and carotenoids are no exception. Nonetheless, since their applications in the food, feed and cosmetic sectors, and because of sustainability issues, carotenoids of natural origin are desirable. Carotenoids can be extracted from several plants [...] Read more.
Several compounds on the market derive from petrochemical synthesis, and carotenoids are no exception. Nonetheless, since their applications in the food, feed and cosmetic sectors, and because of sustainability issues, carotenoids of natural origin are desirable. Carotenoids can be extracted from several plants but also from carotenogenic microorganisms, among which are yeasts. Nonetheless, to meet sustainability criteria, the substrate used for yeast cultivation has to be formulated from residual biomasses. For these reasons, we deploy the yeast, Rhodosporidium toruloides, to obtain carotenoids from Camelina sativa meal, an underrated lignocellulosic biomass. Its enzymatic hydrolysis ensures the release of the sugars, as well as of the other nutrients necessary to sustain the process. We therefore separately optimized enzymatic and biomass loadings, and calculated the yields and productivities of the obtained carotenoids. The best conditions (9% w/v biomass, 0.56% w/wbiomass enzymes) were tested in different settings, in which the fermentation was performed separately or simultaneously with hydrolysis, resulting in a similar production of carotenoids. In order to collect quantitative data under controlled chemo-physical parameters, the process was implemented in stirred-tank bioreactors, obtaining 3.6 ± 0.69 mg/L of carotenoids; despite the volumetric and geometric change, the outcomes were consistent with results from the fermentation of shake flasks. Therefore, these data pave the way to evaluate a potential future industrialization of this bioprocess, considering the opportunity to optimize the use of different amounts of biomass and enzyme loading, as well as the robustness of the process in the bioreactor. Full article
(This article belongs to the Special Issue Food Wastes: Feedstock for Value-Added Products: 3rd Edition)
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20 pages, 4979 KiB  
Article
Improvement of Biohydrogen and Usable Chemical Products from Glycerol by Co-Culture of Enterobacter spH1 and Citrobacter freundii H3 Using Different Supports as Surface Immobilization
by Biniam T. Maru, Francisco Lopez, Francesc Medina and Magda Constantí
Fermentation 2021, 7(3), 154; https://doi.org/10.3390/fermentation7030154 - 15 Aug 2021
Cited by 3 | Viewed by 2144
Abstract
Glycerol is a by-product of biodiesel production in a yield of about 10% (w/w). The present study aims to improve the dark fermentation of glycerol by surface immobilization of microorganisms on supports. Four different supports were used—maghemite (Fe2 [...] Read more.
Glycerol is a by-product of biodiesel production in a yield of about 10% (w/w). The present study aims to improve the dark fermentation of glycerol by surface immobilization of microorganisms on supports. Four different supports were used—maghemite (Fe2O3), activated carbon (AC), silica gel (SiO2), and alumina (γ-Al2O3)—on which a newly isolated co-culture of Enterobacter spH1 and Citrobacter freundii, H3, was immobilized. The effect of iron species on dark fermentation was also studied by impregnation on AC and SiO2. The fermentative metabolites were mainly ethanol, 1,3-propanediol, lactate, H2 and CO2. The production rate (Rmax,i) and product yield (Yi) were elucidated by modeling using the Gompertz equation for the batch dark fermentation kinetics (maximum product formation (Pmax,i): (i) For each of the supports, H2 production (mmol/L) and yield (mol H2/mol glycerol consumed) increased in the following order: FC < γ-Al2O3 < Fe2O3 < SiO2 < Fe/SiO2 < AC < Fe/AC. (ii) Ethanol production (mmol/L) increased in the following order: FC < Fe2O3 < γ-Al2O3 < SiO2 < Fe/SiO2 < Fe/AC < AC, and yield (mol EtOH/mol glycerol consumed) increased in the following order: FC < Fe2O3 < Fe/AC < Fe/SiO2 < SiO2 < AC < γ-Al2O3. (iii) 1,3-propanediol production (mmol/L) and yield (mol 1,3PDO/mol glycerol consumed) increased in the following order: γ-Al2O3 < SiO2 < Fe/SiO2 < AC < Fe2O3 < Fe/AC < FC. (iv) Lactate production(mmol/L) and yield (mol Lactate/mol glycerol consumed) increased in the following order: γ-Al2O3 < SiO2 < AC < Fe/SiO2 < Fe/AC < Fe2O3 < FC. The study shows that in all cases, glycerol conversion was higher when the support assisted culture was used. It is noted that glycerol conversion and H2 production were dependent on the specific surface area of the support. H2 production clearly increased with the Fe2O3, Al2O3, SiO2 and AC supports. H2 production on the iron-impregnated AC and SiO2 supports was higher than on the corresponding bare supports. These results indicate that the support enhances the productivity of H2, perhaps because of specific surface area attachment, biofilm formation of the microorganisms and activation of the hydrogenase enzyme by iron species. Full article
(This article belongs to the Special Issue Food Wastes: Feedstock for Value-Added Products: 3rd Edition)
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11 pages, 3321 KiB  
Article
Aeration and Stirring in Yarrowia lipolytica Lipase Biosynthesis during Batch Cultures with Waste Fish Oil as a Carbon Source
by Paulina Snopek, Dorota Nowak, Bartłomiej Zieniuk and Agata Fabiszewska
Fermentation 2021, 7(2), 88; https://doi.org/10.3390/fermentation7020088 - 01 Jun 2021
Cited by 14 | Viewed by 3137
Abstract
Yarrowia lipolytica is one of the most studied non-conventional forms of yeast, exhibiting a high secretory capacity and producing many industrially important and valuable metabolites. The yeast conceals a great biotechnological potential to synthesize organic acids, sweeteners, microbial oil, or fragrances. The vast [...] Read more.
Yarrowia lipolytica is one of the most studied non-conventional forms of yeast, exhibiting a high secretory capacity and producing many industrially important and valuable metabolites. The yeast conceals a great biotechnological potential to synthesize organic acids, sweeteners, microbial oil, or fragrances. The vast majority of bioprocesses are carried out in bioreactors, where suitable culture conditions are provided. In the current study, the effect of agitation speed (200–600 rpm) and air flow rate (0.0375–2.0 dm3/(dm3 × min)) on the biomass yield and lipase activity of Y. lipolytica KKP 379 is analyzed in a growth medium containing waste fish oil. The increase of aeration intensity limited the period of oxygen deficit in the medium. Simultaneously, an increase in lipolytic activity was observed from 2.09 U/cm3 to 14.21 U/cm3; however, an excessive agitation speed likely caused oxidative or shear stresses, and a reduction in lipolytic activity was observed. Moreover, it is confirmed that the synthesis of lipases is related to oxygen consumption, pH, and the yeast growth phase, and appropriate process selection may provide two advantages, namely, the maximum use of the waste carbon source and the production of lipolytic enzymes that are valuable in many industries. Full article
(This article belongs to the Special Issue Food Wastes: Feedstock for Value-Added Products: 3rd Edition)
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Review

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26 pages, 963 KiB  
Review
Glycolipid Biosurfactant Production from Waste Cooking Oils by Yeast: Review of Substrates, Producers and Products
by Janis Liepins, Karina Balina, Raimonda Soloha, Ieva Berzina, Liva Kristiana Lukasa and Elina Dace
Fermentation 2021, 7(3), 136; https://doi.org/10.3390/fermentation7030136 - 29 Jul 2021
Cited by 35 | Viewed by 8852
Abstract
Biosurfactants are a microbially synthesized alternative to synthetic surfactants, one of the most important bulk chemicals. Some yeast species are proven to be exceptional biosurfactant producers, while others are emerging producers. A set of factors affects the type, amount, and properties of the [...] Read more.
Biosurfactants are a microbially synthesized alternative to synthetic surfactants, one of the most important bulk chemicals. Some yeast species are proven to be exceptional biosurfactant producers, while others are emerging producers. A set of factors affects the type, amount, and properties of the biosurfactant produced, as well as the environmental impact and costs of biosurfactant’s production. Exploring waste cooking oil as a substrate for biosurfactants’ production serves as an effective cost-cutting strategy, yet it has some limitations. This review explores the existing knowledge on utilizing waste cooking oil as a feedstock to produce glycolipid biosurfactants by yeast. The review focuses specifically on the differences created by using raw cooking oil or waste cooking oil as the substrate on the ability of various yeast species to synthesize sophorolipids, rhamnolipids, mannosylerythritol lipids, and other glycolipids and the substrate’s impact on the composition, properties, and limitations in the application of biosurfactants. Full article
(This article belongs to the Special Issue Food Wastes: Feedstock for Value-Added Products: 3rd Edition)
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