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Sustainable Food Waste Valorisation by Membrane Technology

A special issue of Sustainability (ISSN 2071-1050). This special issue belongs to the section "Sustainable Engineering and Science".

Deadline for manuscript submissions: closed (28 February 2023) | Viewed by 17840

Special Issue Editors

Department of Engineering, Lancaster University, Lancaster, UK
Interests: microbial production and downstream processing as a whole bioprocess; utilization of agri-food industry wastes; natural products and food chemistry; green and sustainable chemistry; nanomaterials and membranes technology; chemistry of surfaces and their modification; chemistry of chromatographic materials; molecularly imprinted polymers; encapsulation of substances in edible matrices
National Research Council of Italy, Institute on Membrane Technology, CNR-ITM Via P. Bucci 17/C, 87036 Rende (CS), Italy
Interests: membrane science and membrane bioengineering; nanostructured biohybrid membranes; biocatalytic membrane reactors; membrane emulsification; integrated membrane processes for water, biotechnology; pharmaceutical and biorefinery
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Today efforts are underway to mitigate the agri-food waste problem by using appropriate technologies that allow the efficient recycling of these wastes, thus creating additional value and simultaneously protecting the environment. The appropriate treatment of these wastes is in accordance with the green chemistry and circular economy principles, which both lead to sustainable development. The main purpose of this Special Issue is to highlight and focus on the importance of membrane processes in the valorisation of agri-food wastes. These waste materials can be solids or liquids that are created from the pruning of plants in fields/glass houses, the processing of raw materials or because these plant materials do not comply with industrial quality assurance standards. The latter problem is more intense in the low-income countries. Membrane technologies have a number of advantages, such as their relatively low installation cost compared to other technologies, they are quite compact with lower space requirements, have low energy expenditure, are quite automated and electrifiable and can be easily adopted even in such low-income countries. As they are electrifiable, they can be used in combination with alternative energy resources, providing a lower carbon footprint.

This Special Issue will not only address the recovery of compounds from such waste materials, but will also cover the new membrane materials that can facilitate the isolation of such compounds, how these technologies can be integrated with other pre- and post-treatment steps and the use of natural polymers for membrane fabrication. It will provide evidence of energy and resources required for the recycling of the solvents used for the initial extraction of these compounds. These are the main key areas that will be able to lead us to a more sustainable future, and you are very welcome to participate in this Special Issue.

Dr. Emmanouil Papaioannou
Dr. Lidietta Giorno
Guest Editors

Manuscript Submission Information

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Keywords

  • membrane processes
  • agri-food waste valorisation
  • low-energy technologies
  • value-added products from wastes
  • bio-based economy

Published Papers (8 papers)

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Research

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27 pages, 4920 KiB  
Article
Using Machine Learning to Predict the Performance of a Cross-Flow Ultrafiltration Membrane in Xylose Reductase Separation
Sustainability 2023, 15(5), 4245; https://doi.org/10.3390/su15054245 - 27 Feb 2023
Viewed by 1268
Abstract
This study provides a new perspective for xylose reductase enzyme separation from the reaction mixtures—obtained in the production of xylitol—by means of machine learning technique for large-scale production. Two types of machine learning models, including an adaptive neuro-fuzzy inference system based on grid [...] Read more.
This study provides a new perspective for xylose reductase enzyme separation from the reaction mixtures—obtained in the production of xylitol—by means of machine learning technique for large-scale production. Two types of machine learning models, including an adaptive neuro-fuzzy inference system based on grid partitioning of the input space and a boosted regression tree were developed, validated, and tested. The models’ inputs were cross-flow velocity, transmembrane pressure, and filtration time, whereas the membrane permeability (called membrane flux) and xylitol concentration were considered as the outputs. According to the results, the boosted regression tree model demonstrated the highest predictive performance in forecasting the membrane flux and the amount of xylitol produced with a coefficient of determination of 0.994 and 0.967, respectively, against 0.985 and 0.946 for the grid partitioning-based adaptive neuro-fuzzy inference system, 0.865 and 0.820 for the best nonlinear regression picked from among 143 different equations, and 0.815 and 0.752 for the linear regression. The boosted regression tree modeling approach demonstrated a superior capability of predictive accuracy of the critical separation performances in the enzymatic-based cross-flow ultrafiltration membrane for xylitol synthesis. Full article
(This article belongs to the Special Issue Sustainable Food Waste Valorisation by Membrane Technology)
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17 pages, 8231 KiB  
Article
Low-Fouling Plate-and-Frame Ultrafiltration for Juice Clarification: Part 2—Module Design and Application
Sustainability 2023, 15(3), 2769; https://doi.org/10.3390/su15032769 - 03 Feb 2023
Cited by 2 | Viewed by 1638
Abstract
The purification and concentration of orange juice are crucial to remove undesirable materials, such as pectin, which is responsible for juice clouds; or limonene, which is responsible for bitter taste. Membrane-based juice clarification is preferred due to its capability to separate specific targeted [...] Read more.
The purification and concentration of orange juice are crucial to remove undesirable materials, such as pectin, which is responsible for juice clouds; or limonene, which is responsible for bitter taste. Membrane-based juice clarification is preferred due to its capability to separate specific targeted molecules, while still maintaining the clarified juice’s nutritional content. In this study, a novel designed bench-scale plate-and-frame membrane module composed of low fouling cellulose acetate membrane sheets was manufactured to facilitate orange juice clarification. The experimental results demonstrated the effectiveness of the developed module to be used for juice clarification. After incorporating the functional and structural design parameters, the final module had the following specifications: dimensions of 125 × 168 mm, an effective volume of 0.9–9.4 L, a total active membrane area of 1088 cm2, and a transmembrane pressure of 0.3–0.55 MPa. The results of the juice clarification show no difference in the value of pH, viscosity, total acid, water content, color L* (brightness), and color a* (reddish) of the feed, the permeate, and the retentate streams. The clarified juice had slightly higher total dissolved solids (°Brix), ash content, vitamin C, and color (b* yellowish). Overall, our findings demonstrated that the developed plate-and-frame module could effectively be used to clarify orange juice without altering the quality, i.e., reducing the nutritional contents. Full article
(This article belongs to the Special Issue Sustainable Food Waste Valorisation by Membrane Technology)
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17 pages, 7590 KiB  
Article
Low-Fouling Plate-and-Frame Ultrafiltration for Juice Clarification: Part 1—Membrane Preparation and Characterization
Sustainability 2023, 15(1), 806; https://doi.org/10.3390/su15010806 - 02 Jan 2023
Cited by 2 | Viewed by 1485
Abstract
Membrane technology provides advantages for separating and purifying food materials, including juice clarification. Ultrafiltration processes for fruit juices aim to remove haze components and maintain the stabilization of the juices. However, the membrane process during the clarification of fruit juices suffers from fouling, [...] Read more.
Membrane technology provides advantages for separating and purifying food materials, including juice clarification. Ultrafiltration processes for fruit juices aim to remove haze components and maintain the stabilization of the juices. However, the membrane process during the clarification of fruit juices suffers from fouling, which deteriorates the process performance and products. Biofouling usually is found in the applications of the membrane in food processing. In this study, phenolic substances extracted from garlic bulbs are incorporated into a matrix of polymeric membranes to prevent fouling during juice clarification. Hydrophilic cellulose acetate was used as the polymer matrix of the membrane, and dimethylformamide was used as the solvent. The phenolic substances from garlic bulbs were incorporated into polymer solutions with different concentrations of 0%, 1%, 1.25%, and 1.5% w/v. The composite membrane was prepared using the phase inversion method, and the resulting membranes were later characterized. The results show that incorporating those phenolic compounds as the dope solution additive resulted in membranes with higher hydrophilic properties. They also modeled antibacterial properties, as shown by the reduced attachment of Bacillus subtilis of up to 91.5 ± 11.7% and Escherichia coli of up to 94.0 ± 11.9%. Full article
(This article belongs to the Special Issue Sustainable Food Waste Valorisation by Membrane Technology)
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16 pages, 7445 KiB  
Article
Fabrication and Performance of Low-Fouling UF Membranes for the Treatment of Isolated Soy Protein Solutions
Sustainability 2021, 13(24), 13682; https://doi.org/10.3390/su132413682 - 10 Dec 2021
Cited by 5 | Viewed by 1926
Abstract
Consumers are becoming more conscious about the need to include functional and nutritional foods in their diet. This has increased the demand for food extracts rich in proteins and peptides with physiological effects that are used within the food and pharmaceutical industries. Among [...] Read more.
Consumers are becoming more conscious about the need to include functional and nutritional foods in their diet. This has increased the demand for food extracts rich in proteins and peptides with physiological effects that are used within the food and pharmaceutical industries. Among these protein extracts, soy protein and its derivatives are highlighted. Isolated soy protein (ISP) presents a protein content of at least 90%. Wastewaters generated during the production process contain small proteins (8–50 kDa), and it would be desirable to find a recovery treatment for these compounds. Ultrafiltration membranes (UF) are used for the fractionation and concentration of protein solutions. By the appropriate selection of the membrane pore size, larger soy proteins are retained and concentrated while carbohydrates and minerals are mostly recovered in the permeate. The accumulation and concentration of macromolecules in the proximity of the membrane surface generates one of the most important limitations inherent to the membrane technologies. In this work, three UF membranes based on polyethersulfone (PES) were fabricated. In two of them, polyethylene glycol (PEG) was added in their formulation to be used as a fouling prevention. The membrane fouling was evaluated by the study of flux decline models based on Hermia’s mechanisms. Full article
(This article belongs to the Special Issue Sustainable Food Waste Valorisation by Membrane Technology)
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14 pages, 2985 KiB  
Article
The Chemical and Cytotoxic Properties of Sambucus nigra Extracts—A Natural Food Colorant
Sustainability 2021, 13(22), 12702; https://doi.org/10.3390/su132212702 - 17 Nov 2021
Cited by 4 | Viewed by 2219
Abstract
Elderberry fruits contain valuable components that are beneficial to human health. Owing to the high content of anthocyanins, elderberry extracts can be used as natural food colorants with health-promoting properties. Moreover, the development of new natural food dyes enables the reduction in the [...] Read more.
Elderberry fruits contain valuable components that are beneficial to human health. Owing to the high content of anthocyanins, elderberry extracts can be used as natural food colorants with health-promoting properties. Moreover, the development of new natural food dyes enables the reduction in the use of synthetic ones. Anthocyanins-rich elderberry dry extracts (EDE) were prepared from the same batch of frozen fruits applying water extraction, followed by membrane separation (batch B1) or purification by column chromatography (batch B2) and then spray-dried. Subsequently, the content of anthocyanins, flavonols, and polyphenols was determined. The extract obtained with the application of column chromatography (B2) contained 33% anthocyanins, which is more than typical market standards, whereas the extract B1 contained 14% anthocyanins. The color properties of both extracts were also determined. Since water was used as an extractant, the extracts are well soluble in water and can therefore be used as a natural food colorant. The cytotoxic activity of both extracts was additionally determined using the MTT test and the tumor cells of the A-549, A-2780, MCF-7, Caco-2 line, and Peripheral blood mononuclear cells. It was revealed that both EDEs inhibit the proliferation of cancer cells, except those of the lung cancers. Extract B2 showed a much stronger cytotoxic effect. Additionally, both extracts stimulate the proliferation of peripheral blood mononuclear cells since they may have immunostimulatory properties. Full article
(This article belongs to the Special Issue Sustainable Food Waste Valorisation by Membrane Technology)
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14 pages, 795 KiB  
Article
Dark Fermentation Process Response to the Use of Undiluted Tequila Vinasse without Nutrient Supplementation
Sustainability 2021, 13(19), 11034; https://doi.org/10.3390/su131911034 - 05 Oct 2021
Cited by 3 | Viewed by 1905
Abstract
The technical feasibility of valorizing tequila vinasse (TV), a wastewater with high pollution potential, through the production of biogenic hydrogen via dark fermentation, has long been proven in diverse lab-scale reactors that were operated either in batch or continuous mode. However, such systems [...] Read more.
The technical feasibility of valorizing tequila vinasse (TV), a wastewater with high pollution potential, through the production of biogenic hydrogen via dark fermentation, has long been proven in diverse lab-scale reactors that were operated either in batch or continuous mode. However, such systems have mainly been tested with diluted streams and nutrient supplementation, hindering the techno-economic attractiveness of the TV-to-hydrogen concept at large scale. In this study, the feasibility of producing hydrogen from high-strength undiluted TV with no added extra nutrients was evaluated under batch mesophilic conditions. Additionally, the use of two different acidogenic inocula obtained either by heat or heat-aeration pretreatment was investigated to get a greater understanding of the effect of inoculum type on the process. The results obtained showed that the TV utilized herein contained macro- and micro-nutrients high enough to support the hydrogenogenic activity of both cultures, entailing average hydrogen yields of 2.4–2.6 NL H2/L vinasse and maximum hydrogen production rates of 1.4–1.9 NL H2/L-d. Interestingly, the consumption of lactate and acetate with the concomitant production of butyrate was observed as the main hydrogen-producing route regardless of the inoculum, pointing out the relevance of the lactate-driven dark fermentative process. Clostridium beijerinckii was ascertained as key bacteria, but only in association with microorganisms belonging to the genera Enterobacter and Klebsiella, as revealed by phylogenetic analyses. Full article
(This article belongs to the Special Issue Sustainable Food Waste Valorisation by Membrane Technology)
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16 pages, 2670 KiB  
Article
Effect of Ultrafiltration Operating Conditions for Separation of Ferulic Acid from Arabinoxylans in Corn Fibre Alkaline Extract
Sustainability 2021, 13(9), 4682; https://doi.org/10.3390/su13094682 - 22 Apr 2021
Cited by 10 | Viewed by 1559
Abstract
Corn fibre, a co-product of the starch industry, is rich in compounds with high added value, such as ferulic acid and arabinoxylans, which are released during alkaline extraction. This work aims to optimise an efficient separation method for the recovery of these two [...] Read more.
Corn fibre, a co-product of the starch industry, is rich in compounds with high added value, such as ferulic acid and arabinoxylans, which are released during alkaline extraction. This work aims to optimise an efficient separation method for the recovery of these two compounds from a corn fibre alkaline extract, allowing an efficient valorisation of this co-product. Ultrafiltration was selected as separation method, due to its potential to fractionate these compounds. In order to minimise the loss of membrane permeance, due to mass transfer limitations caused by the high arabinoxylan viscosity, the impact of relevant ultrafiltration operating parameters (membrane molecular weight cut-off, fluid dynamics conditions, transmembrane pressure, and operating temperature) were evaluated. A Nadir UP 150 membrane was found to be an adequate choice, allowing for an efficient separation of ferulic acid from arabinoxylans, with null rejection of ferulic acid, a high estimated rejection of arabinoxylans 98.0% ± 1.7%, and the highest permeance of all tested membranes. A response surface methodology (RSM) was used to infer the effect of ultrafiltration conditions (crossflow velocity, transmembrane pressure and operating temperature) on the rejection of ferulic acid, retention of arabinoxylans (assessed through apparent viscosity of the retentate stream), and permeance. Through mathematical modelling it was possible to determine that the best conditions are the highest operating temperature and initial crossflow velocity tested (66 °C and 1.06 m.s−1, respectively), and the lowest transmembrane pressure tested (0.7 bar). Full article
(This article belongs to the Special Issue Sustainable Food Waste Valorisation by Membrane Technology)
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Review

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21 pages, 2894 KiB  
Review
Agri-Food Industry Waste as Resource of Chemicals: The Role of Membrane Technology in Their Sustainable Recycling
Sustainability 2022, 14(3), 1483; https://doi.org/10.3390/su14031483 - 27 Jan 2022
Cited by 22 | Viewed by 4150
Abstract
The agri-food sector generates substantial quantities of waste material on farm and during the processing of these commodities, creating serious social and environmental problems. However, these wastes can be resources of raw material for the production of valuable chemicals with applications in various [...] Read more.
The agri-food sector generates substantial quantities of waste material on farm and during the processing of these commodities, creating serious social and environmental problems. However, these wastes can be resources of raw material for the production of valuable chemicals with applications in various industrial sectors (e.g., food ingredients, nutraceuticals, bioderived fine chemicals, biofuels etc.). The recovery, purification and biotransformation of agri-food waste phytochemicals from this microbial spoilage-prone, complex agri-food waste material, requires appropriate fast pre-treatment and integration of various processes. This review provides a brief summary and discussion of the unique advantages and the importance of membrane technology in sustainable recycling of phytochemicals from some of the main agri-food sectors. Membrane-based pressure -driven processes present several advantages for the recovery of labile compounds from dilute streams. For example, they are clean technologies that can operate at low temperature (20–60 °C), have low energy requirements, there is no need for additional chemicals, can be quite automated and electrifiable, and have low space requirements. Based on their permselective properties based on size-, shape-, and charge-exclusion mechanisms, membrane-based separation processes have unpaired efficiency in fractionating biological components while presenting their properties. Pressure-driven membrane processes, such as microfiltration (MF), ultrafiltration (UF) and nanofiltration (NF), as well as other advanced membrane-based processes such as membrane bioreactors (MBR), membrane emulsification (ME) and membrane distillation (MD), are presented. The integration of various membrane technologies from the initial recovery of these phytochemicals (MF, UF, NF) to the final formulation (by ME) of commercial products is described. A good example of an extensively studied agri-food stream is the olive processing industry, where many different alternatives have been suggested for the recovery of biophenols and final product fabrication. Membrane process integration will deliver in the near future mature technologies for the efficient treatment of these streams in larger scales, with direct impact on the environmental protection and society (production of compounds with positive health effects, new job creation, etc.). It is expected that integration of these technologies will have substantial impact on future bio-based societies over forthcoming decades and change the way that these chemicals are currently produced, moving from petrochemical-based linear product fabrication to a sustainable circular product design based in agri-food waste biomass. Full article
(This article belongs to the Special Issue Sustainable Food Waste Valorisation by Membrane Technology)
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