Valorisation of Agro-Industrial By-Products Through Fermentation or Eco-Friendly Techniques

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

Deadline for manuscript submissions: 20 November 2025 | Viewed by 590

Special Issue Editors

Consiglio per la Ricerca in Agricoltura e l’Analisi dell’Economia Agraria (CREA), Centro di Ricerca Olivicoltura, Frutticoltura e Agrumicoltura, Corso Savoia 190, 95024 Acireale, Italy
Interests: table olives; fermentation; by-products; bioactive compounds; starter cultures; microbial biotechnology
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Guest Editor
Council for Agricultural Research and Economics (CREA), Research Centre for Olive, Fruit and Citrus Crops, Acireale, CT, Italy
Interests: food by-products as nutraceuticals or antimicrobials; polyphenols; development of new functional foods

Special Issue Information

Dear Colleagues,

The reuse and valorization of the by-products of the agro-food industry represents a functional strategy to reduce waste along the production chain, contain costs, and obtain new matrices that can be reused as “co-products”. Indeed, agro-food by-products provide a source of bioactive molecules that can be effectively recovered and valorized across various application sectors, including food, cosmetics, pharmaceuticals, and animal feeds. Although several conventional strategies have been proposed for the recovery of these by-products, green technologies are playing an increasingly important role from the perspective of sustainability and the transition towards circular models. In this context, fermentation, based on the use of microbial cultures, appears to be a low-cost and low-energy process capable of generating highly added-value products from residual matrices. Biotransformation enables the desired changes, such as improved microbiological safety, nutritional and sensory properties, and extended shelf-life, and fermentation, therefore, represents a promising technological strategy to produce new foods and/or functional ingredients, contributing significantly to the implementation of a sustainable circular model.

Dr. Paola Foti
Dr. Flora Valeria Romeo
Guest Editors

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Keywords

  • by-product
  • fermentation
  • starter cultures
  • bioactive molecules
  • biotechnology approaches

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Published Papers (2 papers)

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Research

15 pages, 2645 KiB  
Article
Bioconversion of a Glycerol- and Methanol-Rich Residue from Biodiesel Industry into 1,3-Propanediol: The Role of Magnesium
by Rafael de Moraes Altafini, Giovana Masson Fachin and Valeria Reginatto
Fermentation 2025, 11(7), 370; https://doi.org/10.3390/fermentation11070370 - 26 Jun 2025
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Abstract
Biodiesel is one of the most important biofuels worldwide. Besides glycerol, the residual aqueous phase of the transesterification reaction (RAPTR) from the biodiesel industry contains a high concentration of methanol. Here, we propose using RAPTR as substrate for Clostridium beijerinckii Br21 to produce [...] Read more.
Biodiesel is one of the most important biofuels worldwide. Besides glycerol, the residual aqueous phase of the transesterification reaction (RAPTR) from the biodiesel industry contains a high concentration of methanol. Here, we propose using RAPTR as substrate for Clostridium beijerinckii Br21 to produce 1,3-propanediol (1,3-PDO). 1,3-PDO is a valuable chemical compound widely used in the production of polymers, cosmetics, and pharmaceuticals. To diminish the methanol content, we pretreated RAPTR by low-pressure evaporation, which minimized water evaporation and prevented other contaminants from being concentrated. We optimized the evaporation conditions by using a 22 central composite rotational design to establish optimal temperature and time of 55 °C and 51.3 min, respectively. Pretreated RAPTR diluted at 20% (v v−1) with a nutrient solution allowed the bacterium to grow, but no glycerol was consumed. Supplementing the nutrient solution with 0.4 g L−1 MgCl2, defined in another experimental design, led the bacterium to consume glycerol and to produce 1,3-PDO. In the optimized conditions, pretreated RAPTR supplemented with MgCl2 gave 2.78 ± 0.01 g L−1 1,3-PDO in higher yield (Y1,3-PDO/glycerol) compared to the theoretical one, 0.61 and 0.50 g g−1, respectively. This result is relevant for biodiesel biorefineries, which could implement the innovative and customized strategy proposed herein to obtain 1,3-PDO, a high-value-added product, from a glycerol- and methanol-rich residue. Full article
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17 pages, 1694 KiB  
Article
Enhancing Bioconversion of Crude Glycerol into Butanol and 1,3-Propanediol After Pretreatment by Coupling Fermentation and In Situ Recovery: Effect of Initial pH Control
by Alejandro Ortega, Alejo Valles, Miguel Capilla, Carmen Gabaldón, Francisco Javier Álvarez-Hornos and Paula Marzal
Fermentation 2025, 11(6), 339; https://doi.org/10.3390/fermentation11060339 - 11 Jun 2025
Viewed by 372
Abstract
The sharp rise in the worldwide production of biodiesel has created an excess in the crude glycerol market, so it is essential to develop new added-value alternatives for crude glycerol. This paper describes a study on fermenting high concentrations of two types of [...] Read more.
The sharp rise in the worldwide production of biodiesel has created an excess in the crude glycerol market, so it is essential to develop new added-value alternatives for crude glycerol. This paper describes a study on fermenting high concentrations of two types of medium-pure crude glycerol to solvents by Clostridium pasteurianum. The effect of media composition (iron, yeast extract, and vitamins) on solvents production was assessed by a full factorial design with pure glycerol. Granular activated carbon (GAC) adsorption was highly effective in removing impurities from crude glycerol. Following GAC pretreatment, fermentation of glycerol at initial concentration as high as 60 g L−1 was possible, resulting in a butanol production of ~9 g L−1. Based on these results, a batch fermentation with in situ gas stripping and pH controlled at ≥6.5 was shown to be the best alternative to enhance biomass growth, glycerol uptake, and solvent production. The combination of controlling pH in the early stages of fermentation with in situ butanol removal stabilised the metabolism of the strain and showed that the fermentation performance with crude glycerol is very similar to that of pure glycerol. With a notable uptake of glycerol (>83%), solvent production was >11 g L−1 butanol (yield > 0.21 g g−1glycerol consumed) and >6 g L−1 1,3-propanediol (yield > 0.13 g g−1glycerol consumed). Setting the fermentation conditions to achieve a high uptake of high levels of glycerol with a similar product distribution is of great interest for the viability of the industrial processing of crude glycerol into chemicals via biological conversion. Full article
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