Centre of Biotechnology and Fine Chemistry

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Publications

Valorization of brewery waste through Polyhydroxyalkanoates production supported by a metabolic specialized microbiome

Publication . Carvalheira, Mónica; Amorim, Catarina L.; Oliveira, Ana Catarina; Guarda, Eliana C.; Costa, Eunice; Ribau Teixeira, Margarida; Castro, Paula M. L.; Duque, Anouk F.; Reis, Maria A. M.

Raw brewers’ spent grain (BSG), a by-product of beer production and produced at a large scale, presents a composition that has been shown to have potential as feedstock for several biological processes, such as polyhydroxyalkanoates (PHAs) production. Although the high interest in the PHA production from waste, the bioconversion of BSG into PHA using microbial mixed cultures (MMC) has not yet been explored. This study explored the feasibility to produce PHA from BSG through the enrichment of a mixed microbial culture in PHA-storing organisms. The increase in organic loading rate (OLR) was shown to have only a slight influence on the process performance, although a high selectivity in PHA-storing microorganisms accumulation was reached. The culture was enriched on various PHA-storing microorganisms, such as bacteria belonging to the Meganema, Carnobacterium, Leucobacter, and Paracocccus genera. The enrichment process led to specialization of the microbiome, but the high diversity in PHA-storing microorganisms could have contributed to the process stability and efficiency, allowing for achieving a maximum PHA content of 35.2 ± 5.5 wt.% (VSS basis) and a yield of 0.61 ± 0.09 CmmolPHA/CmmolVFA in the accumulation assays. Overall, the production of PHA from fermented BSG is a feasible process confirming the valorization potential of the feedstock through the production of added-value products.

2022-08-30Journal article

Open access

Enhancing carob flour (Ceratonia siliqua L.) for by-product utilization in food industries: carob syrup production, functional profiling and application

Publication . Vilas-Boas, Ana Martins; Brassesco, María Emilia; Quintino, Andreia; Medronho, Bruno; Vieira, Margarida; Brandão, Teresa R. S.; Silva, Cristina L. M.; Silva, Beatriz; Azevedo, Miguel; Pintado, Manuela

The focus on by-product valorization in the food industry, particularly from the carob pod, underscores a commitment to sustainability and resource efficiency. This fruit, sourced from the leguminous evergreen carob tree (Ceratonia siliqua L.), is renowned for its adaptable flavour and nutritional value, in Mediterranean regions such as Portugal. Its production yields significant by-products, presenting environmental challenges when not managed efficiently. Innovative approaches, including integral carob flour production, aim to optimize utilization while minimizing waste and energy consumption. This study repurposed carob waste to produce novel, value-added ingredients like carob syrup, by thermal hydrolysis of integral carob flour using water at 1:3 solidto-liquid ratio - obtaining up to 50 % solubility yield. The resulting syrup exhibited 72 % ◦Brix, a melting temperature (Tm) of approximately 130 ◦C and predominantly viscous behavior with minimal elastic (solid-like) response. Lastly, the syrup was incorporated into a carob-based brigadeiro, replacing conventional glucosefructose syrup. Simulated gastrointestinal digestion revealed enhanced bioaccessibility of sugars and phenolics, and increased antioxidant activity during the intestinal phase. Despite sugar availability, the prebiotic activity of the syrup decreased when embedded in the brigadeiro matrix, potentially due to interactions with polyphenols or organic acids. Cytotoxicity and permeability assays confirmed safety at ≤0.5 % (w/v) and supported intestinal barrier integrity. These findings support the use of integral carob flour for producing multifunctional ingredients, contributing to circular economy models while meeting consumer demands for healthier, sustainable food products.

2026-02Journal article

Open access