Circular economy challenges in bioresources valorization - the role of microorganisms

ln a world that is expected to face acute resource shortage in the near future, exploring the possibility of fully using the available biomass and significantly improving the recovery of relevant nutrients/compounds are strategies of the utmost importance. Holistic strategies supporting a circular economy, enabling the sustainable and efficient use of available feedstocks, while targeting minimal environmental impact and zero wastes, are in order. ln this context, selecting efficient strategies, aiming at recovering the maximum number of fractions while simultaneously allowing for high yields and functionality, economic feasibility, environmental sustainability, and holistic integration in biorefinery approaches, is a challenging task. Biorefineries were initially designed to provide energy and chemicals from lignocellulosic biomasses using fermentation processes. The concept can be extended to other types of under-used bioresources, including food wastes or marine biomasses. However, bottlenecks include the need for processes that can cope with different feedstocks and variable feedstock quality. ln fact, improved enzymes and microorganisms are needed, resilient to these highly variable feedstocks and resistant to high(er) amounts of common inhibitors. Microorganisms capable of metabolizing specific compounds, such as oils or marine polysaccharides, into high-value products or ingredients would also allow broadening the range of biomasses that can be included in these circular economy approaches. Simpler valorisation strategies may include to enrich the biomass in different microbial metabolites or in single cell protein. Besides their role as high value commodities producer, microorganisms can also be an important processing aid. For instance, they may be used a stabilizing agent or to degrade packaging. Summing up, microorganisms can be key players in adding value to under-used bioresources by providing feasible processes to convert these bioresources into different high-value products, thus increasing economy circularity.info:eu-repo/semantics/publishedVersio

Identification of yield coefficients in a baker’s yeast model: an optimal experimental design approach

The main objective of this work is to elaborate methodologies that allow the identification of yield coefficients through complete measurements of the state. Experimental design strategies are proposed in order to optimize the richness of data coming out from the experiments, quantified by indexes related to the Fisher information matrix. The objectives of the experimental planning have been addressed in terms of the programming of input trajectories. The experimental planning is envisaged for baker’s yeast aiming at the computation of the substrate feed trajectories

Effect of ferulic acid on the performance of soy protein isolate-based edible coatings applied to fresh-cut apples

The economic importance of fresh-cut fruit market is becoming progressively more significant, while the food industry shows increased interest in innovation of products bringing health benefits. The objective of this work was to assess the potential of incorporating ferulic acid (antioxidant with reported bioactivity that can act as cross-linking agent) in soy protein-based edible coating formulations in order to increase the quality and shelf life of fresh-cut apples (cv. Golden). Glycerol was used as plasticizer and ferulic acid was incorporated in concentrations between 1.0 and 4.0 g L?1. The properties of fresh-cut apples were analysed during seven days of storage at 10 °C. A common commercial antioxidant (sodium ascorbate at 10 g L?1) was tested for comparison. Uncoated apples and apples dipped into antioxidants solution were used as controls. The results emphasized the need to incorporate this phenolic antioxidant in a biopolymer matrix, due to its hydrophobic characteristics and consequently a poor dispersion along the surface of the fruit. They also indicate that the efficiency of the coatings incorporating ferulic acid is highly dependent on pH. The formulation with ferulic acid at 4.0 g L?1 and pH 7.0 has demonstrated potential application in extending the shelf life of fresh-cut apples.Thanks are due to the European Community's Seventh Framework Programme (SusFoFlex, collaborative project number 289829, KBBE.2011.2.3-03). LAQV/REQUIMTE received financial support from FCT/MEC through national funds and FEDER, under the Partnership Agreement PT2020 (reference UID/QUI/50006/2013 - POCl/01/0145/FEDER/007265).info:eu-repo/semantics/publishedVersio

Trypsin immobilisation on zeolites

This work compares different types of zeolites (NaA, NaX and NaY) as potential carriers for trypsin immobilisation. Silica was also used as a traditional carrier. Covalent attachment to the carriers was tested using glutaraldehyde. The efficiency of immobilisation and activity, operation and storage stability of free and immobilised enzyme on the three supports were studied. Optimum value of operation temperature was determined for trypsin immobilised on the best zeolite. Trypsin was most successfully immobilised on NaY by covalent attachment using glutaraldehyde. Though the best efficiencies were still obtained with silica, promising results were achieved with zeolite NaY. The ratio of immobilised protein achieved was very high, especially with silica, NaX and NaY. However there was a significant loss of enzyme activity with the immobilisation of trypsin. Optimal temperature obtained with immobilised enzyme was ca. 60 ºC, higher than the correspondent temperature for free enzyme (50 ºC).Fundação para a Ciência e a Tecnologia (FCT) - POCTI/2000/QUI/36452.European Social Fund (ESF)

A comparative analysis on the efficiency of different carriers for trypsin immobilization

CHISA 2008 - 18th International Congress of Chemical and Process Engineering (CD-ROM of Full Texts)info:eu-repo/semantics/publishedVersio

Olive tree leaves - a source of valuable active compounds

The agricultural and processing activities of olive crops generate a substantial amount of food by-products, particularly olive leaves, which are mostly underexploited, representing a significant threat to the environment. Olive leaves are endowed with endogenous bioactive compounds. Their beneficial/health-promoting potential, together with environmental protection and circular economy, merit their exploitation to recover and reuse natural components that are potentially safer alternatives to synthetic counterparts. These biomass residues have great potential for extended industrial applications in food/dietary systems but have had limited commercial uses so far. In this regard, many researchers have endeavoured to determine a green/sustainable means to replace the conventional/inefficient methods currently used. This is not an easy task as a sustainable bio-processing approach entails careful designing to maximise the liberation of compounds with minimum use of (i) processing time, (ii) toxic solvent (iii) fossil fuel energy, and (iv) overall cost. Thus, it is necessary to device viable strategies to (i) optimise the extraction of valuable biomolecules from olive leaves and enable their conversion into high added-value products, and (ii) minimise generation of agro-industrial waste streams. This review provides an insight to the principal bioactive components naturally present in olive leaves, and an overview of the existing/proposed methods associated with their analysis, extraction, applications, and stability.FCT -Fundação para a Ciência e a Tecnologia(UID/BIO/04469/2020)info:eu-repo/semantics/publishedVersio

Influence of the concentration of locust bean gum on the gelling ability of whey peptic hydrolysates

The gelling ability of whey proteins can be changed by limited hydrolysis and by the presence of other components such as polysaccharides; depending on the environmental conditions it can either be improved or impaired. In this work the effect of LBG on the heat-set gelation of aqueous whey protein hydrolysates (10 % w/w) from pepsin was assessed at pH 7.0 by small deformation rheology. Whey protein concentrate (WPC) and hydrolysates with a degree of hydrolysis (DH) of 1.5, 2.5 and 4.9 % were used. Different LBG concentrations were tested: 0, 0.1, 0.3 and 0.55 % (w/w). The behaviour of gels from whey proteins or whey protein hydrolysates towards the presence of LBG was very similar. The evolution of the viscous and storage moduli followed the general behaviour reported for many biopolymer heat-set gelation processes including whey proteins gelation. The increase in the LBG concentration generally led to a decrease in the gel strength. However, for whey proteins a small amount of LBG (0.1 %) leads to a big enhancement in the gel strength probably due to an increase in the protein concentration of the protein enriched phase. Further increases in the LBG concentration led to a decrease in the gel strength. The gelation process is very sensible to environmental conditions and to processing and often leads to rather coarse data. The factorial planning used allowed validating conclusions using fewer experiments than those needed if no planning had been used, while still getting statistical significance out of the results. However, as many factors are involved, the modelling of the process was not straightforward

Spent-grains and zeolites as potential carriers for trypsin immobilisation

Trypsin is a widely used enzyme for protein hydrolysis and can be used to improve functional and nutritional properties of foods. The immobilization of enzymes on solid supports can offer several advantages over free enzymes including easy handling, recovery from the reaction medium, reuse and operation in continuous reactors. Traditional carriers include porous silica, porous glass and cellulose derivatives. Zeolites are porous alumino-silicates available in a wide range of particle size and porosity and can also be used as carriers. Spent grains are a brewing by-product with a high content in cellulose and can also be interesting as carriers for enzyme immobilization because, besides having the necessary conditions (as stability, rigidity, low mass transfer limitations, for instance), they are cheap and food grade. This work proposes the use of spent grains and zeolites as alternative carriers for trypsin immobilization and compares them with a traditional support (silica). Physical adsorption, ionic attachment and covalent attachment to the supports were tested. The efficiency of immobilization and activity, as well as the operation and storage stability of free and immobilized enzyme on the three supports were studied. Trypsin was most successfully immobilized on the supports by covalent attachment using glutaraldehyde. Though the best efficiencies were still obtained with silica, promising results were achieved with both spent grains and zeolite.Fundação para a Ciência e a Tecnologia (FCT) - project POCTI/2000/QUI/36452.European Social Fund (ESF)

Spent grain as a new carrier for trypsin immobilisation

Trypsin is a widely used enzyme for protein hydrolysis and can be used to improve functional and nutritional properties of foods. This work compares different carriers obtained from spent grains as potential candidates for trypsin immobilisation. Covalent attachment to the carriers was tested using glutaraldehyde. The efficiency of immobilisation and activity, operation and storage stability of free and immobilised enzyme on supports were determined. The amount of immobilised protein achieved was high (up to 70 %) but there was a significant loss of enzyme activity with the immobilisation of trypsin. However, when a more purified enzyme from bovine pancreas was used, activity retention was almost 50 %. Trypsin was most successfully immobilised on the supports by covalent attachment using glyoxyl-derivatives. The stability of these immobilized enzymes was close to 100%.This work was co-financed by Social European Fund (public call 1/5.3/PRODEP/2003, financial application 1012.012, of measure 5/action 5.3 – Post-graduate training for academic staff submitted by Escola Superior de Tecnologia e Gestão do Instituto Politécnico de Viana do Castelo).info:eu-repo/semantics/publishedVersio