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Polylactic acid (PLA) films containing 1 wt % and 3 wt % of lignin nanoparticles (pristine (LNP), chemically modified with citric acid (caLNP) and acetylated (aLNP)) were prepared by extrusion and characterized in terms of their overall performance as food packaging materials. Morphological, mechanical, thermal, UV–Vis barrier, antioxidant and antibacterial properties were assayed; appropriate migration values in food simulants and disintegration in simulated composting conditions were also verified. The results obtained indicated that all lignin nanoparticles succeeded in conferring UV-blocking, antioxidant and antibacterial properties to the PLA films, especially at the higher filler loadings assayed. Chemical modification of the fillers partially reduced the UV protection and the antioxidant properties of the resulting composites, but it induced better nanoparticles dispersion, reduced aggregates size, enhanced ductility and improved aesthetic quality of the films through reduction of the characteristic dark color of lignin. Migration tests and disintegration assays of the nanocomposites in simulated composting conditions indicated that, irrespectively of their formulation, the multifunctional nanocomposite films prepared behaved similarly to neat PLA.

Abstract Every year more than 2 million tons of citric acid (CA) are produced around the world for industrial uses. Although initially extracted from citrus, the low profitability of the process and the increasing demand soon stimulated the search for more efficient methods to produce CA. Currently, most world CA demand (99%) is satisfied by fermentations with microorganisms, especially filamentous fungi and yeasts. CA production with yeasts has certain advantages over molds (e.g. higher productivity and easier cultivation), which in the last two decades have triggered a clear increase in publications and patents devoted to the use of yeasts in this field. Yarrowia lipolytica has become a model yeast that proved to be successful in different production systems. Considering the current interest evidenced in the literature, the most significant information on CA production using Y. lipolytica is summarized. The relevance on CA yields of key factors such as strains, media formulation, environmental conditions and production regimes is thoroughly discussed, with particular focus on increasing CA productivity. Besides, the possibility of tuning the mentioned variables to reduce concomitant isocitric acid production—the biggest disadvantage of using yeasts—is analyzed. Available methods for CA purification/quantification are also discussed. The easier cultivation, higher productivity, lower requirements on C sources used, simpler strain engineering over molds and its classification as GRAS make Y. lipolytica-mediated processes very promising for CA production.

Chemical modification of bacterial cellulose (BC) through carboxymethylation was carried out to prepare a low-cost highly stable lead adsorbent material (CMBC). Aiming to maximize its adsorption capacity, the effect of the carboxymethylation extent conferred to BC on the lead retention ability of the insoluble CMBC products obtained was studied. Results evidenced a strong linear correlation between the lead retention capacity of CMBC samples and their degree of substitution, highlighting a key role on the biobased adsorbents performance of the amount of negatively charged carboxylate groups available for an ion-exchange-governed lead adsorption process. Proper tuning of the carboxymethylation extent conferred to BC thus allowed maximizing its lead adsorption capacity, reaching values ( i.e. 127.2 mg g −1 ) that doubled those previously reported.

Bacterial cellulose pellicles were produced by Gluconacetobacter xylinus using non conventional low-cost carbon sources, such as glycerol remaining from biodiesel production and grape bagasse, a residue of wine production. The carbon sources assayed showed their suitability for microbial cellulose production, with relatively high production values such as 10.0 g/l for the culture medium with glycerol from biodiesel as carbon source and corn steep liquor as nitrogen source; and 8.0 g/l for the culture medium containing grape bagasse and corn steep liquor. Glucose, commercial glycerol and cane molasses were also assayed as carbon sources for comparison. The bacterial celluloses produced were characterized by means of scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy and thermogravimetric analysis. Morphological analysis showed that bacterial cellulose microfibrils produced from the non-conventional media used were several micrometers long and had rectangular cross-sections with widths and thicknesses in the range of 35–70 and 13–24 nm, respectively. X-ray patterns showed crystallinity levels in the range of 74–79 % (area method), whereas both X-ray patterns and infrared spectroscopy evidenced the presence of peaks characteristic of Cellulose I polymorph. Besides thermal properties were similar to those found for the pellicle obtained from glucose. The study performed showed the suitability of using wine residues or glycerol remaining from increasing biodiesel production as cheap carbon sources for production of bacterial cellulose microfibrils, with similar characteristics as those obtained by use of more expensive carbon sources such as glucose or commercial glycerol. On the other hand, the low cost nitrogen sources used (corn steep liquor or diammonium phosphate) also contributed to the economy of the bioprocess.

Poly(lactic acid) (PLA) nanocomposite films reinforced with acetylated bacterial cellulose nanoribbons were prepared by solvent casting. Acetylation of bacterial cellulose (BC) was performed by an innovative and sustainable direct solvent-free route catalyzed by citric acid. The effect of derivatization and its extent on the morphological, optical, thermal and mechanical properties of the nanocomposites was analyzed. Data collected from the above studies showed that acetylation of BC nanoribbons clearly improved the nanofibers dispersion in the PLA matrix with respect to unmodified BC, which in turn resulted in increased transparency and mechanical properties of the nanocomposites produced.

Chitosan (0.1 g l(-1)), assayed in a simple medium, reduced the viability of four lactic acid bacteria isolated during the beer production process by 5 logarithmic cycles, whereas activity against seven commercial brewing yeasts required up to 1 g chitosan l(-1). Antimicrobial activity was inversely affected by the pH of the assay medium. In brewery wort, chitosan (0.1 g l(-1)) selectively inhibited bacterial growth without altering yeast viability or fermenting performance.

The use of agroindustrial wastes not only decreases bioprocesses and disposal costs but also contributes to the upgrading of the residues. An active recombinant methanol-inducible bovine chymosin has been expressed in our laboratory in the yeastKomagataella pastoris, and grape pomace extracts (GRE) were proposed as a convenient C-energy source for the biomass production of the genetically engineered strain. Carbon and nitrogen sources, growth factors, and initial pH conditions were selected by classical methodology; thereafter, growth conditions optimization was performed using statistical designed experiments (DoEs). In the presence of (in g·L(-1)) 67.0 monosaccharides (glucose and fructose) from GRE, 5.0 (NH4)2SO4, and 10.0 sugar cane molasses (CMz), a yield of 20.0 g·L(-1) cell dry weight (CDW) was obtained aerobically after 60 h incubation at 28°C and pH 4.0. Applying a fed-batch strategy with methanol:sorbitol as the enzyme inducers, a chymosin production of 8.53 International Milk Clotting Units (IMCU) per mg protein was obtained in the supernatant. The results presented show that through a statistical design, a simple, cheap, and easy to prepare culture medium could be developed using two agroindustrial derivatives (GRE and CMz) to obtain a higher value added product.

The use of agroindustrial wastes not only decreases bioprocesses and disposal costs but also contributes to the upgrading of the residues. An active recombinant methanol‐inducible bovine chymosin has been expressed in our laboratory in the yeast Komagataella pastoris, and grape pomace extracts (GRE) were proposed as a convenient C‐energy source for the biomass production of the genetically engineered strain. Carbon and nitrogen sources, growth factors, and initial pH conditions were selected by classical methodology; thereafter, growth conditions optimization was performed using statistical designed experiments (DoEs). In the presence of (in g·L−1) 67.0 monosaccharides (glucose and fructose) from GRE, 5.0 (NH4)2SO4, and 10.0 sugar cane molasses (CMz), a yield of 20.0 g·L−1 cell dry weight (CDW) was obtained aerobically after 60 h incubation at 28°C and pH 4.0. Applying a fed‐batch strategy with methanol:sorbitol as the enzyme inducers, a chymosin production of 8.53 International Milk Clotting Units (IMCU) per mg protein was obtained in the supernatant. The results presented show that through a statistical design, a simple, cheap, and easy to prepare culture medium could be developed using two agroindustrial derivatives (GRE and CMz) to obtain a higher value added product. An active recombinant methanol‐inducible bovine chymosin has been expressed in our laboratory in the yeast Komagataella pastoris, and grape pomace extracts were proposed as a convenient C‐energy source for the biomass production of the strain. Applying statistical designed experiments, a simple, cheap, and easy to prepare culture medium could be developed using two agroindustrial derivatives (grape pomaces and cane molasses) to obtain higher value added products.

Bacterial nanocellulose (BNC) was used to synthesize rigid polyurethane foams (RPUFs) based on its reaction with the isocyanate precursor (ISO route) and also by using the conventional procedure (POL route). The results indicated that at only 0.1 wt. % of BNC, drastic improvements of specific elastic compressive modulus (+244.2 %) and strength (+77.5 %) were found. The reaction of BNC with the precursor was corroborated through the measurement of isocyanate number and the BNC caused a significant nucleation effect, decreasing the cell size up to 39.7%. DSC analysis revealed that the BNC had a strong effect on post-cure enthalpy, decreasing its value when the ISO route was implemented. DMA analysis revealed that the RPUFs developed using the ISO route proved to have an improved damping factor, regardless of BNC concentration. These results emphasize the importance of using the ISO route to achieve foamed nanocomposites with improved specific mechanical properties.

El artículo presenta el modelo analítico multidimensional Dispositivo Hipermedial Dinámico (DHD) Creativa Monumento para la sostenibilidad de procesos de sensibilización en patrimonio. Dicho modelo tiene como finalidad colaborar en el análisis de las condiciones de co-construcción y sostenibilidad de una red sociotécnica participativa y no excluyente en un contexto patrimonial situado. La metodología implementada interrelacionó cuatro proyectos bajo el enfoque sociotécnico, y se diseñó en tres fases. Primero, se presenta un reestudio de dos casos relacionados con el patrimonio cultural regional de amplia participación comunitaria. Luego, se aborda el diseño modelo. Posteriormente, siguiendo el mismo, se explicita el proceso de co-construcción y acciones de sostenimiento de una red sociotécnica, tomando el caso Monumento Histórico Nacional a la Bandera. Finalmente, se concluye reflexionando sobre cómo seguir pensando la sostenibilidad del DHD Creativa Monumento, considerando las relaciones complejas y las tensiones sociopolíticas e institucionales mediatizadas por las tecnologías y recursos disponibles.