Development of layered BNC composites for Food Packaging

The food industry is increasingly demanding advanced and sustainable packaging materials with improved physical, mechanical and barrier properties. The currently used materials are synthetic and non-degradable, which raises environmental concerns. Research efforts have been made in recent years towards the development of bio-based sustainable packaging materials. One of those is nanocellulose, which have a potential to be used as matrix, as nanofillers or as coatings for composites [1]. A promising material is bacterial nanocellulose (BNC), a biopolymer extruded by Komagaebacter xylinus as a 3D nanofibrillar network. BNC offers interesting properties such as high porosity, biocompatibility, non-toxicity and biodegradability [2]. From a food packaging perspective, BNC has a great potential due to the great mechanical performance. However, the high water affinity of BNC is ta major obstacle for food packaging applications [3]. Therefore, the first task was to develop a layered biodegradable composite based on a plasticized BNC (either with glycerol or polyethylene glycol) and poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), as an attempt to improve the water vapour permeability. The PHBV coating on plasticized BNC reduced significantly the water vapour permeability (from 0.990 to 0.032 g.m.m².day¹.Pa¹), increased the hydrophobicity (contact angle from 10-40° to 80-90°), but decreased the stiffness (from 3.1 GPa to 1.3 Gpa) of the BNC composite. The mechanical and barrier properties of the obtained layered composite were considered suitable for food packaging applications. Although the results obtained being important for food packaging, its commercial use is still far off due to production costs and low production capacity, especially when compared to plant-based nanocellulose [1]. Nevertheless, BNC is a proven material to support substances that play an active/intelligent role in food packaging, with ability to carry and release active substances [4, 5]. Therefore, a functionalized BNC film was developed, by in situ incorporating zinc oxide nanoparticles (ZnONPs). The synthesis of ZnONPs was based on co-precipitation method, using zinc acetate and sodium hydroxide (NaOH) (added dropwise) as reactants. In order to prevent aggregation of ZnO NPs, polyvinyl alcohol (PVOH) was used as capping agent. Overall, dropwise addition of NaOH in zinc acetate-PVOH (with immersed BNC), allowed the production of ZnONPs (144 nm), with low polydispersity index (0.139) and a homogeneous distribution of ZnONPs on the BNC. Concerning the antimicrobial activity, the minimum ZnO dosage for antimicrobial activity was 20%mZnO/mBNCZnO, being effective on gram bacteria (such Escherichia Coli) but only on some gram + bacteria (such Staphylococcus Aureus). The migration of ZnO onto food simulators are under testing.info:eu-repo/semantics/publishedVersio

Nanocellulose bio-based composites for food packaging

The food industry is increasingly demanding advanced and eco-friendly sustainable packaging materials with improved physical, mechanical and barrier properties. The currently used materials are synthetic and non-degradable, therefore raising environmental concerns. Consequently, research efforts have been made in recent years towards the development of bio-based sustainable packaging materials. In this review, the potential of nanocelluloses as nanofillers or as coatings for the development of bio-based nanocomposites is discussed, namely: (i) the physico-chemical interaction of nanocellulose with the adjacent polymeric phase, (ii) the effect of nanocellulose modification/functionalization on the final properties of the composites, (iii) the production methods for such composites, and (iv) the effect of nanocellulose on the overall migration, toxicity, and the potential risk to human health. Lastly, the technology readiness level of nanocellulose and nanocellulose based composites for the market of food packaging is discussed.This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684) and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte.” The authors also acknowledge the financial support of the FCT (ESF) through the grant given to Francisco A.G.S. Silva (SFRH/BD/146375/2019).info:eu-repo/semantics/publishedVersio

Performance of bacterial nanocellulose packaging film functionalised in situ with zinc oxide: Migration onto chicken skin and antimicrobial activity

Supplementary data associated with this article can be found in the online version at doi:10.1016/j.fpsl.2023.101140.Zinc oxide nanoparticles (ZnO) are cost-effective antimicrobial agents with great potential for the active packaging industry. Bacterial NanoCellulose (BNC) features a porous fibre network, with high absorption capacity, flexible and with good mechanical properties, suitable as a carrier of active agents. In this work, BNCZnO films were developed and optimized regarding the particle size and ZnO concentration. The NaOH dropwise addition to BNC membranes immersed in Zn(CH3COO)2-PVOH enabled the production of ZnO nanoparticles with an z-average of 144 nm and a low polydispersity index. High ZnO incorporation (27%mZn/mBNCZnO) was obtained, with uniform distribution all over the BNC membranes. These composites were then characterized and evaluated for Zn migration using food simulants (10%, 20%, and 50% ethanol) with results lower than the limit. Migration into chicken skin, as a real food model, was low at 4 °C but exceeded the migration limit at 10 and 22 °C. Zn migration was also found to be temperature and pH dependent. When applied to chicken skin, BNCZnO was effective against E. coli, Salmonella (0.51.0 log reduction), and Campylobacter spp. (2.0 log reduction), indicating its potential for active packaging applications.The authors appreciate the technical support from CINATE team, especially Susana Teixeira for the assistance in atomic absorption spectroscopy.info:eu-repo/semantics/publishedVersio

Features and performance of edible films, obtained from whey protein isolate formulated with antimicrobial compounds

The goal of this research effort was to assess the efficacy of edible films produced fromwhey protein isolate (WPI) and glycerol, including incorporation of lactic acid (LA) and propionic acid (PRO), chitooligosaccharideswith nominal MW of 3 kDa (COS) and natamycin (NA) as antimicrobial agents. Their features were evaluated in vitro via agar diffusion and viable cell counting, against spoilage microflora often found contaminating cheese surfaces. The effect of incorporating the aforementioned compounds upon thickness, moisture content (MC), solubility (S), density (ρs),water activity (aw) and water vapor permeability (WVP), as well as upon tensile and optical properties of those films were also evaluated. Films formulated with LA, PRO or COS exhibited antimicrobial activity against all microorganisms tested, yet the viable cell count assay was more sensitive and reproducible. COS was the most active against Gram-negative bacteria, whereas LA was the most active against Gram-positive ones. NA was not active against bacteria, but displayed the strongest effect against yeasts. Incorporation of said antimicrobial compounds did not significantly (pN0.05) affect film thickness, yet it significantly (pb0.05) reduced tensile strength (TS). Incorporation of LA and NA in particular did not significantly (pb0.05) affect MC, S, ρs, WVP, elongation at break (EB) and Young's modulus (YM) values; however, a statistically significant increase (pb0.05) of MC, S andWVP, together with a statistically significant decrease (pb0.05) of ρs were attained upon incorporation of PRO or COS. Moreover, PRO produced the highest variation (pb0.05) in EB, TS and YM,whereas COS produced the highest change (pb0.05) in optical properties.info:eu-repo/semantics/publishedVersio

Effect of whey protein purity and glycerol content upon physical properties of edible films manufactured therefrom

This manuscript describes the detailed characterization of edible films made from two different protein products e whey protein isolate (WPI) and whey protein concentrate (WPC), added with three levels of glycerol (Gly) e i.e. 40, 50 and 60%(w/w). The molecular structure, as well as barrier, tensile, thermal,surface and optical properties of said films were determined, in attempts to provide a better understanding of the effects of proteinaceous purity and Gly content of the feedstock. WPI films exhibited statistically lower (p < 0.05) moisture content (MC), film solubility (S), water activity, water vapor permeability (WVP), oxygen and carbon dioxide permeabilities (O2P and CO2P, respectively) and color change values, as well as statistically higher (p < 0.05) density, surface hydrophobicity, mechanical resistance, elasticity, extensibility and transparency values than their WPC counterparts, for the same content of Gly. These results are consistent with data from thermal and FTIR analyses. Furthermore,a significant increase (p < 0.05) was observed in MC, S, WVP, O2P, CO2P, weight loss and extensibility of both protein films when the Gly content increased; whereas a significant decrease (p < 0.05) was observed in thermal features, as well as in mechanical resistance and elasticity e thus leading to weaker films. Therefore, fundamental elucidation was provided on the features of WPI and WPC germane to food packaging e along with suggestions to improve the most critical ones, i.e. extensibility and WVP.Partial funding for this research work was provided by project Milkfilm, administered by Agência de Inovação e POCTI: Programa Operacional de Ciência, Tecnologia e Inovação (Portugal) Funding for author O. L. Ramos was via a postdoctoral fellowship (ref. SFRH/BPD/80766/2011), administered by Fundação para a Ciência e a Tecnologia (Portugal) and supervised by author F. X.Malcata. A minor part of the experimental work was performed in CBQF premise

Comparação dos teores de ácido vacénico em leites de vaca provenientes dos Açores e de Portugal continental

A composição da dieta dos bovinos é crucial na modelação de alguns nutrientes no leite de vaca (1). O ácido vacénico (VA) é um ácido gordo (AG) monoinsaturado com 18 átomos de carbono e uma ligação dupla trans no carbono 11 (C18:1 Δ11t). Este ácido está naturalmente presente na gordura do leite de vaca representando ca 30 % a 50 % do total dos isómeros trans do ácido oleico (C18:1 Δ9c). A gordura do leite é constituída normalmente por cerca de 3 a 6 % de AG trans, sendo o VA o principal AG trans presente no leite de ruminantes (2). É um percursor endógeno, nos ruminantes e humanos, da síntese do ácido ruménico (C18:2 Δ9,11c,t), sendo o isómero mais abundante do AG linoleico conjugado (CLA). O seu impacto na saúde humana tem sido alvo de diversos estudos (3,4). Os AG trans, principalmente C18:1 Δ9t e C18:1 Δ10t, devem ser evitados na dieta humana dado estarem associados a problemas cardiovasculares. No caso específico do VA não há ainda uma clara conclusão relativamente ao seu impacto na saúde apesar de alguns estudos reportarem um efeito benéfico (3,4).O objetivo deste estudo foi avaliar o teor de VA em leites de vaca nacionais, de diferente origem geográfica de produção. As amostras de leite foram recolhidas no mercado, na primavera de 2016. Foram analisados leites UHT meio gordo (MG), com 1,6 % gordura. As amostras foram recolhidas nos Açores (1 marca, 5 lotes) e em Portugal continental (2 marcas, 3 lotes). Para a amostra recolhida nos Açores foi analisado também o leite cru respetivo (4,0 % gordura).Os teores de VA foram determinados por cromatografia gasosa com deteção por ionização de chama (GC-FID), após derivatização (5). O teor de VA (média ± desvio padrão) na gordura do leite nas duas marcas do continente analisadas foi 9,4 ± 0,5 mg/g (n=6) e 8,6 ± 1,1 mg/g (n = 6). Nas duas amostras dos Açores o teor de VA foi de 12,7 ± 1,7 mg/g (n = 10) e 12,8 ± 1,2 mg/g (n = 10) no leite cru e UHT respetivamente. Os resultados indicam que no leite dos Açores o teor de VA não é estatisticamente diferente (P > 0,05) entre o leite cru e o respetivo leite UHT. Na comparação do leite UHT dos Açores com os dois leites UHT do continente verifica-se que existem diferenças com significado estatístico (P < 0,05). O leite UHT dos Açores apresentou teores de VA de 36 % e 48 % superiores aos outros dois leites UHT. Este estudo parece assim indicar que o leite dos Açores apresenta um teor de VA superior ao dos leites do continente e que o tratamento térmico não afetou a composição da gordura do leite em relação ao teor VA.info:eu-repo/semantics/publishedVersio

Quality changes in fresh-cut ‘Rocha’ pear as affected by oxygen levels in modified atmosphere packaging and the pH of antibrowning additive

Respiratory behavior of fresh-cut ‘Rocha’ pear suggests that optimization of O2 concentration inside modified atmosphere packages (MAP) is of limited benefit. To test this hypothesis, packages were designed to achieve three equilibrium O2 partial pressures. Fresh-cut ‘Rocha’ pear was treated with 250 mM calcium ascorbate solutions buffered at pH 3.0 and pH 7.0, packaged under the three MAP conditions, and stored at 5 ◦C for 20 d. Actual O2 levels (mean ± confidence interval at 95%) during the experiment were 16.7 ± 0.2, 1.8 ± 0.2 and 0.25 ± 0.04 kPa with corresponding CO2 levels of 1.3 ± 0.1, 4.3 ± 0.2 and 6.5 ± 0.4 kPa. Changes in quality attributes related to fruit metabolism, namely firmness, titratable acidity, pH, and soluble solids content were not affected by O2 levels. Overall changes in water activity, levels of ascorbate, and microbial growth were also independent of O2 levels. Oxygen partial pressure inside the packages affected browning, which was more intense at 16.7 kPa O2. Sensory analyses performed after 8 d in storage confirmed that panelists perceived the differences in color but did not detect differences in firmness or taste among the samples under different O2 levels. Browning was more intense at pH 3.0 than at pH 7.0 but the kinetics of other quality attributes were not affected by pH. No significant improvements of quality attributes dependent on the physiology of respiration of fresh-cut ‘Rocha’ pear can be obtained by reducing O2 partial pressure inside the packages.info:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/publishedVersio

Optimization of bacterial nanocellulose fermentation using lignocellulosic residues and development of novel BNC-starch composites

[Excerpt] Introduction In the paper industry, significant fraction of fibers that cannot be re‐utilized are wasted by the paper companies, which raise economic and environmental concerns. Unique properties of BNC have sustained promising applications in the biomedical field, pulp and paper, composites and foods. In order to ally the recycling of lignocellulosic residues and the production of BNC, recycled paper sludge (RPS) was enzymatically hydrolyzed to obtain sugar hydrolysates, which were used for BNC production.SkinShip - Dispositivo de microfluídica inovador baseado em celulose capaz de suportar a modelação 3D de pele”, with reference PTDC/BBB-BIO/1889/2014PAC; Multibiorefinery (POCI-01-0145-FEDER-016403), financiado por fundos nacionais através da FCT/MCTES e pelo Fundo Europeu de Desenvolvimento Regional (FEDER), através do Programa Operacional Competitividade e Internacionalização (POCI). This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684) and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte.info:eu-repo/semantics/publishedVersio

Antimicrobial activity of in-situ bacterial nanocellulose-zinc oxide composites for food packaging

Active substances such as zinc oxide nanoparticles (ZnO) have been extensively explored due to their antimicrobial properties, low cost and scalability. Yet, their effectiveness is highly dependent on their morphology and specific surface area. Bacterial nanocellulose (BNC) is a suitable carrier due to its ability to transport and deliver active substances. In the case of nanocellulose-ZnO composites, conclusions drawn from antimicrobial studies are often based on only a few representatives of Gram-positive and Gram-negative bacteria. A more comprehensive study using different species and strains, and different methods to assess antimicrobial activity is required. Therefore, in this work, the antimicrobial activity of ZnO suspensions and BNCZnO films was assessed against a wide range of Gram-negative and Gram-positive bacteria using disc diffusion and viable cell count assays. Regarding the results of the disc diffusion assay, the increase of ZnO content (2127% mZn/mBNCZnO) (in both ZnO suspensions and BNCZnO films), increased antimicrobial activity against all Gram-negative bacteria tested and some Gram-positive bacteria. In the viable cell count assay, BNCZnO films were effective against Escherichia coli (3 log reduction) and Listeria monocytogenes (13 log reduction) after 24 h. Low temperatures reduced the antimicrobial activity of BNCZnO.This article/publication is based upon work co-financed by Fundo Europeu de Desenvolvimento Regional (FEDER), through the Programa Operacional Competitividade e Internacionalizaçao ˜ (POCI), under the scope of the project BIOPROTECT Development of Biodegradable Packaging Material with Active Properties for Food Preservation - POCI-01–0247-FEDER-069858. The authors also thank the scientific collaboration under the FCT project UIDB/50016/2020 and PEst UIDB/04469/2020. The authors also acknowledge the financial support of the FCT (ESF) through the grant given to Francisco A.G.S. Silva (SFRH/BD/146375/2019).info:eu-repo/semantics/publishedVersio