Desenvolvimento de biofilmes para a indústria alimentar

O desenvolvimento de novos conceitos de embalagens para a indústria alimentar, biodegradáveis e utilizando recursos renováveis, e com propriedades mecânicas e de barreira semelhantes às tradicionais, é um desafio premente. Assim sendo, este trabalho teve como objectivo o desenvolvimento de bionanocompósitos de quitosano/montmorilonite incorporados com óleos essenciais (alecrim e gengibre), tendo-se estudado as suas propriedades e a sua ação como embalagem primária na conservação de carne de aves fresca. Os biofilmes de quitosano (um material biodegradável abundante na natureza) foram incorporados com a nanoargila montmorilonite (MMTCa), com vista a melhorar as propriedades mecânicas, e com óleos essenciais, de modo a aumentar a capacidade antimicrobiana e antioxidante dos mesmos. Os filmes foram produzidos através do método casting. Às soluções de quitosano (1,5% m/v) foi incorporado 2,5% de Cloisite®Ca++ (MMTCa) (m/m quitosano). A exfoliação das nanoargilas foi feita através de métodos mecânicos (três ciclos em banho de ultrassons intercalado com agitação em ultra-turrax). Os óleos de alecrim (OEA) e gengibre (OEG) foram incorporados antes do último ciclo de agitação nas proporções de 0,5, 1 e 2%, tendo-se também testado biofilmes sem óleo. Os bionanocompósitos fundidos foram introduzidos em moldes de vidro e secos naturalmente. Biofilmes sem incorporação de MMTCa foram também testados, como controlo. Todos os biofilmes foram caracterizados em termos de propriedades ópticas, humidade, swelling e solubilidade, propriedades mecânicas e análises de migração. Na avaliação da ação dos biofilmes como embalagem primária, a carne de aves fresca foi embalada nos biofilmes e guardada em refrigeração (5 ºC ± 2 °C) durante 15 dias. Ao logo do armazenamento, estudou-se a ação dos biofilmes na carne, tendo-se avaliado características físicas e químicas (pH, acidez, humidade e cinzas, índice de substâncias reativas ao ácido tiobarbitúrico e cor) assim como o grau de contaminação microbiológica (contagem de micro-organismos viáveis totais e coliformes totais), na carne. Testou-se carne sem estar embalada, como controlo. Os biofilmes produzidos resultaram num plástico homogéneo, predominantemente amarelado, flexível e sem grandes variações na espessura. A incorporação de OE e MMTCa nos biofilmes fez com que estes ficassem menos transparentes aumentando assim a barreira à luz ultravioleta. A incorporação de óleos essenciais, sobretudo de OEA, nos biofilmes de quitosano contribuiu para o aumento da migração de compostos com actividade antioxidante. Em termos mecânicos, a adição de OE fez com que os filmes ficassem mais flexíveis e menos resistentes à rutura, com menor swelling e solubilidade. A adição de MMTCa resultou na diminuição da migração de compostos com actividade antioxidante, observando-se uma menor humidade, swelling e solubilidade dos biofilmes. Em termos de propriedades mecânicas, o efeito observado foi apenas significativo no módulo de elasticidade, tendo-se verificado que a incorporação de MMTCa associada à incorporação de óleos resultou em filmes mais flexíveis. No quitosano sem adição de óleos o MMTCa torna o filme mais rígido. Os biofilmes demonstraram ser eficazes no processo de preservação da carne, reduzindo a oxidação lipídica e a contaminação microbiológica, e mantendo a cor, por comparação com os resultados obtidos nas amostras de carne sem proteção. A incorporação de MMTCa e de OE’s (em especial do OEG) contribuiu de forma significativa para o prolongamento da vida útil da carne de frango, tendo-se demonstrado o potencial de aplicação destes biofilmes em embalagens alimentares

Assessment of interventions in fuel management zones using remote sensing

Every year, wildfires strike the Portuguese territory and are a concern for public entities and the population. To prevent a wildfire progression and minimize its impact, Fuel Management Zones (FMZs) have been stipulated, by law, around buildings, settlements, along national roads, and other infrastructures. FMZs require monitoring of the vegetation condition to promptly proceed with the maintenance and cleaning of these zones. To improve FMZ monitoring, this paper proposes the use of satellite images, such as the Sentinel-1 and Sentinel-2, along with vegetation indices and extracted temporal characteristics (max, min, mean and standard deviation) associated with the vegetation within and outside the FMZs and to determine if they were treated. These characteristics feed machine-learning algorithms, such as XGBoost, Support Vector Machines, K-nearest neighbors and Random Forest. The results show that it is possible to detect an intervention in an FMZ with high accuracy, namely with an F1-score ranging from 90% up to 94% and a Kappa ranging from 0.80 up to 0.89.This work is supported by NOVA LINCS (UIDB/04516/2020) and ALGORITMI (UIDB/00319/2020) with the financial support of FCT- Fundação para a Ciencia e a Tecnologia, through national funds; This work is also supported by the project Floresta Limpa (PCIF/MOG/0161/2019

Current Applications of Bionanocomposites in Food Processing and Packaging

Funding Information: This work was supported by the MEtRICs unit, which is financed by national funds from FCT/MCTES (UIDB/04077/2020 and UIDP/04077/2020). This work was also supported by the Associate Laboratory for Green Chemistry—LAQV, which is financed by national funds from FCT/MCTES (UIDB/50006/2020 and UIDP/50006/2020). The authors also acknowledge FCT/MCTES for funding João Pires’ Ph.D. fellowship (SFRH/BD/144346/2019) and Carolina Rodrigues’ Ph.D. fellowship (2020.04441.BD). Publisher Copyright: © 2023 by the authors.Nanotechnology advances are rapidly spreading through the food science field; however, their major application has been focused on the development of novel packaging materials reinforced with nanoparticles. Bionanocomposites are formed with a bio-based polymeric material incorporated with components at a nanoscale size. These bionanocomposites can also be applied to preparing an encapsulation system aimed at the controlled release of active compounds, which is more related to the development of novel ingredients in the food science and technology field. The fast development of this knowledge is driven by consumer demand for more natural and environmentally friendly products, which explains the preference for biodegradable materials and additives obtained from natural sources. In this review, the latest developments of bionanocomposites for food processing (encapsulation technology) and food packaging applications are gathered.publishersversionpublishe

Application of Biocomposite Films of Chitosan/Natural Active Compounds for Shelf Life Extension of Fresh Poultry Meat

Publisher Copyright: © 2022 by the authors.Active packaging based on chitosan (Ch) incorporated with six different natural hydro-alcoholic extracts (HAE) (rosemary, green tea, black tea, ginger, kenaf, and sage) were developed and tested to extend the shelf life of fresh poultry meat. The quality of the meat packaged was assessed through physical-chemical and microbiological characterization over 15 days of refrigerated storage. In vitro antimicrobial activity of pure extracts and films against Gram-positive (B. cereus) and Gram-negative (S. enterica) foodborne bacteria was also addressed. Pure extracts and the films developed showed antimicrobial activity by the diffusion agar method only against the Gram-positive bacteria. Microbial analysis of the meat wrapped with films incorporated with HAE showed a reduction of 3.1–4.5 log CFU/g and 2.5–4.0 log CFU/g on the total viable microorganisms and total coliforms, respectively. Ch + Kenaf and Ch + Sage films presented the highest antimicrobial activity. Regarding the oxidation degradation, as expected, TBARS values increased for all samples over time. However, the meat wrapped in the biocomposites, except for CH + Sage, presented lower secondary oxidation metabolites (reduction of 75–93%) in the content of malonaldehyde. This protection was superior for the meat wrapped with Ch + Rosemary. Active film also showed promising results by retarding the discoloration process and the increase of pH over time. Thus, the biocomposites produced can pose as an alternative technology to enhance the shelf life of fresh poultry meat and maintain its quality.publishersversionpublishe

A Contribution to the Bio and Circular Economy

and Cássia H. Barbosa’s Ph.D. fellowship (2021.08154.BD). MMA thanks the Instituto Superior Técnico for the Scientific Employment contract (contract No: IST-ID/154/2018) under Decree-Law No. 57/2016 and 57/2017. Publisher Copyright: © 2023 by the authors.The development of innovative/sustainable materials capable of enlarging the shelf-life of food products has lately been a focus of research, aiming to reduce food waste. Due to their good antimicrobial properties, zinc oxide nanoparticles (ZnO NPs) can add activity to food packaging, improving its performance. Furthermore, these nanoparticles are considered GRAS by the Food and Drug Administration (FDA), which represents an advantage in their application. Through an innovative and sustainable approach using tomato and passionfruit extracts, ZnO NPs were produced and incorporated into pectin films. The resulting bionanocomposites were tested for their activity via in situ studies, using fresh poultry meat as a food matrix. Overall, the bionanocomposites presented good antimicrobial activity, with the intrinsic antimicrobial properties of pectin having shown to be enhanced by the incorporated ZnO NPs. When used as primary packaging for the meat, the deterioration rate of the poultry meat, measured through microbiological growth and total volatile basic nitrogen content, was reduced. However, the nanoparticles contributed to the increment of discoloration and meat oxidation processes. Nonetheless, it can be concluded that fresh poultry meat protected with the bionanocomposites presented an extension of its shelf-life time, and it was confirmed that this eco-friendly packaging has potential to be employed by the food industry.publishersversionpublishe

Strategies to Improve the Barrier and Mechanical Properties of Pectin Films for Food Packaging: Comparing Nanocomposites with Bilayers

2020.04441.BD SFRH/BD/144346/2019 UIDB/50006/2020 UIDP/50006/2020 UIDB/04077/2020 UIDP/04077/2020 UIDB /00100/2020Traditional food packaging systems help reduce food wastage, but they also produce environmental impacts when not properly disposed of. Bio-based polymers are a promising solution to overcome these impacts, but they have poor barrier and mechanical properties. This work evaluates two strategies to improve these properties in pectin films: the incorporation of cellulose nanocrystals (CNC) or sodium montmorillonite (MMT) nanoparticles, and an additional layer of chitosan (i.e., a bilayer film). The bionanocomposites and bilayer films were characterized in terms of optical, morphological, hygroscopic, mechanical and barrier properties. The inclusion of the nanofillers in the polymer reduced the water vapor permeability and the hydrophilicity of the films without compromising their visual properties (i.e., their transparency). However, the nanoparticles did not substantially improve the mechanical properties of the bionanocomposites. Regarding the bilayer films, FTIR and contact angle studies revealed no surface and/or chemical modifications, confirming only physical coating/lamination between the two polymers. These bilayer films exhibited a dense homogenous structure, with intermediate optical and hygroscopic properties. An additional layer of chitosan did not improve the mechanical, water vapor and oxygen barrier properties of the pectin films. However, this additional layer made the material more hydrophobic, which may play an important role in the application of pectin as a food packaging material.publishersversionpublishe

Eco-friendly ZnO/chitosan bionanocomposites films for packaging of fresh poultry meat

UID/EMS/04077/2019 UID/QUI/50006/2019 UID/QUI/00100/2019 Contrato No: IST-ID/154/2018) under Decree-Law No. 57/2016 and 57/2017.The advances on the development of novel materials capable to enhance the shelf life of food products may contribute to reduce the current worldwide food waste problem. Zinc oxide nanoparticles (ZnO NPs) are considered GRAS (Generally Recognized as Safe) by the Food and Drug Administration (FDA) and due to their good antimicrobial properties are suitable to be applied as active compounds in food packaging. ZnO NPs were synthesized to be tested in active bionanocomposites through an eco-friendlier route using apple peel wastes. This work aimed to develop bionanocomposites based on chitosan and incorporated with ZnO NPs to characterize its bioactivity via in vitro and in situ studies, using fresh poultry meat as the food matrix. Overall, bio-based biodegradable films presented good antimicrobial activity, being the intrinsic antimicrobial properties of chitosan enhanced by the ZnO NPs added on the system. When used as primary packaging of the meat, the samples protected with the films presented a decrease on the deterioration speed, which was represented by the preservation of the initial reddish color of the meat and reduction on the oxidation process and microbiological growth. The nanoparticles enhanced especially the antioxidant properties of the films and proved to be potential food preservatives agents to be used in active food packaging.publishersversionpublishe

Physical and morphological characterization of chitosan/montmorillonite films incorporated with ginger essential oil

This work was supported by CNPq - Brazil (grant number 200790/2014-5) and the MEtRICs unit which is financed by national funds from FCT/MCTES (UID/EMS/04077/2019). This work was also supported by the Associate Laboratory for Green Chemistry-LAQV which is financed by national funds from FCT/MCTES (UID/QUI/50006/2019) and UCIBIO, which is funded by national funds from FCT/MCTES (UID/Multi/04378/2019). It is also acknowledged the funding of CENIMAT by FEDER through the program COMPETE 2020 and National Funds through FCT-Portuguese Foundation for Science and Technology, under the project UID/CTM/50025/2019.Novel bionanocomposite films of chitosan/montmorillonite (CS/MMT) activated with ginger essential oil (GEO) were produced and characterized in terms of their physical and morphological properties. The homogenization process led to a good interaction between the chitosan and the nanoparticles, however the exfoliation was diminished when GEO was incorporated. Film glass transition temperature did not statistically change with the incorporation of either MMT or GEO, however the value was slightly reduced, representing a relaxation in the polymer chain which corroborated with the mechanical and barrier properties results. Pristine chitosan films showed excellent barrier properties to oxygen with a permeability of 0.184 × 10-16 mol/m·s·Pa being reduced to half (0.098 × 10-16 mol/m·s·Pa) when MMT was incorporated. Although the incorporation of GEO increased the permeability values to 0.325 × 10-16 mol/m·s·Pa when 2% of GEO was integrated, this increment was smaller with both MMT and GEO (0.285 × 10-16 mol/m·s·Pa). Bionanocomposites also increased the UV light barrier. Thus, the produced bioplastics demonstrated their ability to retard oxidative processes due to their good barrier properties, corroborating previous results that have shown their potential in the preservation of foods with high unsaturated fat content.publishersversionpublishe

Atividade "Tinkering" uma ferramenta para a inclusão social

O Projeto C4 – Crianças C com Ciência baseia-se na apropriação pelas crianças C de conceitos científicos e tecnológicos, não pela aquisição de conhecimentos per se mas sim pelo despertar do interesse para esses conceitos e pela pertinência e necessidade da sua aquisição. Durante o ano letivo 2017/2018 desenvolveram-se sessões de Tinkering com duas turmas de 1º ano da Escola da Lejana, em Faro. A avaliação feita na escola deu resultados bastante positivos, ainda sustentados pelo êxito das atividades desenvolvidas pelas crianças de etnia cigana para a comunidade em geral (https://www.facebook.com/criancasccomciencia/). Esta apresentação consiste assim num balanço final do referido projeto nas diferentes vertentes comportamentais, sociais e científicas, que o mesmo abordou através das atividades realizadas.Projeto financiado pelo programa INTEGRA, da Agência Nacional Ciência Viv