Monitoring of the antimicrobial of food packaging by Raman spectroscopy (Extended abstract)
Authors: Ignacio Mena (1), Alexandra Muñoz-Bonilla (1), Adolfo del Campo (2), Julián J. Reinosa (2,3), Javier Menéndez (3), Claudia Fuente (3), José F. Fernández (2)
Instituto de Ciencia y Tecnología de Polímeros (ICTP-CSIC) C/Juan de la Cierva 3, 28006, Madrid.
Instituto de Cerámica y Vidrio (ICV-CSIC) C/ Kelsen 5, 28049 Madrid.
Encapsulae S.L. C/ Lituania, 10, nave 2 12006 Castellón.
imena@ictp.csic.es, sbonilla@ictp.csic.es, adelcampo@icv.csic.es, jjreinosa@icv.csic.es
jmenendez@encapsulae.com, cfuente@encapsulae.com, jfernandez@icv.csic.es
Below you can read the extended abstract of the publication made by CHARISMA partners which was originally written in Spanish and published in RevistaPlásticosModernos in January 2022.
To access the original version of the article, please click here.
Abstract
CHARISMA Project (Characterization and HARmonization for Industrial Standardisation of advanced MAterials; https://www.h2020charisma.eu) funded by the European Union’s Horizon 2020 research and innovation program (GA 952921) and coordinated by CSIC, aims to harmonise and standardise Raman spectroscopy for characterisation across the life cycle of a material, from product design and manufacture to lifetime performance and end-of-life stage. The project will demonstrate the feasibility of its concept in three industrial cases, one of which is led by Encapsulae S.L. The latter will be focused on active packaging with the purpose of increasing safety and shelf-life. CHARISMA project will develop new polymeric formulation based on recyclable and/or biodegradable polymers and micro/nano-fillers with antimicrobial activity. The resulting active food packaging allows for monitoring its activity, and thereby acts as a food quality and safety control during the whole life cycle (fabrication, storage, delivery and consumption). Besides, CHARISMA aims to evaluate end-of-life products, the reusability, recyclability, compostability and waste will be assessed.
Keywords: Raman spectroscopy, active packaging, antimicrobial activity, sustainability, biopolymers, recyclable, compostable.
Introduction
Food industry is a sector highly connected and affected by society changes, such as pandemics, changes in consumer habits or environmental concerns. Indeed, nowadays, this sector has to face an increasing number of challenges. The population growth is projected to reach more than ten billion inhabitants by 2050 [1]. Thus, food industrial must adapt to achieve a more sustainable production, economically efficient, safe for consumers and with less impact on the environment. In this sense, packaging plays a key role in food industry as prevents waste and ensures desired quality throughout its shelf life. However, still 33% of food produced worldwide is wasted each year, and a total of 3.3 billion metric tons of CO2 equivalent is associated with this wasted food. The globalization of this sector together with environmental and safety concerns have favoured the development of packaging in the last years, with more complex materials and enhanced properties. Polymer-based multilayer packaging significantly extends the shelf life of food and reduces packaging weight; however they are usually landfilled or incinerated due to poor recyclability. Indeed, plastic packaging has a serious impact on environment [2], especially single-use packaging and to those made of various packaging materials which are difficult to recycle. Active packaging is considered an innovative approach to reduce food waste by introducing additional functionality that helps to extend shelf-life while preserving food quality and safety of the packaged food. Active compounds added to the packaging can impart antimicrobial and antioxidant capacity, control humidity and temperature; sequester or release certain gases, among other function. Many innovations and studies in active food packaging have focused on the inhibition or prevention of microbial growth, to avoid microbial deterioration as well as decrease health risks. Nowadays, large number of people, about 23 million people only in Europe, is affected every year by foodborne illnesses, such as Salmonella, Campylobacter jejuni, Norovirus or Listeria monocytogenes [3]. The use of such antimicrobial active packaging also contributes to reduce food waste, but packaging sector still has to face the environmental impact of plastic packaging. Currently, the main plastic materials used in food packaging are derived from petroleum such as polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET) and polystyrene (PS), which are cheap, have good mechanical properties, and effective barrier properties against oxygen, carbon dioxide and water vapor. Although in principle, these materials can be recycled, multilayer packagings used in food industry are normally considered non-recyclable. Then, great part of plastic waste are disposed in landfills, are inadequately incinerated or evade waste management systems ending up in oceans and environment. The food packaging industry is now in pursuit of biodegradable polymers as sustainable alternative to replace conventional plastics. In spite of their high cost of production, and limited properties, bioplastics will certainly influence the packaging sector and its market is expected to growth by following years.
Figure 1. CHARISMA concept applied to active food packaging. Food safety monitoring based on the harmonisation tools by in situ Raman measurements through portable spectrometers.
Objectives
Encapsulae S.L., CHARISMA’s industrial partner, aims to implement the concept developed by Charisma based on the harmonization and standardization of Raman spectroscopy to facilitate the characterization of materials. Encapsulae S.L. will develop recyclable/biodegradable food packaging with antimicrobial additives to prevent and reduce microbial growth in packaged food and thus extend its shelf life. This antimicrobial additive will be used as Raman marker to correlate its Raman fingerprint with the antimicrobial activity and food quality. This correlation will be implemented in a harmonised Raman system that will enable real-time monitoring during the whole product life cycle: fabrication of the active additive, encapsulation into the food packaging material, packed food life-cycle, package disposal/reuse/recycle/biodegradation (Figure 1).
Development of active food packaging
The SME Encapsulae S. L. and the Ceramics for Smart Systems group from Ceramic and Glasses (ICV-CSIC) have developed antimicrobial additives (AS020P and AS030C) for food packaging to control bacterial growth and improve food preservation [4]. The additives are based on activated and ground particles of sodium hexametaphosphate included in EC 1129/2011 food additive list. These technological additives (1%) embedded in a polymer matrix have shown proven activity against pathogenic bacteria such as Campilobacter jejuni, Listeria monocytogenes, Escherichia coli, Staphilococus aureus, Salmonella spp, with bacterial reduction > 99,9%. The additives can be incorporated in the main thermoplastic polymers used in the packaging sector including LDPE, PP, PET, PS and PA, easily processable and recyclable. In CHARISMA project, the sustainability of antimicrobial food packaging will be also approached using biodegradable biopolymers as polymeric matrix. Encapsulae S.L., in collaboration with Macromolecular Engineering group (ICTP-CSIC) and Ceramics for Smart Systems group (ICV-CSIC) have developed biocomposites materials for food packaging by incorporating the antimicrobial additives in biopolymers such as polylactic acid (PLA), polybutyrate adipate terephthalate (PBAT) and polycaprolactone (PCL). Then, these active food packages based on such biodegradable biopolymers also offer unique features for home or industrial composting. In addition to providing antimicrobial properties, the additive AS030C significantly accelerates the disintegration process of the polymeric composites under a composting environment, reaching reduction of plastic waste of 95% in 90 days [5]. Figure 2 displays, as an example, the disintegration of polymeric samples based on a blend of PLA and PBAT, during 90 days at 57ºC under anaerobic composting conditions (according to EN 13432).
Figure 2. Disintegration curves under composting conditions of PLA/PBAT films with and without AS030C additive.
It is clearly appreciated that the incorporation of only 2% of AS030C particles to the polymeric matrix improves significantly the disintegration. During the useful life of the packages, the additive remains inactive and does not affect the mechanical or barrier properties. This activity begins once the packages is subjected to composting conditions. Under these conditions, AS031P additive generates a deficit of negative charges, the polymer chains recombining, therefore, breaks are generated and ends up through hydrolysis mechanisms, decomposing the polymer into much shorter chains that end up transforming into carbon dioxide with the action of compost bacteria.
Characterization of the active food packaging by Raman spectroscopy
The development of active antimicrobial food packaging based on both fossil fuel-derived polymers and biopolymers, avoids microorganism proliferation and extends the shelf-life of foods, contributing to food waste reduction. CHARISMA project also aims to develop harmonisation protocols to standardize and implement Raman spectroscopy in food industry with the purpose of monitoring food safety and quality by using a Portable Raman instrument (Smartphone Raman). Real-time Raman spectroscopy of the developed food packages will contribute to safety and traceability of processed foods along the supply chain and offer improved logistics, thus mitigating environmental impact by reduction of food waste.
These new antimicrobial additives based on sodium hexametaphosphate will act as Raman marker, and their presence or absence in the packaging will be correlated with the antimicrobial activity of the packaging as well as with presence of microorganisms, and then, with the quality and safety of packaged food. Figure 3 shows a Raman mapping of a PLA films containing 1 wt% of AS020P particles and its corresponding Raman spectra.
Figure 3. Raman mapping (XY) of a PLA film with 1% of AS020P particles. Objetive, 20x, 175 µm x175 µm (100 spectra; integration time: 0.2 s; 10 mW).
Therefore, CHARISMA aims to stablish a correlation between Raman spectra of the packaging and food safety across the entire product life-cycle. Likewise, Raman characterization will be implemented to the end-of-life stage, including package disposal, reuse, recycle and compostability in the case of bioplastics. The recyclability of the active packaging obtained from petroleum based polymers will be assessed by correlations between permeability, mechanical features and transparency and Raman features as a function of the number of thermal processing cycles to define the limit of times that the polymer/NMs system can be recycled. As a sustainable alternative, the use of food packages based on such biodegradable biopolymers will contribute to reduce environmental impact of plastic materials. On site Raman data will serve to determine the full compostability/biodegradability of active food packaging under home and industrial composting to ensure the absence of microplastics in the environment.
References
UN, Department of Economic and Social Affairs, Population Division. World Population Prospects. The 2017 Revision: Key Findings and Advance Tables; Working Paper No. EDA/P/WP/248; United Nations: New York, NY, USA, 2017.
Wohner, B.; Pauer, E.; Heinrich, V.; Tacker, M.; Sustainability 2019,11(1), 264; https://doi.org/10.3390/su11010264.
Informe “La carga de las enfermedades transmitidas por los alimentos en la Región Europea de la OMS” presentado por Organización Mundial de la Salud (OMS) el 7 de junio de 2019.
Antimicrobial Composite Material. J. F. Fernández, J. J. Reinosa, A. Moure, J. J. Menéndez. WO2019/234276A1.
Macropartículas de óxido de zinc, método de preparación y uso de las mismas. J. F. Fernández, E. de Lucas, F. Rubio-Marcos. ES 2724825 A1.
