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ENVIRONMENTAL ASSESSMENT OF A MULTILAYER POLYMER BAG
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FOR FOOD PACKAGING AND PRESERVATION: AN LCA APPROACH
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Valentina Siracusa1, Carlo Ingrao2, Agata Lo Giudice3*, Charles Mbohwa3 and Marco Dalla Rosa4
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Department of Industrial Engineering (DII), University of Catania, Viale A. Doria 6, 95125 Catania, Italy.
Tel +39.095.7382755, e-mail: vsiracus@dmfci.unict.it
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Department of Civil and Environmental Engineering (DICA), University of Catania, Viale A. Doria 6,
95125 Catania, Italy. Tel: +39.392.0749606, e-mail: ing.ingrao@gmail.com
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Department of Quality and Operations Management, Faculty of Engineering and the Built Environment,
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University of Johannesburg, APB Campus, P. O. Box 524, Auckland Park 2006, Johannesburg, South
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Africa. Tel. +27.11.5591205, email: agatalogiudice@libero.it*; cmbohwa@uj.ac.za
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Alma Mater Studiorum, Department of Food Science, University of Bologna, Piazza Goidanich, 60, 47521,
Cesena (FC), Italy. Tel: +39.0547.338147, e-mail: marco.dallarosa@unibo.it
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ABSTRACT
A screening of LCA for the evaluation of the damage arising from the life cycle of a bi-layer film bag for
food packaging was carried out. Such packages are made of films obtained matching a layer of PA
(Polyamide) with one of LDPE (Low-Density Polyethylene) and are mainly used for vacuum or modified
atmosphere packaging and preservation of food. The study was conducted in accordance with the ISO
standards 14040: 2006 and 14044: 2006 choosing, as the functional unit, 1 m2 of plastic film delivered to the
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food production and packaging firms. The system boundaries go from cradle to factory-gate and include the
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phases of: the raw materials production and processing for the bag manufacturing; and the bag delivering to
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the food production and packaging plant. The damage assessment showed that the most impacting phases are
the production of the Polyamide (PA6) and Low-Density Polyethylene (LDPE) granules due to the
consumption of primary resources, such as natural gas and crude oil, in the amount of 53.55 dm3 and 132.42
g respectively, and to the emission in air of 295.73 g of carbon dioxide, 617 mg of nitrogen oxides, 12.1 mg
of particulates, 349 mg of sulphur dioxide and 2.51 mg of aromatic hydrocarbons. The most affected damage
category is Resources, followed by Climate Change, Human Health, and Ecosystem Quality. For minimizing
the total damage associated with the life cycle of the examined bag, the film thickness thinning and the use
of a recycled PA granule were considered: the assessment showed that the two proposals allowed a reduction
of about 25% and 15% (respectively) of the damage assessed.
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Keywords: Life Cycle Assessment, environmental sustainability, food packaging, improvement hypothesis,
multilayer polymer film
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1. INTRODUCTION
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A sustainable production of goods involves the definition and the design of all their life cycle phases, as the
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technologies and the materials used for the production may adversely affect the environmental quality of the
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other phases, such as the use and the end of life. In this context, the Life Cycle Assessment (LCA)
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methodology can be used in parallel with the design for finding and assessing technical solutions which can
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be adopted in the production for reducing the impacts due to the abovementioned other phases. For better
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understanding this, it is enough to observe, for instance, that: using low-thickness multilayer films and PET
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(Polyethylene Terephthalate) bottles, respectively for food and beverages packaging, allows for a reduction
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of the environmental cost due to the phases of transportation to the food production and packaging plant,
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handling and dismantling; equipping a building envelope with a high thermal resistance insulating material
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leads to a reduction of the environmental impacts linked to the heating and cooling phase, such as CO248
emissions and fossil fuels consumption. For better understanding LCA, environmental impact and
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sustainable development are believed to be the two key concepts of this methodology. The first because the
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methodology application involves the quantification of the environmental impacts associated with each
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phase characterizing the life cycle of a given product or process. The second because, once the Life Cycle
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Impact Assessment (LCIA) is done, the possible improvement solutions can be evaluated, in order to
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guarantee the environmental sustainability of the product throughout its life cycle (Heijungs et al., 1992;
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Zufia & Arana, 2008; Roy et al., 2009; Lo Giudice et al., 2013 a & b). In other words, the aim is to achieve
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the balance, between technological innovation and environmental protection, which sustainable development
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is based on (Chandra, 1991; Schmincke & Grah, 2007). Packaging systems are designed for maintaining the
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benefits of food processing after the process is complete, enabling foods to travel safely for long distances
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from their point of origin and still be wholesome at the time of consumption (Marsh & Bugusu, 2007). From
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an environmental perspective, they affect, more or less significantly, the life cycle of a food because of the
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impacts linked to their production, transportation and disposal (Andersson et al., 1998; Andersson &
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Ohlsson, 1999; Deckers et al., 2000; Keoleian et al., 2004; Humbert et al., 2009; Banar & Çokaygil, 2009).
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For this reason, a package design must be carried out considering not only the issues of cost, shelf-life, safety
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and practicality, but also of environmental sustainability (Leceta et al., 2012; Zampori & Dotelli, 2013). In
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this context, LCA can be applied as a design-support tool for highlighting environmental criticalities and
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improvement solutions in the life cycle of packages, thereby promoting the use of more eco-friendly
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products. Over the years, this methodology has proved in fact to be a valuable tool for analysing
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environmental considerations of product and service systems which need to be part of decision making
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process towards sustainability (González-García et al., 2009). In this regard, the present work aims at
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investigating, from an environmental point of view, the packagingi and, in particular, the one of multilayer
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films. In recent years, these film types have gained importance in many applications, especially in the food
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industry, where they are mainly applied for packaging products, such as fresh pasta, meats, cheese and cut
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vegetables so that goods shelf-life can be extended (Vidal et al., 2007). The study deals with a bi-layer film
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bag for food packaging and preservation with the aim of assessing the environmental impacts due to its
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“from-cradle-to-gate” life cycle and the solutions needed for reducing them. For this purpose, LCA was
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considered a valid tool to be used because, as defined by the International Organization for Standardization
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in the ISO 14040:2006 (ISO, 2006a), it is the compilation and evaluation of the inputs, outputs and the
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potential environmental impacts of a product system throughout its life cycle. The films composing the bag
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in question are made of layers of PA (Polyamide) and LDPE (Low-Density Polyethylene) and are mainly
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used for vacuum or modified atmosphere packaging and preservation of food, such as meat, cheese, fish and
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fresh pasta. The study is the result of collaboration with a Firm, located in the Northern Italy, working in this
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field and sensitive to environmental issues, which provided the research group with all the necessary
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technical support and supplied all the requested data about the bag production. Furthermore, the study arises
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from a previous one presented at the “11th International Congress on Engineering and Food Science”
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(Siracusa et al., 2011) regarding the application of LCA for investigating the multilayer polymer packaging85
film production field and, in particular, for assessing the damage reduction when using a recycled material.
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According to the authors, this hypothesis turned out to be effective, in terms of purpose achievement and
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environmental sustainability level increase and was tentatively applied to both the LDPE and PA granules
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using a 50% recycled material. In the occasion of writing the present paper, this percentage was reconsidered
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since believed too optimistic and then it was lowered to 25%, deciding to better apply it only to the PA layer,
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since not in contact with the food inside. Different percentages are applicable nowadays in the use of
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recycled polymers for food packaging-systems manufacturing, i.e. 10%, 25%, 50%, 75% and 100%,
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depending on the given application. For instance, Chytiri et al. (2008) used 50% and 100% recycled LDPE
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for testing radiolysis products and sensory changes of five-layer food-packaging films. In the present case, a
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25% recycle was environmentally assessed since, according to the Firm technicians, it is, currently, the only
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one to be compatible with the type of package, with the function it has to perform and with the current
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manufacturing technology. The Firm has in fact already begun using this percentage after having developed
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appropriate tests for verifying its technical feasibility. Both of the two studies analyse the same type of
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product, in terms of manufacturing techniques and input materials. They also present the same functional
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unit, quality and type of inventory data, LCIA development criteria and method. On the contrary, the system
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boundaries are different as, in the present study, they go from bag cradle to bag manufacturing plant gate,
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without encompassing the end of life phase. Finally, in the present case, the LCIA results were reported and
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discussed with a higher rank of detail and the film thickness reduction was evaluated as improvement
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solution together with the recycled granule use.
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2. THE USE OF LCA IN THE FOOD-PACKAGING FIELD
According to Meneses et al. (2012), food products today are offered to consumers in a wide range of
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packaging alternatives in terms of materials used, forms and sizes. There are a number of important factors to
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be considered in the food packaging field, such as food quality and freshness conservation, a pleasant image,
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good marketing appeal, correct product identification, storage and distribution convenience (Meneses et al.,
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2012; Williams & Wilkström; 2011). Additionally, a package should be designed considering also the
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environmental issues associated to its life cycle. For this purpose, LCA could be used during the design
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phase for having a complete and detailed view of the main environmental hotpots related to the life cycle of a
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given packaging system.
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One the first studies concerning the application of LCA on food packaging was developed by Zabaniotou &
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Kassidi (2003) for comparing, from an environmental point of view, the use of polystyrene (PS) and recycled
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paper in the production of six-egg packages. According to the authors, at that time, LCA had not reached yet
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its full potential in environmental decision-making, but it was considered a useful tool for lots of
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applications, such as product development, environmental policy setting and different products
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environmental comparative assessment. Since then, LCA has been gaining more and more importance as a
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support-tool in the process of decision-making when a product’s environmental aspects are taken into
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account. Simultaneously, the application of LCA for the environmental assessment of food packaging
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systems has been increasing so much that packaging has become in fact one of the most investigated fields
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from an LCA perspective. For instance, in 2009, Busser & Jungbluth (Busser & Jungbluth, 2009) assessed
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the environmental performance of flexible packaging in the life cycle of food-products, such as coffee and
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butter, while Humbert et al. (Humbert et al., 2009) developed a study regarding the application of LCA for
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comparing glass jars and plastic pots, commonly used for the baby food packaging. Two years later,
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Silvenius et al. (2011) applied LCA to packed-food products developing a series of case studies where
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environmental impacts of different food packaging options were investigated. According to Williams &
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Wilkström (2011), a package can be difficult to empty and thereby it can cause food losses. From this
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concept, the authors developed a study for modelling the balance between food losses and packaging systems
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environmental impacts. Recently, Zampori & Dotelli (2013), focussed on the application of LCA to two
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different packaging systems of a poultry product, considering, in particular, a polystyrene-based tray and an
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aluminium bowl. It’s a common knowledge that different materials can be used in this field depending on the
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type of food which is intended to be packed and preserved. Among them, biodegradable polymers are worth
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to be mentioned since their use has recorded a significant increase over the years. It should be noted for
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instance that Vidal et al. (2007) applied LCA for evaluating the environmental sustainability of
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biodegradable multilayer films, composed of two external layers of PLA (polylactide acid) and an inner one
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of modified starch with polycaprolactone (PCL). This film-type was compared with a conventional one
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characterized by the following stratigraphy: polypropylene (PP) – polyamide (PA6) – polypropylene (PP).
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For this assessment, climate change, fossil fuels depletion, acidification and eutrophication were chosen as
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the most significant environmental impact categories. Six years later, the Journal of Cleaner Production
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published the paper of Leceta et al. (2013) dealing with a comparative LCA of two different food-packaging
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systems, namely a commercial food packaging based on polypropylene (PP) and a new biodegradable
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chitosan-based film. The last two papers were useful for better interpreting the results obtained from the
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present study, as highlighted in the comparative analysis reported in paragraph 4.2 “Life Cycle
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Interpretation”. The paper developed by Siracusa et al. (2008) is also worth to be mentioned since believed
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very useful for entering into the merits of the production and use of biodegradable materials. In their
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manuscript, the authors developed in fact a review aiming at offering a complete state of the art on
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biodegradable polymer packages for food applications. Regarding the food packaging and preservation
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technologies, it was decided to mention and discuss in brief the work developed by Pardo & Zufia (2011)
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about the application of LCA for defining and presenting environmental criteria usable when selecting
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preservation methods for foods. For this study, four thermal and non-thermal techniques, such as autoclave
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pasteurization, microwaves, High Hydrostatic Pressure (HPP) and Modified Atmosphere Packaging (MAP),
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were examined. A realistic shelf-life period was considered for guaranteeing the food-content commercial
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purpose, thereby defining a 30-day threshold. It should be noted that MAP is a food preservation technology
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which can be used in combination with multilayer-film packages. LCIA showed that lower water
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requirements were observed for non-thermal technologies (MAP, HPP) when compared to equivalent
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thermal processes. MAP was found to be the most sustainable solution when a shelf life period below 30
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days is required. The study highlighted the importance of resorting to low environmental impact food
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preservation technologies maintaining food safety by reasonable periods of time. From this point of view, the
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results of this paper are believed to give strength to the goal and the outcomes applicability of the present
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study. If such technologies, MAP for instance, were combined in fact with low-impact packaging systems, an
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increase of the entire food packaging and preservation solution environmental sustainability would be
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recorded. In addition to this, if the food contained was produced using low environmental impact processes
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and products, the entire packed-food would be more eco-friendly.
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That is why it is important to identify how the different stages in the life cycle of food contribute to the
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environmental impact so that more sustainable production can be developed and users can be encouraged to
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consume in a more environmentally friendly way (Meneses et al., 2012).
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In this regard, thanks to the abovementioned studies, it was possible to observe that the contribution due to
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packaging phase, in terms of environmental impact, can be reduced adopting solutions oriented towards
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materials use and energy consumption optimisation. Furthermore, it was observed that multilayer film
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packaging production has been already environmentally assessed in a number of studies, but not as done in
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the present assessment in terms of type of package (bag) and of film stratigraphy. It is believed that this
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aspect highlights the originality of the subject of the present assessment, adding value to the whole study.
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3. MATERIALS AND METHODS
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As reported in the “Handbook on Life Cycle Assessment” (Guinée et. al., 2002), LCA is a methodology for
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the comprehensive assessment of the environmental impact associated with a product or process throughout
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its life cycle (from extraction of raw materials to product disposal at the end of use). The study was
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developed according to the requirements of the ISO standards 14040:2006 and 14044:2006 (ISO, 2006b)
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dividing it in the following phases: Goal and scope definition, which includes the purpose of the study, the
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description of the expected product of the study, system boundaries, functional unit (FU) and assumptions;
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Life Cycle Inventory (LCI) analysis: this phase involves the compilation and quantification of both input and
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output flows and includes data collection and analysis; Life Cycle Impact Assessment (LCIA): thanks to this
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phase, based on the inventory analysis results, it is possible to qualify, quantify and weigh the main
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environmental impacts linked to a product life cycle; Life Cycle Interpretation, in which the results from the
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impact assessment and the inventory analysis are analysed and interpreted for establishing recommendations
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oriented to the total damage reduction. In accordance with the ISO standards 14040:2006 and 14044:2006,
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the phase of Life Cycle Impact Assessment was carried out including both the mandatory elements
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(Classification, Characterization and Damages Evaluation) and the optional ones (Normalization and
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Weighing). In this way, results could be expressed with equivalent numerical parameters (points) so as to be
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able to represent quantitatively the environmental effects of the analysed system. Damage and impact
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categories, processes, and both emitted-substances and used-resources can be easily compared to each other
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based on the damage unit-point. All the on-site collected data (primary data) were uploaded into Simapro 7.1
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software (SimaPro, 2006) accessing the Ecoinvent v.2.2 database (Ecoinvent, 2010) (See paragraph 3.2 for
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further details). For the development of the LCIA phase, choosing the method to use from the most common
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ones was difficult, since each of them has good characteristics but, at the same time, some limits (Udo de
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Haes et al., 1999). In addition, they were all not perfectly suitable for the Italian context in which the system
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under study is placed. After developing a detailed analysis, the Impact 2002+ method was chosen for the
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assessment. According to the ILCD Handbook “Analysis of existing Environmental Impact Assessment
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methodologies for use in Life Cycle Assessment (LCA)”, it proposes a feasible implementation of a
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combined midpoint/damage approach, linking all types of Life Cycle Inventory results (elementary flows
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and other interventions) via 14 midpoint categories to four damage categories. Furthermore, the method
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calculates the non-renewable energy consumption, which represents a fundamental aspect of such studies
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and it recognises carbon dioxide as having the greatest responsibility for the greenhouse effect, considering it
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as a characterization of Climate Change (Jolliet et al., 2003). Finally, its set-up is believed to be more
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comprehensible for insiders and it is also more accessible with respect to other methods. In Table 1 the
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distinction between the damage and the impact categories, provided by Impact 2002 +, is reported: the
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impact categories represent the negative effects to the environment, through which the damage, due to an
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emitted substance or a used resource, occurs. The damage categories are obtained by grouping the impact
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categories and they represent the environmental damage areas (Jolliet et al. 2003).
Table 1 Impact and damage categories contemplated in Impact 2002+
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Damage Category
Human Health
Ecosystem Quality
Climate Change
Resources
Impact Category
Carcinogens
Non-carcinogens
Respiratory inorganics
Respiratory organics
Ionizing radiations
Ozone layer depletion
Aquatic eco-toxicity
Terrestrial eco-toxicity
Terrestrial acidification/nitrification
Aquatic acidiphication
Aquatic eutrophication
Land occupation
Global warming
Non-renewable energy
Mineral extraction
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3.1 Goal and scope
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For its correct development, any LCA analysis must be preceded by an explicit statement of the study’s goal
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and scope that, as stated by the ISO Standards must be clearly defined and be consistent with the application
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intended (Baldo et al., 2008). In particular, the goal of an LCA study must state, unambiguously, what the
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application and the motivation of the study and the type of target audience are.
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In this context, the goal of this study is to apply the LCA methodology for identifying and analysing the
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main environmental impacts associated with the “from cradle to gate” life cycle of vacuum bags used for
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food packaging and preservation under ambient or refrigerated condition of storage. Furthermore, the study
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will allow the identification of measures, techniques and strategies oriented to obtain an eco-designed bag
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using fewer resources and producing less waste and emissions throughout its whole life cycle, while
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maintaining the food quality to desired levels. The study arises with the purpose of pure scientific research
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and targets people working in the LCA sector, as well as in the food packaging one, in order to inform them
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about the environmental impacts linked to such products and to indicate the improvement solutions for
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reducing them. In this context, this study can contribute to increasing the knowledge on LCA in this field
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allowing useful comparisons with products of equal manufacture and function. The results from some of the
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studies mentioned in paragraph 2 will be briefly discussed in paragraph 4.2 and compared to those obtained
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from the present analysis. Furthermore, the development of this study was the occasion that the Firm had for
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re-examining the merits of the environmental issues associated not only with the production but also with the
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life cycle of its products. This allowed the Firm itself to identify not only the environmental hotspots of the
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whole packaging production system, but also the ways that can be used for minimising them. A number of
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multi-layer packaging products could be studied and solutions produced. This study focussed on a type of
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food packaging bag, produced by thermo-sealing two bi-layer films, with a total thickness of 85 microns.
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This product was chosen, because it represents the core-business of the Firm’s entire food packaging
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production. Such products are commonly used for the vacuum and modified atmosphere packaging of
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different kinds of fresh food. The outer layer in oriented PA provides high mechanical strength and creates a
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high barrier to oxygen, main gases and aromas. This layer is characterized by a certain brilliance and
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transparency which allows consumer to verify the quality of the food at the time of purchasing. The PE layer
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provides an excellent performance during the thermo-sealing phase and is a high barrier to the passage of
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moisture.
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Functional Unit (FU) and system boundaries
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In order to provide a reference to link all input and output data and to assure the results comparability,
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according to the ISO 14040:2006 and 14044:2006, it is necessary to choose, a Functional Unit (FU). In the
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present study, it was identified with 1 m2 of plastic film delivered to food production and packaging
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Companies. Regarding the system boundaries, they were appropriately defined so as to create a process-
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model as close as possible to reality. The following phases were included: a) production of the raw materials
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used for the bag production; b) bag production; and c) the transportation to the food production and
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packaging plant. On the contrary, it was decided to exclude the use of the bag for packaging the food,
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because no environmental impacts are believed to be attributable to this phase. As a matter of fact, once
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transported to the food production and packaging plant, the package enters into the packed-food production
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as an input material at all effects. It is used as such, consequently accounting for all the environmental
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impacts linked to its life cycle. The food content production was excluded, because the package can be for
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any type of food. Moreover, the transportation of the packed-food from the production and packaging plant
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to the distribution centres and then to the final user have not been taken into account, because considered not
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easy to quantify due to their location variability. The polymer granule production, through the recycle of the
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films matching and thermo-sealing process waste was taken into account including the transportation to the
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respective recycling plants. On the contrary, the granules processing for producing garbage bags was
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excluded for avoiding an excessive expansion of the system boundaries. Regarding the bag end-of-life, as
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observed by the Firm technicians, contrary to what happens to the scrap produced during the heat sealing
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process, in this case, the environmental management system provides that the bag is disposed of in a local
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sanitary landfill. This is because the prolonged contact with the oily substances, as typical for the food
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normally contained, leads to the exclusion of the recycling treatment. According to Siracusa et al. (2011), the
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landfill scenario is contributing only for 4.8% and so it is believed not a significant source of environmental
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impact compared to the bag production. The low percentage indicated above is attributable to the fact that
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the environmental impacts associated to the landfill plant, considering its shelf-life and the tons of municipal
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waste that it is used for, is proportioned to the bag considered. For this reason, the end of life was excluded
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from the system boundaries, thereby focussing attention on the most impacting phases.
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3.2 Inventory analysis and data collection
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This phase analysis quantifies the use of resources and materials and the consumption of energy, as well as
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the involved transportations associated to a product life cycle (Lo Giudice et al., 2013a). For a correct
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development of the inventory analysis, the bag production process was studied in detail (Fig. 1). This was
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possible thanks to the support of the Firm involved which provided not only all the necessary data and
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information, but also let the researchers visit the production plant and interview the Technical Department
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staff. This allowed the understanding of the multilayer films packaging production process and the
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development of a study of better scientific value and reliability. All the main activities and materials within
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the system boundaries were indicated, including those not belonging to the bag production process. For this
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phase, since a particular specialised production system was assessed, great importance was given to using
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primary data, in other words specific data supplied by the Firm. The processes used for representing the
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consumption of resources, materials and energy, as well as the use of transport means, were extrapolated
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from Ecoinvent v.2.2, because believed a reliable background data source. The data collection was carried
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out continuously accessing the Ecoinvent v.2.2 database within the SimaPro software in the 7.1 version for
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verifying what processes and raw materials were necessary to be created since not already existing. From this
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analysis, it was resulted that all data needed was already included within Ecoinvent, thereby avoiding
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creating new items or making assumptions and hypothesis for using background data within the database. As
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shown in Fig. 2, the bag is produced by heat-sealing two films, previously obtained by matching a layer of
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PE with one of PA; such layers have different thickness and surface weight (PE: 65 µm, 64.4 g/m2bag; PA:
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20 µm, 23 g/m2bag). Furthermore a detail of the involved transports is reported in it.
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Fig. 1. System boundaries
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Each thin film (layer) is produced by granule extrusion: such process implies a scrap of about 5% which is
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purified and reused by the Firm itself. Once the bi-layer film is produced by flat-head extrusion, generating
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5% scrap, the next step is the thermo-seal. This process is realized by high efficiency machines in order to
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reduce the scrap to between 2% and 2.5 %. For both processes, the generated scrap is stored in roll-off boxes
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and transported by truck to local mixed plastic recycling plants where it is re-processed for producing
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garbage bags. The production of the PA-PE type stratigraphy films and of the bags is done in two different
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Firms. The average transportation distance for the granules from the production site to the extrusion plant
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where the layers are produced and matched is 700 km. The transportation distance of the bi-layer films to the
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thermo-sealing plant where the bags are produced is 500 km. Once the bag is manufactured, it is sold to food
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producers and used for the food packaging: in this study, for taking into account the contribution of
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transportation, a value calculated as weighted average was used. This was done considering all the distances,
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between the bag manufacturing plant and those of production and packaging of food, not only in terms of
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travelled kilometres, but also in terms of frequency of travelling resulting in an average weighted value of
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about 850 km. The transportation of other items, such as the packed-food from the food production and
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packaging plant to the distribution plants and then to the end-consumers have not been taken into account,
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since they are outside of the system boundaries. The scrap due to both phases of production and of thermo-
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sealing is re-processed at the recycling plants located at 20 km and 35 km from the respective factories. In
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Tables 2-5 the main input data is listed: it is observed in particular that the indicated extrusion process
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contains the auxiliaries and energy demand for both layers production and thermo-seal.
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Fig. 2. Bag production process flow chart
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Table 2 Input data for the bag production and delivering
Input flow
Reference flow
Physic
amount
1
Measure
unit
p
0.0102
kg
Comment
1 p represents 1 m2 of bag. Such bag weighs 82.7 g
Resources
Water, process, well in ground
Bi-layer film production
Thermo-seal
Transport of
1.024
m
0.0213
0.0683
44.75
70.34
kWh
Scrap from thermo-seal (to
external recycling plant)
Main processes and transports
The film production process was created in a separate file, choosing 1m2 as FU. Then, it was computed
within the life cycle of the bag, associating the amount required for its production.
The value was calculated taking into account the waste produced during the thermal sealing.
The reported value corresponds to the electric energy required in this phase.
the scrap to the recycling treatment plant (d= 35 Km)
the bi-layer film to the thermo-seal plant (d = 500 Km).
the bag to the food production and packaging plant (d=850 Km)
Waste treatments
2
kg*km
1.98
g
This scrap is treated as the one coming from the film’s production process
312
Table 3 Input data for layers (films) matching process
313
Input flow
Reference flow
LDPE layer (produced)
PA layer (produced)
Extrusion of plastic films
Transport
Scrap from layers matching
(to external recycling plant)
Physic
amount
1
Measure
unit
m2
64.4
g
23
g
87.4
0.094
g
kg*km
4.7
g
Comment
1 m2 of bi-layer film weighs 82.7 g
Main materials, processes and transports
After being separately represented, choosing 1 kg of layer as FU, both the alongside processes were
computed in the bi-layer film production with association of the corresponding requirements, inclusive of
the scrap produced during the extrusion phase.
The value, reported alongside, corresponds to the amount of film, processed by extrusion.
Transportation of the scrap to the recycling plant (d=20 Km)
Waste treatments
The scrap material produced in this phase is disposed of in a recycling plant: the re-obtained granule is
commonly used for producing garbage bags.
314
Table 4 Input data for the PE film production
315
Input flow
Reference flow
Physic amount
1
PE granule
1.05
Extrusion of plastic films
Transport
1.05
735
LD-PE scrap
0.05
Measure unit
Comment
kg
Film
Raw materials
kg
Main processes and transports
kg
kg*km
Transport of the granule to the extrusion plant (distance = 700 Km).
Waste treatments
kg
Internal purification and re-processing (IPR)
316
317
318
319
12
Table 5 Input data for the PA film production
320
Input flow
Reference flow
Physic amount
1
PA granule
1.05
Extrusion of plastic films
Transport
1.05
735
PA scrap
0.05
Measure unit
Comment
kg
Film
Raw materials
kg
Main processes and transports
kg
kg* km
Transport of the granule to the extrusion plant (distance = 700 Km).
Waste treatments
kg
Internal purification and re-processing (IPR)
321
322
For both granules, the (Internal Purification and Re-processing) IPR was separately implemented considering
323
the consumption of 0.275 l of water and of 0.0192 kWh of electric energy for grinding, cleaning and drying
324
0.05 kg of plastic waste before reprocessing.
325
3.2.1 Input data and damage allocation
326
All the input and output flows were allocated on the various phases of the plastic bag production using
327
appropriately defined procedures and tools: as a matter of fact, interviews to the Firm’s technicians during
328
the bag production-site investigation were made and check-lists were used for recording data and
329
information. Additionally, once the system boundaries were defined, a further cut-off was applied assuring as
330
much as possible the maximum level of detail. All the processes and materials considered significant in
331
contributing to the total damage associated with the bag production and delivering were in fact accounted for
332
based on the environmental impacts expected. Only the processes and materials contributing more than 2.5%
333
were in fact taken into account. In this way, it was possible to include those processes, such as the electricity
334
consumption for thermo-sealing and some transports, because, though resulting not far less impacting than
335
the others, they were believed important since contributing to the study consistency. With regard to the total
336
damage, because of the absence of co-products in all the phases of the examined packaging system
337
production, in accordance with the ISO standards 14040: 2006 and 14044:2006, no allocation was done.
338
100% of the total damage corresponds in fact to 1 m2 of bag produced, namely 82.7 g.
339
4 RESULTS AND DISCUSSIONS
340
4.1 Life Cycle Impact Assessment
341
The total damage associated with the bag “from-cradle-to-gate” life cycle corresponds to 1.577E-5 points
342
(pt) and it is, principally, due to the layers production and matching and, in particular, to the production of
343
the granules to be extruded. Regarding the damage categories considered by Impact 2002+, the total damage
344
is distributed as follows: 1) 49.1% Resources; 2) 30.2% Climate Change; 3) 19% Human Health; 4) 1.7%
13
345
Ecosystem Quality. In Table 6, each damage category is allocated a corresponding weighing point and the
346
damages assessment value with the relative measurement unit.
347
Table 6 Weighing points and the damages assessment values for each damage category
Damage category
Weighing points
Damages assessment
Units
Resources
7.743E-6
11.8
MJ primary
Climate Change
4.763E-6
0.472
kgeqCO2
Human Health
2.996 E-6
2.13E-7
DALY
Ecosystem Quality
2.681E-7
0.0348
PDF*m2* yr
348
349
350
351
352
353
354
The substances causing the most impacts are listed in Table 7: the amounts indicated are referred to 1 m2 of
355
bag produced.
356
Table 7 Substances emission and resources consumption
DALY (Disability-Adjusted Life Year): a measure of the overall severity of
a disease, expressed as the number of years lost due to illness, disability or
premature death.
PDF (Potential Damage Fraction): the fraction of species that have a high
probability of not surviving in the affected area due to unfavourable living
conditions.
Substance
Emission compartment
Amount
Units
Resources
Gas natural in ground
---
66.4
dm3
Oil, crude, 42.7 MJ per kg, in ground
---
74.2
g
Oil, crude, in ground
---
76.7
g
Carbon dioxide
air
207
g
Carbon dioxide, fossil
air
254
g
Nitrogen oxides
air
945
mg
Particulates < 2.5 microns
air
40.8
mg
Sulphur dioxide
air
655
mg
Hydrocarbons, aromatic
air
3.28
mg
Climate Change
Human Health
Ecosystem Quality
Nitrogen oxides
air
945
g
Zinc
soil
157
mg
Aluminium
soil
699
mg
357
358
Details of the processes mostly causing the consumption and the emission of the resources and substances
359
listed in Table 7 are reported in Tables 8 and 9. In these tables, “A” is used for labelling the film production
360
from layers matching (LD-PE and PA), while (LD-PE)p and (PA)p indicate, respectively, the production of
361
Low-Density Polyethylene and Polyamide granules. For a better comprehension of the developed study, it
362
should be noted that, since the extrusion phase is the same for both the phases of layers production and
14
363
matching, for the LCIA development method, the percentage reported alongside to the item “Extrusion” is
364
equal to the sum of the two contributions reported in Table 8.
365
366
367
Table 8 Detail of the processes mostly causing the consumption and the emission of the resources and
substances listed in Table 7
Resource/substance
Amount
Units
Gas natural in ground
66.4
Oil, crude, 42.7 MJ per kg, in ground
Due to
For (%)
And, in particular, to
For (%)
dm3
98.6
(LD-PE)p
81.8
74.2
g
100
(PA)p
100
Oil, crude, in ground
76.7
g
88.3
(LD-PE)p
85.97
Carbon dioxide
207
g
93.23
(PA)p
100
(LD-PE)p
45.67
Carbon dioxide, fossil
254
g
88.58
Extrusion
40.74
(PA)p
44.3
(LD-PE)p
32.92
Extrusion
18.52
Extrusion
58.1
(LD-PE)p
33.79
(LD-PE)p
55.84
Extrusion
40.16
(LD-PE)p
77.95
A
Nitrogen oxides
Particulates < 2.5 microns
Sulphur dioxide
Hydrocarbons, aromatic
945
40.8
655
3.28
mg
mg
mg
mg
84.55
87.74
95.42
98.17
368
369
Therefore, from table 8, it results that the granules production causes the consumption of primary resources,
370
such as natural gas and crude oil, in the amount of 53.55 dm3 and 132.42 g respectively, and the emission in
371
air of: 295.73 g of carbon dioxide; 617 mg of nitrogen oxides; 12.1 mg of particulates; 349 mg of sulphur
372
dioxide; 2.51 mg of aromatic hydrocarbons.
373
374
375
Table 9 Detail of the processes mostly causing the consumption and the emission of the resources and
substances listed in Table 7 (table 8 continuation)
Resource/substance
Zinc
Amount
157
Units
mg
Due to
For
(%)
A
44.84
Transport of the produced bag to the food
production and packaging factory
Transport of the two layers matched film to the
bag manufacturing plant
A
Aluminium
699
mg
Thermo-sealing phase electric energy demand
Transport of the produced bag to the food
production and packaging factory
Transport of the two layers matched film to the
bag manufacturing plant
And, in particular, to
For
(%)
Transport of the two granules (PA and PE) to the
extrusion and matching plant
67.89
Extrusion
32.1
32.55
---
---
20.7
---
---
Extrusion
67.15
Transport of the two granules (PA and PE) to the
extrusion and matching plant
32.56
22.46
---
---
17.31
---
---
10.9
---
---
49.21
376
15
377
The impact categories, which the above-listed substances and resources belong to, are those causing the
378
highest damages. They are listed in Table 10, indicating for each of them the corresponding characterization
379
value and the weighing point.
380
Table 10 Weighing points and the characterization values for each of the impact categories causing the
381
greatest damage
Impact category
Weighing points
Characterization
Unit of measurement
Non-renewable energy
7.75E-5
11.8
MJ primary
Global warming
4.77E-5
0.472
KgeqCO2
Respiratory inorganic
2.41E-5
0.000244
KgeqP.M.2.5
382
383
4.2 Life Cycle Interpretation
384
The study showed that the criticality of the analysed system is represented by the production of LDPE and
385
PA granules to be extruded for the layers production. This result is clearly highlighted in Fig. 3, in which the
386
damage-flows, arising from the processes characterizing the “from-cradle-to-gate” life of the examined bag,
387
are reported.
388
389
Fig. 3. Life cycle of the bag: damages flow – Impact 2002+
390
Furthermore, it can be said that: the most environmental impacts are due to the granule production, as well as
391
its processing phases to the ends of the bag production; the most affected damage category is “Resources”;
392
the most significant impact categories for the environmental assessment are “Non Renewable Energy
393
(NRE)”, “Global Warming (GW)” and “Respiratory Inorganics (RI)”; in all the three above mentioned
16
394
impact categories, the main contributions are due to the to the granule production and extrusion for the PA-
395
PE layers production; transportations mainly affect the damage category “Ecosystem Quality”.
396
Comparing these results with those from Vidal et al. and Leceta et al., although different methods are used
397
for the LCIA, it can be noted that in all the three studies, including the present, the most significant impact
398
categories related to the use of synthetic-polymer films are referred to: Resources depletion coming from the
399
use of fossil fuels for producing the energy process-demand; and Climate Change, because of the global
400
worming due in turn to the emission of greenhouse gases (GHGs). The present study farther highlighted
401
Respiratory Inorganics as one of the most significant impact categories affecting Human Health because of
402
the emission of particulates with a grain size less than 2.5 micron due to the LDPE granule requirements
403
production and processing. Lastly, the comparison developed, besides highlighting that the present study
404
outcomes are in agreement with literature data, allowed for asserting that the use of biodegradable polymers
405
does not mean producing 100% sustainable food packages. From Leceta et al., according to the normalized
406
impact values, it resulted in fact that chitosan-based films are more impacting than the PP-based ones for all
407
the impact categories, considered by the method (Ecoindicator 99) used for the LCIA development, except
408
for fossil fuels and carcinogens. For these two, PP film is more contributing to damage, because of resources
409
extraction and processing; in particular, the damage associated to carcinogens is principally due to PP410
granule production. Similarly, in the present paper, as shown in Table 7, the production of the LDPE
411
granulate in the amount needed for the film production causes the emission of aromatic hydrocarbons
412
affecting Human Health through Carcinogens. However, it should be observed that the damage
413
corresponding to Carcinogens is one of the lowest among all the impact categories considered by Impact
414
2002+ it is equal in fact to about 5E-6 points. For this reason, this category was not considered significant for
415
the present assessment and so not reported in Table 10. Finally, Leceta et al. reported that the damage on
416
Climate Change is quite the same between chitosan-based and synthetic polymers. Regarding the main
417
results from Vidal et al, it can be said that acidification and eutrophication are more affected by the
418
biodegradable polymer film; the impact on fossil fuels depletion due to the two film-types is quite
419
comparable; and conventional films are most contributing to global warming. The comparative analysis of
420
the two studies was useful because it also highlighted that the gap, in terms of environmental impacts
421
between conventional and biodegradable films, appears not to be so relevant. Therefore, improvement
17
422
solutions can be found for reducing this gap and making conventional packaging environmentally
423
comparable to the biodegradable ones. For instance, if food shelf-life was not too much extended for
424
marketing reasons, packaging material use could be optimised. If recycled polymers were used the impacts
425
due to the production phase would proportionally decrease. If packages would be produced so to be
426
recyclable after disposal, the impacts due to the end of life would be reduced. In addition to this, renewable
427
energy could be used for supplying the energy requirements of most processes in the packaging system life
428
cycle, thereby reducing the impacts in terms of global warming and fossil fuels consumption.
429
4.3 Life Cycle Improvement Assessment
430
Based on LCIA results, the solution of reducing the thickness of the film layers was considered, since it is
431
expected to allow a reduction of the amount of granules to be produced and of the total damage associated
432
with the bag’s life cycle. This solution would not cause any change in the production line, because no
433
different industrial machinery would be required, but mainly in the amount of raw materials transported and
434
used for the film manufacturing plant. Therefore, specific laboratory tests were developed for verifying this
435
solution technical feasibility assessing, in particular, the possible changes occurring in the film permeability
436
and mechanical behaviour after the film thickness was reduced. The obtained qualitative and quantitative
437
results are not reported for reasons of confidentiality. By conducting such analysis, it was established that it
438
was possible to reduce the layer of the film, but only up to 65 microns guaranteeing food well-preservation
439
for its entire shelf-life and, so, avoiding food losses. Further thickness reduction would affect the properties
440
compromising the bag’s quality and functionality, causing the food content deterioration .The analysis
441
highlighted that the bag made by 85 micron thick film is oversized for the function that has to perform and
442
represents a waste of raw materials and money. This, in a time of such economic and environmental crisis,
443
cannot be tolerated and needs to be avoided. Therefore it was decided to implement the suggestion to use a
444
film with a thickness of 65 microns, composed by PE for 76% and by PA for 24%. For assuring the quality
445
and reliability of the results, a comparison was developed using the same functional unit, system boundaries
446
and quality of data. Fig. 4 shows that the thickness reduction causes a reduction of the total environmental
447
damage by 25.3 %: from 1.577E-5 pt to 1.178E-5 pt. The damage difference in favour to the bag of 65
448
microns thickness film is classified as follows: Resources: due to the reduced consumption of natural gas and
449
crude oil for the production of PA and PE pellets used for the film production; Climate Change: due to the
18
450
lower carbon dioxide emissions during the production of PA and PE resin; Human Health: due to lower
451
nitrogen oxides emissions during the production of PA and PE resins; Ecosystem Quality: due to lower
452
nitrogen oxides emissions arising from the production of PA and PE resins and lower emission of zinc in soil
453
due to transportation of the resins to the film extrusion plant.
454
455
Fig. 4. Bag types comparison. Personal elaboration of the impact assessment results (Impact 2002+)
456
Finally, the use of a 25% recycled PA-granule was applied and environmentally assessed and compared to
457
the initial study. For doing so, the bag production process was first updated (according to the firm practices)
458
considering the new amounts of virgin and recycled plastic materials as well as their supply to the film
459
manufacturing plant in terms of travelled distance and, then, transported-amount (kg*km). It should be
460
observed that the total damage decreases from 1.577E-5 to 1.333E-5 points (Fig. 5), thereby being reduced
461
by quite more than 15%. This solution, though allowing for increasing the environmental sustainability level
462
associated to the bag life cycle, results to be less effective compared to the one regarding the film thinning.
463
This is mainly because of the electricity used in the PA-waste recycling treatment and also of the
464
transportation of the recycled granule to the film production factory. This is due in turn to a 10% increase of
465
the distance compared to the one travelled for the virgin PA-granule supply.
466
467
468
469
470
Fig. 5. Assessing 25% recycle in the bag production process compared to the initial study. Personal
elaboration of the impact assessment results (Impact 2002+)
19
471
5
CONCLUSIONS
472
The study had the aim of reporting and discussing an LCA application in the food production and packaging
473
field. The conclusions are specific to the examined case, the obtained results, as well as the bag production
474
technologies and the input data. The accessibility and availability of the study Firm was of fundamental
475
importance for the correct study development. Without its technical support, it would not have been possible
476
to study the merits of the bag manufacturing process and to collect on-site specific data. The study allowed to
477
demonstrate what we already expected, namely that the total damage, due to the bag production, can be
478
reduced by thinning the thickness of the films. In particular, the use of 65 micron thick films would lead to a
479
reduction of the total damage by about 25%: the eventual production and marketing of this type of bag would
480
prove the Firm’s interest of making a significant mark in implementing environmental sustainability.
481
Furthermore, it is believed that the present study outcomes can be used by the firm for orienting its internal
482
policy towards the development of more and more innovative and efficient technologies for optimizing the
483
granule use, also in terms of recycled fraction percentage producing more eco-friendly packaging systems. In
484
this context, it would be important and interesting at the same time to entice the Firm to use the Life Cycle
485
Impact Assessment (LCIA) results as a starting point for obtaining the Environmental Product Declaration
486
(EPD), one of the most common and used type III environmental declarations, for both the types of bag. By
487
doing so, the Firm will provide buyers and consumers with the right tools for being informed about the
488
environmental performances of the above mentioned bags during their whole life cycles. This will enable
489
them to make more sustainable choices. Beside, this approach could help increasing the awareness regarding
490
the importance of manufacturing products as environmentally sustainable as possible. This can be achieved
491
using less primary resources and raw materials, recycling the internal scrap, generating less waste and
492
emission of gaseous substances in air, water and soil. This awareness will further promote new studies
493
oriented to economical-environmental improvements in food products. This will also assist to eco-develop
494
new more efficient production and consumption concepts characterized by lower environmental impacts. The
495
production of eco-design goods is the key to remove the link between economic growth and resources
496
consumption.
497
498
20
499
AKNOWLEDGEMENT
500
We wish to warmly thank the Firm, who has kindly assisted us since the very beginning of the study showing
501
its interest and willingness to participate to the project and providing all data and information.
502
CONTRIBUTION OF AUTHORS
503
This paper has been thought, discussed and written by the five authors and it is the results of their common
504
commitment. In particular, C. Ingrao, A. Lo Giudice and V. Siracusa contributed to bibliographical research,
505
data collection-classification-evaluation, LCA development. C. Mbohwa, and M. Dalla Rosa have
506
contributed to planning and final review of the research study.
507
508
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509
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