Environmental assessment of canned tuna manufacture with a life-cycle perspective

Environmental assessment of canned tuna manufacture with a life-cycle perspective

Resources, Conservation and Recycling 47 (2006) 56–72 Environmental assessment of canned tuna manufacture with a life-cycle perspective A. Hospido a ...

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Resources, Conservation and Recycling 47 (2006) 56–72

Environmental assessment of canned tuna manufacture with a life-cycle perspective A. Hospido a , M.E. Vazquez c , A. Cuevas c , G. Feijoo b , M.T. Moreira b,∗ a

Chemical Engineering Department, Institute of Technology, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain b Chemical Engineering Department, School of Engineering, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain c R&D Department, Luis Calvo Sanz S.A., 15100 Carballo, Spain Received 30 November 2004; accepted 24 October 2005 Available online 24 January 2006

Abstract Growing awareness of environmental problems during recent years has led to increased demand for environmental information about seafood products. In particular, this report is an attempt to evaluate the manufacturing process of canned-tuna products. Bearing in mind the lifestyles of people in the 21st century, canned products are one of the commonest ways in which seafood products are presented. Spain is the second largest exporter of processed tuna in the world, behind Thailand. The fish and shellfish canning industry is mainly grouped in Galicia where 65% of the total production takes place. To this aim, the method used to study the environmental impact of these products is Life Cycle Assessment (LCA), which follows a product through its entire life cycle. The system under study includes landing at harbour, transport to the factory, processing inside the factory, final product distribution to markets and use in households. The results show that processing accounted for the greatest percentage in all the impact categories, except human toxicity potential. Inside the factory, the production and transportation of tinplate was identified as the most significant contributor and, consequently, improvement actions were proposed and evaluated, such as an increase in the percentage of the recycled tinplate used and the substitution of tinplate by another packaging material. Both proposals would diminish the adverse environmental effects of this process; however

Corresponding author. Tel.: +34 981 56 31 00x16776; fax: +34 981 54 71 68. E-mail address: [email protected] (M.T. Moreira).

0921-3449/$ – see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.resconrec.2005.10.003

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they imply a change in the final appearance of the product to be consumed and, therefore, acceptance by consumers is a fundamental factor in their success. © 2005 Elsevier B.V. All rights reserved. Keywords: Canned tuna; Environmental management; Life Cycle Assessment (LCA); Life cycle inventory (LCI); Seafood

1. Introduction For public health reasons, authorities in many countries promote the health benefits of seafood and encourage the consumption of more marine products. Such campaigns, together with the recent image problems of the meat and poultry industries in health, animal welfare and environmental issues, have probably contributed to the increasing demand for seafood products (Ziegler, 2003). In fact, fish is gaining ground as a protein source in the human diet. In Spain (year 2002), the consumption of fish was 27 kg per capita as against 68 kg of meat per person, the most significant source of protein for humans (Langreo, 2003). Nevertheless, modern lifestyles and news habits of consumption have had a market influence on seafood consumption and tendencies are different with regard to diverse types of seafood. As can be seen in Fig. 1, canned products have risen continuously since 1990 whereas fish, frozen fish, shellfish, molluscs and crustaceans have been somewhat unstable in Spain during the same period of time (Langreo, 2001). Among the species available in the markets, tuna is the commonest canned seafood product. According to FAO (2004), Spain is the second largest exporter of processed tuna in the world, behind Thailand. Specifically, the fish and shellfish canning industry is mainly located in Galicia (NW of Spain) where around

Fig. 1. Evolution in consumption of products from fisheries in Spain (1990–2000). Fresh fish in black columns; frozen fish in dark grey columns; shellfish, molluscs and crustaceans in light grey columns; and canned products in dotted columns.


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65% of the total production takes place. Five large factories are responsible for around 58.6% of the total turnover (Omil et al., 2004), and, one of these facilities in particular was selected to carry out the present analysis. The consumers, companies and the authorities responsible for the development of improved sustainability have all increased their interest in the environmental performance of food products (Consoli, 1993). The future systems for food production and consumption in particular need to be based on global and ecological points of view, where minimal environmental impact and efficient utilisation of natural resources must be important criteria in the development of food products and the selection of food systems (Andersson, 2000). When discussing the environmental impact of food production, it is important to use a holistic approach as the food supply chain is complex and entails several steps that need to be evaluated (Mattsson and Sonesson, 2003). Life Cycle Assessment (LCA) makes the evaluation of the environmental impact of a product through its entire life cycle possible. According to the International Organisation for Standardisation (ISO), LCA is a structured process developed in four stages (ISO, 2000): • goal and scope definition, in which the intended application as well as the extent of the study has to be clearly exposed; • inventory analysis (LCI), where information about the product system is gathered and relevant inputs and outputs are quantified; • impact assessment (LCIA), which converts the flows from the inventory into simpler indicators related to the potential impacts associated; • interpretation of the results, where the findings of the two previous steps are combined and evaluated to meet the previously defined goals of the study. However, these phases are not currently performed in the cited sequence. Carrying out an LCA is an iterative process, in which subsequent reiterations may imply increasing levels of detail, from a screening LCA to a full LCA, or even, the necessity for changes in the first phase prompted by the results of the previous phases (UNEP-DTIE, 2003). In the early 1990s, the first LCA studies of food products were carried out and, since then, this environmental tool has been used to address questions about food processing relating both to the identification of the subsystems that contribute most to their total environmental impact and to a comparison of products and processes with an identical function (Mattsson and Sonesson, 2003). Seafood products in particular have hardly been studied from an LCA perspective; to the best of our knowledge, the available references are few and recent. Ziegler et al. (2003) have studied the entire life cycle of frozen cod as an example of seafood emphasising the fishery-specific types of environmental impact. Thrane (2004) has worked on the analysis of a wide range of Danish fish products, such as flatfish, also from a life cycle perspective. A finding common to both studies is that the fish harvesting stage of the production cycle typically accounts for 70–95% of the total impact regardless of the impact category considered. As a consequence of this finding, that stage was studied in detail separately (Hospido and Tyedmers, 2005) and this paper deals with the post-landing activities, from transport harbour-factory to consumption in households.

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2. Goal and scope definition 2.1. Objectives The principal objective of this paper is to evaluate the environmental impact of canned tuna manufacture as a first approach in the evaluation of the seafood sector from an environmental point of view. To achieve this goal, a representative Galician factory that processes more than 26,000 tonne of raw tuna annually was inventoried and analysed from a gate-tograve perspective, that is to say, from the gate of the factory to the disposal of the wastes generated during the production and the consumption stages. The identification of the activities with a great environmental impact will make it possible to establish how to modify the process and to quantify the impact reduction associated to the proposed strategies. This study is complementary to the analysis of the fishery stage (Hospido and Tyedmers, 2005) and enables us to have a global overview of the environmental impact of the canned tuna life cycle. 2.2. Functional unit The functional unit is defined by the ISO standards as a quantified performance of a product system for use as a reference unit in an LCA study (ISO, 2000). Here, the functional unit (FU) selected is 1 tonne of raw frozen tuna entering the factory. 2.3. Description of the system under study Fig. 2 shows a graph of the process under study. The system starts at the harbour, where frozen carcasses are landed and transported to the factory by trucks (named subsystem 1). Inside the factory, the canned tuna manufacture is divided into seven subsystems, six of which are related to the process itself and the seventh comprises the ancillary activities, such as wastewater treatment and tinplate production for packaging: • Subsystem 2: Reception, thawing and cutting. Frozen tuna is unloaded and stored in cold rooms awaiting processing. After quality controls, whole fish are thawed initially by leaving them in a warmer room and thereafter they are submerged in ponds. Then, the fish is cut manually, and, afterwards, the vast majority of the blood is removed. • Subsystem 3: Cooking. This is a key step as the quality of the finished product greatly depends on it. Steam is used to cook the fish which is then sprayed with water to cool it before it is cleaned. • Subsystem 4: Manual cleaning. Skin, viscera, bones and other useless parts are taken out by hand. • Subsystem 5: Liquid dosage and filling. Cans are filled with cut or flaked fish and different kinds of sauces such as olive oil, vegetable oil or pickle. Thereafter, they are sealed and washed. • Subsystem 6: Sterilisation. The cans are sterilised and cooled in tunnels with steam and water, respectively. Then, they are dried for final activities.

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Fig. 2. System under study: P and T inside circles indicate that production and transportation are included; letters with arrows stand for water (W), wastewater (WW), vapour (V) and cans (C). The dark grey block is the cogeneration plant and the light grey blocks represent the down and upstream stages. Blocks presented in discontinuous lines have been left out of the boundaries.

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• Subsystem 7: Quality control and packaging. Different quality control processes take place before the final packaging. Apart from cans, cardboard is used as the primary packaging material as in the case of the triple pack (the most widespread option for canned tuna). Additional packaging is necessary for product transportation: plastic film to wrap the packs is often used. • Subsystem 8: Ancillary activities. Two facilities have been included here: the assembly shop for cans and easy-open rings as well as the wastewater treatment plant (WTP) where both high and low organic load effluents are treated before being released into the river. Downstream from the canning factory, two more subsystems were considered: subsystem 9 (labelled transport to wholesale and retail) considers final product distribution to the market and subsystem 10 comprises the use of canned tuna at home (household use). 2.4. Data acquisition The quality of an LCA is only as good as the information upon which it is based. Data may be collected from the production facilities associated with the processes included in the system or they may be obtained or calculated from published sources or databases. During one year, data of all the input and output flows were collected to obtain a detailed inventory for each subsystem. In addition, materials production and transportation data were obtained from the SimaPro 5.1 database (Goedkoop and Oele, 2003) and scientific papers, such as (Nicoletti et al., 2001). As a summary, Table 1 presents a list of the data taken from databases, their main sources, the period of time to which they correspond and their geographical origin. According to Thrane (2004), it was assumed that for pelagic species, such as tuna, the material consumption is insignificant at the landing and auction stages. Therefore, only the transport of frozen carcasses from the harbour to the factory gate was included in subsystem 1. The shorter road routes were established (ViaMichelin, 2003) and associated fuel and emissions were estimated from a real world analysis of frozen fish transport systems (Karlsen and Angelfoos, 2000). With regard to subsystem 9, an internal market study (Cuevas and Vazquez, 2003) made possible to divide the distribution of the final product into two areas – the Spanish market (90%) and the European market (10%) – and transportation by road were included (ViaMichelin, 2003). Besides, and according to Thrane (2004), it was assumed that for non-perishables, such as canned tuna, wholesale and retail phases are irrelevant. Subsystem 10 starts with shopping: data for transport from retailers to households were based on internal data from the company (Cuevas and Vazquez, 2003) and, in all cases, an economical allocation was performed for this transport (Ekvall and Finnveden, 2001), i.e. the environmental impact was divided between the different products bought on the basis of their economic value. Life cycle ends at the waste management step and, here, average national recycled percentages were handled concerning packaging waste: 63.6% for tinplate cans1


http://www.ecoacero.com/cifrasreciclado.php (figure for the year 2004).


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Table 1 Sources, period of time and geographical origin of data Element



Geographic area

Materials Laboratory products Olive and vegetable oils Steel stainless Polypropylene Tin plate Cardboard Polyethylene

ECOINVENTb Scientific Paperc IVAM LCA BUWAL 250 BUWAL 132 BUWAL 132 BUWAL 250

1992–2002 1998–2000 Unspecified 1990–1994 1985–1989 1985–1989 1990–1994

Europe Europe, Italy Unspecified Europe, Western Europe, Western Europe, Western Europe, Western

Energy Cogeneration unit




Transportation Frozen truck Truck 28 t Delivery van <3.5 t Passenger car

Scientific Paperd BUWAL 250 BUWAL 250 BUWAL 250

1999–2000 1990–1994 1990–1994 1990–1994

Europe, Norway Europe, Western Europe, Western Europe, Western

Waste treatment Recycling of several substances Recycling of several substances


1985–1989 1990–1994

Europe, Western Europe, Western


Consult literature references at SimaPro and www.ecoinvent.ch. See the special issue of the International Journal LCA for additional information: No. 1, 2005. http://www.scientificjournals.com/sj/lca/inhalt/Band/10/Ausgabe/1/Jahrgang/2005. c Data presented at Table 1 of Nicoletti et al. (2001): See references section. d Data presented at the Annexe of Karlsen and Angelfoos (2000): see references section. b

and 81.7% for cardboard2 . The remaining waste was supposed to be disposed of in landfills. 2.5. Considerations • Canning processing: Some of the environmental impacts of the process have not been included in full extension, e.g. food sealer, as it has not been possible to gather information on the environmental costs of their production. However, transportation has been always quantified and considered. On the other hand, viscera, entrails and fats are obtained and were quantified in the inventory. They can be considered as a raw material for fishmeal process and, in this sense, it would be a co-product rather than waste. However, due to the lack of available data this production process was left beyond the limits of our study and those quantities were considered as waste. Finally, the canning factory has a cogeneration plant that requires heavy fuel oil to function (the dark grey block at Fig. 2) and provides both electricity and thermal energy. In addition, two secondary boilers (running with heavy fuel oil) supply thermal energy when the cogeneration goes off. As a consequence, 2

http://www.aspapel.es/upload/estadisticas.pdf (figure for the year 2003).

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no profile of electricity production was considered as all the electricity comes from the cogeneration plant. • Storage at retail sites: Energy consumption from illumination and air conditioning systems were considered negligible taking into account the small percentage that canned tuna represents among all the products displayed in stores. • Consumption in households: Canned tuna is usually used for salads, Russian salads, sandwiches and filling eggs (Cuevas and Vazquez, 2003). Cooking or frying is not necessary in any case so energy consumption is not associated to this step. Regarding the disposal of sauces, the common options are to tip them into the sink or use them in salads (Cuevas and Vazquez, 2003). Some load could be attributed to the former alternative; however, due to its smaller contribution to the total organic pollution load per person per year (1.02%), this effect was disregarded in this study. • Transportation: On the one hand, the capacity of trucks was chosen bearing in mind that it was the most similar option among those available from the database (BUWAL250, 1996). On the other hand, transportation distances were estimated by means of road guides (ViaMichelin, 2003). If transport turns out to be an important contribution to the global environmental impact, a sensitivity analysis would be necessary.

3. Life cycle inventory As was mentioned, subsystem 1 only relates to the transportation of tuna from the harbour to the factory gate. The average distance of 37 km is covered by trucks (frozen cargo) with a capacity of 26 tonne (Karlsen and Angelfoos, 2000). The inventory at the canning factory was mainly based on site-specific data for the year 2003 and represents average data from a typical day of production. A summary for each subsystem located in the canned factory is presented in Tables 2–8, where the term technosphere refers to those process or products related to the use of technology. In the case of computing transportation at subsystem 9, extra weight for packaging (triple pack) was included as it corresponds to a significant percentage of the total mass (28%3 ). As was mentioned, two different areas of distribution were identified (the Spanish and the European markets) and in both cases the distances, 650 and 2500 km, respectively, were assumed to be covered by 28-tonne trucks (BUWAL250, 1996). As far as subsystem 10 is concerned, Table 9 displays the inventory data obtained. According to an internal report of the company (Cuevas and Vazquez, 2003), canned tuna is bought in the following shopping areas: 30% at superstores (where an average distance of 10 km, roundtrip, covered by car was supposed), 54% at stores (where an on foot route was assumed) and 16% at grocery stores (where also an on foot route was considered). As far as we know, inventory data related to seafood products have only been presented by Ziegler (2002) where data for production, resource use and emissions from the industrial process were provided by a Norwegian company. However, direct comparison between

3 The 3-pack final presentation weights 334.4 g, where 240.0 g correspond to canned tuna (71.77%), 81.6 g to cans (24.40%) and the remaining 12.8 g to cardboard (3.83%).


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Table 2 Inventory data for subsystem 2 (Reception, thawing and cutting) Inputs from the Thecnosphere Materials 1. Raw frozen tuna (tonne) 2. Iron shelfa (g) 3. Laboratory products Sodium hydroxide (98%) (mg) Boric acid (99.8%) (mg) Ether (99%) (ml) Nitric acid (65%) (ml) Hydrochloric acid (37%) (ml) Mercury (mg) 4. Water For thawing (m3 ) For cutting (m3 ) Thermal Energy 1. Thawing (MJ) Electricity 1. Reception and Thawing (kWh) 2. Cutting (kWh) Transport 1. Laboratory Products (kg km) 2. Entrails and residual fish (t km) Outputs to the Thecnosphere Products 1. Tuna to subs. 3 (tonne) Waste to treatment 1. Wastewater to subs. 8 (m3 ) 2. Entrails and residual fish (tonne)

1 569 (selected) 417 258 1.25 0.83 0.83 0.33 0.83 1.67 111 0.67 23.62 1.07 3.08

0.92 2.50 0.08

a A typical shelf is made of iron (185 kg) and can store between 250 and 400 frozen carcasses. However, they last for years and can be reused indefinitely. As a consequence, this input was not considered a real input as the amount allocated to each tonne of tuna would be insignificant.

Table 3 Inventory data for subsystem 3 (Cooking) Inputs from the Thecnosphere Materials 1. Tuna from subsystem 2 (tonne) 2. Water For cooking (m3 ) For washing and cooling (m3 ) Thermal Energy 1. Cooking (MJ) Electricity 1. Cooking and Washing and cooling (kWh) Outputs to the Thecnosphere Products 1. Tuna to subs. 4 (tonne) Waste to treatment 1. Wastewater to subs. 8 (m3 )

0.92 0.33 0.92 1385 24.19

0.72 1.25

A. Hospido et al. / Resources, Conservation and Recycling 47 (2006) 56–72 Table 4 Inventory data for subsystem 4 (manual cleaning) Inputs from the Thecnosphere Materials 1. Tuna for subsystem 3 (tonne) 2. Cleaning instruments (Ua ) Electricity 1. Manual cleaning (kWh) Transport 1. Cleaning instruments (kg km) 2. Dark meatb and entrails (t km) Outputs to the Thecnosphere Products 1. Tuna to subsystem 5 (tonne) Waste to treatment 1. Entrails (tonne) 2. Dark meat (tonne) a b

0.72 1.67 9.69 0.16 10.05

0.46 0.17 0.09

U stands for Units. Also called sangacho.

Table 5 Inventory data for subsystem 5 (liquid dosage and filling) Inputs from the Thecnosphere Materials 1. Tuna From subs. 4 (tonne) From other factories (tonne) 2. Cans from subs. 8 (U) 3. Tops from subs. 8 (U) 4. Plastic bags (U) 5. Liquid (sauces) Olive oil (l) Vegetable oil (l) Pickle (l) 6. Water for can washing (m3 ) Electricity 1. Liquid dosage and filling (kWh) Transport 1. Tuna from other factories (t km) 2. Plastic bags (t km) 3. Liquid (sauces) (t km) 4. Entrails (t km) Outputs to the Thecnosphere Products 1. Tuna to subsystem 6 (tonne) Waste to treatment 1. Entrails (kg) 2. Wastewater to subs. 8 (m3 )

0.46 0.20 12083 12083 125 107.5 346.7 53.3 0.5 47.19 14.69 6.25 0.47 0.25

0.66 6.42 0.5



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Table 6 Inventory data for subsystem 6 (sterilisation) Inputs from the Thecnosphere Materials 1. Tuna from subsystem 5 (tonne) 2. Coagulants (ml) 3. Flocculants (ml) 4. Water from subs. 6a (m3 ) Electricity 1. Sterilisation and recycling water system (kWh) Thermal Energy 1. Cans sterilisation (MJ) 2. Bags sterilisation (MJ) 3. Thawing room (MJ) Transport 1. Coagulants (kg km) 2. Flocculants (kg km) 3. Fats (kg km) Outputs to the Thecnosphere Products 1. Tuna to subsystem 7 (tonne) Waste to treatment 1. Fats (kg) 2. Wastewater to subs. 66 (m3 )

0.66 5.33 8.25 2.5 45.61 1245 692 146 3.10 4.78 4.88

0.66 0.12 2.5

a This stream is reused by means of a recycling water system included in this subsystem, so water here circulates in a closed-circuit.

Table 7 Inventory data for subsystem 7 (quality control and packaging) Inputs from the Thecnosphere Materials 1. Tuna from subsystem 5 (tonne) 2. Cardboard boxes (kg) 3. Film (kg) 4. Pallets (U) Electricity 1. Packaging (kWh) 2. Storage (kWh) Transport 1. Cardboard (t km) 2. Film (t km) 3. Pallets (t km) 4. Cardboard and film to recycling (t km) Outputs to the Thecnosphere Products 1. Tuna to subs. 9 (tonne) Waste to treatment 1. Cardboard to recycling (kg) 2. Film to recycling (kg)

0.66 92.01 5.42 2.08 33.33 0.17 10.93 0.01 5.27 0.09

0.66 1.92 1.14

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Table 8 Inventory data for subsystem 8 (Ancillary Activities) INPUTS from the Thecnosphere Materials 1. Lubrication oil (ml) 2. Tinplate (kg) 3. Food sealer (ml) 4. Copper thread (kg) 5. Flocculants at WTP (kg) 6. Water for general cleaning (m3 ) Electricity 1. Packaging assembly shop (kWh) 2. WTP (kWh) Transport 1. Lubrication oil (kg km) 2. Tinplate (t km) 3. Food sealer (kg km) 4. Copper thread (t km) 5. Flocculants (kg km) 6. Residual tinplate (t km) 7. Residual food sealer (kg km) 8. Oil used and fats (t km) Outputs To the Thecnosphere Waste to treatment 1. Wastewater to subs. 8 (m3 ) 2. Residual tinplate (kg) 3. Residual food sealer (ml) 4. Used oil and fats (ml) To the Environment Emissions to water 1. Treated wastewater (m3 ) CODa (g/m3 ) N-NO3 − (g/m3 ) Emissions to soil 1. Sludge (kg) Emissions to air 1. Biogas (m3 ) a

50 350 633 3.88 0.01 1.42 58.73 5.56 1.20 415.45 0.55 4.37 4.63 0.71 8.23 1.33

1.42 50 63.33 47.50

5.67 130 0.5 1.74 3.60

COD stands for Chemical Organic Demand.

those and these data is not possible as they are rather different case studies (frozen cod versus canned tuna).

4. Life cycle impact assessment The purpose of the third phase of the LCA is to analyse the inventory results to understand their environmental significance better by classifying the inputs and outputs of the inventory phase in specific categories and modelling the inputs and outputs of each category into an aggregate indicator (ISO, 2000).


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Table 9 Inventory data for subsystem 10 (Household Use) Inputs from the Thecnosphere Materials 1. Tuna from subs. 7 (tonne) 2. Plastic bags (kg) Transport 1. Shopping (km) Outputs to the Thecnosphere Waste to treatment 1. Tinplate cans (kg) 2. Cardboard (kg) 3. Plastic bags (kg)

0.66 2.51 0.09

346.47 54.35 2.51

In accordance with the default list of impact categories elaborated by Guin´ee et al. (2001), some categories were chosen among the so-called “baseline impact categories”: eutrophication, stratospheric ozone depletion, climate change (also called global warming), acidification, photo-oxidant formation and abiotic resources depletion. First, emissions and resources are sorted into different categories according to their potential impact on the environment. Once classification is complete, characterisation takes place in order to quantify the potential contribution of an input or output, J, to the impact, CIJ , allowing aggregation into a single score by means of the following equation: CIJ = AJ WIJ , where AJ is the amount of input or output and WIJ is the weighting factor. The total potential contribution of all inputs and outputs to the effect, CI , is the sum of each CIJ . Afterwards, normalisation is intended to perceive the relative magnitude of each environmental indicator from a non-dimensional approach. This procedure transforms the result of an indicator by dividing it by a selected reference value, such as the total emissions or resource use for a given area (ISO, 2000). In the present study, the situation in Western Europe (data from the year 1995) was taken as the reference scenario for all the impact categories as this is the most complete list available (Huijbregts et al., 2003). Fig. 3 shows the results obtained from the normalisation phase.

5. Interpretation of results and discussion 5.1. Contribution analysis Once the more significant impact categories were identified, a contribution analysis allowed us to identify the subsystems with the highest environmental loads. In fact, Fig. 3 indicates that both acidification and global warming potentials are the impact categories where efforts have to be directed in order to decrease the overall impact of canned tuna manufacture processing.

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Fig. 3. Normalisation values per functional unit. EP: Eutrophication Potential, ODP: Ozone Depletion Potential, GWP: Global Warming Potential, AP: Acidification Potential, POFP: Photo-Oxidants Formation Potential, ADP: Abiotic resources Depletion Potential.

In both categories, processing represents the greatest contribution with almost 85 and 95%, respectively. Fig. 4 shows a detailed analysis for these categories: Subsystem 8, mainly due to tinplate production and transportation, was responsible for 60.85% of the total Global Warming Potential and 54.76% of the total Acidification Potential associated to processing. The next step implies the proposal of diverse improvement actions in order to reduce the environmental impact of the whole system. 5.2. Improvement actions The first option proposed is related to the recycled percentage of packaging materials. As it only concerns managers in factories, it may be easy to implement. In the inventory tinplate in particular with 23% of recycled was considered as it is the most similar to the real tinplate used at the factory (15–20%). However, a higher percentage is achievable without risking the required characteristics of the packaging and two values were compared with

Fig. 4. Contribution analysis for significant categories (characterisation values).


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Table 10 Comparative data associated to the improvement actions proposed

No action Action 1a Action 1b Action 2a Action 2b



100 83.86 69.70 48.70 44.68

100 90.00 80.81 51.72 44.95

the original one: 50% (named action 1a) and 100% (named action 1b). Comparative results from evaluation are displayed in Table 10, where the real percentage was established as the baseline at 100 (called no action). Another type of action proposed and evaluated is the substitution of packaging materials. In Spain, some canning factories have recently initiated some activities in this direction and plastic bags have been put on the market. In order to evaluate this alternative, three scenarios were defined (Table 10): • No action: The present situation where tinplate cans of 52 g (dry weight) grouped 3 by 3 with cardboard are used. • Action 2a: Plastic bags of 140 g (dry weight). • Action 2b: Plastic bags of 618 g (dry weight). The former is the common option used for canned tuna and the last two are technologically feasible as they are used nowadays for salads for individual consumers and canned tuna for the catering sector, respectively. Each scenario comprises the production of the packaging material, its transportation to the canning factory as well as the treatment of the waste generated after using it. This treatment consists of recycling and landfilling according to the average national recycled percentages for each type of material. As Table 10 shows, important reduction is likely to be achieved if changes related to packaging are carried out. However, and according to Dainelli (2003), three elements should be taken into consideration when dealing with the recycling of packaging materials: (i) best environmental performance; (ii) economic balance of the whole processes, including collection, sorting and transportation; and (iii) consumer acceptance of recycled materials, particularly in sensitive applications such as food packaging. Here, only the environmental performance has been evaluated and, consequently, no general conclusions can be derived.

6. Conclusions A detailed inventory was carried out to evaluate the environmental performance of the activities, excluding fishery, necessary to have canned tuna ready for consumption in our households. In particular, processing was pointed out as the greatest contributor to the environmental impact. Going further, production and transportation of tinplate, the primary packaging material used here, was identified as the least environmentally-friendly aspect of the industrial process. As a result, improvement actions were focused on this point and

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two alternatives were proposed and evaluated: an increase in the percentage of the recycled material and the replacement of the triple pack of tinplate cans by another option, such as plastic bags. Although both strategies have pointed to a beneficial outcome for the environment, consumers, at least in Spain, are not very keen on changing food habits and, specifically, canned products are linked to tinplate cans. As a consequence, an important marketing campaign is necessary to bring nearer these results and all the stakeholders involved.

Acknowledgements This work has been partially financed by the Xunta de Galicia (Project references: PGIDIT04TAL262003PR). Almudena Hospido would like to express her gratitude to the Spanish Ministry of Education for financial support (Grant reference: AP2001-3410).

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