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Sustainability assessment of educational approaches as food waste
prevention measures in school catering
Niina Sundin
a,*
, Christopher Malefors
a
, Christina Strotmann
b
, Daniel Orth
c
,
Kevin Kaltenbrunner
c
, Gudrun Obersteiner
d
, Silvia Scherhaufer
d
, Amanda Sj¨
olund
a
,
Christine Persson Osowski
e
, Ingrid Strid
a
, Mattias Eriksson
a
a
Department of Energy and Technology, Swedish University of Agricultural Sciences, Box 7032, Uppsala, 75007, Sweden
b
Institute of Sustainable Nutrition, Münster University of Applied Sciences, Corrensstr. 25, 48149, Münster, Germany
c
Austrian Institute of Ecology, Seidengasse 13/3, 1070, Vienna, Austria
d
Department of Water, Atmosphere and Environment, University of Natural Resources and Life Sciences, Muthgasse 107, 1190, Vienna, Austria
e
Department of Public Health Sciences, M¨
alardalen University, V¨
asterås, Sweden
ARTICLE INFO
Handling Editor: Yutao Wang
Keywords:
School meals
Plate waste
Intervention
Waste tracker
Pedagogic meals
Climate impact
Sustainable nutrition
ABSTRACT
A large proportion of school meals are wasted, leading to missed opportunities to nourish pupils, environmental
impacts, and economic losses. This intervention study evaluated the long-term efcacy of three educational
approaches (giving feedback to guests via plate waste tracker, pedagogic meals, and kitchen workshops) in
reducing plate waste in school canteens across Europe (Austria, Germany, and Sweden). Following the inter-
vention, a sustainability assessment was conducted, including environmental, economic, and social perspectives.
The results showed that the plate waste tracker signicantly reduced plate waste, by 17% (4 g/guest) from an
already lower baseline level of 23 g/guest, while demonstrating long-term efcacy with sustained waste
reduction up to 15 months post-implementation. This reduction lowered the environmental impacts (by 212 kg
carbon dioxide equivalents per school & year) and nutrient losses (1018 MJ, 12 kg protein, and 4 kg ber per
school & year), while proving cost-effective with a payback period of only 1–2 years. Therefore, despite upfront
costs and implementation barriers, food waste reduction measures in school canteens provide substantial long-
term benets across environmental, economic, and social dimensions, making them a valuable investment for
sustainable school meal programs.
1. Introduction
School meal programs reach broad audiences and can be promising
avenues to improve the sustainability of food systems as they serve large
volumes of food regularly over long periods from an individual’s
perspective, facilitating normative behavior among pupils (H¨
oijer et al.,
2020). They positively impact pupils’ diets across countries (Andersen
et al., 2014; Eustachio Colombo et al., 2020; Hayes et al., 2018). How-
ever, approximately 20% of food served in public catering, up to 178
g/guest in schools, is wasted (Boschini et al., 2020; Lonska et al., 2022;
Malefors et al., 2022a; Pancino et al., 2021; Silvennoinen et al., 2015).
This waste has signicant environmental impacts, causes economic
losses, and exacerbates social injustice (UNEP, 2021). In school meals,
most waste comprises serving waste and plate waste, both of which
involve resource-intensive preparation processes (Malefors et al., 2022;
Read et al., 2020).
School meal programs differ globally in regulations, goals, target
groups, menu composition, and nutritional content (Lucas et al., 2017).
In low-income countries, such programs enhance food security and
reduce undernutrition, while in high-income countries they promote
healthy eating and seek to combat obesity (Alderman and Bundy, 2012;
Aliyar et al., 2015). However, meeting children’s nutritional needs is a
universal objective (GCNF, 2022). Some countries, like Sweden, legally
mandate that school meals must be nutritious, with published guidelines
* Corresponding author.
E-mail addresses: niina.sundin@slu.se (N. Sundin), christopher.malefors@slu.se (C. Malefors), Christina.Strotmann@fh-muenster.de (C. Strotmann), orth@
ecology.at (D. Orth), kaltenbrunner@ecology.at (K. Kaltenbrunner), gudrun.obersteiner@boku.ac.at (G. Obersteiner), silvia.scherhaufer@boku.ac.at
(S. Scherhaufer), amanda.sjolund@slu.se (A. Sj¨
olund), christine.persson.osowski@mdu.se (C. Persson Osowski), ingrid.strid@slu.se (I. Strid), mattias.eriksson@
slu.se (M. Eriksson).
Contents lists available at ScienceDirect
Journal of Cleaner Production
journal homepage: www.elsevier.com/locate/jclepro
https://doi.org/10.1016/j.jclepro.2024.144196
Received 4 July 2024; Received in revised form 21 October 2024; Accepted 8 November 2024
Journal of Cleaner Production 481 (2024) 144196
Available online 12 November 2024
0959-6526/© 2024 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (
http://creativecommons.org/licenses/by/4.0/ ).
recommending that these meals cover 30% of pupils’ daily nutritional
needs (Swedish Food Agency, 2022). In Finland, meal provision is also
mandated by law, and legally binding guidelines ensure these meals are
nutritionally balanced, steered by the national nutrition and food rec-
ommendations (National Nutrition Council, 2017). Others, like Austria
and Germany, offer ofcial guidelines for voluntary use (Ages, 2021;
DGE, 2022). There is also a trend toward promoting organic and
plant-based foods for increased sustainability (GCNF, 2022; Swedish
Food Agency, 2022; DGE, 2022). However, if school meals are wasted
due to low acceptance, the core objectives of these programs are
undermined, representing a missed opportunity (Sundin et al., 2023).
Previous studies have identied several causes of food waste in
school catering. Planning and preparation issues include lack of ordering
and planning systems, overproduction, and whether food is prepared
from scratch or heated on-site (Boschini et al., 2020; Cordingley et al.,
2011; Falasconi et al., 2015). Guest-related factors include large por-
tions, dish unpopularity, meal sensory characteristics, stressful eating
environment, short lunch duration, and scheduled recess immediately
after lunch (Byker et al., 2014; Cohen et al., 2013; Martins et al., 2016a;
Painter et al., 2016; Sundin et al., 2023). Age of pupils has mixed effects,
with some studies observing more waste with older students and others
the opposite (Cordingley et al., 2011; Niaki et al., 2017; Steen et al.,
2018). Lack of awareness about the sustainability impact of food waste is
also a factor, although pupils may be well aware of this issue (Blondin
et al., 2015; Painter et al., 2016; Wilkie et al., 2015).
Potential solutions to prevent food waste in school catering include
staff training, saving food for later, serving smaller portions, measuring
food waste, fostering a less stressful environment, and enhancing staff
support during mealtimes (Blondin et al., 2015; Persson Osowski et al.,
2022). Teacher presence during lunches can reduce plate waste (Liz
Martins et al., 2020), while accurate forecasting can reduce serving
waste (Malefors et al., 2021). Regular monitoring and tools like waste
trackers and table talkers can signicantly reduce food waste (Malefors
et al., 2022b; Pancino et al., 2021). Visual, participatory, and educa-
tional nudges also show promise, although some nudging interventions
may increase food waste despite higher meal participation (Metcalfe
et al., 2020; Vidal-Mones et al., 2022). To strengthen the current evi-
dence, more longitudinal studies backed up with control groups are
required (Byker Shanks et al., 2017; Reynolds et al., 2019).
Current sustainability efforts in school canteens focus more on
recycling or composting food waste than on prevention (dos Santos
et al., 2022). Ethnographic research in Japan has identied some
effective practices, such as measuring food waste, teacher involvement
during meals, and integrating waste and nutrition education into the
curriculum (Izumi et al., 2020). However, these practices often lack
quantied evidence of success (Reynolds et al., 2019). Behavioral fac-
tors are crucial in food waste prevention, suggesting interventions
should raise awareness and educate on food waste and nutrition (Derqui
et al., 2018). Nutrition education mainly achieves short-term success in
reducing plate waste, emphasizing the importance of the teacher role for
sustained results (Martins et al., 2016a). Cross-curricular approaches,
while limited in evidence, show great promise in promoting healthy
eating habits in elementary pupils (Karpouzis et al., 2024; Metcalfe
et al., 2020; Peralta et al., 2016). In such approaches, the pedagogic
meal (PM) is a key strategy supported by Nordic policymakers (Persson
Osowski and Fjellstr¨
om, 2019; Sarlio-L¨
ahteenkorva and Manninen,
2010).
There is growing interest in mitigating the environmental footprint
of school meal programs, aligning with the drive for sustainable food
systems under Agenda 2030 (GCNF, 2022). Food waste reduction is a
crucial target, alongside dietary changes, to ensure sustainability within
the planetary boundaries (Springmann et al., 2018; Willett et al., 2019).
Educational approaches, similar to those promoting healthy eating, are
increasingly proposed to raise awareness about food waste (Balzaretti
et al., 2020; Derqui et al., 2018; Persson Osowski et al., 2022). However,
robust evidence of their long-term efcacy is scarce (Reynolds et al.,
2019; Sundin, 2024). This study aimed to bridge this knowledge gap by
examining the short- and long-term efcacy of educational approaches,
here plate waste trackers (PWT), kitchen workshops (KWS) and PM, in
reducing plate waste in school canteens. The sustainability impacts
(environmental, social, and economic) of these measures were then
examined, where applicable, to evaluate their contribution to more
sustainable school meal programs.
2. Material and methods
2.1. Study design
A quasi-experimental design with non-randomized intervention and
control groups was employed (Cook and Campbell, 1979). Schools
participated voluntarily in the interventions and control group data
were collected from similar schools based on data availability, allowing
for comparison between intervention and control groups to assess the
efcacy of the plate waste reduction measures.
The study involved four main phases (Fig. 1). First, baseline food
waste was quantied in a pre-intervention phase. Second, interventions
involving PWT, PM, and KWS were implemented and tested, with food
waste quantied to capture reduction potential. Third, food waste was
quantied in a post-intervention phase to analyze long-term efcacy.
Finally, an evaluation phase analyzed food waste composition, carbon
footprint, nutritional, and economic data in a sustainability assessment.
2.2. Intervention groups
The educational approaches were tested in 10 Swedish primary
schools (2020–23), three German secondary schools (2021–24), and 11
Austrian secondary schools (2022–23) (Table 1). The PWT approach was
tested in 12 canteens (n =12), PM in ve (n =5), and KWS in 11 (n =
11) (Fig. 1). The types of schools varied to accommodate the specic
requirements of each intervention under local circumstances, such as
literacy skills or the ability to handle kitchen equipment. The schools
participating in Sweden were public schools with a buffet serving style,
with half of the kitchens being satellite and the other half production
kitchens. In Austria, 10 out of the 11 participating schools provided in-
house meal services, while one relied on a private catering organization.
In Germany, all three participating schools used a cook-and-serve sys-
tem, with two kitchens operated by the local community and one by an
external catering company. Outreach rates (calculated as (participants/
enrolled pupils in school) * 100%) differed across interventions due to
varying intervention design requirements, such as need for space or
kitchen equipment availability for KWS.
2.3. Interventions - educational approaches
The educational approaches involved three interventions aimed at
reducing plate waste: 1) testing a PWT in school canteens to raise
awareness among guests (i.e. mostly pupils and in some cases also
teachers eating school lunch), 2) implementing PM to raise awareness
among pupils, staff, and teachers, and 3) conducting KWS to educate
kitchen staff and pupils.
2.3.1. Plate waste tracker
The PWT is an interactive system with a tablet computer connected
to a scale beneath the food waste bin. When guests discard leftovers, the
tablet displays the wasted amount and its impact. Kitchen staff can set a
daily waste goal and the tablet provides feedback on meeting this goal,
illustrating the waste in terms of portions, such as number of cinnamon
buns. In addition, visual cues like happy or sad faces and color schemes
(red or green) amplify the message, and user feedback can be given to
the kitchen on why food was wasted. These latter features are optional
and were used only in Swedish schools in this study (Fig. 2). The system
also allows kitchen staff to record the food waste generated in the school
N. Sundin et al.
Journal of Cleaner Production 481 (2024) 144196
2
canteen. The main intention with the plate waste tracker is for guests to
act upon the feedback and throw away less food over time.
2.3.2. Pedagogic meals
In the PM concept applied in this study, a xed framework in terms of
duration of the intervention (10 consecutive weeks) and a minimum
number of teaching occasions (10) was provided to participating
teachers. Within this framework, the teachers were asked to integrate
themes, such as food waste prevention, nutrition and health, and food
production into their existing curriculum, and keep a journal listing
their chosen topics and activities. The teachers were also encouraged to
use school lunches as learning occasions for the pupils, to eat school
meals together with pupils, and to integrate lunches to classes before
and/or after meal times. The teachers were provided with tips on age-
appropriate teaching materials available online, free of charge, suit-
able for natural and social sciences, arts, and language classes. They
were given the freedom to use these materials or their own materials for
the teaching occasions. Moreover, at the beginning of the intervention
phase, the catering staff received a lecture on how to reduce food waste
in the school kitchen and canteen. During the intervention, food waste-
Fig. 1. Design of the present study and its four main phases: pre-intervention, intervention, post-intervention, and evaluation. Number of schools participating in
each intervention and in the control group is indicated in brackets.
Table 1
Overview of participating schools and interventions tested. Outreach rate of guests indicates proportion of canteen guests reached by the intervention.
Country Location School Age of pupils [years] Enrolled pupils [n] Intervention type
a
Outreach rate of guests
Sweden Falk¨
oping S1 7–15 424 PWT 100%
Sala S2 7–12 200 PWT 100%
Sala S3 7–12 200 PWT 100%
Sala S4 7–12 260 PWT 100%
Sala S5 7–15 430 PWT 100%
Uppsala S6 6–9 300 PWT 100%
PM 100%
Uppsala S7 6–9 400 PWT 100%
PM 35%
Uppsala S8 6–12 320 PWT 100%
PM 100%
Uppsala S9 13–15 480 PWT 100%
PM 19%
Uppsala S10 8–12 615 PM 45%
Germany Münsterland G1 10–19 660/178
b
PWT 100%
Münsterland G2 10–19 780/249
b
PWT 100%
Münsterland G3 10–16 435/165
b
PWT 100%
Austria Vienna A1 14–16 492 KWS 1%
Graz A2 14–16 115 KWS 7%
Graz A3 14–16 115 KWS 7%
Bad Ischl A4 15–17 324 KWS 2%
Vienna A5 14–16 280 KWS 3%
Krems A6 14–16 116 KWS 11%
Vienna A7 14–16 337 KWS 3%
Vienna A8 14–16 600 KWS 2%
Hollabrunn A9 14–16 670 KWS 1%
Vienna A10 14–16 533 KWS 2%
Vienna A11 14–16 157 KWS 9%
a
Plate waste tracker (PWT); pedagogic meals (PM); kitchen workshops (KWS).
b
Number of pupils participating in school meal scheme.
N. Sundin et al.
Journal of Cleaner Production 481 (2024) 144196
3
related posters and table talkers were placed in the canteens. In addition,
school kitchen staff supported the teachers by supplying them with plate
waste quantication data and food items such as fresh fruit and vege-
tables that could be used during teaching activities.
2.3.3. Kitchen workshops
The KWS comprised a combination of a lecture or knowledge transfer
and a cooking workshop. As an introduction, a lecture was given with
general information about food waste. Pupils were informed about the
different types of food waste and loss, and the huge quantities generated
each year. Initial tips and tricks for avoiding waste in a commercial
kitchen and at home were also provided. The second part was a practical
workshop where, under the guidance of a renowned chef, the students
prepared some delicious dishes (Fig. 3). The aim was to teach them in a
playful way why and how to avoid food waste, using unusual ingredients
or parts of foods that are edible, but rarely used in cooking.
2.4. Control groups
Control-group data were collected from 55 public primary schools in
Sweden and 32 primary and secondary schools in Austria that are in the
same geographical areas as the intervention groups and serve similar
ages of pupils. These control schools did not actively aim to reduce food
waste during the intervention. The Swedish data served as the control
for the PWT and PM, while Austrian data served as the control for the
KWS. No control group data was available from Germany. The control
Fig. 2. Plate waste tracker (PWT) in operation and (right) screen shot of its display screen showing various communications to waste generators at individual and
group level in terms of meeting the waste goal set by kitchen staff.
Fig. 3. Kitchen workshop (KWS) in a school in Austria, where pupils learned to cook delicious meals with zero waste.
N. Sundin et al.
Journal of Cleaner Production 481 (2024) 144196
4
groups were used to check whether food waste reductions were due to
interventions or other factors. The Swedish data were divided into
similar periods as the data from the intervention groups (i.e., baseline,
intervention, and post-intervention), while the Austrian data were
divided into two periods, with the rst of these representing baseline
and the second the intervention and post-intervention.
2.5. Data collection
Swedish canteens used pre-existing food waste data from 2012 on-
wards, averaging ve years of baseline data. These data were collected
by kitchen staff during their daily routines, typically in spring and
autumn semester to capture seasonal variations. Food waste was
weighed using kitchen scales and recorded in kilograms, while the
number of guests was noted to calculate plate waste per guest (Malefors
et al., 2022). German and Austrian canteens started collecting baseline
data in a similar manner for one month before starting interventions.
Data collection was conducted by kitchen staff after a thorough brieng
by the researchers, with the exception of one school in Germany where
waste measurement was carried out by the researchers. Another
exception was that the PWT was used to quantify baseline data in four
out ve school canteens where the PM intervention was implemented.
Variations in Covid-19 management affected the starting point,
duration, and frequency of data collection (Appendix B). In one German
canteen, baseline data collection started in late 2021, whereas in the
other two canteens it started in late 2022, lasting approximately one
month. In Austria, baseline data collection began in late 2022 and was
concluded in late 2023, with quantication for at least one month before
interventions.
The PWT intervention was implemented in three canteens in 2020,
six in 2021, and three in 2023 (Appendix B). The device was tested over
1–6 months (average ve months) with post-intervention data collected
from two canteens on average 12 months later, averaging eight months
with a data gap (Appendix B). Five of the 12 canteens continued using
the PWT during the post-intervention quantication period, whereas
seven canteens returned to their regular procedure as described above.
The PM intervention commenced in 2022, lasted for 10 consecutive
weeks and included an additional one-month intervention quantica-
tion at a minimum before commencing with post-intervention quanti-
cation (Appendix B). Four canteens continued measuring their plate
waste using the PWT, while the fth canteen measured waste manually
as described above. At the time of commencement of the post-
intervention quantication, which lasted seven months on average,
three canteens were continuing to use the PWT to measure their plate
waste, whereas the other two canteens measured waste manually.
The KWS intervention occurred over one day during 2023, followed
by one month of intervention quantication, after which any data
collected were considered in post-intervention quantication (Appendix
B).
In addition to plate waste, serving waste was quantied and analyzed
to examine possible unintended spillover effects. Serving waste includes
food served but not consumed, while plate waste includes leftovers and
inedible items such as napkins (Malefors, 2022). In Austrian canteens,
data collection combined kitchen and serving waste (food preparation
scraps, excess food, and buffet leftovers) into a single measurement,
alongside plate waste.
2.6. Analysis
To compare the different interventions during their different phases,
two metrics were calculated: “plate waste per guest per day” and
“serving waste per guest per day”. Guest refers to those eating school
lunch in school canteens, typically pupils and occasionally their teach-
ers. Only days where schools reported serving waste, plate waste, and
number of guests were considered in the analysis. Additionally, any
instances of obvious reporting errors were corrected, such as reporting
food waste quantities in grams instead of kilograms.
The material used for analysis of plate waste, including the baseline,
intervention, and post-intervention for all the interventions and control
groups, comprised 41,386 observations (in total from 115 school can-
teens), as summarized in Table 2.
To increase the reliability of plate waste analysis (g/guest), the
median value was used to mitigate the inuence of outliers. Results for
both the intervention and control groups are presented as grouped
scatter plots, with 95% condence intervals calculated using the normal
approximation method to assess the precision and potential signicance
of observed differences. By examining the overlap or separation of
condence intervals, the potential signicance of results was inferred.
Intervention results were compared across the baseline, intervention,
and post-intervention periods, with control group results presented
similarly to identify changes in plate waste outside the intervention.
Serving waste was also analyzed and compared with that reported for
the control group. When reductions were observed in both groups, the
control group’s reduction was subtracted from the intervention group’s
reduction (g/guest).
2.7. Sustainability assessment
For educational approaches resulting in signicant reductions in
food waste, a sustainability assessment covering environmental, social
and economic impacts was conducted. The economic impact of all
educational approaches was also assessed.
2.7.1. Environmental impact assessment
To assess the average annual environmental impact mitigation of an
intervention per school, the climate mitigation impact of the food waste
reduction was calculated using a carbon footprint of 1.0 kg CO
2
e/kg
plate waste (Sundin et al., 2024). The calculation was based on the
average food waste reduction minus any reduction observed in the
control group, average number of daily guests (298), and annual number
of school days (178). The following assumptions were made: 1) plate
waste reduction took place in similar proportions to the composition
reported by Sundin et al. (2024); and 2) the reduction substituted for
similar foods. Environmental impacts related to conducting the in-
terventions, such as the use of electronic devices or electricity, were
excluded from the assessment, despite their potential signicance
(European Parliament, 2020). To make the results more tangible, the
CO
2
e savings were converted into an equivalent number of school meals
based on a carbon footprint of 0.83 kg CO
2
e per meal (Eustachio
Colombo et al., 2020).
2.7.2. Social impact assessment
To assess the social impact of an intervention, average annual re-
ductions in energy and nutrient losses per school were calculated based
on the composition of plate waste and corresponding nutrient loss re-
ported by Sundin et al. (2024). As indicators, energy, protein, and di-
etary ber per kg plate waste were used, due to their high value for both
human and planetary health. In addition, the calculations were based on
the average amount of food waste reduced, average number of daily
Table 2
Number of observations related to plate waste, specied for each intervention
a
,
including the baseline, intervention, post-intervention, and control group
quantications. In total, the study material comprised 41,386 observations.
Baseline Intervention Post-intervention Control group
PWT 1235 634 411 18,659
PM 726 149 454 18,649
KWS 238 132 63 36
Total 2199 915 928 37,344
a
Plate waste tracker (PWT); pedagogic meals (PM); kitchen workshops
(KWS).
N. Sundin et al.
Journal of Cleaner Production 481 (2024) 144196
5
guests (298), and annual number of school days (178). The results were
made more tangible by comparing the energy and nutrient savings to an
equivalent amount of school meals covering 30% of the daily re-
quirements of pupils according to the Nordic nutrition recommenda-
tions (Nordic Council of Ministers, 2023).
2.7.3. Economic impact assessment
To assess the economic impact of the interventions tested, cost-
benet analysis was conducted based on the difference between the
cost of implementation of the interventions and the economic benets
accrued through the reduction in plate and/or serving waste per school
during one year (Caldeira et al., 2019). In addition, the payback period
of the investment was calculated where applicable.
For the PWT, the cost of purchasing a tracker (18,000 SEK, or 1600
EUR) was included as the only cost factor. To demonstrate differences in
the cost-benet structures between Sweden and Germany, an assessment
of the PWT implemented in Germany was also conducted. Compared
with Sweden, where staff were employed on a monthly salary and ex-
pected to integrate use of the PWT into their ordinary working hours, in
Germany staff expenses were included based on an hourly rate of 24.82
EUR and working time of 5 h/year and 5 min/day to operate the PWT.
Another difference was that all children enrolled in schools in Sweden
participated in school meals, while this was not the case in Germany (see
Table 1). The German calculation was based on the average reduction in
plate and serving waste (assuming no changes took place in control
group), average number of daily guests (144), and annual number of
school days (178).
For the PM, the costs included paid lunches for an average of 13
teachers per school at 46 SEK (4 EUR) per meal over a 10-week period.
Since PM are intended for continuous implementation, a yearly cost
estimate was also calculated, assuming that 50% of the teaching staff (19
teachers) participate in school lunches throughout the entire school
year. For the KWS, the costs for the food waste reduction experts and the
professional chef were calculated as 300 EUR and 660 EUR per work-
shop, respectively.
The benet calculation was based on the average amount of food
waste reduced, from which any reduction in the control group was
deducted when applicable, average number of daily guests, annual
number of school days (178), and the purchasing price of school meal
ingredients. In Sweden, the latter was assessed with 33 SEK/kg (3 EUR)
(Sundin et al., 2024) (Appendix A). In Germany, a value of 2.44
EUR/meal was used, which was adjusted for ination effects (DGE,
2022). In Austria, a purchasing price of 5.86 EUR per school meal was
used.
3. Results
3.1. Food waste reduction potential of educational approaches
3.1.1. Plate waste tracker
Among the three educational approaches tested, the PWT designed
to raise awareness of waste among lunch guests resulted in a signicant
reduction in plate waste, of 17% from the baseline (23 g/guest) to
intervention quantication (19 g/guest), while no change in plate waste
Fig. 4. Median food waste per guest in grams, divided into serving and plate waste, with uncertainty indicated as 95% condence interval. Baseline (B), intervention
(I), and post-intervention (PI) quantication values are presented for interventions involving the plate waste tracker, pedagogic meals, and kitchen workshop in-
terventions in comparison with a control group (CG).
N. Sundin et al.
Journal of Cleaner Production 481 (2024) 144196
6
level was observed in the control group (Fig. 4). The PWT-induced
reduction persisted in the long-term, with post-intervention quantica-
tion indicating a signicant reduction of 22% from the baseline and no
signicant difference between intervention and post-intervention
quantications (18 g/guest).
On ruling out any unintended spillover effect from plate waste to
serving waste, a signicant reduction in serving waste was also
observed. In comparison with the baseline of 40 g/guest, a reduction of
6 g/guest (16%) was observed in the intervention quantication (34 g/
guest) and a reduction of 7 g/guest (18%) in the post-intervention
quantication (33 g/guest). However, signicant reductions of 6 g/
guest (21%) in the intervention period and 9 g/guest (32%) at post-
intervention were also observed in the control group, in comparison
with the baseline of 29 g/guest.
3.1.2. Pedagogic meals
The PM intervention resulted in a 7% reduction in plate waste from
baseline (22 g/guest) to intervention (20 g/guest), but this reduction
was not statistically signicant (Fig. 4). However, a signicant reduction
in plate waste of 14% was observed at post-intervention quantication
(19 g/guest) in comparison with the baseline (22 g/guest) in the can-
teens using PWT. In canteens manually measuring their plate waste,
plate waste rebounded to the baseline level (22 g/guest) at post-
intervention. No change was seen in the control group. However,
there was a signicant increase of 38% in serving waste at intervention
(31 g/guest) in comparison with the baseline (23 g/guest) (Fig. 4). At
post-intervention, canteens using the PWT continued to show an
increased amount of serving waste (35 g/guest), whereas canteens not
using the PWT had serving waste of 20 g/guest, with no signicant
difference to the baseline. Meanwhile, the control group signicantly
reduced serving waste from the baseline of 29 g/guest to intervention
(23 g/guest) and post-intervention (20 g/guest).
Based on teachers’ journals, three of the schools participating in PM
had on average 16 teaching occasions, one had 10, and one had fewer
than 10. Two schools spent over 70% of their sessions on food waste
topics, one spent 50%, and two spent 20%. On average, 50% of the time
was focused on food waste, 30% on nutrition and health, and 20% on
food production topics. Examples of materials and topics used for the PM
included short lms and news articles about retail and consumer food
waste, and food waste prevention and management, leading to class-
room discussions. Furthermore, calculations were conducted based on
food waste statistics from the school kitchens.
3.1.3. Kitchen workshops
The KWS resulted in a 3% reduction of plate waste from baseline (43
g/guest) to intervention (42 g/guest), and a 31% reduction from base-
line to post-intervention (30 g/guest), although the observed differences
were considered non-signicant. A reduction of 26% (from 54 to 40 g/
guest) was observed in the control group, also considered non-
signicant. Further, an increase of 15% in serving waste from baseline
(65 g/guest) to intervention (75 g/guest) was observed, although this
returned to the baseline levels at post-intervention (61 g/guest).
Meanwhile, a reduction of 38% was observed in the control group.
3.2. Sustainability impacts of educational approaches
Estimated reductions in sustainability impacts (environmental, so-
cial, and economic) for the intervention (PWT) observed to bring about a
signicant reduction in waste are presented in Table 3.
3.2.1. Environmental impact
The climate mitigation impact of PWT through plate waste reduction
amounted to 212 kg CO
2
e per school and year, based on the average
daily reduction in plate waste of 4 g/guest. In other words, the abated
environmental impact from reduced plate waste corresponded to the
CO
2
e of 255 school meals. No environmental mitigation was included
for PM and KWS due to the lack of signicant waste reduction observed
in the ndings.
3.2.2. Social impact
The abated nutrient losses due to reduced plate waste using the PWT
amounted to 1018 MJ (243,000 kcal) of energy, 12 kg protein, and 4 kg
dietary ber per school and year. These nutrient savings corresponded to
339, 920, and 538 school meals, respectively, based on fullling 30% of
the respective daily nutrition needs of pupils. No social impact mitiga-
tion was included for PM and KWS due to the lack of signicant waste
reduction observed in the ndings.
3.2.3. Economic impact
The net economic benets of all three interventions were negative
when calculated on a rst-year basis. The net benet of the PWT over all
participating schools was −10,998 SEK (−980 EUR) per school
(Table 3), so the investment costs were recouped and positive net ben-
ets generated during the third year of use. In the case of German school
catering establishments, the net benet of the PWT amounted to −121
EUR per school and year based on a food waste reduction of 15 g per
meal (5 g plate waste and 10 g serving waste reduction) and 144 daily
meals served (Table 4). The break-even point for the PWT investment in
that case was reached when serving a minimum of 153 meals per school,
or the investment costs were recouped during the second year of use.
The net economic benet of the PM and KWS interventions was
negative, as there was no signicant reduction in waste and therefore no
benet was gained, while the cost of the interventions amounted to
29,900 SEK (2600 EUR) and 960 EUR per school and year, respectively.
Table 3
Annual reduction in environmental, social, and economic impacts resulting from
prevented plate waste due to implementation of the plate waste tracker (PWT).
Prevented plate waste (kg/school and year) 212
Environmental impact reduction
Carbon footprint (kg CO
2
e/school and year) 212
Corresponding number of school meals
a
255
Social impact reduction
Energy (MJ/school and year) 1018
Corresponding number of school meals
b
339
Dietary ber (g/school and year) 4031
Corresponding number of school meals
b
538
Protein (g/school and year) 12,094
Corresponding number of school meals
b
920
Economic impact reduction
Benets (abated plate waste, SEK (EUR)/school and year)
c
7002 (620)
Costs (plate waste tracker, SEK (EUR)/school) 18,000 (1600)
Net benets SEK (EUR) −10,998 (−980)
a
Based on carbon footprint of 0.83 kg CO2e/meal (Eustachio Colombo et al.,
2020).
b
Number of school meals fullling 30% of the daily energy (10 MJ), ber (25
g), and protein (44 g) requirement of schoolchildren (averaged for 7–16 years of
age).
c
Based on 4 g/guest plate waste reduction, 298 guests/day, 178 school days/
year, and cost of 33 SEK/kg plate waste.
Table 4
A breakdown of the factors contributing to the net economic benet results
calculated for the rst year of implementing and using the plate waste
tracker in German school catering establishments.
Plate waste tracker (Germany)
Prevented plate waste (kg/year) 128
Prevented serving waste (kg/year) 256
Prevented total waste (kg/year) 384
Economic benets (EUR/school and year) 1971
Costs (staff resources EUR) 492
(plate waste tracker EUR) 1600
Net benets (EUR/school and year) ¡121
N. Sundin et al.
Journal of Cleaner Production 481 (2024) 144196
7
Additionally, the annual cost of continuous implementation of PM was
estimated at 154,000 SEK (13,000 EUR) per school.
4. Discussion
This study investigated the sustainability outcomes of educational
approaches as a plate waste reduction measure in school canteens in
three European countries, Austria, Germany, and Sweden. The results
showed signicant waste reduction potential for a PWT device designed
to raise awareness of food waste among lunch guests. The PWT reduced
plate waste by 17% (4 g/guest) from the baseline of 23 g/guest. This
reduction was also sustained in the long-term (up to 15 months after the
intervention implementation). In addition to mitigating environmental
impacts by 212 kg CO
2
e per school and year, the PWT also saved
valuable nutrients, such as protein (12 kg per school and year) and ber
(4 kg per school and year). On the other hand, no signicant waste
reduction was observed for the interventions of PM and KWS in this
study. Educational methods, such as PM and workshops, are often seen
as entailing potential for raising awareness and reducing food waste
(Balzaretti et al., 2020; Derqui et al., 2018; Engstr¨
om and
Carlsson-Kanyama, 2004; Martins et al., 2016b; Painter et al., 2016).
However, our results did not support this expectation. Reasons for this
failure are identied with the low outreach rate of pupils as well as the
diffuse ow of information (compared to a more targeted information
ow from the PWT).
The small sample size of schools testing the PM (n =5) and the low
outreach rates of pupils, especially with KWS (4%) compared with PWT
(100%) and PM (60%) are shortcomings for testing the efcacy of in-
terventions in practice. The COVID-19 pandemic was also challenging
for implementation of the interventions and conducting quantications,
due to lockdown and/or restrained staff resources contributing to
reduced sample sizes and datasets. Moreover, interventions such as PM
may be hindered by teachers’ high stress levels and lack of time
(Berggren et al., 2021), which can limit their ability to participate in
additional activities, such as implementing new food waste reduction
programs (Agyapong et al., 2023). Adding PM as a distinct topic could
allow more time for teachers, but would come at the expense of existing
subjects, given the xed hours allocated for each topic in the curriculum.
Furthermore, PWT may be easier to standardize as a food waste pre-
vention method, whereas PM could be more subjective and inuenced
by the personal enthusiasm level of individual teachers (Persson
Osowski et al., 2013), which may have impacted the results in this study.
While the framework given to the participating teachers for the PM
specied the duration and frequency of the PM, it offered them great
freedom in designing the content of the intervention and thus lacked
standardization, which may have been a drawback. Thus, further studies
addressing these limitations are warranted.
A main difference between PWT and other educational approaches,
such as PM and KWS, is furthermore the direct access to those guests
who generate waste, rather than addressing all pupils, including those
who do not waste any food. A previous study found that the majority of
plate waste (60%) is generated by a small minority of canteen guests
(20%), while 40% of guests do not waste any food (Malefors et al.,
2024), highlighting untapped food waste prevention potential in school
canteens. This raises the challenge of identifying waste generators and
effectively reaching out to them. Since the PWT communicates directly
to those wasting food, it has the advantage of reaching out to these in-
dividuals without personally singling them out. Future studies are
warranted to identify the type of message that best inuences the
behavior of waste generators.
The ndings obtained in this study are noteworthy for several rea-
sons. The novelty of the work lay in investigating the long-term efcacy
of interventions while also using control groups to verify the results.
Control group data revealed that there were changes even in schools
without interventions, highlighting the necessity of control data for
accurate interpretation of results. Importantly, data conrming the long-
term efcacy of PWT indicated sustained plate waste prevention, a top
priority in food waste action (European Commission, 2020). Once suc-
cessfully implemented, the tracker appears to become an integral and
permanent part of operations, impacting new pupils and staff as they
join (Malefors, 2022), possibly explaining the enduring results.
Previous research has highlighted the importance of controlling for
possible unwanted spillover effects between different types of food
waste in canteens when implementing reduction measures. For example,
Malefors et al. (2022b) found that tasting spoons reduced plate waste,
but increased serving waste. However, spillover effects can also be
benecial. The PWT implemented in Germany, although targeting plate
waste, appeared to have an even larger waste-reducing effect on serving
waste (although non-signicant). Serving waste is often a greater
problem in primary school canteens than plate waste, while the opposite
is true in secondary schools (Eustachio Colombo et al., 2020; Malefors,
2022). In the present study, the baseline for plate waste when testing the
PWT was 23 g/guest, while the baseline for serving waste was 40
g/guest. The participating schools thus had a lower range of plate waste
(21–38 g/guest), but a higher range of serving waste (23–28 g/guest),
than recorded in previous studies (Malefors, 2022). This indicates that
while plate waste was at a relatively low level, there was still signicant
plate waste prevention potential and associated cost, nutrient, and
environmental savings. Therefore, PWT could become best practice,
especially in sufciently large canteens with high initial amounts of
plate and possibly even serving waste. Further studies are needed to
conrm the potential of the PWT in such contexts.
The economic assessment of PWT implementation in Germany
highlighted several interesting factors inuencing the net results. Not all
enrolled pupils participated in the school meals program (144), which
negatively impacted the net results in comparison with the overall PWT
results with a higher number of participants (298). However, the addi-
tion of just nine more participants in German schools would have ach-
ieved break-even already in the rst year. The results indicated a dual
benet, in reducing both plate and serving waste, as also found by
Malefors et al. (2022b), addressing two issues with one measure. This
generated sufcient economic benets to cover the investment by the
second year, despite including staff costs. Additionally, preventing
serving waste likely leads to production cost savings, while plate waste
prevention avoids resource wastage by ensuring food is eaten instead of
wasted, although this is yet to be conrmed and requires future study.
Demonstrating the long-term efcacy of interventions is crucial for
transitioning from merely testing reduction measures to real-life
implementation. Overcoming barriers such as high stress levels, lack
of time, comfort with old habits, and implementation costs is essential
for the implementation process (Laitinen et al., 2023; Persson Osowski
et al., 2022). Management decisions are pivotal, as the initial investment
often has to be justied by long-term savings (Kaur et al., 2021). The
PWT proved to be cost-effective, paying for itself by the second or third
year after installation. This short payback period makes it a highly
effective investment (Kagan, 2024).
The ndings in the present study should be interpreted in light of
strengths and limitations of the work. While we utilized an average
carbon footprint for assessing plate waste based on Swedish school meal
composition (Sundin et al., 2024), it is important to acknowledge that
not all food waste necessarily carries the same carbon footprint. Meat,
for example, has a signicantly higher carbon footprint compared to
vegetables. Therefore, variations in the proportions of meat and
plant-based foods in other countries’ meal compositions may inuence
the generalizability of our ndings. While the challenges posed by each
country’s unique food culture and organizational structures can be seen
as a limitation, the diversity can also be viewed as a strength. The
contextual differences may affect comparability, however, the core
principles of each intervention have universal relevance, highlighting
the need for contextual adaptation in generalizing the ndings in future
studies.
European school meal programs are generally more mature in global
N. Sundin et al.
Journal of Cleaner Production 481 (2024) 144196
8
terms, with comprehensive policies, widespread coverage, and high
nutritional standards (GCNF, 2022). However, the structures of these
programs vary across Europe due to cultural, economic, and policy
differences (European Commission, 2023). A key limitation in this study
was the low sample size, which reduced the overall certainty of some
results due to increased variability and wider condence intervals. A
strength was the ability to test different educational approaches across
various European countries, capturing key differences in the school meal
landscape. Sweden provides universal free meals, while Germany offers
targeted free meals and Austria provides free meals in parts of the
country, reecting the overall variation in Europe (Guio, 2023). How-
ever, governance and operational differences exist not only between
countries, but also within countries and municipalities, and a small
sample size may not represent this variety, leading to potential biases
and limiting generalizability. Despite these differences, all school meal
programs share the goals of nourishing children and reducing their food
waste. European school meal programs often benet from decades-long
implementation, with purpose-built facilities, well-established food
service systems, and adequate funding models supporting sustainable
operations (Manson et al., 2024). However, due to the high variability,
no single design ts all contexts, highlighting the need to consider
specic local contexts when developing food waste reduction measures.
This study showed signicant potential of a PWT device in reducing
food waste, whereas PM and KWS struggled to reach all pupils. Tech-
nical solutions like PWT offer cost benets over staff-intensive measures
like PM. However, the results were also inuenced by the limitation that
the focus was on quantiable aspects only. The success of PWT, espe-
cially in Swedish canteens, likely also stems from staff’s prior knowledge
and level of engagement, and municipalities’ decade-long efforts to
reduce food waste, thus creating a mature environment for the PWT.
Staff discussions about food waste with pupils were likely to enhance the
PWT’s efcacy, indicating the importance of the social context in
technical innovations. Thus, while technical solutions like the PWT can
be highly effective and cost-efcient, their success is deeply intertwined
with the social environment and staff engagement and it is important not
to overlook the social context of any technical innovation. Policymakers
should therefore implement tools like PWT along with social in-
terventions such as KWS or PM as standard solutions in school canteens.
A reasonable approach would be to start with schools where other
simpler waste-reducing activities like reusing leftovers, setting goals,
and communicating with guests are already in place (Eriksson et al.,
2023). Starting with the basic measures and progressively adding more
can be the most cost-efcient way to reduce food waste, save money, and
lower environmental emissions, which are necessary in transition to a
sustainable food system.
5. Conclusions
The PWT signicantly reduced plate waste (by 17%), mitigating
environmental impacts (by 212 kg CO
2
e per school and year) and losses
of nutrients such as protein (12 kg per school and year) and ber (4 kg
per school and year). These reductions were maintained in the long
term, indicating substantial food waste prevention potential over time
rather than an initial reduction. In addition, PWT proved highly cost-
efcient, with a payback period of only 1–2 years. The PM and KWS
approaches achieved non-signicant reductions in food waste reduction
(7% and 3%, respectively), and require further research. In conclusion,
the upfront costs of implementing food waste reduction measures in
school canteens can be signicant and barriers such as lack of time
among kitchen staff need to be overcome. However, the long-term
benets in terms of all three sustainability perspectives (environ-
mental, economic, and social) make these initiatives worthwhile in-
vestments for more sustainable school meal schemes.
CRediT authorship contribution statement
Niina Sundin: Writing – original draft, Visualization, Validation,
Methodology, Investigation, Formal analysis, Data curation, Conceptu-
alization. Christopher Malefors: Writing – review & editing, Visuali-
zation, Methodology, Investigation, Formal analysis, Data curation.
Christina Strotmann: Writing – review & editing, Methodology,
Investigation, Formal analysis, Data curation. Daniel Orth: Writing –
review & editing, Methodology, Investigation, Formal analysis, Data
curation. Kevin Kaltenbrunner: Writing – review & editing, Method-
ology, Investigation, Formal analysis, Data curation. Gudrun Ober-
steiner: Writing – review & editing, Data curation. Silvia Scherhaufer:
Writing – review & editing. Amanda Sj¨
olund: Writing – review &
editing. Christine Persson Osowski: Writing – review & editing. Ingrid
Strid: Writing – review & editing. Mattias Eriksson: Writing – review &
editing, Methodology, Funding acquisition.
Funding
This work was supported by the H2020 project LOWINFOOD (Multi-
actor design of low-waste food value chains through the demonstration of
innovative solutions to reduce food loss and waste), which is funded by the
European Union’s Horizon 2020 research and innovation program
under Grant Agreement no. 101000439. The views reected in this
article represent the professional views of the authors and do not
necessarily reect the views of the European Commission or other
LOWINFOOD project partners.
Declaration of competing interest
The authors declare the following nancial interests/personal re-
lationships, which may be considered as potential competing interests:
The authors Christopher Malefors and Mattias Eriksson developed the
PWT device and own the rights to the innovation, through the company
Matomatic AB. There is a potential conict of interest as these authors
have a nancial interest in the innovation.
Acknowledgments
The authors would like to extend their gratitude to the Meal Services
of Uppsala, Sala, and Falk¨
oping Municipalities in Sweden, including
participating kitchen and teaching staff for their continuous support,
and to participating schools and canteens in Germany and Austria.
N. Sundin et al.
Journal of Cleaner Production 481 (2024) 144196
9
Appendix A
Table A1
Purchasing price of food ingredients for school meals in Uppsala Munic-
ipality, Sweden, in 2023
Food item Purchasing price (SEK/kg)
Pasta 17
Potato 18.4
Rice 27
Chicken 76.5
Pork
Pork 79
Ham 86
Beef
Beef 101
Meatballs 94.5
Minced meat 108.5
Fish 95.5
Cheese 77
Eggs 42
Pancakes 40
Vegetarian meal options (lasagna, quorn, vegetarian patties)
Quorn 79
Vegan burger 60
Falafel 47
Vegan mince 60
Salad buffet:
Broccoli 32
Tomato 43
Lettuce 20
Olives 40
Carrots 25
Bell peppers 70
Beans 40
Chickpeas 39
Bread
Hard bread 60
Soft bread 33
Hamburger bread 37
Appendix B
Table B1
Quantication periods, including start and stop dates, and number of observations for each school canteen participating in the interventions
Intervention
group
Baseline
quantication
Intervention
implemented
Intervention
quantication
Post intervention
quanticaton
School Start Stop #
observations
Start Stop #
observations
Start Stop #
observations
PWT S1 2014-
03-31
2019-
10-25
94 2021-04-06 2021-
04-06
2021-
04-16
9 2021-
10-11
2023-
02-20
11
S2 2014-
11-24
2019-
04-05
113 2020-04-02 2020-
04-02
2021-
04-30
36 2021-
09-27
2022-
04-29
10
S3 2015-
03-02
2020-
10-09
130 2021-04-26 2021-
04-26
2021-
06-10
32 2021-
09-27
2022-
04-29
10
S4 2014-
11-24
2019-
04-05
121 2020-04-01 2020-
04-01
2020-
10-09
26 2021-
04-26
2021-
10-08
15
S5 2014-
11-24
2019-
04-05
115 2020-04-01 2020-
04-01
2020-
10-09
34 2021-
04-26
2022-
04-29
10
S6 2012-
10-08
2021-
06-15
99 2021-08-19 2021-
08-19
2022-
02-25
114 2022-
06-07
2022-
12-27
64
S7 2012-
10-08
2021-
03-26
129 2021-04-06 2021-
04-06
2022-
01-14
108 2022-
05-01
2023-
02-06
88
S8 2015-
10-16
2020-
12-18
90 2021-01-12 2021-
01-12
2021-
09-15
143 2022-
06-07
2022-
12-23
108
S9 2012-
10-08
2021-
08-31
286 2021-09-24 2021-
09-24
2022-
02-25
78 2022-
10-03
2023-
01-31
72
G1 2021-
12-06
2022-
01-17
20 2023-04-17 2023-
04-17
2023-
05-26
26 ––0
(continued on next page)
N. Sundin et al.
Journal of Cleaner Production 481 (2024) 144196
10
Table B1 (continued )
Intervention
group
Baseline
quantication
Intervention
implemented
Intervention
quantication
Post intervention
quanticaton
School Start Stop #
observations
Start Stop #
observations
Start Stop #
observations
G2 2022-
08-29
2022-
09-30
25 2023-03-01 2023-
03-01
2023-
03-29
17 ––0
G3 2022-
10-17
2022-
11-11
13 2023-05-03 2023-
05-03
2023-
06-05
11 2024-
02-05
2024-
03-22
23
PM S6 2021-
08-19
2022-
02-25
114 2022-02-28 2022-
02-28
2022-
04-29
32 2022-
06-07
2022-
12-27
64
S7 2021-
04-06
2022-
01-14
108 2022-01-17 2022-
01-17
2022-
03-24
37 2022-
05-01
2023-
02-06
88
S8 2021-
01-12
2022-
02-25
143 2022-01-24 2022-
02-28
2022-
04-29
36 2022-
06-07
2022-
12-23
108
S9 2021-
09-24
2022-
02-25
78 2022-02-28 2022-
02-28
2022-
04-01
22 2022-
10-03
2023-
01-31
72
S10 2012-
10-08
2021-
09-28
283 2022-01-24 2022-
02-28
2022-
04-01
22 2022-
06-07
2023-
01-31
122
KWS A1 2022-
11-07
2022-
12-15
16 2023-01-23 – – 0 2023-
03-21
2023-
12-14
28
A2 2023-
02-13
2023-
03-16
17 2023-03-22 2023-
03-24
2023-
04-21
13 2023-
04-24
2023-
04-28
5
A3 2023-
02-16
2023-
03-21
13 2023-03-22 2023-
03-23
2023-
04-19
12 2023-
04-25
2023-
05-04
7
A4 2023-
03-22
2023-
04-11
7 2023-04-12 2023-
04-12
2023-
04-26
9––0
A5 2023-
03-20
2023-
04-19
13 2023-04-19 2023-
04-20
2023-
05-15
7––0
A6 2023-
03-27
2023-
05-08
60 2023-05-09 2023-
05-09
2023-
06-01
14 ––0
A7 2023-
04-24
2023-
05-22
61 2023-05-23 2023-
05-24
2023-
06-22
45 2023-
06-23
2023-
06-29
8
A8 2023-
02-20
2023-
03-30
24 2023-09-19 2023-
10-02
2023-
10-17
10 2023-
10-19
2023-
11-14
9
A9 2023-
10-02
2023-
10-18
13 2023-10-19 2023-
10-20
2023-
11-17
12 2023-
11-20
2023-
11-27
6
A10 2023-
10-16
2023-
11-07
10 2023-11-08 2023-
11-08
2023-
11-14
5––0
A11 2023-
11-09
2023-
11-16
4 2023-11-23 2023-
11-23
2023-
12-14
5––0
Data availability
Data will be made available on request.
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