FROM QUANTIFICATION TO REDUCTION -
IDENTIFICATION OF FOOD WASTE
REDUCTION STRATEGIES IN PUBLIC FOOD
C. MALEFORS*, M. ERIKSSON*, C. PERSSON OSOWSKI**
*Department of Energy and Technology, Swedish University of Agricultural Science,
Box 7070, S-75007 Uppsala, Sweden
**Department of Food, Nutrition and Dietetics, Uppsala University, Box 560, S-75122
SUMMARY: Public sector food services are a major contributor to food waste generation in
Sweden, with schools, preschools, elderly care homes, hospitals etc. producing approximately
70 000 ton of food waste per year. Sweden already has appropriate infrastructure for treating
this waste to recycle nutrients and energy, but there is still great potential to move up in the
waste hierarchy and prevent waste. A first step on the path to achieving waste reduction is to
quantify the waste, in order to get useful statistics on which to base the design of waste-
reducing actions. Since the municipality of Sala has already been investigated and analysed
regarding the quantities of food waste it produces, this follow-up study investigated how the
whole municipality can move from waste quantification to successful waste reduction. The
material used comprised quantified volumes recorded by the municipal catering organisation in
Sala from 2014 to 2017. These data were combined with interviews with managers and with
staff in the kitchens that had achieved the greatest reduction in waste during the study period, in
order to identify successful food waste reduction measures. From the results, two general
tactics for waste reduction were identified; a trial and error tactic imposing the same actions on
all kitchens, irrespective of their food waste volumes or potential problems, and systematic
improvement of individual kitchens through actions based on their specific problems and
conditions. Systematic improvement was found to be the most efficient for the individual kitchen,
but since very few kitchens actually employed this tactic it had only minor effects on the whole
organisation compared with the trial and error approach.
Public sector food services are a major contributor to food waste generation in Sweden.
According to the Swedish Environmental Protection Agency (2016), public food services,
including schools, preschools, elderly care homes, hospitals etc., generate approximately 70
000 ton of food waste per year, which is roughly the same amount as all other food services
such as hotels and restaurants combined. Since landfilling of organic waste is forbidden in
Sweden (Ministry of the Environment and Energy, 2001), this food waste is mainly managed
through anaerobic digestion, and to some extent through composting. In a global perspective
this must be considered a fairly advanced waste management, but this recovery option is still far
from the waste reduction strategy identified as the highest priority in the EU Waste Framework
Directive (EC, 2008). Moreover, the environmental benefits of producing biogas are much lower
than the potential benefits of preventing food waste or of using it for higher priority valorisation
options and thereby replacing more resource-demanding products and services (Eriksson et al.,
2015; Eriksson & Spångberg, 2017).
A first step in reducing food waste is to start quantifying it, in order to facilitate systematic
improvement actions that lead to waste reduction. In a previous study (Eriksson et al., 2017),
we quantified the food waste from 30 public sector food services in the municipality of Sala in
Sweden. In this follow-up study, we investigated whether, and to what extent, waste
quantification has led to concrete waste-reducing measures in the municipality. The objective of
the present study was describe developments based on more recent quantifications, identify
where major improvements have occurred and identify examples of actions taken that explain
In the EU, about 90 Mt of food are wasted every year (EC, 2010). Food waste has been the
focus of several studies and projects, but more research of better scientific quality is needed. To
our knowledge, only Kallbekken et al. (2012, 2013) have used an experimental set-up aiming at
reducing food waste. They tested nudging in 52 Norwegian hotels using two intervention groups
(reduced plate size; or a sign stating that guests can help themselves more than once) and one
control group. Each intervention resulted in food waste being reduced by approximately 20%
Other studies have performed interventions in food services, but with inconclusive
quantitative results in terms of waste reduction (WRAP, 2011; Barr, 2015; Björklund, 2015). In
WRAP (2011), three interventions (improving familiarity and appreciation of school meals;
improving the dining experience; and meals cooked to advance orders from the children) were
tested in 39 schools and were found to lead to a 4% waste reduction, but this decrease was not
significant. In Barr (2015), the LEAN philosophy (a systematic method for elimination of waste
within manufacturing systems) was introduced to reduce overproduction and thereby food waste
in public school canteens in Sweden, but the project was unable to demonstrate any reduction
in food waste due to insufficient waste quantification. In a Swedish project study, Björklund
(2015) tested ‘educational meals’ intended to raise awareness among pupils about sustainable
development, including reduced food waste, but since food waste was not measured before the
project, no statements regarding the effect could be made.
In most scientific studies of food waste the measurement period has been short, ranging
from two days to about a month (Barton, 2000; Engström et al., 2004; Sonnino et al., 2011;
Martin et al., 2014; Byker et al., 2014; Katajajuuri et al., 2014; Betz et al., 2015). In a survey in
Sweden, only half the participating schools measured their waste for at least one week per
semester (School Food Sweden, 2013). A literature review by Møller et al. (2014) as part of the
EU-FUSIONS project found that quantification periods are very seldom longer than a year. This
may lead to inconclusive results and makes it impossible to investigate long-term effects.
There is strong justification for focusing on lowering food waste within the public sector in
general, and in school restaurants in particular. Food service organisations, i.e. restaurants
within the public sector such as schools, are large producers of food waste (Goonan et al.,
2013) and municipalities need knowledge and support if they are to lower their waste (Boij,
2013). With a few exceptions, it is obvious that the literature does not contain data for long
quantification periods combined with waste reduction measures. Even in our previous study
(Eriksson et al., 2017), the full potential of the data was not exploited for this purpose. However,
in Sala municipality there has been a change in how waste quantification is conducted, a
change that was not captured in the more static middle period analysed in Eriksson et al.
Sala municipality started to conduct food waste measurements according to the current
method back in spring 2014. It started with 15 kitchens participating in food waste quantification,
measuring waste in different categories and number of portions served. The number of kitchens
participating in quantification gradually increased to cover all kitchens within the municipal area
by autumn 2015. Since then, all kitchens in Sala have continued to participate in waste
quantification. The number of quantification days has undergone a similar change, starting with
5 days per semester in spring 2014 to autumn 2014 and expanding to around 20 days per
semester from spring 2015. By spring 2015, all the participating kitchens had also started to
measure how much food they produced and served.
The first quantification periods involved only half the total number of kitchens and data were
only collected for a brief time. However, Sala municipality established the ambition to follow up
on food waste in all kitchens and to provide more reliable statistics, which is why the number of
kitchens was increased, as well as the number of quantification days in each period.
Since autumn 2015 onwards, the numbers of kitchens and quantification days have
remained more or less the same, with minor changes in participating kitchens due to
rearrangement of the organisation increasing or decreasing the number of kitchens.
Various measures for reducing waste have been tested. During autumn 2015, the
municipality took away the third lunch option in kitchens serving three alternatives, in order to
see what impact this action would have on overall food waste. During spring 2016, a “kitchen’s
alternative” option was introduced into the menu, in order to give the kitchens more flexibility to
handle their overproduction by making leftovers on a regular alternative. The municipal authority
also encouraged the kitchens to try local actions based on their own knowledge, as an
complementary measure to reduce food waste in individual kitchens.
3. MATERIAL AND METHOD
3.1 Description of the study material and data collection
The material for this study comprised data on public catering services in Sala municipality,
representing all kitchens managed by the municipal public catering department. The material
differed to some extent from that presented in Eriksson et al. (2017) in that the period covered
by the data was spring 2014-spring 2017, compared with autumn 2014-spring 2015 in Eriksson
et al. (2017). However, quantifications were still only conducted for lunches, although
preschools serve snacks and sometimes breakfast, and elderly care homes serve breakfast and
dinner. The quantification periods were selected by managers at Sala municipal authority, in
order to find periods in the middle of the semester with full activity in the kitchens, resulting in
just a few days’ interruption due to external activities or holidays. Thus the selection of
quantification periods might have had an influence on the results and they might not necessarily
be representative of the rest of the year. The other difference is that some of the data gaps
present in the material analysed in Eriksson et al. (2017) have now been filled, which means
that the results covering the same period are to some extent different.
The food waste quantified was categorised into three main categories and several sub-
categories. Waste from beverages was not recorded or quantified. The main data collection was
performed by the kitchen staff using electronic scales (of any sort available in the kitchen), pen
and paper for making notes and an Excel spreadsheet to report the mass of food waste. A new
way of reporting mass of food waste and information about number of portions served was
introduced during the quantification period for spring 2017, which focused on collecting the
information manually via an internet service (Matomatic, 2017) as an alternative to paper and
pen or Excel spreadsheets. Seven of the kitchens used this alternative for data collection.
The mass of each category was reported together with the mass of food prepared (for which
measurement started in spring 2015). For the latter, only one unit of the food prepared was
weighed and the other units were assumed to have the same mass. For sauces and soups, the
volume was quantified and translated to mass with the assumption that all food served had a
density of 1 kg/dm³.
To estimate the number of portions served, the number of plates used by guests was
counted every day. It is possible that some guests used more than one plate, but this was
considered a minor source of error. The internet service (Matomatic, 2017) used by seven of the
kitchens for reporting data was also used for analysing the data for all kitchens after importing
all the Excel spreadsheets into the same database. This quantification tool was primarily used
to generate figures and key statistics that were communicated back to the kitchen staff, but it
also generated a database with all quantified data used in the present study.
There are two quantification measures that have always been used in the quantifications,
waste quantification and number of portions served. These two measures are fairly exact and
easy to measure compared with quantification of mass of food served, which is estimated and
extrapolated as described above and also not performed throughout all quantification periods.
This study therefore focused on the key statistics derived from the data collected on waste
quantification and number of portions served, i.e. waste per portion.
In the collected data, there were some missing values. Cases with missing values were
excluded from the relevant parts of the analysis, i.e. only days with complete data were included
in the calculation of waste per portion. Waste per portion was calculated individually for
kitchens, but also aggregated for the whole municipality, giving key statistics on the average
waste per portion per kitchen and also the waste per portion for the whole municipality per
quantification period. To determine the range of performance of all kitchens, the maximum and
minimum waste per portion per quantification period were calculated.
3.3 Identification and impact of actions
One of the waste-reducing measures that was implemented in spring 2015 was feedback of
the data to the kitchens. This feedback was provided in the form shown in Figure 1, with a set of
diagrams presenting different results structured in a printable sheet sent out to each kitchen.
The kitchen staff were then expected to analyse the data, identify their individual problems and
take actions appropriate for their specific conditions (and corresponding to their level of interest
and engagement). However, the staff did not receive any specific training in data analysis or
improvement management to conduct this work and were not given any kind of incentive or
recompense to perform this additional task.
Figure 1: Example of the feedback diagram from a single school canteen visualising food waste
quantification that was sent to individual kitchens (since the figure is in its original form, the text
is in Swedish). The top graph shows waste per portion for each day, together with number of
portions served. The lower left diagram shows the percentage waste for each category of meal
in relation to mass served, and the lower right diagram waste per portion for each semester
To identify the actions the management team took on an overall level, the manager in the
relevant municipal department were interviewed about the kind of food waste-reducing actions
they took, and when. The effect of these actions was analysed by comparing the average waste
per portion for the semesters in which the action was implemented with the corresponding value
in previous semesters.
Waste-reducing actions in individual kitchens were identified by comparing the mean value of
waste per portion for the last two quantification periods with that in all previous periods. The
kitchens with the greatest relative decrease in waste in comparison with previous periods were
identified (Table 1). Staff in the two kitchens with the greatest decrease in waste during both
semesters were interviewed to identify what actions they had taken, and why. The effect of the
actions was then analysed using the same method as for the whole organisation, i.e. by
comparing the waste per portion in the semester with the measure implemented with the waste
per portion in semesters without the measure.
Table 1: Kitchens in Sala municipality with the greatest relative decrease in waste in
comparison with the mean value of previous periods
Björkgården elerdly care
Möklinta primary school
Ösby secondary school
Ösby secondary school
Ekeby Elderly care
Klockarbo pre school
Salbo pre school
Varmsätra primary school
Västerfärnebo pre school
Salbo pre school
4. RESULTS AND DISCUSSION
On average, 72.4 g waste per portion served was wasted in the municipality as a whole
during all quantification periods. This is lower than the average reported in our previous study
(75 g waste per portion) (Eriksson et al., 2017). The data cover five more quantification periods,
falling both before and after the quantification periods in the previous study. Another
contributing factor was the correction of some faulty data after the previous study. However,
since the present study also relied on data collected by users, some caution is needed when
interpreting the results. In this case, more data altered the results and gave more findings
regarding the change in the key statistic, waste per portion.
At the start, the managers just wanted to have underlying data on how much food was
wasted and it took a year before they started to work with feedback and present the data to the
different kitchens. Since then, feedback has been presented to the kitchen staff every semester.
In order to try and reduce food waste, common actions were later implemented for all kitchens,
and the managers also encouraged all kitchens to find their own food waste-reducing actions.
Overall, the quantification periods in Sala municipality can be divided into different phases: i)
start of quantification, when the methodology was being developed and kitchens started to
participate; ii) quantification with feedback, when the kitchens started to get back the results
from their data collection; iii) implementation of common actions set by the managers; and iv)
implementations of actions by individual kitchens. This is an interpretation of the periods
presented in Table 2 and highlights how long it takes from starting to quantify food waste to
actually see measures being implemented at different levels.
Table 2: Change in amount of food waste per portion over time and information on actions
introduced by managers and individual kitchens
taken by individual
optimised portion size
optimised portion size
Through first quantifying and later making extensive quantifications and providing feedback,
the municipal authority has been slowly but surely decreasing food waste per portion for the
municipality as a whole (Table 2). Several factors can explain this slow but steady progress.
One is greater awareness of the issue of food waste among staff as a result of the feedback
provided, another is implementations of general solutions set by the public catering managers at
the municipal authority level. One such solution was to reduce the number of lunch options
served, which was implemented in autumn 2015, and to some extent lowered the total waste
per portion for the whole municipality. Another action set by the managers was to allow kitchens
to serve a “kitchen’s option” (i.e. leftovers), which was implemented during spring semester
2016. However, this action did not have a marked impact and only lowered the total waste per
portion by a fraction compared with the previous quantification period. The managers were
trying to find ways to reduce the food waste, but since they did not have full insights into
conditions in every kitchens and since individual kitchens responded very differently to the
various attempts, the managers tried different approaches and examined the effects. This top-
down tactic to implementing food waste-reducing actions can be categorised as a trial-and-error
approach, since it focuses on general improvements that are later evaluated, but does not set
out to solve a specific problem in a specific kitchen.
Figure 2 provides information about the maximum and minimum amount of waste per portion
recorded per semester in the participating kitchens. The area between the lines in the diagram
shows the range of performance for kitchens in the municipality in terms of waste per portion.
As can be seen, starting with a fairly large spread it narrows down over time. It should be borne
in mind, however, that the first two quantification periods did not have as comprehensive data
as the following periods, which makes the results for the first two periods less resilient. For
example, the abnormally high maximum value for autumn 2014 was caused by a kitchen that
had an exceptionally bad week or erroneous data. This emphases the value of longer
quantification periods in order to smooth out such fluctuations.
Figure 2: Change over time in the maximum, minimum and average food waste per portion in all
kitchens, and in two individual kitchens.
Figure 2 also shows the average waste per portion for the whole municipality and for two
kitchens that took the step of implementing their own actions in combination with the actions set
by management to reduce food waste. Those two kitchens shared one vital characteristic, in
that they found a major cause of food waste in their specific kitchen and implemented a solution
suitable for their specific conditions. We categorised this type of strategy as systematic
improvement, since the actions were based on some type of problem definition for the individual
kitchen. The specific problem was then solved by implementing a solution designed to fit within
the specific conditions and opportunities in the kitchen, and it was possible to quantify the effect
using subsequent waste quantification data.
The actions that the kitchens took in autumn 2016 had a strong impact on their waste per
portion (Figure 2). In the case of Ösby, which decided to make lunchboxes from overproduced
food and sell it to students, it went from being the kitchen which had the most waste per portion
in spring 2016 to close to the municipality average in the succeeding period. Its situation is quite
unique, however, since it is the only boarding school within the municipality, so it would not be
easy for other kitchens to copy its action and expect similar results. However, it should be
possible for other kitchens to find similar alternative uses for their leftovers.
Salbo, a small preschool, showed a similar trend in waste reduction to Ösby, but the reason
in its case was a change of personnel in the beginning of autumn 2016, with the new staff being
very committed to food waste reduction. They introduced a new way of working which included
very accurate calculation of portion sizes and the number of pupils/staff present every day. The
staff had not looked at the results from previous quantification periods when they started
quantification in autumn 2016, but still managed to perform very well, achieving slightly above
the minimum waste per portion for autumn 2016. In spring 2017 they managed to perform even
better and ended up with the lowest waste per portion within the whole municipality.
Despite the encouragement from management to try out their own solutions, only two of 30
participating kitchens managed to find feasible solutions that successfully reduced their food
waste for more than a single quantification period. Feedback on food waste is a good start for
problem analysis, but it is obviously not enough for most kitchens to find suitable food waste-
reducing actions. More help is needed in order to find measures that work individually for the
broader spectrum of kitchens. One solution could be to implement faster feedback loops when
using an internet service as the data collection tool and to require all kitchens to use this way of
reporting data. This would allow the kitchens to get feedback in real time, instead of once per
quantification period. Other alternatives could be to introduce pay rises for kitchen staff who
contribute to reducing waste, in order to incentivise a wanted behaviour. However, this needs to
be investigated further in terms of its efficiency.
Two waste-reducing strategies were identified in this study, a trial-and-error approach in
which general measures were introduced from above and a systematic improvement approach
where individual kitchens identified their own problems and solved these based on their
opportunities discovered through feedback from food waste quantification.
Proper food waste quantification in terms of complete datasets, which act as the foundation
for feedback to each kitchen, can help food service organisations reduce their food waste.
Feedback is essential for individual kitchens to identify solutions to their specific food waste
situation, but most kitchens also need help in designing suitable food waste-reducing measures.
General solutions for reducing food waste have an effect, but the greatest potential lies in
resolving the specific problems and exploiting the opportunities of every single kitchen.
Feedback is important to give kitchens an indication of how they are performing over time and
to raise awareness of how to address their specific problems and the action they need to take to
minimise their food waste.
The study was funded by the organisations that employ the authors, which include the
Swedish University of Agricultural Science and Uppsala University. Data were collected by the
kitchen staff in Sala municipality, in cooperation with the consultant company Matomatic AB.
The authors would like to thank Sala municipality and Matomatic AB for their help in this study.
Barr, U-K., Prim, M., Björk, S., Esbjörnsson, C. (2015). Minska överproduktionen i storkök -
Laga mat till gästen- inte till komposten eller fjärrvärmeverket. Slutrapport SJV projekt Dnr 19-
698/11, SP Food and Bioscience, Gothenburg.
Barton, A., Beigg, C., MacDonald, I., Allison, S. (2000). High food wastage and low nutritional
intakes in hospital patients. Clinical Nutrition, 19, 445-449.
Betz, A., Buchli, J., Göbel, C., Müller, C. (2015). Food waste in the Swiss food service
industry – Magnitude and potential for reduction. Waste Management, 35, 218-226.
Björklund, J. (2015). Hållbara måltider i Örebro län 1.0 – ett bra exempel på lärande för
hållbar utveckling. Department of Science and Technology, Örebro University, Örebro.
Boij, A. (2013). Mindre matsvinn. Utvärdering av Hushållningssällskapets nationella projekt.
Byker, CJ., Farris, AR., Marcenelle, M., Davis GC., Serrano, EL. (2014). Food waste in a
school nutrition program after implementation of new lunch program guidelines. J Nutr Educ
Behav, 46, 406-411.
EC (2008) Directive 2008/98/EC of the European Parliament and of the Council of 19
November 2008 on waste and repealing certain Directives, Official Journal of the European
EC (2010). Final Report – Preparatory Study on Food Waste Across EU27, European
Commission. DG ENV – Directorate C, Brussels.
Engström, R., Carlsson-Kanyama, A. (2004). Food losses in food service institutions.
Examples from Sweden. Food Policy, 29, 203–213.
Eriksson, M., Strid, I., Hansson, P-A. (2015) Carbon footprint of food waste management
options in the waste hierarchy – a Swedish case study, Journal of Cleaner Production, 93,115-
Eriksson, M., Persson Osowski, C., Malefors, C., Björkman, J., Eriksson, E. (2017)
Quantification of food waste in food canteens – a case study from Sala municipality in Sweden,
Waste Management, 61, 415-422.
Eriksson,M., Spångberg, J. (2017) Carbon footprint and energy use of food waste
management options for fresh fruit and vegetables from supermarkets, Waste Management, 60,
Goonan, S. Mirosa, M., Spence, H. (2014). Getting a Taste for Food Waste: A Mixed
Methods Ethnographic Study into Hospital Food Waste before Patient Consumtion Conducted
at Three New Zealand Foodservice Facilities. Journal of the Academy of Nutrition and Dietetics,
Kallbekken, S., Sælen, H. (2012). Redusert matavfall Resultater fra eksperimentet,
Kallbekken, S., Sælen, H. (2013). ‘Nudging’ hotel guests to reduce food waste as a win–win
environmental measure. Economics Letters, 119, 325–327.
Katajajuuri, J-M., Silvennoinen, K., Hartikainen, H., Heikkilä, L., Reinikainen, A. (2014). Food
waste in the Finnish food chain. Journal of Cleaner Production, 73, 322-329.
Matomatic (2017) www.matsvinn.se, Accesed 2017-05-02.
Martins, L., Cunha, L., Rodrigues, S., Rocha, A. (2014). Determination of plate waste in
primary school lunches by weighing and visual estimation methods: A validation study. Waste
Management, 34, 1362–1368.
Ministry of the Environment and Energy (2001) Förordning (2001:512) om deponering av
avfall, Ministry of the Environment and Energy, Stockholm.
Møller, H., Hanssen, O-J., Gustavsson, J., Östergren, K., Stenmarck, Å., Dekhtyar, P.
(2014). Report on review of (food) waste reporting methodology and practice, FUSIONS,
Wageningen UR, Wageningen.
School Food Sweden (2013). SkolmatSveriges kartläggning av skolmåltidens kvalitet läsåret
2012/13. Solna: Centrum för epidemiologi och samhällsmedicin.
Sonnino, R., McWilliam, S. (2011). Food waste, catering practices and public procurement: A
case study of hospital food systems in Wales. Food Policy, 36, 823–829.
Swedish Environmental Protection Agency (2016) Matavfall i Sverige - Uppkomst och
behandling 2014, Report 8765, Swedish Environmental Protection Agency, Stockholm.
WRAP (2011) Food waste in schools, Waste & Resources Action Programme, Branbury, UK.