Evaluation of the potential in a measurement method for minimizing food waste in public sector food service

Abstract: Focus of this paper was on waste quantification and evaluation of the used measurement method for large scale catering units. The method included daily measurement of food waste at Kevinge Kindergarten and Kevinge School as well as observation; a comparison of data with statistics over collected food waste by the municipality of Danderyd; calculating recipe and consumption costs for all consumed food (breakfast, lunch and afternoon snacks); as well as total waste costs from the food production at Kevinge Kindergarten. Data from the weekly average food consumption calculations at Kevinge Kindergarten, and municipal waste collection statistics for both units served as control measures for calculating the missing values and unsorted food waste. The total measured waste at Kevinge Kindergarten (K.K.) was 396 kg through 16 weeks, and at Kevinge School (K.S.) 733 kg through 7 weeks. The calculated average waste per portion was 69 grams at K.K., while it was 55 grams at K.S. The difference between measured and collected waste data was 137 kg (28 % of the collected waste) at K.K., and 449 kg (38 % of the collected waste) at K.S. This constituted the unrecorded portion of the food waste at both locations. At K.K., where a cost analysis was also executed, an added category of unsorted food waste was also calculated with an estimated quantity of 4 % of the municipally collected organic waste. The method of daily measurement combined with periodical waste cost calculations seemed effective towards minimizing food waste at K.K. Such a trend was not visible at K.S. under the data collection period, where waste measurement data were not evaluated daily and costing was not executed. In comparison with results from previous research based on weighing under short periods of time, estimates of food waste at a school kitchen could prove much more reliable with this longitudinal method. The potential to reveal systematic mistakes seems to be verified from the example of the data base collected at K.K. through a longer time interval. Through longitudinal studies in the future, it could be possible to reveal systematic reasons to food waste and offer suggestions to solve such problems in large scale catering units. The data collection method tested in this study seemed viable when looking at components as well as at the whole usability of the achieved data. The optimal category depth for short and long term data collection seems to allow registering different waste categories which tend to be produced daily and can be sorted during the day, such as plate waste and canteen/bar waste. Categories which are not typically measurable daily - storage waste, safety waste and preparation waste - can be standardised after continued measurement for a shorter time interval. Even peel waste can be followed up more closely with such a method. Additional findings were that wastage costs and quantities of waste correlated strongly (Pearson´s r=0,67) when looking at the data from Kevinge Kindergarten. Regarding correlations between waste categories, possibly more sensitive processing tools are necessary to break down cost data to data points suitable for environmental cost analyses (e.g. in CO₂.Equivalents). Other findings were that observations into different phases of production and consumption suggest multiple reasons of wastage and offer various strategies for minimizing waste effectively on the long run.