1. Introduction
The United Nations and the European Commission have set a target to reduce consumer and retail food waste by half and minimise overall food waste in the food chain by 2030 [
1,
2]. Hence, there is a high political pressure to reduce food waste and find better utilisation for side streams. Food waste is generated during food production and consumption [
3,
4]. On farms, part of the yield does not enter the next step in the food chain due to several reasons, e.g., quality defects, overproduction or lack of suitable marketing channels [
5]. According to the European Waste Hierarchy [
6], the creation of waste should above all be prevented, meaning that food waste materials with good microbial and nutritional quality should be directed to food use, either directly or through light processing. This can be conducted, for instance, by finding new ways to market the products (e.g., farm shops) or processing the materials into new products (e.g., juices, jams). De Brito Nogueira et al. [
7] list different possibilities to use fruit and vegetable waste biomass. These include the direct recovery of high-value compounds, the production of bioenergy or packaging material, and use as a low-cost culture medium in biotechnological processes.
However, while the scientific literature identifies several solutions to reduce or utilise food waste [
8,
9,
10,
11,
12], most of the studies fail to evaluate the scalability and food waste prevention potential of the suggested solutions. Additionally, since the target of food waste reduction is also to reduce the overall environmental impact of food production systems and preferably be economically sound, there is also call for indicators to evaluate the overall sustainability of the suggested actions [
13]. There are several studies on creating sustainability evaluation frameworks for eco-innovations. For instance, the European Commission has established Circular Economy Indicators for its member countries to compare the performance of each country [
14]. Moreover, Geng et al. [
15] and Hansen et al. [
16] suggest more complex frameworks to rate sustainability innovations, including ecological, social and economic aspects of sustainability.
Different kinds of decision-making models have been developed to assess the sustainability of solid waste management. Morrissey and Browne [
17] identified three different types of decision-making models used in municipal solid waste management: models based on cost–benefit analysis, models based on LCA (Life Cycle Assessment), and models based on the use of multi-criteria decision-making (MCDM). Models using cost–benefit analysis consider economic aspects, while models based on life cycle analysis are based on the assessment of environmental impacts of all phases of a production chain that lead to the creation of waste. Models based on MCDM, on the other hand, consider both economic and environmental criteria in combination with social aspects. They typically include a large set of indicators and the assessment is based on ranking several different alternatives (of, for example, waste management options). For example, Milutinovic et al. [
18] developed an MCDM method for the sustainability assessment of different municipal waste management options. The indicators included environmental (greenhouse gas, acid gases, NOx, VOC and heavy metal emissions, energy consumption, waste volume reduction, recycling rate), economic (investment costs, operational costs, fuel cost, revenues) and social indicators (job creation, public acceptance). Moreover, Iacovidou and Voulvoulis [
19] developed a screening and decision support framework to assess and compare the sustainability performance of municipal food waste management options based on MCDM. The framework includes economic, environmental and social criteria. The environmental criteria used were energy resource consumption, non-energy resource consumption, renewable energy generation, greenhouse gas emissions, eutrophication potential, land use, chemical fertilisers/peat substitution, and human toxicity potential. The economic criteria included operational and maintenance cost, capital cost, utilities cost, taxation, revenue generation and subsidy and incentives. Social criteria included acceptability, job creation, health and safety, implementation and adaptability, noise implications and odour implications.
Mourad [
20] suggested to rate food waste reduction solutions based on waste hierarchy [
6], where food waste prevention is the most desirable solution. Furthermore, Mourad suggests dividing food waste prevention strategies between optimisation strategies, which Mourad labels as ‘weak prevention stategies’, and structural change strategies (thus, ‘strong prevention stategies’). Mattsson et al. [
21] studied the economic cost and climate impact associated with the retail waste of fruit and vegetables. Moreover, De Menna et al. [
22] presented a framework for the LCA and life cycle costing of food waste prevention and valorisation solutions, taking into account environmental and economic aspects. Goossens et al. [
23] reviewed the existing food waste prevention measures and the methodologies applied for evaluating their economic, environmental and social performance. They found that the environmental performance was evaluated for 65%, economic performance for 77% and social performance only for 9% of the reported measures. The European Commission Joint Research centre has developed a more comprehensive evaluation framework for food waste prevention actions [
24]. The framework includes six criteria: quality of the action design, effectiveness, efficiency, sustainability of the action over time, transferability and scalability and intersectorial cooperation.
Based on the above-mentioned existing literature on innovation sustainability frameworks, food waste management and reduction sustainability frameworks, the consensus is that an optimal feasibility framework should consider both overall sustainability (including economic, environmental and social aspects) as well as waste hierarchy level and scalability of the different food waste utilization solutions. We also found out that while the existing literature provides a good basis to evaluate different food waste prevention and utilisation solutions, they often lack specificity and/or are too complex. Therefore, in this paper we propose a feasibility framework specified for the utilization solutions of agricultural food waste that would be specific and simple enough to be used especially in the early design stage where the main aim is to screen through the most promising solutions. Our aim was to provide a simple enough tool for a wide range of food chain actors also without expert knowledge in MCDM. The suggested feasibility indicators include (1) edible food waste reduction potential, (2) scalability, (3) level at waste hierarchy, (4) climate impact reduction potential, (5) economic impact, and (6) social impact. To demonstrate the feasibility assessment, we use data collected as part of the project ArvoBio (Puutarhatuotannon uusi kiertotalous—The new circular economy of horticultural production (2015–2019);
https://www.hamk.fi/projektit/arvobio-puutarhatuotannon-uusi-kiertotalous/#perustiedot, accessed on 1 September 2022), in which novel solutions for utilising horticultural by-products were studied. From the project case examples, we selected two case examples representing ways to utlise side flow originating from the production of carrot, which is one of the most important horticultural crops in Finland. The case example ‘an artisan bar soap’ uses carrot peels as a key ingredient and represents a non-food high-value product (case example 1). The second case is ‘retail store selling of 2nd class carrots’, where the pricing is lower but the carrot ends up as food (case example 2).
4. Discussion
Since there is a high political pressure to reduce food waste and improve the uses of food side flows [
1,
2,
6], tools to evaluate different measures are also needed. In previous literature, it has been shown that several indicators are needed in the sustainability assessment frameworks of different waste management options [
18,
19] as well as frameworks designed for the assessment of sustainability innovations [
13,
15,
16]. The two case examples in the present study also demonstrate that we need several indicators to highlight different aspects in order to choose the most desirable options and find critical improvement needs. For instance, whilst the cosmetic industry will turn low-value ingredients into high-value products, it can only utilise a low proportion of agricultural side streams. Since the European Commission target is to cut food waste mass in half by 2030, more effective large-scale solutions are required, such as better usage of 2nd class vegetables. Hence, it is probable that scalability is actually the most pressing indicator at the moment.
In this study, we have suggested that edible food waste reduction potential, scalability, level at waste hierarchy, climate impact, economic impact and social impact bring important information of the effectiveness of different options. Besides these indicators, there could be several other indicators, for instance, other environmental impacts such as biodiversity and eutrophication [
35,
36]. Additionally, other social impacts than acceptability could be evaluated. For example, job creation and health and safety have been used in previous studies assessing the sustainability of waste management options [
18,
19]. In this study, our aim was to develop a simple-enough tool for a wide range of food chain actors also without expert knowledge in MCDM. However, similar indicators could be used as a part of a more structured MCDM method.
We propose that a similar, more holistic approach would be used in every situation when deciding between different food waste reduction and utilisation measures. Our approach is suitable when deciding whether one should upscale the chosen case studies. In fact, the suggested approach would be suitable already when deciding whether it is even worthwhile to begin the trial. In addition, before the actual feasibility assessment, it is useful to consider the following questions in the planning phase of the side flow reduction and utilisation measures: (1) Are more pre-treatments required for food waste to be suitable for the planned new use compared to a situation where an alternative product is used? Do they require remarkable additional use of energy, water or human labor? (2) Can the new utilisation solution create added value for the new product or significantly decrease the costs related to the current use of food waste? (3) Can the new utilisation solution provide a way to utilise a large amount of the available food waste?
4.1. Artisan Bar Soap
Our results show that the most critical aspects related to the use of carrot peels in the production of an artisan bar soap are the edible food waste reduction potential and climate impact reduction potential (
Table 3). The edible food waste reduction potential could be increased by finding other cosmetic products in which the carrot peel mass could be used, utilising its skin-nourishing compounds, such as vitamin A and E [
37]. Moreover, commercial use could be found for the fiber mass that comes as a side product from the juicing of the peel mass. Possible alternatives could be used as an ingredient in bakery products or animal feeds and pet foods.
Similar results related to climate impact have been found previously by Secchi et al. [
38], who assessed the environmental impacts of replacing synthetic ingredients in a face cream product with natural compounds derived from olive oil industry by-products. Moreover, their results show that the use of new, more natural compounds does not necessarily decrease the environmental impacts, such as the climate impact of the product, because more pre-treatments can be required for the compounds to become suitable for use as cosmetic ingredients. However, with careful design of product formulations and ingredient dosage, the environmental performance could be remarkably improved.
4.2. Retail Selling of 2nd Class Carrots
The most critical aspect related to the retail selling of 2nd class carrots is the climate impact reduction potential (
Table 3), which was relatively small compared to the current practice, where only the 1st class carrots are sold to food use. Previously, Ribeiro et al. [
39] studied the sustainability of the operation of a non-profit co-op, called Fruta Feia (Ugly Fruit), which commercialises 2nd class fruits and vegetables that Portuguese farmers cannot sell through the conventional marketing channels. The assessment included greenhouse gas emissions associated with the transport and packing of the products as well as estimates of how greenhouse gas emissions were lowered by avoiding the landfilling of the products. The results show that the utilisation of 2nd class products results in an emission reduction of 0.14 kg CO
2-eq/kg compared to the situation where the 2nd class products are deposited to landfill.