Introduction

The handling and preparation of food generates waste that is often thrown away as garbage [9]. Restaurants experience the daily challenge of adjusting the quantities of meals that will be served that day, minimizing food waste, and making the best use of the food selected for meal preparation. In addition to the goodwill demands of cooks and professionals who work daily in food preparation, so that tasty meals are prepared, making the best use of all the items acquired by the restaurant to serve its customers is a second important task. Above all, the objective is to make dishes that are attractive to the consumer’s eye, beautiful, tasty and nutritious, and of reliably good quality [5].

However, a combination of elements often conceals a sad reality that many countries, including Brazil, experience. This reality is revealed by the high rates of food waste that accompanies the sectors of inputs, rural production, transportation, industrialization, processing, distribution, and consumption. Therefore, previous research [28] indicates that food is lost or wasted as a result of technical, economic, and/or social aspects specific to each stage of the supply chain. The amount of food waste generated in developed and developing countries, in the food supply chain, from production to consumption, corresponded in 2017 to approximately US $ 680 billion and US $ 310 billion [20]. On the other hand, according to a report from the United Nations Food and Agriculture Organization [12], 11% of the world population suffers from food insufficiency or goes hungry. This makes the topic of food loss and waste subject to analysis by the United Nations (UN), using the United Nations Food and Agriculture Organization (FAO) channel. Indicators show that one-third of what is produced is wasted [36]. The percentage of food wasted before consumption is 30–50% [18]. Finally, 46% of the total wasted food will end up in the landfills, and 54% of food waste corresponds to the losses generated in the production, storage, and transportation phases [12]. Therefore, reducing food loss is a relevant aspect [36]. Besides, food wastes have also emerged as a serious environmental concern in recent years [35]. Furthermore, several of the Sustainable Development Goals (SDGs) are pertinent to this investigation. Particularly, SDG 2 refers to zero hunger, SDG 3 reports on well-being and health, SDG 12 deals with responsible consumption and production, and SDG 17 considers partnerships in favor of goals [25]. To seek a solution to the worrisome indicators of food waste, this study aims to map the amount of waste generated in restaurants located in a medium-size city in the south of Brazil.

In this perspective, the circular economy emerges as an alternative that seeks to contribute to the circularity of materials [23]. It presents a set of practices [15] that contribute to the optimization of the use of food [24]. There is even a current research focused on circular gastronomy [19]. Furthermore, it includes an orientation of sustainable processes that prioritize reductions in water, energy, and materials to eliminate or minimize waste generation and to extend the useful life of products with fewer socio-environmental impacts and in an inclusive manner [30]. It also values practices such as Fair trade. In this perspective, companies have an important role in the production and consumption of sustainable products, especially in the circularity of resources.

Studies show that to produce the quantities of food wasted in the world, enough water is consumed to fill 100 million Olympic swimming pools and 3.3 million tons of carbon equivalent (tCO2e) are emitted [13,14,15,16, 18,19,20, 23,24,25, 27,28,29,30]. This negligent use of natural resources is yet another reason that underscores the need to avoid the loss or waste of food, and to make the most of all food waste available elements, such as the peel of fruits [30]. Considering the scope of this study, in relation to the consumption phase, in commercial points, namely, restaurants, bars, bakeries, etc., waste tends to occur through inadequate meal preparation procedures, low quality of storage systems, and storage and marketing of individual portions larger than normally consumed [30].

No previous studies have been mapped in medium-sized cities at the level of America (consult the Scopus, Wos, and Science Direct databases) the amount of food waste in food preparation, during meals and after meals. This study seeks to fill this gap and generate insights to promote reflections and advances in reducing food waste. In addition, the city where the research was carried out is a medium-sized city that has joined the Zero Waste Program and it is committed to generating solutions for the disruptive in all productive segments, as well as generating alternatives to increase the circularity of wasted food.

The city of Chapecó has approximately 220 thousand inhabitants. As described in the methodology of our study, the city has 729 establishments in the food sector. Many of them adopt the peculiar characteristic of Brazilian restaurants to sell food in kilograms, that is, the person serves a plate of food and pays for the quantity of grams of food acquired for their consumption. It is a habit in the city for a large percentage of the population to dine in restaurants, either for practicality, for the diversity of foods they can consume and also because it is a relatively cheap meal.

The study is organized as follows: subsequent to this introduction, the next section addresses food waste and circular economy. The second section covers the methodological procedures followed to carry out the research. In another section, the results of the research, the relevant framework, and guidelines for managing food waste supported by the circular economy are presented. Finally, the references used to prepare this study are presented.

Food waste and circular economy

Food loss refers to lost, rejected, or spoiled food, and it can occur in the production and harvest stages or in the processing and distribution stages of the supply chain [10,11,12,13,14,15,16, 18,19,20, 23,24,25, 27,28,29,30]. Food waste, on the other hand, is associated with the portion of good quality foods that are still suitable for consumption and are either discarded or not used. It usually occurs in the commercialization and consumption links of the supply chain [10,11,12,13,14,15,16, 18,19,20, 23,24,25, 27,28,29,30].

Efficient management of food waste is a complex challenge experienced around the world. Associated with complexity, governments are imposing taxes or service fees on the improper handling of waste [9]. The possibility of food poisoning emerges when food is not stored and handled properly. According to [24], studies addressing risks associated with food security have increased substantially in recent years.

In Brazil, approximately 20% of food is wasted [12]. This ranking places us among the 10 nations that most waste food—Singapore, Malaysia, New Zealand, United Kingdom, Germany, Norway, Canada, Denmark, Australia, and the United States. [12]. At the same time, approximately 7 million people are hungry, and 52 million people suffer from some food restriction [10]. These wastes occur at different levels. In residential household consumption, waste, in general, is associated with the purchase of food in excessive quantities, due to the lack of validity of the products, low utilization of leftovers, production in quantities greater than family consumption, and the partial disposal of food that is used or damaged [30].

In distribution centers and sales outlets, the main causes for waste include a lack of training for personnel handling and sorting food; the use of low-quality storage packaging; inadequate storage boxes, shelving systems, or improper shelves; the disposal of what does not meet a desired minimum visual standard; or a surplus greater than consumer demand [30].

In handling and transportation, the main causes for waste occurrences are the long distances traveled for distribution; the low conditions of conservation of the highways, which cause delays and interruption of trips; vehicles without refrigeration or unsuitable for the transportation of goods sensitive to temperature variations; and the use of packaging not ideal for the transport of certain types of food [30].

In rural properties, losses and wastes are associated with the use of low-quality seeds, the mistake of choosing a type of seed ill-suited for climatic conditions in the producing region, in the failures in the process of soil preparation, in the involvement of biological infestations, the inadequate training of harvesting equipment operators, and inadequate storage or storage infrastructure [30].

A meta-analysis on the theme of risk management associated with food security shows that the main factors (trust, knowledge, subjective characteristics, and sociodemographic characteristics) of the perception of risk and food safety and a consequent robust negative effect on the desire to buy are investigated [24]. In addition, the moderating variables of food origin, type of risk, healthiness, expiration date, and pleasure are highlighted in previous research.

The Environmental Protection Agency [11] has developed a food recovery hierarchy. It is a taxonomy that encompasses six levels of actions, practicable at any level of the chain, even within the scope of small businesses, aiming to make the most of food and minimize waste [30]. This hierarchy suggests:

  1. (1)

    Reduction at source: this category aims to reduce food waste, from production to the final consumer. It is recommended that organizations and end consumers start to adopt more conscious consumption, production, and food processing actions.

  2. (2)

    Feeding needs people: consists of donating leftovers, developing donation campaigns for people/institutions of a social nature, aiming at the reuse of the productive leftovers from commercial establishments and food close to the expiration date, which still holds quality and appropriate consumption conditions by human beings.

  3. (3)

    Animal feeding: use leftovers for animals in shelters or on streets. This category includes actions for the reuse of food residues not suitable for human consumption, but which can still be transformed into nutritious products capable of promoting animal feed.

  4. (4)

    Industrial use: recommends the implementation of industrial recycling through projects that aim to assist in environmental and economic issues, associated with food waste, generating energy, biomass, liquid fertilizer, among others.

  5. (5)

    Composting: consists of developing projects for transforming food waste into organic fertilizer.

  6. (6)

    Incineration or landfill: purpose for the destination or disposal of food waste that could not be reused in any way during the process. It is the least desirable path, which should be used only when all higher levels are not viable.

They are alternatives that seek to contribute to avoid waste. As mapped by previous research [4, p. 136] who investigate the “different management options that were investigated for the surplus bread are donation, use as animal feed, beer production, ethanol production, anaerobic digestion, and incineration”.

The circular economy is understood to be an alternative that contributes effectively to the management of food waste. To make this process more effective, the British Standards Institution recently launched the BS 8.001 [7] standard. This pattern seeks to reconcile the long-term prospects for reaching the circular economy with the existing commercial routines [27]. The standard presents a comprehensive list of circular economy terms and definitions. It also includes a set of general principles that deal with the structure of the circular economy, the flexible management system to implement the materials circularity strategies, aspects related to economic, environmental, design, marketing, and legal issues that converge with the implementation of the circular economy [6, 7]. Also, adopted Organic Waste Treatment Facility, as, for example, China [21] is a good way to improve the waste manager.

Recent studies show that the concern with food waste is the subject of scientific investigations in different contexts. For example [21], carry out a study on the system dynamics model for evaluating food waste management in Hong Kong [3]; upcycled by-product use in agri-food systems from a consumer perspective [22]; Post-treatment of food waste digestate toward land application [17]; nutrients cycle, humification process, and agronomic efficiency of organic wastes composting [1]; measurement of levels of food waste, applies the Material Flow Analysis (MFA) methodology to the Italian meat industry, testing its reliability in sustainability assessments [26]; food loss and waste in the context of the circular economy [34] and upcycling food waste using black soldier fly larvae. Therefore, it is well known that food waste is considered a relevant issue on the agenda of researchers at a global level. In addition to improving efficiency, it is well known that measurement processes, resources, techniques, and procedures are the scope of analysis observed by researchers in the field.

Methodological procedures

The research approach is predominantly quantitative with the application of a survey (questionnaire in Appendix). Consultation was carried out in the database of the City Hall in the city of Chapecó/SC. The database consisted of 729 establishments in the food sector, which includes bars and warehouses, snack bars, other establishments specializing in serving drinks, snacks, tea shops, juices, and the like; pizzerias, restaurants, and the like and wiskeria. To carry out invitations to participate in the research, priority was given to the 156 establishments registered in the category of restaurants on the list received from the City Hall. Subsequently, the other categories were invited to participate in the research. We obtained data from 177 establishments.

Thus, the sample has a 95% confidence level, with a margin of error of 6% (p = q = 50). The establishments are mainly located in the city center; however, we had respondents representing different neighborhoods, as shown in Table 1. The justification for the adoption of a 4-point scale (frequency in which the restaurant serves meals: 5 days, 6 days, 7 days, another frequency). And for the question related to the wasted volume, a 7-point scale was adopted, where

Table 1 Distribution of the sample by neighborhood
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I have no waste (1).

Less than one dish a day (2).

Up to 1 to 5 medium dishes per day (3).

6 to 10 medium dishes per day (4).

11 to 15 medium dishes per day (5).

16 to 20 medium dishes per day (6).

Above 21 average dishes per day (7).

At the time of tabulation, the categories that appeared to answer were included. For this reason, a 4-point scale was used in the responses. Attached is the complete version of the questionnaire.

In total, 6 students, 2 at the undergraduate level and 4 at master’s level, received training to conduct face-to-face data collection with those surveyed. The applied questionnaire was adapted from the Food Waste UK and Food Waste Brazil studies, conducted by Embrapa and FGV. It also follows the guidelines of the Pan-European survey for the quantification of food waste in the consumer sector [29]. The justification for choosing this questionnaire is especially associated with its validation in an academic and empirical context and with the purpose of generating indicators capable of measuring food waste. Additionally, it considers indicators similar to those that our study proposes to evaluate in an emerging country.

Data collection involved the following steps:

  1. (a)

    Previous telephone contact to schedule the date and time of the visit.

  2. (b)

    Previous explanation of the research purposes and the anonymity of the respondent establishment surveyed.

  3. (c)

    Oral application of questions to the respondent.

  4. (d)

    Clarifications of doubts, replication of inquiries when necessary, and notes of responses in a physical questionnaire.

The choice of the respondent was made by the restaurant. The initial orientation addressed to those involved was to identify who had more information about preparing food at the restaurant and managing leftovers. Once identified, a time for the oral application of the questionnaire to the respondent was scheduled.

Once in possession of the data, results were tabulated in cross tables and meanings were extracted from the mapped evidence. In addition, economic losses and the volumes of wasted food were estimated.

Data presentation and analysis

Table 2 presents a brief characterization of the profile of the 177 restaurants surveyed.

Table 2 Profile of the surveyed restaurants
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It can be seen in Table 2 that most of the researched enterprises offer buffets and snacks. The predominant office hours are noon and night. Establishments that offer up to 100 meals a day for 6 days a week predominate. Concerns about separating leftovers from other materials that can be reused in restaurants stand out in the survey. A variety of different destinations for leftovers were reported, with a significant percentage of 65.5% of establishments allocating part of their leftovers to landfills.

Table 3 shows the attributes pursued by the restaurants. The scale measures the importance perceived by the respondents, where 1 is less important, and 4 is very important.

Table 3 Attributes of prepared food
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It is worth highlighting the concern of the interviewees with the quality of the prepared food. The cost is considered to be very unimportant (1 on the scale), by 141 (79.7%) of the respondents, while 60 respondents consider a portion of healthy food to be very important (they assigned 4 on the scale to this item), and 75 rated it as high. It is noteworthy that the major concerns of the interviewees corroborate with meeting customer preferences and having enough food in the restaurant to prepare it properly.

To determine the amount of food waste generated by restaurants, three stages of the food process were investigated: (a) waste during food preparation; (b) waste due to consumption during the meal; and (c) waste post preparation. Food preparation is understood as the stage of washing, separating, cutting, preparing, and cooking food (the steps that happen in the kitchen before taking the food to the customer’s table). Food waste during meals is defined as that which occurs when the customer serves the food and its leftovers on the plate when the meal is finished. Post-preparation food waste is understood as the excess of prepared food, that is, the leftovers of meals after all customers have served themselves.

Table 4 shows the reported responses, as well as the total wasted, by type of food and at each stage of the process.

Table 4 Daily food waste in restaurants—observed frequency and quantity calculated, by type of food, per stage
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With the average prices by food category, Table 5 shows the total wasted, the different stages of the process, as well as the amount in Reais (R$), taken in October 2019.

Table 5 Daily and monthly amount wasted by type of food and estimated cost
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The largest physical volumes wasted are vegetables (35 tons/month—59%), followed by carbohydrates (12 tons/month—21%) and meat and bones (9.5 tons/month—16%). Another 2.4 tons (4%) come from desserts and drinks. The revenue losses caused by the waste generated in the three stages of food analyzed in this research are R $ 175 thousand in meat and bones (38%), followed by vegetables (R $ 169 thousand—37%) and carbohydrates (R $ 97 thousand—21%). Another R $ 13 thousand (3%) are for drinks and desserts. Considering a total of 177 establishments surveyed, there is an average waste of 339 kg/month (or 13 k/day) per restaurant, with a loss of revenue of R $ 2577.85/month/establishment. It is interesting to note that the average volumes of leftovers found in our study are close to those found by previous research [8] in a study carried out in the same city in a community restaurant, subsidized by the City Hall.

Discussion of results

The results show that the food losses generated in the researched restaurants are potential sources of economic losses. This volume of food waste could alleviate the hunger of more than 3 thousand people a month. As previous studies [19] reiterates, when we apply the circular economy in relation to food systems, there is an interest in reducing the amount of waste generated in the food system. This can occur through the reuse of food, the use of by-products and food waste, and the recycling of nutrients. The measures must be implemented at both producer and consumer levels, that is, from the cook and the customer who serves or receives meals at the restaurant. Finally, it is necessary to implement efficient alternatives in the management of residues and food surpluses. Food waste and surplus management refer to the use of by-products and food waste in the production phase and the reuse of food and to avoid surpluses in the consumption stage, mainly based on the competence and ability of the consumer.

Previous studies [10] also showed substantial losses in university restaurants. The author indicates an average waste of 68 g per consumer, which is also considered high. To circumvent these wastes, the sustainability literature rescues the framework of sociotechnical transitions, which are fundamental and long-term transformation processes through established sociotechnical systems to change production and consumption processes in more sustainable ways [16]. For this to become possible, it is necessary to invest in infrastructure and technology compatible with the objective of reducing food waste. At the same time, it is necessary to invest in the refining of skills, practices, and worldviews of all the actors who work along the supply chain [33].

The mapping of waste indicators in a pilot project is an important advance. It can be a warning to think about alternatives to recover energy from organic waste [2]. Based on the mapped percentages, it is possible to design new alternatives to contribute to the reduction of food losses. Based on the indicators presented, some ways are proposed, so that the circular economy can contribute to the reduction of food waste in the restaurant sector presented in Table 6. Besides, disruptive alternatives are possible. For example, previous research [32] shows that the agro-food wastes could be used as a resource and valuable materials to synthesize value-added engineering materials like glasses. Therefore, a transformative alternative for the use of waste.

Table 6 Paths to progress toward efficient management of food waste
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The novelty of the paper alluding to the circular economy is associated with the typification of the types of food that are wasted. From this initial diagnosis, it will be possible for restaurants and the municipal government to forward alternatives to generate creative solutions for the regeneration of materials, biocomposting, resource recovery, and integrated processes for managing food waste. This type of alternative tends to obtain effective results when there is the engagement of political rulers in the establishment of local public policies that outline guidelines, and procedures to be adopted by local organizations.

Furthermore, the nature of encouraging biological cycles recommended by the circular economy is a mechanism that can contribute to the generation of organic compost, useful for fertilizing lawns and flowers in the municipality. It can even be used to grow vegetables to feed people in socially vulnerable situations.

Finally, there is a need for awareness, engagement of all people. This post-consumption behavior implies important cultural aspects for the successful implementation of the circular economy. Clear communication between the actors involved and the official campaigns of public entities can serve as mechanisms to create a synergy between consumers, restaurants, and municipal government. Only in this way, the circular economy has the potential for adhesion and effective implementation in municipalities, within the scope of food waste management [37].

Final remarks

This study aimed to map the amount of waste generated in restaurants located in the city of Chapecó/SC as soon as generate alternatives to increase the circularity of wasted food. Research evidence indicates that this waste is significant in meals and after preparation.

The mapped results are useful for multiple actors:

  1. (a)

    For owners: so that they can be aware of how much money is underutilized with food waste.

  2. (b)

    For public managers: to create awareness campaigns on the importance of reducing food waste.

  3. (c)

    For the restaurant union: to set specific goals for the sector to reduce food waste.

  4. (d)

    For social assistance entities: so that they can legally contribute by offering alternatives to the enterprises; they can donate the surplus to entities that shelter people in a state of social vulnerability.

  5. (e)

    For customers: to make them aware of the damage they cause to society by "throwing away food".

  6. (f)

    For academics: to articulate new research to minimize food waste and try to circumvent it.

The practical contribution of the study is associated with an unprecedented mapping, through the realization of a pilot project in a medium-size city, of approximately 210 thousand inhabitants, which recently joined the Zero Waste Program. New research initiatives in the sector are necessary to create ways of progress in reducing losses and waste and in generating healthy habits for the entire population; whether in the consumption of healthy foods or in the reduction of waste. The theoretical contribution of the study is based on the diagnosis made to propose alternatives supported by a systematic review previously conducted [31], to increase the circularity of wasted food.

The main contribution of the study is to make a diagnosis of the estimated volume of food waste that occurs in the city of Chapecó. This estimate shows the amount of food that could be destined for other uses. Knowing waste is the first step toward finding solutions to reduce it and make the food system more efficient. Based on this mapping, it is possible to send alternatives for raising awareness, reducing waste, and comparing with other countries and regions; especially because the production of food demands water, energy, labor, use of natural resources that must be used in an efficient and appropriate way.

As a limitation of the research, one can observe the resistance of the owners and managers of the restaurants to adhere to the research. There was insecurity about the data handling, uncertainty about the disclosure of information, and disbelief in the environment issues, making them feel uncomfortable about contributing to the research. This resistance also makes it difficult to map food waste indicators more precisely. All data generated in terms of measuring waste were estimated based on the perception of respondents surveyed. Therefore, they carry a bias.

For future studies, it is proposed to proceed with research based on available innovations that can be useful to combat food waste. Research should explore in more depth the circular business models and their contribution to the success of combating food waste.