Assessment of Food Sustainability in School Canteens: Menu Quality and Environmental Performance

Abstract

This study aims to evaluate the environmental performance and menu sustainability in Portuguese primary school canteens. A total of 58 canteens were assessed using two checklists: one evaluating the sustainability and nutritional quality of menus (maximum score: 183 points), another assessing canteen environmental performance (maximum score: 195 points). Canteens were categorized into four performance levels based on their final scores: Very good (90–100%), Good (75–89.9%), Acceptable (50–74.9%), and Not Acceptable (<50%). The mean sustainability score was 130.5 ± 2.8. None of the canteens fully meet the recommended standards for vegetable portion sizes, reuse of leftovers, or inclusion of pulses in soups. The average environmental performance score was 137.9 ± 12.2. Canteens with on-site meal preparation demonstrated better environmental performance (142.3 ± 2.5) than those relying on off-site prepared meals (106.0 ± 3.6; p < 0.001). Additionally, canteens serving more than 150 meals daily achieved higher environmental performance scores (144.5 ± 1.7) compared to those serving fewer than 50 meals (125.5 ± 18.3). No significant correlation was observed between environmental performance and menu sustainability scores. Findings indicate a generally positive evaluation of both environmental performance and menu sustainability. Nevertheless, substantial improvements are needed, particularly in ensuring adequate vegetable portion sizes, minimizing food waste, and increasing the inclusion of plant-based protein sources.

1. Introduction

There is widespread recognition that current global food systems are unsustainable [1]. Given their complexity, the sustainability of food systems must be assessed using multiple indicators, one of the most critical being greenhouse gas emissions [2]. It is estimated that food systems contribute up to 30% of total greenhouse gas emissions, significantly impacting climate change [3]. In response to these challenges, the United Nations Sustainable Development Goals (SDGs) emphasize the importance of sustainable consumption and production. Specifically, SDG 12 advocates for “doing more and better with less”, promoting resource and energy efficiency, sustainable infrastructure, and equitable access to essential services, green jobs, and improved quality of life [4]. To achieve these objectives, food systems must undergo profound transformations, particularly in production models and consumption patterns, with a shift towards more sustainable and healthier, adequate diets [5].

According to the Food and Agriculture Organization (FAO), sustainable diets are those that minimize environmental impact while ensuring food and nutrition security, thereby promoting the health of present and future generations. These diets are characterized by their ability to protect biodiversity and ecosystems, maintain cultural acceptability, ensure economic fairness and affordability, and optimize natural and human resources [6]. In this context, a sustainable diet is frequently described as one that prioritizes plant-based, fresh, and minimally processed foods [7].

The Mediterranean Diet (MD) exemplifies a food model that aligns with the principles of both health and sustainability. It is predominantly plant-based, emphasizing vegetables, fruits, legumes, whole grains, and olive oil, while including moderate amounts of dairy products and fish, and only occasional consumption of meat [8]. Additionally, this dietary pattern supports the use of seasonal and locally sourced foods, thereby reducing the environmental footprint associated with processing, packaging, and transportation. By promoting moderation in food consumption, the MD also plays a role in minimizing food waste [9]. This is particularly relevant considering that, in 2022, approximately 1.05 billion tons of food were wasted worldwide, with food services accounting for 28% of this total [10]. Within the European Union, 9% of total food waste is generated by restaurants and food services, including school canteens [11]. Given their scale and influence, school food systems represent a critical component of the global food system and have the potential to drive significant improvements in sustainability [12].

The structure and functioning of school food systems, from procurement to consumption, play a pivotal role in shaping students’ dietary preferences and long-term eating behaviors [12,13]. Consequently, food education within schools should integrate the principles of social, economic, and environmental sustainability across all stages of the food system [14]. UNESCO underscores the importance of education in fostering a transformative vision of sustainable global development, reinforcing the role of schools in this transition [15].

Beyond their role in promoting balanced nutrition, school meals can serve as a powerful tool for reducing the environmental impact of food systems. The composition of school menus, the selection of ingredients, and the sourcing of food products all contribute to the ecological footprint of school food services. By prioritizing plant-based meals, using seasonal and locally sourced ingredients, and reducing the inclusion of highly processed and resource-intensive foods such as red meat, school canteens can significantly decrease greenhouse gas emissions, water consumption, and land use associated with food production [16]. Additionally, school menus designed with sustainability principles in mind can serve as educational instruments, familiarizing students with healthier and more sustainable food choices from an early age and encouraging shifts in household consumption patterns [17].

Sustainability in school food services extends beyond menu composition. Effective resource management, including waste reduction strategies such as composting, recycling, and food donation programs, is crucial in minimizing the environmental impact of school meals [18]. Reducing energy and water consumption in food preparation and service further contributes to lowering the ecological footprint of school food systems [19]. Given that schools provide meals to large populations on a daily basis, optimizing these processes can yield substantial environmental benefits. To maximize the positive impact of school food services, it is essential to evaluate the sustainability performance of school canteens systematically. This involves assessing key aspects such as food procurement policies, menu composition, food waste levels, energy and water usage, and waste management practices. By identifying strengths and areas for improvement, such evaluations can inform the development of targeted strategies to enhance sustainability in school food systems [20].

Furthermore, the assessment of school menu sustainability is fundamental in ensuring that dietary recommendations align with environmental considerations. This allows for the refinement of guidelines and policies that support both health and sustainability objectives, such as those outlined in the EAT-Lancet planetary diet [7,19]. By continuously monitoring and improving sustainability practices in school food services, institutions can contribute to the broader goal of fostering more sustainable food production and consumption patterns at both local and global levels. In this context, the evaluation of sustainability in school food systems serves not only as a tool for improving current practices but also as a foundation for developing long-term strategies that align with global efforts to combat climate change, preserve biodiversity, and promote food security. Schools, as key influencers in children’s food choices and behaviors, have a unique opportunity to shape future generations’ attitudes toward food sustainability, ultimately contributing to a more resilient and equitable food system.

This study aims to assess the environmental performance and sustainability of menu offerings in primary school canteens.

2. Materials and Methods

2.1. Sample Selection

This descriptive study included a sample of 58 school canteens located in northern Portugal. These canteens serve children aged 3 to 10 years, totaling 6294 students. The number of meals provided daily at each school varied between 8 and 266. The meals were either prepared and cooked on-site in school kitchens (in situ kitchens, n = 51) or produced in a central kitchen, packed, and subsequently delivered to school canteens in hot containers (hot transported meals, n = 7). This observational study was conducted without any direct contact with humans and was developed in accordance with the guidelines of the Declaration of Helsinki.

2.2. Data Collection

Data was collected using two structured checklists designed to evaluate the sustainability of the school canteens. The data collection process involved two complementary approaches: (i) direct observation of canteen operations, and (ii) consultation of relevant documents, including menus and records of monthly electricity, gas, and water consumption.

The first checklist was adapted from the School Meal Planning and Evaluation System [21] and included 88 items assessing both health and sustainability aspects (

Table 1. Description of criteria from School Meal Planning and Evaluation System.

Domains (n = 7)	Maximum Score (n = 183 Points)	Items (n = 88)	Score per Item	Item Classification *
General items	91 points	46	3 or 0 points 2 or 0 points 1 or 0 points	legal requirement (3 points) best practice (2 points) recommended strategy (1 point) did not meet the criteria received (0 points)
Soup	12 points	5
Meat, fish, and eggs	25 points	12
Vegetarian options	15 points	5
Side dishes (cereals, tubers, or legumes)	9 points	5
Vegetables and salads	13 points	6
Desserts	18 points	9

* 42 items = legal requirement; 11 items = best practice; 35 items = recommended strategy.

). These were categorized into seven domains: General items (n = 91 points); Soup (n = 12 points); Meat, fish, and eggs (n = 25 points); Vegetarian options (n = 15 points); Side dishes (cereals, tubers, or legumes) (n = 9 points); Vegetables and salads (n = 13 points); and Desserts (n = 18 points). Each item was assigned a score based on its level of compliance, weighted according to its classification as a legal requirement (3 points)—examples: “Existence of technical sheets with the composition of the meal, raw materials used, with respective capitations, and description of preparation methods” and “Chopped vegetables in soup at least 3 times a week”; best practice (2 points)—examples: “Prioritize the presence of products that meet their seasonality (in at least 50% of all products present in the monthly menu, namely, vegetables, fruits and fish)” and “Strategies to minimize food waste”; or recommended strategy (1 point)—examples: “Regular assessment of food supply satisfaction, monitoring waste and/or conducting surveys” and “Weekly offer of fruits rich in vitamin C”. Items that did not meet the criteria received 0 points. The maximum possible score was 183 points (100%). Based on the final percentage score, canteens were classified as: Excellent (>90–100%); Good (>75–90%); Acceptable (≥50–75%); or Not Acceptable (<50%).

The second checklist, developed by Nóbrega et al. [22], was used to assess the environmental performance of the canteens. This instrument consisted of 72 items covering key environmental aspects, including: Water, electricity, and gas consumption; Management of chemicals and waste; Use of fresh fruit and vegetables; and Evaluation of user satisfaction. Each item was scored on a scale from 1 to 3, where 3 points were assigned to practices with the lowest environmental impact; 2 points corresponded to intermediate environmental impact; and 1 point was given to practices associated with the highest environmental impact. For binary (yes/no) questions, only scores of 3 or 1 were assigned. Some items were deemed not applicable, leading to variations in the maximum possible score among different schools. Based on the final score, the environmental performance of each canteen was categorized as: Excellent (90–100%); Good (75–89%); Acceptable (50–74%); or Unacceptable (≤49%).

2.3. Statistical Analysis

Statistical analyses were performed using IBM SPSS Statistics for Windows, version 27 (IBM Corp., Armonk, NY, USA). Descriptive statistics were used to summarize the characteristics of the school canteens, including means and standard deviations for continuous variables, and frequencies and percentages for categorical variables. Comparisons between in situ kitchens and hot transported meal canteens were conducted using independent samples t-tests for normally distributed continuous variables and the Mann–Whitney U test for non-normally distributed variables. Chi-square tests (or Fisher’s exact test when appropriate) were applied to compare categorical variables. To assess associations between sustainability scores and key operational factors (e.g., type of meal service, number of meals served, resource consumption), Pearson’s correlation coefficient was used for normally distributed variables, while Spearman’s rank correlation coefficient was applied for non-parametric data. The level of statistical significance was set at p < 0.05 for all analyses.

3. Results

3.1. School Menu Sustainability

The evaluation of school menus revealed that only one school canteen achieved a classification of “Good”, while the remaining 57 were classified as “Acceptable”. The most prevalent non-conformities included the absence of eggs as the main protein source at least once per week and the lack of legumes as the primary protein source at least once per month in all canteens. Furthermore, all menus contained bread with a salt content exceeding 1 g per 100 g, and recipes failed to specify the supplier, origin, or organic status of food items. The prioritization of locally, regionally, or nationally produced foods, which should constitute at least 30% of the monthly ingredients, and the inclusion of seasonal products, expected to represent at least 50% of the total ingredients, were also universally neglected. Additionally, none of the canteens ensured that at least three-quarters of the plate was occupied by plant-based foods, nor did they implement strategies for reusing leftovers. Moreover, general portioning recommendations for lunch meals were not met, with observed servings often falling below the recommended quantities, indicating a trend of underserving. Regarding soups, none of the evaluated menus complied with the requirement of including legumes as a base ingredient at least two to three times per week, nor did they prioritize the use of seasonal vegetables. In terms of protein sources, the previously mentioned lack of egg-based meals was confirmed, with 57% of canteens also failing to meet the recommended per capita portions for meat, fish, and eggs. Concerning vegetarian options, all canteens exceeded the recommended frequency for offering tofu, seitan, tempeh, or soy-based protein alternatives, which should not be included more than once per month. With respect to side dishes, none of the canteens ensured an equitable distribution between carbohydrate sources such as rice, pasta, and potatoes. Regarding vegetables, seasonality was not considered in any of the schools, and all canteens failed to comply with the pre-established portion recommendations, with servings generally falling short of the required amounts. Finally, in terms of desserts, all canteens offered sweet desserts more than twice per month.

3.2. Environmental Performance of School Canteens

Regarding the environmental performance of school canteens, most institutions (91.4%) were classified as “Acceptable”, while five canteens (8.6%) received a “Good” classification. In the category of water consumption, none of the canteens had established objectives or targets, and 43% used dishwashing equipment with a processing capacity of approximately 300 dishes per hour, while 10% had lower efficiency, processing fewer than 300 dishes per hour. In terms of electricity consumption, all canteens relied on manually controlled artificial lighting and conventional air conditioning systems, contributing to higher energy demand. Similarly, no canteen had established objectives or monitoring mechanisms for gas consumption, and none measured gas temperature. The predominant type of gas used was propane, which was present in 62% of canteens. Regarding the management of chemical products, all canteens used corrosive and/or flammable chemicals, posing potential risks to both human health and the environment. Waste management practices were also found to be inadequate, with none of the canteens recording food waste from preparation, cooking, or plate leftovers. Additionally, waste from food preparation and cooking was not separated from general waste. All canteens used disposable items, such as caps, aprons, and gloves, and none possessed a shredder for organic or inorganic waste. A fat separation box was identified in only one canteen (0.58%). Moreover, all canteens exclusively purchased non-organic fruits and vegetables, and none provided the option for users to customize meals by adjusting portion sizes, potentially increasing food waste and environmental impact.

3.3. Menu Sustainability and Environmental Performance According to the Production Systems and Meals Produced

A comparison between different food production systems showed that on-site cooking canteens exhibited a significantly higher environmental performance (142.29 ± 2.47) than those operating with transported hot meals (106.00 ± 3.56; p < 0.001). However, no significant differences were observed in the sustainability of menus according to the production system (

Table 2. Environmental performance of school canteens and menu sustainability according to the meal production system (n = number of meals provided).

Environmental Performance	On-Site Cooking (n = 5087)	Meals on Wheels (n = 241)	p-Value *
	(Mean ± SD)	(Mean ± SD)
Water Consumption	32.24 ± 1.45	26.00 ± 1.63
Electricity Consumption	35.00 ± 0.00	32.71 ± 2.14
Gas Consumption	23.59 ± 0.92	0.00
Chemical Management	16.90 ± 0.70	16.29 ± 1.89	p < 0.001
Waste Management	21.57 ± 1.01	18.00 ± 0.00
Use of Fruit and Vegetables	5.00 ± 0.00	5.00 ± 0.00
Evaluation of User Satisfaction	8.00 ± 0.00	8.00 ± 0.00
Total of Items	142.29 ± 2.47	106.00 ± 3.56
Menu Sustainability	On-Site Cooking (n = 5087)	Meals on Wheels (n = 241)	p-Value *
	(Mean ± SD)	(Mean ± SD)
General Items	64.61 ± 2.49	64.57 ± 1.13
Soup	6.59 ± 1.04	7.00 ± 0.00
Conduit (Meat, Fish, or Egg)	17.86 ± 2.39	19.14 ± 1.86
Vegetarian Option	10.94 ± 1.78	10.29 ± 2.36	p < 0.001
Accompaniment (Cereals and Derivatives, Tubers, and Legumes)	5.47 ± 1.16	5.57 ± 1.13
Vegetables (Raw or Cooked)	8.00 ± 0.00	8.00 ± 0.00
Dessert	16.92 ± 0.27	16.71 ± 0.49
Total of Items	130.39 ± 2.74	131.29 ± 3.09

SD—standard deviation. * p-value according to the Mann–Whitney test at a 95% confidence level.

).

When considering the number of meals served per day, canteens that provided more than 150 meals exhibited a significantly higher environmental performance score (144.50 ± 1.72) compared to those serving fewer than 50 meals (125.50 ± 18.27; p < 0.001). Nevertheless, no significant association was observed between environmental performance and menu sustainability (p > 0.05) (

Table 3. Environmental performance of school canteens and menu sustainability according to the meals produced.

Environmental Performance	<50 Meals	50–100 Meals	101–150 Meals	>150 Meals	p-Value *
	(Mean ± SD)	(Mean ± SD)	(Mean ± SD)	(Mean ± SD)
Water Consumption	29.36 ± 3.34	31.65 ± 1.81	32.63 ± 1.69	33.10 ± 1.20
Electricity Consumption	33.86 ± 1.88	35.00 ± 0.00	35.00 ± 0.00	35.00 ± 0.00
Gas Consumption	13.29 ± 11.95	22.19 ± 4.54	24.00 ± 1.07	24.80 ± 0.63
Chemical Management	16.29 ± 1.82	17.00 ± 0.00	17.00 ± 0.00	17.00 ± 0.00	p < 0.001
Waste Management	19.71 ± 1.73	21.54 ± 1.17	21.75 ± 0.71	21.60 ± 1.27
Use of Fruit and Vegetables	5.00 ± 0.00	5.00 ± 0.00	5.00 ± 0.00	5.00 ± 0.00
Evaluation of User Satisfaction	8.00 ± 0.00	8.00 ± 0.00	8.00 ± 0.00	8.00 ± 0.00
Total of Items	125.50 ± 18.27	140.38 ± 6.65	143.38 ± 2.00	144.50 ± 1.72
Menu Sustainability	<50 Meals	50–100 Meals	101–150 Meals	>150 Meals	p-Value *
	(Mean ± SD)	(Mean ± SD)	(Mean ± SD)	(Mean ± SD)
General Items	64.14 ± 1.70	65.00 ± 2.62	64.75 ± 3.01	64.10 ± 1.97
Soup	7.00 ± 0.00	6.31 ± 1.29	6.63 ± 1.06	7.00 ± 0.00
Conduit (Meat, Fish, or Egg)	18.21 ± 1.53	17.81 ± 2.94	17.13 ± 2.03	19.00 ± 1.63
Vegetarian Option	10.71 ± 2.27	10.62 ± 1.53	11.25 ± 2.12	11.40 ± 1.90	p < 0.001
Accompaniment (Cereals and Derivatives, Tubers, and Legumes)	5.57 ± 1.09	5.42 ± 1.21	5.25 ± 1.39	5.70 ± 0.95
Vegetables (Raw or Cooked)	8.00 ± 0.00	8.00 ± 0.00	8.00 ± 0.00	8.00 ± 0.00
Dessert	16.86 ± 0.36	16.96 ± 0.20	16.88 ± 0.35	16.80 ± 0.42
Total of Items	130.50 ± 2.96	130.12 ± 2.27	129.88 ± 2.85	132.00 ± 3.46

SD—standard deviation. * p-value according to the Kruskal–Wallis test at a 95% confidence level.

). These findings highlight the need for improvements in both food and environmental sustainability in school canteens, with particular attention to the management of food resources and energy consumption.

4. Discussion

This study assessed the environmental performance and sustainability of menu offerings in primary school canteens located in northern Portugal. Only one canteen was classified as “Good”, while the others were rated as “Acceptable” about menu sustainability. Regarding environmental performance, five canteens were classified as “Good”, while the remaining were categorized as “Acceptable”. Sustainability assessment of school canteens was conducted using two checklists, as this method offers an optimal cost-benefit and easy application. Additionally, the use of such tools enhances accountability for actions and fosters awareness of best practices. The connection between school meals and food education underscores the critical role of collaboration in fostering sustainable practices within the school food system [23,24]. School canteens serve as both a social and educational space, where eating habits and food-related behavioral patterns are established, often persisting into adulthood [25].

School meal production relies on conventional methods involving food processing, distribution, and preparation, which consume large amounts of resources, including fossil fuels, water, and energy [26]. In addition to resource use, environmental impacts are exacerbated by food waste, post-consumer packaging disposal, food residue generation, and the use of chemicals for sanitation [27]. Decisions made by school food services significantly influence environmental sustainability and can mitigate adverse effects through strategies such as sourcing organic and locally produced food, promoting the consumption of fresh and seasonal vegetables, regulating meat procurement, and adopting sustainability measures like portion adjustments, food donation, composting, purchasing products with minimal packaging, recycling, and reducing energy and water usage [17,18,27,28,29,30,31,32,33]. Menus assessment revealed that purchasing decisions were predominantly driven by factors such as product price, market availability, and food safety, rather than considerations of seasonality or local and regional sourcing. However, in most cases, canteens comply with what is established on the menus; when a certain food is not available, it is replaced by a similar one, thus safeguarding the quality of the menu.

Minimal variation in menu assessment scores among schools visited within the same month can be attributed to adherence to standardized menus, recipe specifications, and ingredient portioning guidelines. Our findings indicate that 31% of canteens failed to comply with menu specifications and, consequently, did not adhere to the recipe specifications. The main reasons for non-compliance included ingredient shortages and low acceptance by children. A study assessing planning, production, distribution, and nutritional adequacy of meals offered in early childhood education units in Brazil reported that 78.4% of meals produced did not comply with the planned menu, primarily due to ingredient shortages (51.7%), unexplained deviations (19.6%), short ingredient shelf life (13.4%), and low children acceptance (11.5%) [34].

Regarding portion compliance, vegetables consistently failed to meet pre-established portions across all school canteens, which was easily verified using the observation method. A previous study has shown that vegetables are the most wasted food component, with children discarding nearly half of their servings. However, increased knowledge and more favorable attitudes toward fruit and vegetable consumption have been linked to reduced waste [35]. In Sweden, a government report led to the implementation of so-called “pedagogical meals,” where teachers are required to eat with the students in the school canteen. This recommendation proved effective in encouraging children to try new foods and eat better, while also promoting the role of teachers as role models, teaching proper table manners and fostering discussions about food and nutrition during mealtimes [36,37,38].

However, to mitigate excessive food waste, canteens often serve smaller portions than planned, while still encouraging students to taste the vegetables provided, in order to achieve greater student acceptance of vegetables over time. Vegetable rejection by children is frequently attributed to factors such as appearance, color, and flavor, and also a lack of exposure in the family context [39,40]. Similar findings were observed in a study by Rodríguez-Tadeo et al., which identified food neophobia as a barrier to the acceptance of 53% of vegetables and legumes analyzed, including eggplant, broccoli, zucchini, pumpkin, onion, peas, green beans, cucumber, bell pepper, and tomato [37]. Lettuce, however, demonstrated high acceptance among school-aged children (75%), whereas vegetables such as bell peppers, cauliflower, broccoli, asparagus, chard, cabbage, and artichokes were consumed by fewer than 25% of the children [40]. Therefore, school food policies should include food handlers in the process, aiming to enhance the sensory aspects of meals. Promoting workshops to exchange cooking techniques and plating methods can help make meals more appealing and, in turn, reduce food waste during school lunches [41]. According to a study by Yoon and Kim conducted in Korean primary schools, students who were satisfied with the school lunch showed significantly lower food waste rates than those who were dissatisfied [42].

The significant investment in school meals and the statutory status of food education present a unique opportunity to incorporate a planetary health diet into school curricula [23]. A meta-analysis by Clune et al. demonstrated that cereals, fruits, and vegetables exhibit lower greenhouse gas emissions compared to ruminant meats, which have the highest environmental impact [43]. Similarly, research by Cerutti et al. analyzing policies aimed at reducing greenhouse gas emissions in public food services found that dietary modifications, particularly reducing animal product consumption, yielded the most significant reduction (32%) in carbon footprint [44]. One of the most effective approaches involves transitioning toward diets with a lower proportion of calories derived from animal-based foods [45].

Thus, improving diet quality while simultaneously minimizing environmental impact and promoting sustainable development is a critical global priority [46,47]. The scientific targets set by the EAT-Lancet Commission advocate for increased consumption of plant-based foods and a substantial reduction in animal-based product intake [7]. Therefore, offering vegetarian meal options to all students could serve as an effective strategy for reducing environmental impact. According to a French study that aimed to estimate the proportion of parents interested in having more vegetarian school meals for their children, the results showed that 49% of parents would opt for a second vegetarian meal per week, while 26% would choose a daily vegetarian meal [48]. For parents who are not yet convinced by the changes in school meal offerings, clear communication about the risks and benefits of vegetarian meals is essential [49]. In addition, barriers such as lack of sensory appeal and unfamiliarity with vegetarian dishes can be addressed through attractive descriptions that highlight their sensory qualities, the inclusion of plant-based recipes that children already know and enjoy, and training kitchen staff to prepare tasty vegetarian meals with attention to seasoning and presentation [48,50,51,52,53,54]. For recipes that are less familiar or not well-received by children, repeated exposure is one of the most effective strategies to increase acceptance and intake [55,56]. Furthermore, initiatives focused on food education can support the development of more positive attitudes and increased preference among children for healthy foods [57].

While this study supports the recommendation to increase the provision of vegetarian options in school menus due to their environmental and nutritional advantages, the findings on food waste—particularly the high levels of discarded vegetables—highlight an important challenge. The potential benefits of plant-based meals can only be realized if these foods are actually consumed. When such items are frequently wasted, their contribution to both dietary quality and sustainability is significantly compromised. This underscores the need for strategies that not only increase the availability of vegetarian meals but also enhance their acceptability among students. Culinary adaptation, sensory education, and participatory menu planning may be effective approaches to improve student engagement and reduce waste [50,51,52]. Therefore, future interventions should prioritize foods that combine a low environmental footprint, high nutritional value, and proven acceptability in the school context.

In addition to food education and school meal policies or recommendations, nudges can also influence automatic decision-making processes by making it easier to choose the desired option through reduced cognitive or physical effort. In this way, incentives can be implemented to support and complement traditional measures. When adopting nudge techniques, the focus is on changing the presentation or framing of existing food options to encourage the selection of healthier choices. This may include modifications to the physical space (positioning, availability, contrast, and display of food), as well as changes in how information (descriptions, semiotics, and suggestions about healthy foods) is provided [58]. A study conducted in the USA investigated how the presentation of fruit (apples and oranges) influences selection and consumption among children aged 5 to 10 in primary school. The fruit was served in two formats: sliced (on the first day) and whole (on the second day). The results showed that sliced oranges were significantly more frequently chosen and consumed than whole ones, whereas this effect was not observed for apples. Nonetheless, children generally showed a preference for cut fruit [59].

Other aspects of sustainability, including resource efficiency (e.g., water and electricity) and waste reduction, tend to be, at best, secondary concerns [26]. However, the environmental impacts resulting from the indiscriminate use of natural resources are a major concern [60]. Large-scale meal production, such as that in school canteens, contributes significantly to environmental degradation through waste generation and resource consumption [61]. Food service establishments, including school canteens, have been reported to consume up to five times more energy per square meter than other commercial buildings [62]. Approximately 25% of the energy used in catering services is spent on food preparation, cooking, and serving, with a significant portion being wasted due to inefficient equipment use and mismanagement [63]. The acquisition of energy-efficient equipment, particularly models rated “A” under the European A-G efficiency label, has been shown to positively impact energy and water consumption in school canteens [26,63]. This effect was observed in a procurement initiative by the German Central Procurement Agency (BeschA), where the installation of a highly efficient commercial dishwasher led to a 50% reduction in water usage [64]. Nonetheless, as water and energy are indispensable to meal production, it is imperative to implement staff training and continuous monitoring to optimize resource use [18]. Most catering services rely on gas as the primary fuel for cooking, with propane accounting for approximately 62% of fuel use in the assessed canteens, while natural gas constituted only 26%. Natural gas is generally regarded as the most environmentally favorable fossil fuel, as it emits less carbon dioxide per unit of energy produced and generates fewer pollutants [65].

In addition to functional requirements, detergents used in school canteens should be minimally corrosive, chemically stable, and environmentally friendly. Selection criteria should consider the type and extent of dirt removal required, solubility properties, and supplier recommendations [66]. Improper disposal of everyday materials contributes significantly to environmental pollution, highlighting the importance of recycling initiatives [67]. A systematic review conducted by Santos et al. identified composting as a widely endorsed practice for reducing organic waste, while recycling was recognized as an effective strategy for non-organic waste [18]. The sustainability checklist assessment revealed that 26% of canteens did not engage in the recycling of solid waste materials such as cardboard, plastic, and glass. The strategy involves placing containers in all school canteens to make recycling possible. Similarly, 19% of canteens lacked proper oil recycling systems, despite legal mandates prohibiting the disposal of used cooking oils in wastewater drainage systems [68]. Compliance with these regulations ensures the traceability, collection, treatment, and proper disposal of used oils by authorized operators [68]. Finally, studies on school meals indicate that food service procurement decisions-particularly regarding the sourcing and selection of fresh versus processed foods, as well as different food groups-carry significant environmental implications in the pre-production stages [18,69,70,71].

While the use of checklists provided valuable insights into school canteen sustainability, certain limitations were identified. As the assessments were conducted on a single day per school, compliance with menus, recipe specifications, and portioning on that day may not necessarily reflect overall adherence throughout the year. Additionally, measurement inconsistencies in ingredient preparation, often reliant on staff estimations rather than precise weighing, limited the accuracy of portioning evaluations. Another limitation arose from checklist scoring, which was based on predominant service practices rather than exceptions. For instance, while manual faucets may be the standard, a single pedal-operated faucet could be present; similarly, a dripping faucet observed during assessment may not have persisted over time. These factors should be considered in future studies to enhance the robustness of sustainability evaluations in school canteens.

Although the sample of schools included in this study is not nationally representative, the organization of school meal services across Portugal shares several structural similarities with those evaluated. In general, school food services are managed under the supervision of local municipalities, following national guidelines for the design and implementation of school menus. These guidelines aim to ensure nutritional adequacy and promote healthy eating habits among students. Moreover, both types of meal service identified in our sample— on-site cooking meals and meals on wheels (hot meals transported from external facilities)—are common practices throughout the country. Therefore, despite the limited size of the sample, the findings are likely to reflect broader trends and challenges within the Portuguese school meal system.

5. Conclusions

The findings suggest a generally favorable assessment of the environmental performance and menu sustainability in the evaluated school canteens. However, substantial improvements are necessary to enhance overall sustainability, particularly in achieving compliance with vegetable portion recommendations, minimizing food waste, and increasing the integration of plant-based protein sources. The implementation of targeted interventions is essential to advancing the sustainability of school canteens. The use of structured checklists enables the systematic identification of areas requiring improvement and should be established as a standard practice, given their cost-effectiveness, efficiency, and ease of application. Furthermore, continued research on the sustainability of school canteens is imperative, as early dietary exposure plays a critical role in shaping long-term eating behaviors and health outcomes.