Food production and consumption have a major impact on the environment (1–8). Current estimations show that food production is responsible for about 25–30% of greenhouse gas emissions (8–11), 70% of (fresh) water use and 40% of land use (10, 11). Considering the prospects for population growth in the coming decades (10–12), it is expected that these rates will increase with devastating consequences for the planet (10, 11), and the increase of malnutrition, both due to lack of access to food and excessive consumption of low nutritional value food (13).

Between 1961 and 2009, the availability of animal protein sources increased by 59%, while plant-based protein sources grew only by 14% and, the demand for animal protein is expected to increase by 80% until 2050 (11). When compared to plant-based alternatives, particularly pulses, animal protein is the least sustainable food source (2–4, 10, 11), resulting in 20 times higher greenhouse gas emissions per unit of protein for consumption (8).

The last National Portuguese Food Survey showed that the dietary patterns have drifted from the recommendations (14), revealing an increasing consumption of meat and processed foods, and a decrease in non-starchy vegetables, fruit and pulses (2, 10, 11). Traditionally, animal food sources are served as the central component of the dish (11, 15), particularly meat, which plays a very important role in the diet due to its association with wealth, success, conviviality and pleasure (11). This meat centrality (15, 16), contradicts the promotion of the plant-based foods which are often disregarded in the menu descriptions.

The food services sector is responsible for providing around 67 million meals per day in Europe, reaching approximately 13.2% of this population and amounting to a total of 6 billion meals per year (17, 18). Particularly in Portugal, the annual number of meals served in this sector is approximately 300 million (17). Given the demands placed on food production in the 21st century, the food services sector stands out as a relevant actor in sustainability, and in promoting more sustainable eating habits (5, 17), by reducing the supply of less sustainable foods such as animal protein sources. This sector has an important impact on consumers’ eating habits, as they are regular suppliers for a long period of time, which supports the responsibility of this sector in public health (5, 17).

Information nudges are reported as a way of inducing behavioral change, and choices, enabling the information provided more appealing (4). In the food service context, nudging can be applied to menus (19), which represent the customers’ first contact with the service, triggering expectations and possible interest. Reformulation may concern the ordering of components (20), the type, size and color of the font used (21, 22), the use of more descriptive names (20, 23, 24) or the enhancement of sensory aspects or the cooking method (20, 24). They may also exert a stronger effect on taste perception and eating behavior than nutrition information alone (20, 24) and are associated with increased consumption of the highlighted food (25). The menus should be designed creatively, including all the menu characteristics, item layout, descriptions and labels, aiming to provide information, but driving consumer focus to the food items we aim to promote (26). Some studies reported that menus designed considering the mentioned principles are important tools that can contribute to modulating food choices (10, 20, 21, 24–27). Dayan et al. (20) observed an increased popularity of the item placed in the first (55%) and second (57%) position vs. the last and penultimate position. Wansink et al. (21) discuss different strategies to increase consumer acceptance of specific menus, such as the description of the texture, taste, smell to enhance taste expectations, or the inclusion of geographical references to the dish creating proximity and familiarity with the food origin. The use of nostalgic words can also help to trigger emotions related to tradition or family. Magnini et al. (28) changed the menu’s font style and physical weight and observed that consumers start to judge restaurants by their menus, finding that italicized font in menu descriptions has a significant influence, improving consumers’ perception of quality service.

Therefore, the main objective of this study was to evaluate the impact of menu reformulation and food offer change, favoring plant-based products, on consumer perception and acceptance.

The main objective of this study was to evaluate the impact of menu reformulation and changes in the food offer, promoting plant-based products, on consumer perception and acceptance. The participants were mostly women with a bachelor’s degree or a higher education title, which was expected, considering the type of canteen (hospital unit). Most of the participants use the canteen daily, which means that they are familiar with the type of service, menus, and meals.

The ranking of food groups reveals that meat is considered the most important component in the participants’ diet, which is in line with the perception of most consumers (11, 14, 15, 31), promoted by the social norm of creating menus around animal food sources (16). Canteen employees share the same perception and, in addition to meat, fish and eggs are also highlighted. At the same time, whole-grains, vegetables, pulses, fruit, nuts and fat are considered of lower importance to the diet. While meat is socially a food with a very prestigious symbolic meaning, associated with purchasing power and physical strength, plant-based foods are seen as discreditable, linked to poverty and food shortages (16). Moreover, as a result of extensive experience preparing and cooking meat and fish, chefs and individuals are not very creative when it comes to preparing and cooking plant-based products, which are associated with longer and harder preparation times (27). Indeed, from a very young age, consumers are encouraged to consume meat and animal products as a source of protein, which is more evident in more urban areas, perhaps due to the greater consumption of meals outside the home, high exposure and quantity of pre-cooked foods that promote their consumption (32).

This emphasis (11, 15, 29) is coupled with the need to reduce meat consumption both because it is less sustainable (2–4, 33) and because of the negative impact that its high consumption has on health (13, 34–36). Protein is one of the essential nutrients in the diet and can be obtained through the consumption of various foods, but meat is the most common source, although other sources, particularly of plant origin, are considered healthier and more sustainable (37). The current (32, 37) consumption of fruit and vegetables is lower than recommended (14), emphasizing the need to change current food patterns by promoting the consumption of vegetables, pulses, nuts and seeds and whole-grains, promoting more sustainable dietary patterns such as the Mediterranean Diet (38–41) and the Planetary Health Diet (3, 42). Positive health and environmental impacts could be achieved by changing the current view, based primarily on the importance of animal food sources, particularly meat.

Fats are the food considered least important by the participants among the various food groups, something that is partly due to the link between fat and negative health effects, such as cardiovascular diseases, that have been highlighted over the years (34, 43). However, it is important to note that there are different types of fat with different effects on our bodies. The main source of fat in the Mediterranean diet is olive oil, whose composition includes monounsaturated fatty acids and antioxidants that have positive effects on health, particularly the protective effect against coronary heart disease, some types of cancer and cognitive decline due to aging (44). It is therefore a group of foods that should be given importance, but in which olive oil should be chosen as the fat of choice (44), in order to obtain the health benefits of its consumption.

In general, participants considered food and nutrition important for themselves and for their health. However, a significant percentage do not consider that their choices have an impact on sustainability. This may be due to the emotional connection that consumers have with the consumption of animal food products, mainly meat (45, 46). A study that aimed to identify barriers to reducing meat consumption found that many consumers are skeptical of the need to reduce meat consumption, value the sensory quality of meat, and do not have the cooking skills needed to prepare meat-free meals, expressing a desire to have control over their food choices (45).

Also, taste perception has the largest impact on consumers’ choices, affecting the maintenance of unbalanced eating habits (47). Therefore, the attractiveness of a dish can be guaranteed through more appealing descriptions and presenting the dish in a more agreeable way (21, 30). Nevertheless, consumers’ satisfaction with the new food offer was lower than expected. A study by Atwood et al. (10) that used the ‘decoy effect’ also failed to confirm the initial hypothesis that a price-based decoy strategy could encourage diners to shift their food choices away from meat toward plant-based alternatives. A possible explanation for the low satisfaction may be the strong predisposition for meat preference (46). Another strategy could be the incorporation of more Mediterranean dishes, which incorporate all food items in one pot, facilitating the reduction of animal protein sources inclusion and allowing for more diverse, appealing and accessible cooking techniques, promoting the consumption of plant-based products (48).

Contrary to expectations, most consumers (74%) did not perceive the change in the menu’s description, as reported in a similar study, in a public canteen in Portugal (49). This might be because regular users are used to menu cycles and the type of food regularly provided. However, those who perceived it highlighted that the adjustments carried out at this stage of the study were due to concern for “health and nutrition,” which may reveal some awareness of the importance of dietary patterns on health promotion (50). However, the changes were not related to sustainability, which may indicate that the concept of sustainability may not be clear to the population and that the food impact on sustainability may not be fully perceived by consumers, which is an interesting topic to explore in the future.

In the second phase of the study, most participants still did not notice the menu changes. However, those who identified them presented a low level of satisfaction. Once again, this result may be due to the importance given to animal food sources in the diet (11, 15, 31). The low level of customer satisfaction may also be related to changes made in the plating (vegetables served on the plate instead of as a side dish), preconceived ideas related to vegetables and the association with the reduction of meat offered to control costs. As stated before, meat is associated with the increased power of purchase (51, 52) and, while consumers may value the increased vegetable availability, either on the menu or on the plate, that they associate to health, the actual reduction of the meat portion size on the plate (that was not previously perceived on the menu description), may play a more complex role on emotions and expectations.

Most participants considered that changes in food offer contribute essentially to a more balanced diet and increase vegetable consumption (57.5 and 50%, respectively), which may be a positive point for raising awareness to the fact that the Portuguese population consumes non-starchy vegetables below the recommendations (14, 41). According to the results obtained, participants associated the change in supply with the need to promote their consumption.

Despite the majority scoring changes negatively, most participants (65.8%) expressed interest in maintaining the changes, particularly in increasing the variety of vegetables available, which might be related to the recognition of the importance of nutrition and plant-based food patterns on health (46) and may be a good indicator for future interventions in canteens. Another explanation may be the influence of social desirability, which is understood as the adoption of a culturally accepted stance by avoiding criticism when exposed to tests (53). Therefore, the acceptance of the proposed changes may have the effect of social desirability on the participants in the study, trying to get closer to the eating habits promoted.

The evaluation of the perception and acceptance of the changes of food offer was also applied to the employees of the canteen. Although they also considered meat to be the most important food group, these participants associated the changes with sustainability and half of the respondents were quite satisfied with them. It is interesting to identify this perception from this group, which is less educated, a social-demographic characteristic usually associated with low food literacy (54). To implement the changes in the food offered, this group was tutored on sustainability, Mediterranean diet and more appealing ways of cooking vegetables. Although the importance of meat was highly scored, probably due to emotional reasons already explained, this group might have had a good understanding of the sustainability issues related to meat and vegetables. Therefore, this might be an important stakeholder to consider for permanent changes in the food service offer.

This research was intended to promote new practices to change perceptions and encourage sustainable consumption. Changes in menu descriptions were not perceived by consumers, and in general, changes in the food offered were accepted. Consumers and employees showed interest in maintaining the proposed practices, which constitutes a window of opportunity for future interventions in food service toward sustainability.