Environmental impact of microbial protein from potato wastewater as feed ingredient: Comparative consequential life cycle assessment of three production systems and soybean meal

Livestock production is utilizing large amounts of protein-rich feed ingredients such as soybean meal. The proven negative environmental impacts of soybean meal production incentivize the search for alternative protein sources. One promising alternative is Microbial Protein (MP), i.e. dried microbial biomass. To date, only few life cycle assessments (LCAs) for MP have been carried out, none of which has used a consequential modelling approach nor has been investigating the production of MP on food and beverage wastewater. Therefore, the objective of this study is to evaluate the environmental impact of MP production on a food and beverage effluent as a substitute for soybean meal using a consequential modelling approach. Three different types of MP production were analysed, namely consortia containing Aerobic Heterotrophic Bacteria (AHB), Microalgae and AHB (MaB), and Purple Non-Sulfur Bacteria (PNSB). The production of MP was modelled for high-strength potato wastewater (COD = 10 kg/m3) at a flow rate of 1,000 m3/day. LCA results were compared against soybean meal production for the endpoint impact categories human health, ecosystems, and resources. Soybean meal showed up to 52% higher impact on human health and up to 87% higher impact on ecosystems than MP. However, energy-related aspects resulted in an 8-88% higher resource exploitation for MP. A comparison between the MP production systems showed that MaB performed best when considering ecosystems (between 13 and 14% better) and resource (between 71 and 80% better) impact categories, while AHB and PNSB had lower values for the impact category human health (8-12%). The sensitivity analysis suggests that the conclusions drawn are robust as in the majority of 1,000 Monte Carlo runs the initial results are confirmed. In conclusion, it is suggested that MP is an alternative protein source of comparatively low environmental impact that should play a role in the future protein transition, in particular when further process improvements can be implemented and more renewable or waste energy sources will be used.

Challenges and progress towards industrial recombinant protein production in yeasts: A review

Recombinant proteins (RP) are widely used as biopharmaceuticals, industrial enzymes, or sustainable food source. Yeasts, with their ability to produce complex proteins through a broad variety of cheap carbon sources, have emerged as promising eukaryotic production hosts. As such, the prevalence of yeasts as favourable production organisms in commercial RP production is expected to increase. Yet, with the selection of a robust production host on the one hand, successful scale-up is dependent on a thorough understanding of the challenging environment and limitations of large-scale bioreactors on the other hand. In the present work, several prominent yeast species, including Saccharomyces cerevisiae, Pichia pastoris, Yarrowia lipolytica, Kluyveromyces lactis and Kluyveromyces marxianus are reviewed for their current state and performance in commercial RP production. Thereafter, the impact of principal process control parameters, including dissolved oxygen, pH, substrate concentration, and temperature, on large-scale RP production are discussed. Finally, technical challenges of process scale-up are identified. To that end, process intensification strategies to enhance industrial feasibility are summarized, specifically highlighting fermentation strategies to ensure sufficient cooling capacity, overcome oxygen limitation, and increase protein quality and productivity. As such, this review aims to contribute to the pursuit of sustainable yeast-based RP production.

Shifting towards optimized healthy and sustainable Dutch diets: impact on protein quality

PURPOSE

To reduce the environmental impact of Western diets, a reduction of meat consumption and a substitution by plant-based protein sources is needed. This protein transition will affect the quantity and quality of dietary protein. Therefore, the aim of this study was to evaluate the protein adequacy of diets optimized for nutritional health and diet-related greenhouse gas emission (GHGE).

METHODS

Data from 2150 adult participants of the Dutch National Food Consumption Survey were used, with diet assessed using two non-consecutive 24 h dietary recalls. Utilizable protein of current diets per day was based on meal composition and the Protein Digestibility-Corrected Amino Acid Score and was compared to protein requirements. Optimized diets were derived as linear combinations of current diets that minimized GHGE and maximized the Dutch Healthy Diet 2015 score, with/without constraints to keep dietary change within 33% of current consumption. Protein adequacy was evaluated in both current and optimized diets.

RESULTS

In all age and gender strata, the healthiest diets had higher GHGE, the most sustainable diets had the lowest dietary quality, though higher than current diets, and protein adequacy remained sufficient. When limiting dietary change to 33% of current consumption, in the most promising trade-off diet GHGE was reduced by 12-16%. The current diet provided 1.4-2.2 times the required amount of utilizable protein.

CONCLUSION

These results suggest that a realistic aim for the next decade might be to reduce diet-related GHGE to 12-16% of the current levels without compromising protein adequacy and diet quality. To achieve global targets, upstream food system transformations are needed with subsequent dietary changes.

Diversity of protein food sources, protein adequacy and amino acid profiles in Indonesia diets: Socio-Cultural Research in Protein Transition (SCRiPT)

The ongoing nutrition transition in lower- and middle-income countries (LMIC) in South East Asia may have a positive impact on protein nutrition. This study assessed the diversity of plant and animal protein food sources in relation to essential amino acid (EAA) adequacy in a population-based sample (N 1665) in Indonesia. Dietary intakes from in-person 24 h recalls provided data on energy and protein intakes (in g/d) from plants (grains, legumes), meat, poultry and fish, and eggs and dairy. Protein diversity scores were based on the number of protein food sources over 24 h. EAA scores were the ratio of amino acid intakes to recommended values. Protein diversity and EAA scores were then compared across multiple socio-demographic indices. Analysis of variance and χ 2 tests were used to test for differences among groups. Energy intakes were 1678 kcal/d for men and 1435 kcal/d for women. Average protein intakes (and prevalence of inadequacy) were 59⋅4 g/d (41⋅7 %) for men and 51⋅5 g/d (51⋅1 %) for women. In regression analyses, higher protein diversity scores were associated with higher protein intakes, more animal protein and less plant protein and with higher EAA scores. Lower protein diversity scores were associated with lower intakes of lysine, leucine and valine relative to requirements, as well as with lower EAA, rural settings, less wealth and less modernisation. Greater diversity of animal protein food sources, observed among groups of higher socio-economic status, was linked to better amino acid adequacy and protein nutrition.

The farmers' dilemma: Meat, means, and morality

Evidence overwhelmingly supports the view that we need to drastically reduce our consumption of animal products for reasons related to the environment and public health, while moral concerns about the treatment of animals in agriculture are becoming ever more common. As governments increasingly recognize the need to change our food production and alternative protein products become more appealing to consumers, agriculture finds itself in a unique period of transition. How do farmers respond to the changing atmosphere? We present secondary analyses of qualitative and quantitative data to highlight some of the uncertainty and ambivalence about meat production felt throughout the farming community. Survey data from France and Germany reveals that in both countries, those who work in the meat industry have significantly higher rates of meat avoidance than those who do not work in the industry. While non-meat-industry workers are more likely to cite concerns for animals or the environment, meat industry workers more often cite concerns about the healthiness or safety of the products. Concurrently, interviews with people who raise animals for a living suggest that moral concerns among farmers are growing but largely remain hidden; talking about them openly was felt as a form of betrayal. We discuss these findings in the context of the ongoing agricultural transition, observe how tension has manifested as polarization among Dutch farmers, and offer some thoughts about the role of farmers in a new world of alternative proteins.

Nudging plant-based alternatives to meat and dairy in a real-life online supermarket: A randomized controlled trial

A shift from predominantly animal-based to plant-based consumption can benefit both planetary and public health. Nudging may help to promote such a shift. This study investigated nudge effects on plant-based alternatives to meat and dairy in an online supermarket. We conducted a two-arm, parallel-group, randomized controlled real-life online supermarket trial. Each customer transaction was randomized to a control arm (regular online supermarket) or an intervention arm (addition of placement, hedonic property and dynamic social norm nudges promoting meat and dairy alternatives). Outcomes were the aggregate of meat and dairy alternative purchases (primary outcome), the number of meat purchases, dairy purchases, meat alternative purchases, and dairy alternative purchases (secondary), and retailer revenue (tertiary). Generalized linear mixed models with a Conway-Maxwell Poisson distribution were used to estimate incidence rate ratios (IRRs). Analyzed data included 8488 transactions by participants (n = 4,266 control arm, n = 4,222 intervention arm), out of which 2,411 (66%) were aged above 45 years, 5,660 (67%) were females, and 1,970 (23%) lived in socially disadvantaged neighborhoods. Intervention arm participants purchased 10% (IRR 1.10 (95% CI 0.99-1.23)) more meat and dairy alternatives and 16% (1.16 (0.99-1.36)) more meat alternatives than control arm participants, although these findings are not statistically significant. There was no difference in dairy alternative purchases (1.00 (0.90-1.10)). Intervention arm participants purchased 3% less meats (0.97 (0.93-1.02)) and 2% less dairy products (0.98 (0.95-1.02)) than control participants. Retailer revenue was not affected (0.98 (0.95-1.01)). Online nudging strategies alone did not lead to a statistically significant higher amount of plant-based purchases, but replication of this work is needed with increased study power. Future studies should also consider nudging strategies as part of a broader set of policies to promote plant-based purchases. TRIAL REGISTRATION: Prospectively registered on 14th of May 2022. ISRCTN16569242 (https://doi.org/10.1186/ISRCTN16569242).

How can consumer science help the foodservice industry replace meat? A critical review

In the pursuit of more sustainable diets, researchers have been studying ways to promote a transition from animal-based to plant-based meals in foodservice contexts by influencing participants' conscious choices through names, labels, claims, and information. This critical review found that these interventions usually mobilize only those already engaged in reducing the consumption of animal products and often only during the intervention period, failing to influence those who eat most meat or to create long-lasting effects. Analyzing the choice for vegetarian meals against meals with meat in recently published studies conducted in foodservice contexts, we argue that the transition to more sustainable diets should rely less on consumers' willpower and more on public policies and institutional measures that change the availability, price, and visibility of plant-based meals. Inspired by behavioral sciences, this paper discusses interventions that challenge meals with meat as the default option and suggests hybrids as a path to increase the availability, convenience, and sensory familiarity of vegetarian meals. The paper ends with proposals for questions, interventions, metrics, and issues to be researched by consumer science, including questions on the degree of freedom of consumers' choice and what would be the ethical limits to telling half the truth about hybrids.

Structure and physical stability of plant-based food gel systems: Impact of protein (mung bean, pea, potato, soybean) and fat (coconut, sunflower)

Despite their popularity, plant-based food gel systems (GS) sometimes have suboptimal texture compared to animal-based products. Therefore, 4 commercial plant proteins (from mung bean, pea, potato and soybean) and 2 commercial plant fats (sunflower oil and coconut fat) in 2 contents (7.5 wt% and 17.5 wt%) were evaluated towards their contribution to structure and physical stability a lean (LGS, no fat) and an emulsified GS (EGS). Generally, protein source had a larger effect on structure and physical stability than fat source and content. Unheated, GS with soybean protein showed most structure and highest physical stability. Heated till 94 °C, the structure of GS increased drastically, but EGS showed less structure than LGS, attributed to low solid fat contents (SFC), hence low rigidity, of the incorporated oil droplets at 94 °C. Cooled till 5 °C all GS showed an additional increase in structure, for GS with mung bean and pea protein accompanied with an increase in physical stability. Overall, EGS with sunflower oil showed less structure and lower stability than EGS with coconut fat, likely due to their different SFC. At 5 °C, Peak force of GS with potato protein was highest. Across protein sources, EGS displayed a higher Peak force with coconut fat than with sunflower oil, again likely due to different SFC, hence, rigidity of the oil droplets. Physical stability of GS did not vary significantly between protein sources, fat sources nor fat contents, after a freeze-thaw cycle, nor during prolonged cold storage.

Creating a healthy and sustainable food environment to promote plant-based food consumption: clear barriers and a gradual transition

BACKGROUND

A shift away from diets high in animal-based foods towards diets high in plant-based foods is desirable considering human health, environmental sustainability, and animal welfare. As the food environment plays a crucial role in shaping consumption patterns, understanding of how changes in the food environment can facilitate plant-based consumption is crucial for the so-called protein transition. The current study aims to garner insight into barriers and facilitators for food outlet managers to take action to stimulate plant-based consumption within a local food environment.

METHODS

Using a maximum-variation sample approach, we examined possible barriers and facilitators to promote plant-based consumption across different types of food outlets located within a geographically shared food environment (a city in the Netherlands). We conducted in-depth semi-structured interviews among food outlet managers and applied multi-stage thematic analysis to the interview transcripts.

RESULTS

Most managers underscored the urgency of shifting towards more plant-based diets, and perceived a growing demand for plant-based products. However, three barriers hindered most of them from taking decisive action: Managers' perception of low consumer demand for plant-based food options; fear of consumer resistance when stimulating plant-based food options; and limited behavioral agency to offer attractive plant-based food options. The few managers who made changes, or intend to make changes, are individuals with high intrinsic motivation, knowledge and skills.

CONCLUSIONS

The present work suggests the key for change towards a food environment stimulating plant-based consumption lies in addressing three (perceived) barriers shared among diverse outlets. These are partly different from barriers for stimulating healthy consumption in general. Furthermore, current changes appear to be driven incidentally by individuals who are motivated and able to stimulate more plant-based purchases among a small targeted group of consumers.

Diversity of dietary protein patterns across Europe - Impact on nutritional quality and environmental sustainability

Transitioning from animal-based to plant-rich diets could potentially improve both human and planetary health, but a thorough understanding of the protein component in the diet is essential. This research aimed to identify dietary protein patterns in the European adult population and evaluate differences in nutritional quality and environmental sustainability. Individual-level food consumption data were obtained from 25 European countries (40,101 participants, 18-64 years), available from the EFSA Comprehensive European Food Consumption Database. We applied statistical clustering to classify individuals according to their consumption of 24 protein source food groups. The patterns were evaluated for nutrient requirements, the Nutrient Rich Diet (NRD) 15.3 score, greenhouse gas emissions (GHGE) and land use (LU). Six patterns emerged: Common (42.2%), Fast-food (19.5%), Traditional (14.8%), Health-conscious (12.0%), Milk-rich (9.8%) and Plant-forward (1.6%), with country-specific variations. Most patterns obtained 64-69% of their protein intake from animal products, except for the Plant-forward pattern (52%). The Plant-forward pattern achieved the highest NRD15.3 (+11%), and lowest GHGE (-20%) and LU (-25%) compared to the population average and was most commonly consumed in Austria, Finland, Spain, Portugal and Belgium (4.1-4.5%). The Health-conscious pattern also scored high in nutritional quality (NRD15.3: +9%), whereas the Traditional pattern showed higher environmental impacts (GHGE: +5%, LU: +7%). These findings highlight the diversity of dietary protein patterns across Europe, each with unique nutritional profiles and varying environmental impacts. The Plant-forward pattern provides a promising example for healthier, more sustainable diets, but tailored approaches that consider the cultural and demographic contexts of individual countries are needed to optimize health and environmental outcomes for all patterns.

Unfamiliar familiarity: A scoping review on the role of familiarity in consumer acceptance of cultivated meat

The potential introduction of cultivated meat products to the market, framed as sustainable alternative to conventional animal-source foods, underscores the need to examine psychological barriers and predisposing factors influencing consumer acceptance. Familiarity is often considered a facilitating factor, based on the premise that higher familiarity with cultivated meat is associated with greater acceptance. However, evidence remains contradictory and poorly integrated. This review examines and organizes the literature on familiarity with cultivated meat and its influence on consumer acceptance. A scoping review of peer-reviewed and grey literature was conducted on June 7, 2024, following PRISMA-ScR and Joanna Briggs Institute guidelines. Comprehensive searches across Scopus, Web of Science, PubMed, and PsycInfo included no restrictions on participant type, geographic location, social and cultural contexts, language, or publication time. 63 articles were analyzed to examine (i) definitions of familiarity, (ii) methodologies measuring familiarity with cultivated meat, and (iii) evidence regarding its influence on consumer acceptance of cultivated meat. Results indicate that current research on familiarity is largely based on non-representative samples, with data recency limitations, and inconsistent operationalization. Familiarity is often conflated with the related yet distinct constructs of awareness and knowledge, revealing a lack of clarity in literature. The review also identified various approaches for assessing familiarity, all lacking psychometric rigor, hindering replicability and comparability of findings. This review highlights the need for further research to clarify the theoretical and operational definition of familiarity and its role in consumer acceptance of cultivated meat.

Risk ranking of mycotoxins in plant-based meat and dairy alternatives under protein transition scenarios

While reducing the consumption of animal-source foods is recommended for planetary and human health, potential emerging food safety risks associated with the transition to dietary patterns featuring plant-based meat (PBMA) and dairy alternatives (PBDA) remain unexplored. We assessed the exposure to mycotoxins and ranked the associated health risks related to the consumption of PBMA and PBDA. We simulated diets by replacing animal-source proteins with their plant-based alternatives. A risk ratio method, based on the hazard quotient (HQ), was applied to rank mycotoxin-related food safety risks. An aggregated dataset containing contamination data of 45 mycotoxins distributed over 182 PBDA and 131 PBMA samples, collected and analyzed in Europe, representing a convenience sample, was used as input in our risk assessment. The highest risk mycotoxins identified for PBMA in the lower bound scenario (LB) were the sum of aflatoxins (sum AF), alternariol monomethyl ether (AME), aflatoxin B1 (AFB1) and alternariol (AOH), with HQs for children of 121.3, 66.8, 24.0 and 4.3, respectively. In the milk substitution model (LB), HQs of 4.9 (sum AF) and 1.4 (AFB1) were calculated for children, indicating a potential food safety risk. Further analysis demonstrated that soy-based meat alternatives are the highest risk food products, in particular for sum AF, AME, AOH and AFB1. With regard to PBDA, highest HQs were found for sum AF in almond and oat drink, and AFB1 in oat drink. This research presents an approach to overcome the lack of data in the assessment of emerging risks associated with the shift to more sustainable dietary patterns.

Meat consumption and flexitarianism in the Low Countries

Against the backdrop of meat production and consumption being increasingly contested, this paper presents a narrative descriptive review of (reductions in) meat consumption in the Netherlands and Belgium with a focus on trends during the period 2010-2020. Based on household panel purchasing data and supply balance sheet data as proxies, our analysis shows that meat consumption in the Netherlands is relatively stable, based on supply balance sheet data, despite an estimated annual decrease of around 250 g per capita per year based on household panel purchasing data. Meanwhile, household purchasing panel data for Belgium show a more steady and stronger decline with an annual decrease of slightly >1 kg per capita per year over the past decade, as well as more fluctuations based on supply balance sheet data. The 'Covid-year' 2020 displays a distinct pattern in both countries which deserves further exploration. Both countries face growing shares of (self-declared) flexitarians (ranging from around or above 30% in Belgium to 40% or more in the Netherlands depending on the data source and its definition of flexitarians) and consumers who claim to intend reducing their meat consumption in the future. The analysis reveals important differences in research methodologies, sample compositions, and analytical techniques. Such differences raise caveats for direct comparison between countries and impose challenges for the (European) monitoring of the so-called 'protein transition'. Although some change is occurring, the data suggest that meat reduction calls resonate still more in terms of people's attitudes, awareness, and intentions than in overt dietary behavioral change. Overall, our findings provide reason to conclude that the established meat-centered food system and its dominant meat-eating culture are still prevailing in the Low Countries.

Plant protein dominant enteral nutrition, containing soy and pea, is non-coagulating after gastric digestion in contrast to casein dominant enteral nutrition

Enteral Nutrition (EN) is used for the dietary management of patients requiring tube feed and who are at risk of disease related malnutrition. Previously, EN with a dairy-dominant p4 protein blend (DD-P4: 20% soy, 20% pea, 25% casein and 35% whey) was shown to not coagulate in the stomach, increase gastric emptying rate and reduce gastric residual volume compared to EN with casein-dominant protein blends (CD; 80% casein and 20% whey), which is relevant for upper gastrointestinal tolerance. In line with the EAT-Lancet report, a new plant-dominant protein blend (PD-P4: 46% soy, 32% pea, 16% casein and 6% whey) was developed. Coagulating properties of PD-P4 are compared to DD-P4 and dairy proteins in protein solutions as well as in EN matrices, using a semi-dynamic in vitro gastric model simulating adult conditions, followed by solid particle (> 0.25 mm) separation using analytical sieving. Sieve retentates and filtrates were assayed for weight, dry matter, and protein content where possible. Whey protein, PD-P4 and DD-P4 protein solutions as well as PD-P4 and DD-P4 EN variants had minimal total particle weights. In contrast, casein protein solution coagulation amounted to ∼ 21 % of its initial wet weight, containing ∼ 51 % of its initial protein content, and CD EN coagulation amounted to 21 %- 45 % of the initial wet weight, containing 59-65 % of the initial protein content. EN with the new PD-P4 blend can be considered non-coagulating after in-vitro gastric digestion, similar to the DD-P4 blend. This was independent of energy density, protein content, and the presence of dietary fiber. EN with a non-coagulating plant-dominant protein blend might support upper gastrointestinal tolerance and promote the worldwide protein transition.

Transitioning towards more plant-based diets: sharing expert knowledge through a system lens

Transitioning towards more plant-based protein diets is essential for public and planetary health. Current research about consumption practices of protein sources provides limited insight in the multidisciplinary nature and interconnectivity of the food environment. This study aimed to collect mental models of review authors by synthesizing both their implicit and explicit system views into an overarching system view. Published reviews were used to select participants and identify variables that explain the protein transition in relation to the food environment. To overcome differences in disciplines and scale levels (e.g. individual, interpersonal, environmental), variables were organized according to the Determinants of Nutrition and Eating Framework. Eight review authors shared their mental models in an interview. Participants were asked to construct a causal loop diagram (CLD), a tool proven valuable in making one's ontology explicit to others. Implicit system views in narrative were converted into CLDs using a coding framework. The overarching system view suggests that a multitude of feedback loops sustain current consumption patterns of protein sources, for example by reinforcement through habit, availability and peer support. Several aspects require further research, such as variable relationships that were subject to disagreement and the lack of reciprocity between the physical and social elements of the food environment. In addition, knowledge gaps were exposed, including long-term behaviour and interaction of multiple variables. As a boundary object, the overarching system view can facilitate the direction of future research. The findings underscore the interconnected nature of many disparate elements within the food environment, stressing the need for holistic methods like systems thinking. These are essential in developing a systemic understanding and facilitating the transition towards more plant-based diets.

Food-feed nexus in the agrifood chain - Quantification and alternatives assessed using a novel protein flow analysis on a systemic level

Sustainable food systems are one of the primary goals within the EU's Green Deal. To achieve and benchmark this, proteins should be traceable throughout the system. This study achieves this with a novel layered analysis approach, treating crude protein as a traceable property within the Flemish agri-food system, revealing a complex protein network. Protein efficiency indicators highlight the competition between food and feed. This study found that only 24 % of processed food protein reaches consumers, with the remainder sent to residual streams. In Flanders, pork is the most dominant animal protein produced, followed by dairy, which produced 75 % of cattle output, and poultry, where eggs made up 7.5 % of the animal protein supplied to retail. To maintain the current means of livestock production, 21-34 % of the protein input in the form of feed consists of protein that could be food instead. Feed production depends on protein-containing residual streams, revealing a tightly interdependent protein network. The study highlights the ratios of non-humanly digestible to digestible protein in pork (66:34), poultry (75:25), and cattle (79:21). The results propose a scenario where a decrease in pork production could reduce imported feed demand (12 %) while having a 7 % increase in by-product generation. A further 11 % decrease in animal protein to retail is seen, while a 29 % increase in plant protein availability to retail is observed, with notable differences in protein quality between plant and animal sources. In conclusion, this study unveils the protein dynamics in Flanders' agri-food system, emphasizing the importance of optimizing protein allocation, mainly through strategic adjustments in pork production, while grappling with balancing nutritional efficiency and quality in animal products.

Flexitarians in Brazil: Who are they, what do they eat, and why?

In this study, we conducted the first scientific investigation focusing on Brazilian flexitarians, aiming to characterize their socio-economic and demographic profiles, motivations for adopting flexitarianism, the frequency of animal-based meat consumption, and the primary meat substitutes they consume. To accomplish this, we distributed an online questionnaire with the assistance of university students and researchers from various regions of the country. Data were collected from 1029 individuals in Brazil who self-identified as flexitarians. Our findings reveal that the flexitarian dietary model is primarily adopted by women, constituting 76% of the sample (n = 786). Their motivations include concerns about the environmental impact of meat consumption (n = 361, 35%), personal health (n = 344, 33%), and animal welfare (n = 219, 21%). Flexitarians exhibit varying consumption patterns, which can be categorized into three groups: light flexitarians (consuming meat 36 times a week), medium flexitarians (consuming meat 7 times a week), and heavy flexitarians (consuming meat 4 times a week). The flexitarian dietary pattern is characterized by reduced beef consumption (less than 2 times per week) and higher consumption of chicken (3 times per week). It is complemented by plant-based protein sources and eggs as the primary meat substitutes. The recognition of legumes as the principal meat substitutes opens avenues for an expanded discussion on sustainable food systems and alternative meat products in Brazil. This provides opportunities to enhance the availability and accessibility of these foods and to develop nutritional interventions that prioritize plant-based proteins.

Mental models of the protein shift: Exploring consumers' perceptions of the transition

The protein transition is one of today's major societal challenges to mitigate climate change. To support lasting consumer engagement, it has been suggested to look into consumers' understanding of the protein transition to identify barriers that go beyond the practical issues of changing one's diet. The current study explored consumers' mental models of how the transition unfolds to examine which factors consumers perceive as important drivers of the transition. With a fixed set of factors and actors identified with a questionnaire, Dutch consumers (N = 214) mapped their mental models. The content and structure of the mental models were analyzed with a focus on how consumers perceive their own role. Animal well-being and environmental concerns were most often included as important drivers. The findings showed a lack of consensus about which actor(s) drive the transition (i.e., none of the actors were included by a majority of the participants). This diffusion of responsibility may be a barrier for consumers to act. Moreover, the relative simplicity of the observed mental models suggests that consumers do not yet employ systems thinking. A systems thinking mindset may help consumers understand how the system behind the transition works and how their individual contributions matter. Two avenues to encourage consumer engagement were identified: 1) emphasizing the responsibility of different actors and what consumers can contribute, and 2) encouraging a systems thinking mindset.