Food system technologies (FSTs) are rapidly emerging to address sustainability challenges within the food sector. Driven by factors such as the COVID-19 pandemic and substantial venture capital investments, these technologies often enjoy a "sustainability halo." However, a true assessment of sustainability requires consideration of environmental, economic, and social dimensions, acknowledging potential synergies and trade-offs. While comprehensive tools exist to analyze food systems broadly, a similar toolset and inventory of sustainability indicators specifically for assessing FSTs is lacking. This multidisciplinary scoping review aims to examine the extent, range, and nature of peer-reviewed literature assessing the sustainability performance of FSTs, focusing on plant-based alternatives (PBAs), vertical farming (VF), food deliveries (FD), and blockchain technology (BT). These FSTs were chosen based on investment flows into Nordic food start-ups in the first half of 2021. The review synthesizes empirical evidence on FST sustainability performance compared to existing technologies and identifies implications for research and practice.

The review examined existing literature to identify sustainability indicators used to assess FSTs and synthesize evidence comparing FST sustainability to baseline technologies. It incorporated various study designs, including life cycle assessments (LCA), cross-sectional and intervention studies, nutritional analyses, and economic modeling studies. The review acknowledges a lack of a standardized set of indicators for comprehensively evaluating FST sustainability across all three pillars, making comparisons challenging.

The scoping review followed the PRISMA-ScR guidelines. Searches were conducted in Web of Science Core Collection and Scopus databases in September 2021, including literature published since 2016 due to the exponential growth of research in this area. The search strategy focused on concepts of sustainability assessment and the four selected FSTs. CADIMA software was used for study screening and duplicate removal. A multi-stage screening process involved title/abstract screening and full-text screening by multiple reviewers. Inclusion criteria required studies to assess the sustainability of one of the four FSTs, provide quantification for at least one sustainability indicator (with an exception for blockchain literature due to limited empirical evidence), and be peer-reviewed. English language literature was prioritized. Data charting involved extracting information on study design, location, sustainability indicators, methods, LCA assumptions, and results. A traffic light system (green, yellow, red) was developed to classify the level of agreement on sustainability performance compared to baseline technologies (animal-based products for PBAs, open-field/greenhouse cultivation for VF, individual retail trips/restaurant dining for FD). Blockchain literature, lacking empirical comparisons, was excluded from this comparative performance analysis.

The review retrieved 1493 initial studies, with 79 meeting the inclusion criteria. The majority (n=37) assessed PBAs, predominantly meat and dairy alternatives, followed by VF (n=16), BT (n=14), and FD (n=11). Geographical representation varied across FSTs, with VF studies concentrated in Europe, FD in Asia, and PBAs across Europe and North America. BT literature presented a more global perspective. LCA studies were most frequent for assessing environmental impact. For PBAs, a wide range of indicators were used across all three sustainability pillars. Environmental assessments focused on GHG emissions, land use, and water use, along with nutrient release (eutrophication, acidification, ecotoxicity). Social indicators included nutritional adequacy, consumer acceptance, and WTP. Economic indicators encompassed energy use and product price. VF studies primarily assessed GHG emissions and water use, along with energy use, yield efficiency, and financial profit. FD studies concentrated on GHG emissions, plastic waste, and energy use, with some assessment of human health consequences. BT literature largely focused on qualitative descriptions of potential social, economic, and environmental benefits and limitations, lacking empirical evidence for performance assessment. The comparative sustainability performance analysis (using the traffic light system) indicated that PBAs generally show lower environmental impact than animal-based products, with varied results on nutritional and socioeconomic aspects. VF outperforms open-field and greenhouse cultivation in terms of land and water use but shows higher GHG emissions and energy use. FD services demonstrate better GHG and energy performance compared to car trips for grocery delivery but worse compared to home-cooked meals or restaurant dining for meal delivery. Overall, the review found a bias toward environmental sustainability indicators in the reviewed literature, with considerable gaps in research on social and economic indicators, particularly for VF and FD, and a complete lack of empirical data on BT's impact.

The findings highlight the potential of FSTs to contribute to sustainable food systems, but also emphasize the need for more comprehensive and rigorous sustainability assessments. The dominance of environmental indicators necessitates a shift towards incorporating social and economic factors. The lack of empirical evidence for BT emphasizes the critical need for further research. Methodological inconsistencies across studies (e.g., variations in functional units and system boundaries in LCA) highlight the challenge of making direct comparisons. Regional and cultural differences in consumer acceptance and resource availability also need consideration. The review identified specific gaps for future research, including the sustainability of plant-based seafood alternatives, public health and socioeconomic consequences of FD, and empirical validation of BT's potential benefits.

This scoping review synthesized evidence on the sustainability of four FSTs. While demonstrating their potential to contribute to sustainable food systems, it revealed considerable gaps in research, particularly concerning social and economic sustainability. A more holistic sustainability assessment framework is needed, incorporating comprehensive indicators across all three pillars, to guide investment and development in sustainable food innovations and mitigate unintended consequences.

The review's breadth and interdisciplinarity posed challenges in analyzing heterogeneous data. The focus on peer-reviewed articles excluded grey literature. The review was limited to English-language publications and did not perform a risk of bias assessment. The traffic light classification for sustainability performance, while useful for harmonizing data, is a subjective approach and does not reflect the scientific strength of the evidence. Comparisons were made against baseline scenarios rather than between different FSTs.