Research Landscape of Tempeh: A Bibliometric Study of Research Focus, Applications, and Product Development Opportunities

Tempeh, a traditional Indonesian fermented soybean product, has gained increasing global recognition for its nutritional value and functional health benefits. Characterized by high protein bioavailability, essential vitamins, minerals, and bioactive compounds such as isoflavones and peptides, tempeh plays an important role in plant-based and functional food innovations. This study aims to systematically map the research landscape on tempeh over the past decade (2015–2025) using bibliometric analysis. Data were exclusively retrieved from the ScienceDirect database and analyzed using VOSviewer (version 1.6.20). A total of 9,338 publications were examined to identify trends in research themes, publication dynamics, and keyword co-occurrence networks. Three types of visualization network, overlay, and density maps were generated to illustrate the intellectual structure and thematic evolution of tempeh-related research. The network analysis revealed six major thematic clusters: (1) plant-based meat alternatives and consumer preferences, (2) fermentation processes and Rhizopus oligosporus, (3) antioxidant and bioactive compound studies, (4) plant-based dietary strategies, (5) isoflavones and bone health, and (6) microbial identification and antimicrobial activity. The overlay visualization highlighted a temporal shift from microbial and biochemical studies (2021–2022) towards market-driven and consumer-focused research (2023–2024), particularly emphasizing sensory evaluation and plant-based food product development. Meanwhile, the density map pinpointed emerging research hotspots in market trends, antioxidant studies, and microbial functionality. In conclusion, this bibliometric study demonstrates a clear evolution in tempeh research, moving from fundamental microbiological and nutritional analyses towards applied food technology and market acceptance studies. These findings provide valuable insights for researchers, industry stakeholders, and policymakers in guiding future research priorities and supporting the development of innovative, sustainable, and health-promoting tempeh-based food products.