Allergenicity Assessment of Plant-Derived Sweet Proteins—In Silico, In Vitro, In Vivo, and Clinical Approach: A Systematic Review

Plant-derived sweet proteins are promising low-calorie natural sweeteners that may reduce dietary sugar intake and prevent non-communicable diseases. Although seven have been identified—thaumatin, miraculin, monellin, mabinlin, brazzein, pentadin, and curculin (neoculin)—only thaumatin is currently approved as a food additive. The development of others requires comprehensive safety assessments, particularly regarding allergenicity. This systematic review aims to investigate and synthesize allergenicity assessment methods (in silico, in vitro, in vivo, and clinical) applied to these seven sweet proteins. The literature searches were conducted following PRISMA guidelines across Scopus, PubMed, and Wiley Online Library databases, up to 30 November 2025, with no time restrictions. The risk of bias in selected studies was evaluated using GRADE. After the selection process, 14 out of 2634 studies met the inclusion criteria. Thaumatin, miraculin, monellin, and brazzein emerged as the most extensively studied proteins. In silico approaches (sequence and structural homology) and in vitro assays (digestibility and cell-based methods) were the most commonly employed methods. In contrast, in vivo studies (animal models) and clinical evaluations (skin prick tests, oral food challenges) were rarely reported. Allergenicity studies on pentadin, mabinlin, and curculin (neoculin) are limited, indicating a research gap that requires further study to support regulatory approval and consumer acceptance.