Melon Seed Proteins: From Waste to Wellness—Functionality and Opportunities in Future Foods

The global population growth and the transformation of dietary structure are intensifying the contradiction between protein supply and demand, so there is an urgent need to develop sustainable alternative protein sources. Melon seeds, as a major by-product of the melon processing industry, are estimated to have an annual recyclable volume of approximately 738,000 tons. They are often discarded, causing resource waste and environmental pressure. Due to its well-balanced amino acid profile, melon seed proteins are regarded as a valuable source of nontraditional proteins. Building upon and extending previous foundational studies, this review systematically integrates current knowledge on melon seed proteins across multiple species, with emphasis on varietal differences, protein compositional, amino acid composition, and emerging extraction techniques. It also systematically introduces the functional characteristics of melon seed proteins and their wide applications in the conventional food matrices and emerging food systems. In addition, the key challenges limiting industrial translation and potential strategies, including lower technofunctional properties relative to conventional proteins, inherent antinutritional factors, and economic hurdles in large‑scale extraction and modification are also discussed. Melon seed proteins exhibit species-dependent nutritional advantages and favorable functional attributes, positioning them as promising complementary ingredients to conventional plant proteins. The development and utilization of melon seed proteins can effectively transform agricultural waste into health-promoting food ingredients.