Foodomics of Rice Grains in Astrobiology: Spaceflight-Induced Modulation of Aroma, Texture, and Protein Digestibility in Thai Landrace Rice (466HM) Aboard the Shijian-19 (SJ-19) Low Earth Orbit Mission

Ensuring a sustainable source of nutritious food is critical for long-duration space missions. Thai landrace rice 466HM exhibits high nutritional value and stress resilience, making it a promising candidate for space cultivation, yet its response to low Earth orbit (LEO) conditions remains poorly understood. This study compared rice grains maintained under terrestrial conditions with grains stored aboard the Shijian-19 (SJ-19) reusable satellite, orbiting at ~336 km for 13.5 days under microgravity (2−7 × 10−7g) and an absorbed radiation dose of ~0.153 rad (Si). Volatile compound profiling, texture analysis of cooked grains, and simulated gastrointestinal digestion followed by peptide mass fingerprinting were performed. LEO-exposed rice grains exhibited a 1.67-fold increase in adhesiveness compared to Earth-based rice (p < 0.01), while hardness remained unchanged between the two groups (p > 0.05), alongside distinct alterations in flavor-related volatile compounds and peptide profiles. Principal component analysis revealed clear separation between Earth and LEO-exposed samples, indicating microgravity-associated shifts in digestible peptide composition. Cytotoxicity assessment using MTT assays in HT-29 and HepG2 cells confirmed the safety of both rice types. These findings demonstrate that orbital conditions influence the compositional, functional, and sensory attributes of rice, providing insights relevant to space agriculture and astronaut nutrition.