Chiang Mai Journal of Science

     Soaking is a crucial preparatory step that strongly influences the texture and sensory quality of cooked glutinous rice. In northern Thailand, the indigenous Lanna practice of partially reusing soaking water, termed wild fermentative soaking, is traditionally believed to enhance the eating quality of glutinous rice. This study investigated the effects of soaking duration (8, 16, and 24 hours) and successive reuse of soaking water (first, second, and third batches) on the physicochemical, microbiological, and sensory properties of two Thai glutinous rice varieties, Kor Khor 6 (RD6) and Sanpatong (SPT). The results showed that extended soaking and water reuse significantly reduced rice hardness while increasing adhesiveness, springiness, and microbial activity. RD6 was more responsive to soaking duration, whereas reused soaking water accelerated fermentation, shortening the time needed to achieve comparable texture level. Microbial analysis revealed a progressive increase in lactic acid bacteria and titratable acidity, with a corresponding decline in pH, especially in reused soaking water. These microbial and biochemical changes were strongly correlated with improvements in textural attributes. Although texture preference did not differ significantly among treatments, correlation analysis showed modest positive associations between adhesiveness (r = 0.28) and gumminess (r = 0.23) with perceived texture. Prolonged soaking beyond 16 hours led to diminished aroma and reduced consumer appeal. Principal component analysis confirmed that early fermentation stages were associated with desirable sensory characteristics, while over-fermentation negatively impacted product quality. These findings indicate that moderate fermentative soaking, particularly an 8-hour soak using reused water, significantly improves texture and sensory appeal of glutinous rice. This approach offers a practical, culturally grounded technique for improving rice quality in both traditional and industrial applications.