###### Abstract  
This study investigated the impact of gradient milling on the cooking properties and sensory characteristics of Yangxian black rice. The results showed that as the degree of milling increased, the gelatinization time decreased (36.85-23.54 min) and the water uptake ratio of whole black rice (188.29%) was significantly lower compared to that of refined grains (194.05%). Low-field nuclear magnetic resonance (NMR) was further used to monitor the water concentration and distribution of black rice during soaking and cooking. It was found that the bran layers of black rice, as a physical barrier, impeded the water penetration into the kernels for a given soaking and cooking duration. The sensory evaluation conducted by a panel of trained volunteers demonstrated a high score for all sensory attributes in slightly milled black rice, corroborating findings from the taste analyzer. Through correlation analysis of volatile components determined by gas chromatography-mass spectrometry (GC-MS), smell scores in sensory evaluation, and electronic nose response values, 2-pentyl-furan (54.84-12.72 mg/g) and guaiaol (19.39-5.51 ng/g) were found to be the predominant volatile flavor contributors in cooked black rice. Overall, this study provides valuable insight into the intricate relationship between milling degrees and the cooking properties, sensory characteristics, and volatile flavor compounds of Yangxian black rice.  
Y 2024  
Black rice has a purple-black or black kernel color due to the presence of anthocyanin in its bran layer [6]. Under the global consensus that a healthy human diet must be rich in whole grain rather than refined grain, pigmented rice, especially black rice, has emerged as a preferred alternative staple food [10; 11; 12]. China is the largest producer of black rice, contributing 62% of global production [6; 12]. Among its ancient varieties, Yangxian black rice has been cultivated for more than 2000 years and was historically reserved for emperors. This precious variety was designated as a Chinese national geographical indication protected product in 2006 (standard DB 61/T 1011-2018 [13]).  
The increasing consumption of rice is accompanied by stricter consumer demands for rice products with premium qualities. Rice industries tend to measure the economic value of rice in terms of cooking and eating qualities that can be tested by gelatinization time (cooking duration), water uptake ratio, solids in the cooking water, and sensory characteristics [14]. The starch gelatinization induced by hydration and heating is strongly associated with the texture and eating quality of cooked rice [15]. The sensory characteristics including appearance, aroma, taste, and texture play a crucial role in consumer acceptance since rice is generally eaten without seasoning. Besides the complicated sensory test by trained panelists, the instrumental measurements of the textural attributes to predict the overall eating quality of cooked rice have met with partial success [16; 17]. Although a rice taste analyzer developed in Japan correlates key constituents with \"taste\" scores, it failed to capture volatile flavor characteristics, especially for pigmented rice. Therefore, determining the dominant volatile flavor compound in cooked pigmented rice remains challenging.  
The present work was undertaken to investigate the cooking properties and sensory characteristics of cooked black rice under gradient milling. Changes in moisture distribution during the soaking and cooking of black rice were monitored by low-field nuclear magnetic resonance (NMR). Sensory characteristics of black rice were comprehensively evaluated by a sensory test and instrumental measurements. Particularly, for volatile components determined by GC-MS, the smell score by sensory evaluation and the response value of electronic noses were correlated to screen predominant volatile flavor contributor in cooked black rice.