BACKGROUND Semi‐glutinous japonica rice (SGJR) is increasingly a popular choice for rice consumption and more commonly cultivated in the middle and lower reaches of the Yangtze River in China. Here, 58 SGJR and 75 non‐semi‐glutinous japonica rice (NSGJR) cultivars were evaluated for their characteristics of grain quality by assessing the taste of cooked grains, flour/paste properties, chemical compositions and starch physicochemical properties. RESULTS Comparisons of factors related to taste showed that cooked rice characteristics of SGJR were better in appearance, lower in hardness, lower in springiness and higher in stickiness. There were no significant differences in contents of total starch and total protein between the two types of rice. Further analysis indicates that thinner lamellar thickness, smaller starch particle size, and higher contents of amylopectin and albumin of SGJR (resulting in higher weights of dried matter from rice slurries) contributed to better appearance of cooked SGJR. Lower contents of amylose and prolamin led to a weaker and less elastic gel network in rice paste samples and contributed to a stronger moisture migration capability of cooked SGJR that showed higher stickiness and lower hardness and springiness. CONCLUSION A SGJR line with low apparent amylose content does not indicate good taste. Physicochemical properties of starch and protein contributed to better appearance, higher stickiness and lower hardness and springiness of cooked SGJR. These findings provide empirical data to help breed better‐tasting cultivars of japonica rice. © 2021 Society of Chemical Industry.

Four types of japonica rice including non-soft japonica rice from northern China planted in the northern region (NSJRNN), non-soft japonica rice from northern China planted in the southern region (NSJRNS), non-soft japonica rice from southern China planted in the southern region (NSJRSS), and soft japonica rice from southern China planted in the southern region (SJRSS) were adopted as materials to reveal the quality characteristics of japonica rice in southern and northern China and the effect of environments on its quality. Compared with NSJRNN, higher temperatures during the grain-filling stage in southern China resulted in poor processing and appearance qualities of NSJRNS and NSJRSS. Due to the increased protein content (PC), the eating qualities of NSJRNS and NSJRSS were bad. While for SJRSS, with low apparent amylose content (AAC) and few large-sized starch granules, the eating quality was better than that of NSJRNS and NSJRSS and even comparable to NSJRNN. Therefore, with a relative high PC of rice under high temperature condition in southern China, it could be one of the effective ways to reduce AAC appropriately to obtain a good eating quality of rice.

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Abundant normal alkanes, isoprenoid hydrocarbons, terpanes and steranes were detected in 23 samples taken from the carbonate platform to basin facies in the Devonian