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Authentication of geographical indication (GI) is important for the protection of GI rice due to its unique quality characteristics and high economic value in the market. This paper compared the appearance quality, cooking quality and nutritional quality of four types of GI rice products (Luoding rice, Zhefang Tribute rice, Xijiang rice and Wanbaozhen rice) in China. Luoding rice was found to have the highest nutritional value with respect to protein and amino acid profile. The vitamin content of Xijiang rice was significantly higher than that of other types of GI rice. Principal component analysis showed that Luoding rice had a quite different protein, aspect ratio and amino acid profile from other GI rice samples. Zhefang Tribute rice had quite different cooking quality, fatty acid and sugar profile from Xijiang rice and Wanbaozhen rice. Geographical origin was predicted by using a multilayer perceptron artificial neural network model with quality characteristics as the input variables. It was found that all the samples were accurately predicted in both training and test sets, indicating the potential of using quality characteristics to discriminate GI rice samples from different geographical origins. • Appearance, cooking, nutritional quality of four GIs were investigated and compared. • LD possessed different protein, aspect ratio and amino acid profile from other GI rice. • ZF possessed different cooking quality and fatty acid, sugar profile from XJ and WBZ. • GI rice was predicted using quality characteristics as input variables. [ABSTRACT FROM AUTHOR]

Rice flavor is one of the most important rice qualities, consisting of aroma and taste. In this paper, aroma- and sweetness-related compounds were investigated and compared in glutinous, japonica , and indica rice. More volatile compounds were found in glutinous rice, as compared with japonica and indica rice. Hexanal, nonanal, octanal, trans -2-octenal, trans -2-nonenal, heptanal, decanal, (E,E)-2,4-nonadienal, (E,E)-2,4-decadienal, 2-pentylfuran, 2-n-butylfuran, 1-octen-3-ol, 2-ethylhexyl acrylate, 2-decanone, and 2-nonen-4-one were important contributors to the aromatic profile, according to their relative odor activity values. Sucrose was found to be the main contributor to sweetness, while other soluble sugars had little sweetness contribution. During storage, the contents of fatty acids and soluble sugars decreased, except for fructose. The decrease in soluble sugar content had an adverse effect on the sweetness of cooked rice and the Maillard reaction during cooking, resulting in lower quality rice flavor. In addition, the content of volatiles, such as aldehydes, ketones, and furans, increased during rice storage and negatively impacted rice aroma. • Glutinous rice possessed volatile profile distinct from non-glutinous rice. • Glutinous rice showed green and fat odor due to high aldehydes and furans contents. • Aldehydes, ketones, furans increased during rice storage, deteriorating rice odor. • As the main rice sweetness contributor, sucrose decreased during rice storage. • Fatty acids decreased to some extent during rice storage. [ABSTRACT FROM AUTHOR]