## 1 Introduction  
China, which is the largest producer and consumer of rice worldwide, covers a vast area that includes widely different geographical and climatic conditions. These environmental differences have given rise to a rich variety of rice germplasms, including many rice varieties [1]. In general, rice is classified as either aromatic or non-aromatic depending on whether or not it is fragrant [2]. The fragrance of rice will affect its price and consumer acceptance. Aromatic rice (_Oryza sativa_ L) is a special rice species that can give off fragrance from their whole grain. Moreover, it still has aroma after cooking and is rich in amino acids, proteins and other nutrients, so it is highly favored by consumers around the world [3]. The aroma of aromatic rice is greatly influenced by geographical origin indication, and the economic return can be enhanced by the specific trait of the commodity in the specific producing area [4]. The most famous varieties of aromatic rice in China are produced in the Guangdong, Guangxi, Zhejiang, Liaoning, and Heilongjiang provinces [5]. Of these, Wuchang rice, originating from Wuchang in Heilongjiang province, is one of the most famous aromatic rice sold in the world [4]. Most aromatic rice varieties have substantially lower yields than non-aromatic rice varieties because aromatic rice varieties are less adaptable to changes in environmental conditions and are thus more affected by planting locality [3]. According to Chinanews, Wuchang produces only about 1.05 million tons of rice every year, but it is estimated that there are at least 10 million tons of Wuchang rice on the market [6]. Therefore, up to 90% of all Wuchang rice on the market must be counterfeit. Moreover, the price of aromatic rice is two or three times higher than that of non-aromatic rice [7]. To increase profits, inferior or non-aromatic rice is often mixed with aromatic rice and then labeled as premium quality rice [6]. This practice directly impacts consumers and impairs brand credibility [8]. In the past decades, the varieties of rice have been identified based on morphology (shape, width, and length), physiochemical properties such as amylose, starch, and protein content, cooking properties and eating properties [1,4]. However, most of the rice evaluation standards used at present are not graded strictly, i.e., the standard of ISO 7301-2011 and Codex Alimentarius Commission (CAC) [1]. It is thus critical to clarify the difference between aromatic rice and non-aromatic rice to ensure the authenticity of high-quality aromatic rice varieties [9]. Understanding the aroma traits of rice grain in different region will be of great benefit to the identification of geographical origin and the formulation of standards for aromatic rice in the future. Rice aroma is greatly affected by the composition and proportion of volatile compounds in the rice grain [10]. Currently, more than 250 volatile compounds have been identified in rice. 2-Acetyl-1-pyrroline (2-AP) is a symbolic substance that distinguishes aromatic rice from non-aromatic rice [3]. It has a popcorn-like flavor and has been identified as the main compound that gives rice natural flavor [3]. Furthermore, hexanal, octanal, nonanal, (_E_)-2-octenal, decanal, 1-heptanol, and 1-octanol were identified as major aroma-active compounds in Jasmine rice [11]. [PERSON] et al. [12] using a dynamic headspace solid-phase extraction system coupled to a two-dimensional gas chromatography (GC \(\times\) GC) coupled with a time-of-flight mass spectrometric detector (TOFMS) to distinguish the aromatic from non-aromatic rice grains. Fifty one kinds of volatile compounds were detected by this methods, and eight key-marker volatile compounds (i.e., pentanal, hexanal, 2-pentylfuran, 2,4-nonadienal, pyridine, 1-octen-3-ol and (_E_)-2-octenal) were selected for identifying the aromatic rice of Indonesia.