Integrated Volatile Compounds and Transcriptional Gene Analysis Elucidate the Deterioration Mechanism of Embryo Rice During Storage  
[PERSON]  
1 College of Food Science, Heilongjiang Bayi Agricultural University, Daqing 163319, China; [EMAIL_ADDRESS] (X.Y. ); [EMAIL_ADDRESS] (T.S. ); [EMAIL_ADDRESS] (L.M. ); [EMAIL_ADDRESS] (X.M. ); [EMAIL_ADDRESS] (H.W. ); [EMAIL_ADDRESS] (L.X. ); [EMAIL_ADDRESS] (C.W. ); [EMAIL_ADDRESS] (L.W.) stable food [2] which is in great market demand. Due to the milling process, the germ loses the protection of the bran layer and is susceptible to oxygen, temperature, and humidity [3]. Therefore, embryo rice is prone to oxidative rancidity and quality deterioration during storage, but because of its strong spontaneous respiration, it will secrete a large amount of lipase, amylase, and protease, which promotes the metabolism of nutrients and aggravates quality deterioration [4]. At normal temperature, germ rice can only be stored for about 30 d, which makes it difficult to meet the needs of market production, processing, transportation, and sales [5]. Therefore, improving storage conditions and upgrading storage technology to protect storage quality and extend shelf life have become urgent problems for scholars domestically and internationally. Currently, research on the storage of embryo rice mainly focuses on nutritional [6], sensory [7], and quality indexes [8], but there are few studies on the changes in volatile components and the deterioration mechanism. Volatile compounds play a crucial role in the formation of food flavor, and their types and contents are affected by many factors, including storage conditions and surrounding temperature [9]. During grain storage, the changes in volatile compounds are usually closely related to lipid oxidation and enzymatic reactions [10]. It has been shown that the storage process of rice will produce aldehydes, alcohols, ketones, and other volatile compounds, and the accumulation of these compounds may lead to undesirable flavors, such as aging or a rancid taste [11]. Although there have been some studies on the changes in volatile compounds during embryo rice storage, most of these studies focus on chemical analysis and lack a genetic analysis of the deterioration in quality of embryo rice. The synthesis of volatile compounds involves complex metabolic networks, and their regulatory mechanisms may be affected by the expression of multiple genes [12]. Therefore, it is difficult to fully reveal the molecular mechanism of volatile compound changes through chemical analysis alone. Transcriptome analysis, as a high-throughput technique, can fully reveal the changes in gene expression and provide a powerful tool for studying the regulatory mechanisms of metabolic pathways [13]. In recent years, the application of transcriptome analysis in the food science field has been increasing, especially in the study of the molecular mechanisms of quality change during food storage [14]. For example, through transcriptome analysis, researchers can identify key genes involved in lipid oxidation [15], antioxidant defense systems [16], and secondary metabolism [17], thereby revealing the molecular basis of food quality changes [18]. However, transcriptome studies on the changes in volatile compounds during the storage of embryo rice are still rare [19]. By combining the chemical analysis of volatile compounds with transcriptome data, the molecular basis of quality change during the storage of embryo rice can be more comprehensively revealed. In this study, volatile compound changes were combined with transcriptomic analysis to systematically investigate the dynamic changes in volatile compounds and their gene regulation mechanisms during embryo rice storage.