###### Abstract  
The growing altitude is an important factor affecting the quality of coffee. We explored the flavor precursors, sensory characteristics, and cupping qualities of coffee growing at different altitudes and discussed their associated relationships. The altitude at which coffee is grown has different effects on its chemical composition. Fatty acid contents increased with increasing altitudes, whereas alkaloid and chlorogenic acids contents decreased with increasing elevation. There was no obvious trend in either organic acids or monosaccharides. Eleven of the 112 detected volatile components were significantly affected by the growing altitude. The contents of pyrazines and alcohols tended to decrease, whereas those of aldehydes tended to increase. A significantly altered composition reduces the nutty and roasted flavors of coffee, while increasing the sweet sugar and caramel aromas. The aroma and flavor tended to increase with increasing altitudes during cupping, whereas the other indicators did not change significantly. The results provide a theoretical reference for the sales and promotion of Pu'er coffee.  
c 2024  
The altitude at which coffee is cultivated has been shown to be one of the factors affecting the quality of coffee [5]. It is generally believed that coffee grown at less than 900 m is called low-altitude coffee, 900-1200 m is called medium-altitude coffee, 1200-1500 m is called high-altitude coffee, and coffee grown at more than 1500 m is called super high-altitude coffee. The altitude of coffee is often mentioned in terms of production, trade, roasting, brewing, and sales. An adequate altitude determines coffee quality [6]. Therefore, some countries even mark the growth altitude on packaging bags in the coffee trade.  
Although the cultivation of coffee at high altitudes positively influences the final quality of the beverage [7], few researchers have connected the final quality to the growth altitude. The sensory profile of coffee produced at various times within the same region may differ. Consequently, studies examining the effects of altitude on flavor characteristics may lack representativeness. Despite variations in climatic conditions over different periods, sampling at the same time can reduce errors associated with the climate's impact on coffee quality [8].  
The quality of coffee is closely related to the precursor components. This was described by researchers in previous studies. The precursor components include both chemical components that affect flavor and quality, such as trace elements [9], alkaloids, and amino acids [10], as well as nutritional components such as organic acids, monosaccharides, and fatty acids [11]. The chemical components mainly directly affect the quality of coffee cups. There are also a small number of components that react with other components in the brewing part, indirectly affecting the quality of coffee. The nutritional components of coffee beans mainly produce the Maillard reaction in the roasting process, forming the aroma component and contributing to the quality of coffee.  
Coffee from Pu'er City in Yunnan Province was chosen as the subject of this research. Coffee samples were collected from the same area at altitudes ranging from 930 to 1520 m to analyze the flavor precursor and volatile components. Additionally, a professional team was formed to assess the cupping quality and evaluate the impact of growing altitude on sensory quality. This study aimed to investigate the effects of altitude on the composition of raw coffee beans and the sensory and cupping characteristics of roasted coffee, thereby providing valuable insights for potential applications.