The researchers studied 63 different types of longan fruits to see what kinds of sugars they contain. They used a method called high performance liquid chromatography to analyze the sugars. The main sugars found in longan fruits were fructose, glucose, and sucrose. Sucrose was the most common sugar, making up over half of the total sugar content. The levels of fructose and glucose were similar. The researchers also found that the sweetness of the fruits was related to the amount of sugar they contained. Overall, the study showed that longan fruits have a variety of sugars, with sucrose being the most abundant.