Effects of different drying methods on nutritional components and dissolution property of blueberry leaf powder

Background With the continuous expansion of blueberry planting area, a large amount of blueberry leaf biomass resources has been generated. Preliminary research has found that these leaves contain polysaccharides and flavonoids, which possess antioxidant, hypoglycemic, and other physiological functions. But so far, blueberry leaves have not been fully studied and utilized industrially. Objective This study aimed to analyze the effects of four methods, namely hot air drying (HAD), vacuum drying (VD), vacuum freeze drying (VFD) and far-infrared drying (FIRD), on the nutrient composition and dissolution property of blueberry leaf powder (BLP). Results The results demonstrated that VFD was the optimal method for preserving the quality of blueberry leaves. Compared to the other three drying methods, the BLP treated with VFD exhibited a slower moisture reduction rate and drying rate, while achieving a rehydration ratio of 2.85 ± 0.04 mg/g. Moreover, the VFD-treated BLP showed significantly higher contents of flavonoids (19.94 ± 0.41 mg/g) and phenolics (106.23 ± 0.69 mg/g). Additionally, the BLP obtained through VFD treatment displayed the highest levels of free amino acids and reducing sugars, along with superior solubility and hydration capacity. Finally, radar chart further confirmed that VFD is the most effective method for maintaining blueberry leaf quality. Conclusion In this study, the nutritional composition and dissolution characteristics of BLP with different drying technologies were studied for the first time, and then the optimal drying method was determined, which provided a theoretical reference for the development and utilization of blueberry leaves.