Drying methods affect nutritional value, amino acids, bioactive compounds, and in vitro function of extract in...

Mulberry leaves (ML) are nutrient-rich and beneficial for food and feed. Our study evaluated five drying methods-sun drying (SD), air drying (AD), oven drying (OD), freeze drying (FD), and vacuum-microwave drying (MD) for preserving nutrients and bioactivity. In vitro models tested the bioactivities of ML extracts. Results showed that machine-based methods (OD, FD, and MD) were superior to natural processes (SD, AD) retaining nutrients and bioactivity. OD preserved amino acids effectively, FD and MD retained crude protein and fibers, and MD excelled in maintaining the total polyphenols, vitamin E, minerals, and bioactive compounds, enhancing the antioxidant capacity and beneficial effects on lipid metabolism, ROS scavenging, and anti-apoptotic in lipid-laden HepG2 cells. Overall, FD and MD are ideal for high-value products like food and pharmaceuticals, while OD is cost-effective for animal feed. SD and AD lead to significant nutrient loss and are not recommended unless cost is a major concern.