An Experimental Study on the Freeze-Drying Process for Cordyceps militaris

This study presents experimental results on the freeze-drying process of Cordyceps militaris. Key focus areas included the construction of the freezing curve, product temperature profile, drying curve, and drying rate curve. Freezing experiments showed that reducing the temperature from ambient (20 °C) to −41.2 °C required approximately 4200 s, and the average initial freezing point was determined to be −0.6 °C. Freeze-drying experiments conducted at three heating shelf temperatures (−5, 0, and 5 °C) demonstrated that raising the shelf temperature to 5 °C reduced the total drying time by approximately 16.7% compared to −5 °C. Analysis of the drying and drying rate curves revealed that the sublimation rate is strongly influenced by both the drying temperature and the mass transfer resistance of the dried layer. Furthermore, sensory evaluation showed that the dried Cordyceps militaris retained the color, shape, and volume of the fresh material. These findings provide a valuable basis for optimizing freeze-drying conditions to preserve both product quality and bioactive efficacy.