Optimization of Vacuum Freeze-Drying Process and Quality Evaluation of <i>Stropharia rugosoannulata</i>

Abstract

Stropharia rugosoannulata is a valuable medicinal and food fungus with high nutritive value. Freeze-drying addresses the storage and transportation challenges of fresh Stropharia rugosoannulata, expanding its market while preserving its flavor and quality more effectively than other drying methods. This study optimizes the vacuum freeze-drying process for Stropharia rugosoannulata using an orthogonal experiment method. The process parameters were optimized to determine their effects on the quality of the vacuum freeze-dried product, including pre-freezing temperature, pre-freezing time, and freeze-drying time. The optimal conditions were identified as a pre-freezing time of 60 h, a pre-freezing temperature of −80 °C, and a freeze-drying time of 72 h. The optimal product exhibited a bright color close to its natural state, with minimal browning and its natural white color maintained post-drying. During the drying process, the internal structure of the raw materials remained intact. After drying, the finished product retained its natural form, making it suitable for sale on the market. The soluble protein content of the vacuum freeze-dried Stropharia rugosoannulata reached 68 mg/g. Optimizing the freeze-drying process can better preserve the tissue structure and bioactive substances of Stropharia rugosoannulata, providing a reference for high-quality food processing and showing potential for sustainable development.

Keywords

• <i>Stropharia rugosoannulata</i>
• vacuum freeze-drying
• process optimization
• texture
• color