Exploration of Different Pre-Processing and Drying Methods on Volatile Organic Compounds in Bletilla striata Based on GC-IMS

Abstract

Rationale: Bletilla striata (Thunb.) Rchb.f. (Orchidaceae), a traditional Chinese medicine herb known as baiji, exhibits diverse pharmacological activities. Despite extensive research on its phytochemistry, the volatile organic compounds (VOCs) of B. striata remain largely unexplored. Methods: Gas chromatography-ion mobility spectrometry (GC-IMS) was used to analyze and compare the VOCs of three pre-processing methods (fresh, boiling, and steaming) and four drying methods (sun-drying [SD], vacuum freeze drying [VFD], hot air drying [HAD], microwave drying [MD]) in B. striata. Results: A total of 137 VOCs were detected and 124 VOCs were identified, primarily including aldehydes, alcohols, and ketones. Principal component analysis (PCA) and fingerprint similarity analysis revealed that the drying method has a greater impact on VOCs than pre-processing method. Partial least squares-discriminant analysis (PLS-DA) and heat map cluster analysis identified 34 VOCs as main characteristic markers to differentiate the samples of B. striata with different processing methods. Additionally, the samples subjected to sequential steaming followed by sun-drying demonstrated a superior ability to retain both the quantity and variety of non-harmful VOC. Conclusion: This research conducted a detailed analysis of the fundamental VOCs in B. striata and provided a scientific theoretical guidance for optimizing processing of B. striata medicinal materials.