Variations of volatile flavors and microbial communities in Chinese Chaozhou pickle during natural fermentation revealed by GC-IMS and high-throughput sequencing

Chaozhou pickle, a traditional Chinese fermented vegetable product, is highly regarded among consumers due to its unique flavor. This work monitored the flavor substances and microbial communities of Chaozhou pickles during fermentation by gas chromatography-ion mobility spectrometry (GC-IMS) and high-throughput sequencing. A total of 70 volatile compounds were identified from Chaozhou pickles. In addition to fruit aroma esters, the pickles also contain aldehydes, ketones, alcohols, acids, and heterocyclic compounds. The four pickles exhibited a prevalence of Cyanobacteria, Proteobacteria, and Firmicutes as the leading bacterial phyla, while Weissella, Leuconostoc, and Lactobacillus were identified as the predominant bacterial genera. Physiochemical quality and acid properties of Chaozhou pickle were also investigated. Results revealed a significant reduction in hardness, chewiness and pH during fermentation, as well as a notable increase in free amino acids, and organic acid levels. These results could contribute to a greater comprehension of the role of microorganisms in flavor formation during fermentation and provide a scientific foundation for the industrialization of Chaozhou pickle.