“Chinese paocai” is typically made by fermenting red radish or cabbage with aged brine (6–8 w/w). This study aimed to reveal the effects of paocai raw materials on fermentation microorganisms by metagenomics sequencing technology, and on volatile organic compounds (VOCs) by gas chromatography–mass spectroscopy, using red radish or cabbage fermented for six rounds with aged brine. The results showed that in the same fermentation period, the microbial diversity in cabbage was higher than that in red radish. Secundilactobacillus paracollinoides and Furfurilactobacillus siliginis were the characteristic bacteria in red radish paocai, whereas 15 species of characteristic microbes were found in cabbage. Thirteen kinds of VOCs were different between the two raw materials and the correlation between the microorganisms and VOCs showed that cabbage paocai had stronger correlations than radish paocai for the most significant relationship between 4-isopropylbenzyl alcohol, α-cadinol, terpinolene and isobutyl phenylacetate. The results of this study provide a theoretical basis for understanding the microbiota and their relation to the characteristic flavors of the fermented paocai.

Sichuan Paocai is a representative traditional fermented vegetable in China, which is deeply embedded in local geographical and cultural heritage. However, regional differences in product characteristics remain poorly understood. In this study, the physicochemical properties, volatile compounds, and microbial communities of Paocai from seven production regions in Sichuan (named FB, AB, BZ, CD, DZ, MY, and YS) were systematically investigated. Parameters including pH, salinity, nitrite, organic acids, and color were determined, while volatile profiles were analyzed using an electronic nose and comprehensive two-dimensional gas chromatography–mass spectrometry. A total of 294 volatile compounds were identified, with alcohols, esters, and isothiocyanates emerging as the major contributors to flavor differentiation. UMAP and OPLS-DA analyses revealed distinct regional clustering, which was consistent with electronic nose profiling, and 111 volatile compounds were identified as key aroma markers. Microbial diversity was assessed using 16S rRNA gene sequencing, demonstrating that Lactobacillus, Lentilactobacillus, Pediococcus, and Weissella were the dominant taxa, although the richness varied significantly across regions. An LEfSe analysis further identified region-specific biomarkers, including Pediococcus, Lactococcus, and Leuconostoc in FB; Lactobacillus in AB; Pediococcus ethanolidurans in BZ; Levilactobacillus in DZ; Lentilactobacillus in MY; and a more diverse microbiota in MS. A correlation analysis highlighted the pivotal roles of distinct microbial groups in shaping and transforming flavor compounds across different regions. Overall, these findings provide scientific guidance for the development of high-quality, region-specific products and contribute to the protection, branding, and market competitiveness of geographically indicated foods.

The paocai industry faces challenges related to the production of large volumes of high-salinity and acidic brine by-products. Maintaining paocai quality while reducing brine production is crucial. This study utilized high-throughput sequencing technology to analyze microbial changes throughout the fermentation process, along with the non-volatile flavor compounds and physicochemical properties, to assess the impact of hot-air and salt-pressing pre-dehydration treatments on paocai quality. The findings indicate that pre-dehydration of raw material slowed the fermentation process but enhanced the concentration of non-volatile flavor substances, including free amino acids and organic acids. Hot-air pre-dehydration effectively reduced initial salinity to levels comparable to those in high-salinity fermentation of fresh vegetables. Furthermore, pre-dehydration altered microbial community structures and simplified inter-microbial relationships during fermentation. However, the key microorganisms such as Lactobacillus, Weissella, Enterobacter, Wallemia, Aspergillus, and Kazachstania remained consistent across all groups. Additionally, this study found that biomarkers influenced non-volatile flavor formation differently depending on the treatment, but these substances had minimal impact on the biomarkers and showed no clear correlation with high-abundance microorganisms. Overall, fermenting pre-dehydrated raw materials presents an environmentally friendly alternative to traditional paocai production.

Anthocyanin stability substantially determines the postharvest storage quality of red Huajiao (Zanthoxylum bungeanum Maxim.). Herein, the composition of red Huajiao anthocyanins (RHAs) was characterized, and the copigmentation performance of seven phenolic compounds with RHAs was comparatively evaluated, together with verifying their practical efficacy in maintaining the overall quality of red Huajiao during frozen storage. UPLC-Q-TOF-MS/MS analysis identified ten anthocyanin monomers in RHAs, among which delphinidin-3,5-diglucoside (D3,5G, 28.23%), and delphinidin-3-O-glucoside (D3G, 14.86%) were verified as the predominant monomers. Naringin (NA) exhibited an optimal copigmentation effect, achieving a maximum color enhancement rate of 19.46% at a 1:40 molar ratio and a pH of 3.0 at 20 °C, while thermodynamic tests verified the excellent stability of the naringin–RHA complex. The copigmentation interactions between RHAs and copigments were largely attributed to hydrogen bonds, π–π stacking, and alkyl hydrophobic interactions. Considering practical application cost and flavor compatibility, chlorogenic acid (CGA) was selected as the preferred alternative copigment. Frozen storage tests suggested that soaking pretreatment with 10 mmol/L CGA effectively delayed color fading and maintained the integrity of the oil gland and the good sensory quality and color attributes of red Hujiao, with no adverse impacts on its inherent flavor and numbing components. Collectively, phenolic-mediated intermolecular copigmentation represents an efficient technical means for stabilizing color and maintaining the commercial quality of postharvest red Huajiao during frozen storage.