Abstract: In response to the problems of low efficiency and unstable quality in the traditional processing of star anise, this study systematically explored the impact of different blanching techniques on the “color-metabolite” correlation network of star anise and analyzed the correlation between color parameters and characteristic metabolites. An electronic nose and gas chromatography-mass spectrometry (GC-MS) were used to analyze the effects of six blanching techniques (boiling water, steam, microwave blanching alone and combined with sweating) on the odor and color of star anise. Non-targeted GC-MS-based metabolomics was used for analysis of volatile metabolites, and the non-volatile metabolites shikimic acid, total phenols, and total flavonoids were quantitatively detected. The results showed that a total of 69 volatile metabolites were identified across the six blanched samples. Using variable importance in projection (VIP) value > 1 as the threshold, orthogonal partial least squares discriminant analysis (OPLS-DA) identified 24 differential metabolites to effectively distinguish star anise treated with different blanching techniques. The relative contents of the characteristic components trans-anethole ((83.93 ± 8.33)%) and anisaldehyde ((1.55 ± 0.45)%) were the highest in the sample treated with microwave blanching combined with sweating. Traditional boiling water blanching effectively retained shikimic acid ((90.35 ± 0.84) mg/g) and total phenols ((68.00 ± 4.10) mg/g), and maintained the diversity of volatile metabolites (48). The total flavonoid content in microwave-treated star anise was 57.8% higher than that star anise subjected to traditional boiling water blanching, but the number of volatile metabolites was smaller (17). Pearson’s correlation analysis showed that the color parameters L* and b* were positively correlated with trans-anethole, anisaldehyde, anisole, total phenols, and shikimic acid (P < 0.05), and a* was positively correlated with total flavonoids (P < 0.05). In terms of color and odor, star anise processed by microwave blanching and steam blanching met the standards for da-hong star anise. Microwave blanching optimized the color and flavor, while boiling water blanching was more conducive to the retention of active components. The color values L*, a*, and b* can be used as indicators for process optimization, providing a basis for the targeted production of star anise products with highly active components or superior sensory characteristics.

Key words: star anise; blanching; colorimeter; electronic nose; gas chromatography-mass spectrometry; metabolomics; trans-anethole; shikimic acid; total phenols