A volatile-based aroma complexity index for Nongxiangxing baijiu.

Aroma complexity is a comprehensive indicator for sensory evaluation of high-quality aromatic products, yet it traditionally relies on subjective assessment and remains difficult to estimate from objective chemical information. In this study, we developed a preliminary, chemistry-informed proxy framework to approximate aroma complexity in Nongxiangxing Baijiu by integrating odor-descriptor diversity, model-estimated odor persistence, and molecular structural complexity. The framework uses abundance-weighted chemical features to generate an interpretable volatile-based total aroma complexity index. Commercial Baijiu samples had calculated total aroma complexity index values of 438.69-513.57. The index values generally increased with manufacturer-declared product tier and revealed brand-dependent patterns. A small sensory evaluation subset showed a positive association between the index and expert-rated complexity, suggesting preliminary sensory relevance. This approach provides an interpretable way to summarize Nongxiangxing Baijiu volatile profiles from objective compositional information and may support exploratory comparative analysis within Baijiu systems, while requiring broader validation before industrial application.