Effect of Silicon-Based Anti-foaming Agent on the Aroma of Oolong Tea Beverage Using Electronic Nose and HS-SPME-GC-MS

This study employed sensory evaluation, electronic nose and headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) to evaluate the efficacy of different concentrations of silicone-based anti-foaming agent in Rougui oolong tea beverage and evaluate their effects on the flavor and aroma characteristics of the beverage. The results demonstrated that the low and medium concnentrations of anti-foaming agent effectively reduced the foam height and shortened the collapse time, with the effect being more pronounced upon the addition of the anti-foaming agent before than after foam generation. The addition of excess anti-foaming agent caused the tea infusion to become turbid and increased the astringency and off-flavors, leading to quality deterioration. Significant differences in sensor responses among the different treatment groups were observed for E-nose sensors W5S (nitrogen oxides), W1S (short-chain alkanes), W1W (inorganic sulfides), and W2W (aromatic components and organic sulfides). Different concentratons of anti-foaming agent had a significant effect on the aroma components of the beverage. A total of 110 aroma compounds were identified, and 26 key differential compounds were selected by orthogonal partial least squares-discriminant analysis (OPLS-DA) and Kruskal-Wallis H test. Relative odor activity value (ROAV) analysis revealed that the contents of aroma components such as linalool, dihydrolinalool, phenylethyl alcohol, and trans-nerolidol remarkably declined with increasing concentration of anti-foaming agent, and the release of these aroma components was inhibited by the anti-foaming agent, possibly altering the overall aroma profile. Based on the anti-foaming efficacy and sensory balance, the optimal anti-foaming agent concentration was determined as 0.005–0.025 g/kg, effectively controlling foaming while preserving the flavor well. This study helps elucidate the mechanism by which antifoaming agents influence tea beverage aroma, providing theoretical insights for quality control and aroma optimization in tea beverage production.