Defoamer Selection and Application for Processing Oolong Tea Beverage

Objective Effect of defoamer usage in oolong tea beverage processing on the flavor of the drink was evaluated by a sensory panel and two electronic devices for the application.

Method Along with no added agent as control (CK), three types of defoamers including siloxane F695, silicone emulsion F1520, and silicone F3011 at the addition concentrations of 5, 25, and 45 mg·kg⁻¹ were applied in processing the Rougui oolong tea beverage. Sensory evaluation was conducted on the various beverage samples. In addition, detection by an electronic nose (E-nose) and an electronic tongue (E-tongue) was performed for objective measurements.

Result The beverage made with an added silicone emulsion F1520 at the low rate of 5 mg·kg⁻¹ exerted no significant negative impacts (e.g., turbidity, pronounced astringency, weak aroma, or noted off flavor) on the sensory quality. Statistically, addition of the three defoamers at the designed concentrations did not produce significant differences from CK on the evaluation scores. However, the E-nose showed silicone emulsion F1520 causing significantly highest responses on 7 sensors, i.e., W2S, W3S, W6S, W5S, W1S, W1W, and W2W, among the three defoamers. And the E-tongue displayed a desirable effect of all three defoamers, with siloxane F695 being the most effective one, in mitigating bitterness in the drink. In addition, the device picked silicone F3011 as one that outperformed other agents on the umami and richness in taste and silicone emulsion F1520 being the one that slightly heightened the sweetness.

Conclusion Taking both aroma and taste attributes of the drink into considerations, the addition of silicone emulsion F1520 at a rate of 5 mg·kg⁻¹ in processing Rougui oolong tea beverage might be appropriate with little undesirable side effect on the product quality.