Effect of pretreatment methods on naringin and bioactive comounds in kumquat seeds (Fortunella japonica)

Kumquat seeds (Fortunella japonica) are a valuable raw material, particularly rich in bioactive compounds. However, their characteristic bitterness remains a major limitation, hindering the effective utilization of kumquat seeds in food processing. Therefore, appropriate pretreatment methods are necessary to reduce the bitter compound naringin while minimizing the loss of bioactive compounds. In this study, the pretreatment methods included: NaOH solution at pH 8.5, 90°C for 2 min; electrolyzed water at pH 8.5, 90°C for 2 min; NaOH solution at pH 8.5, 90°C for 2 min combined with 3% naringinase at 50°C for 3 h; electrolyzed water at pH 8.5, 90°C for 2 min combined with 3% naringinase at 50°C for 3 h; a combination of 10% cellulase at 50°C for 2 h and 3% naringinase at 50°C for 3 h; electrolyzed water at pH 8.5 combined with ultrasound treatment at 40 kHz and 80°C for 2 min; and 4% NaCl solution combined with ultrasound treatment at 40 kHz and 80°C for 2 min, along with an untreated control. The results showed that pretreatment with electrolyzed water at pH 8.5 combined with ultrasound treatment at 40 kHz and 80°C for 2 min effectively reduced the naringin content while maintaining a high level of bioactive compounds.