A simple and effective method to enhance the level of gamma-aminobutyric acid in Chinese yam tubers while preserving its original appearance

Hot-air drying is an effective method to enhance the levels of gamma-aminobutyric acid (GABA) in edible tubers/tuberous roots. However, consumers prefer fresh food to processed food. Therefore, this study aims to develop an effective method to increase the GABA levels in the tubers of Chinese yam (CY tubers) and the tubers/tuberous roots of other plants while preserving its original appearance. Among nitrogen treatment (treatment under a nitrogen atmosphere), carbon dioxide (CO₂) treatment (treatment under a CO₂ atmosphere), vacuum treatment, and water immersion, CO₂ treatment was the most effective GABA-level-increasing method for CY tubers, with water immersion being more effective than nitrogen treatment and vacuum treatment. The GABA level in CY tubers treated with CO₂ for 72 h reached 1.25 ± 0.08 mg/g. CO₂ treatment and water immersion were also effective GABA-level-increasing methods for CY bulbils, potatoes, and lotus tubers, but they were less effective for carrots.