Changes in γ-Aminobutyric Acid (GABA) Content and Related Components in Eggplant Fruits by Combination of Short Term Anaerobic and Aerobic Treatments

Abstract

　We investigated the effects of aerobic, anaerobic, and anaerobic-aerobic storage on the γ-aminobutyric acid (GABA), amino acid, organic acid, free sugar, and total polyphenol content, and eggplant fruit quality. These fruits were sealed in gas-barrier bags to initiate anaerobic respiration and stored at 25℃. GABA content increased after one day of anaerobic storage. This high GABA content was maintained until day five post-storage under aerobic conditions. Fruit placed under anaerobic conditions for one day contained 1.4-1.7 fold higher GABA content than that stored under aerobic conditions. We did not observe any differences in GABA content between anaerobic and anaerobic-aerobic storage. Amino acids and organic acids associated with GABA metabolism, including alanine, succinic acid, lactic acid, and acetic acid, increased under anaerobic conditions. In contrast, glutamic acid, glutamine, aspartic acid, malic acid, and citric acid contents decreased under the same conditions. The content of these components was found to be equivalent between the fruits continuously stored under aerobic conditions and those switched to aerobic conditions after one day of anaerobic storage. When the fruits were stored under anaerobic conditions for more than three days, their marketability was strongly decreased owing to color fading and off-flavor development. These results suggest that short term anaerobic treatment by respiration in a sealed package followed by aerobic storage is an effective method for increasing GABA without quality loss.