Regulation mechanism of sodium citrate on fresh-cut yam yellowing

The fresh-cut yam will turn yellow under 25 ℃ during storage. The present study investigated the regulation mechanism of sodium citrate treatment on fresh-cut yam yellowing under the detection of enzyme activities (commercial kits), gene expressions (qRT-PCR) and metabolites (commercial kits and HPLC). Sodium citrate apparently inhibited fresh-cut yam yellowing. Key genes regulating glycolysis, pentose phosphate pathway and the tricarboxylic acid pathway were down-regulated by sodium citrate, leading to reduced energy and precursor supply. ATP contents and energy charge in the sodium citrate-treated were lower than those in the control. In addition, enzymes that participated in energy metabolism, such as H + -ATPase and Ca 2+ -ATPase, were markedly decreased by sodium citrate treatment. Notably lower flavonoid, carotenoid, and bisdemethoxycurcumin contents were detected in the sodium citrate treatment, which were in connection with the restriction of the activities of critical enzymes, and their relative gene expressions participating in flavonoid, carotenoid, and curcuminoid biosynthesis. These findings verified the mechanism of fresh-cut yam yellowing reversely, and provided theoretical basis and technical supports for the preservation of fresh-cut yam. • Sodium citrate (SC) inhibited yellowing of fresh-cut yam. • SC weakened glycolysis, pentose phosphate pathway and tricarboxylic acid pathway. • SC reduced flavonoid, carotenoid, and bisdemethoxycurcumin biosynthesis.