Effects of hydrogen sulfide on yellowing and energy metabolism in broccoli

The effects of H2S on yellowing and energy metabolism of broccoli florets treated with hydrogen sulfide (H2S) or DL-propargylglycine (PAG) were investigated after four days of storage at 20 degrees C. Our study showed that H2S treatment enhanced endogenous H2S content by 28.19% and 49.78% in comparison to the control and PAG-treated group respectively. This result might be related to the increase of L-cysteine desulfhydrase (LCD) and D-cysteine desulfhydrase (DCD) activities. Meanwhile, H2S treatment can maintain chlorophyll content at 0.329 g kg(-1), whereas the control at 0.298 g kg(-1) and PAG-treated group at 0.275 g kg(-1). This led to an alleviation of the yellowing in broccoli florets. In addition, high endogenous H2S content also activated the key enzymes, involved in energy metabolism, including ATPases, cytochrome C oxidase (CCO), succinate dehydrogenase (SDH), glucokinase, fructokinase, glucose-6-phosphate dehydrogenase (G6PDH) and 6-phosphogluconate dehydrogenase (6PGDH). As a result, significantly higher energy charge was observed in H2S-treated group (p < 0.05). These results suggest that H2S can effectively inhibit the yellowing and maintain high energy charge, therefore prolong the shelf life of postharvest broccoli.