Hydrogen sulfide delays softening of banana fruit by inhibiting cell wall polysaccharides disassembly.

Summary: Harvested banana undergoes rapid softening, which limits its shelf life. To delay softening, banana fruit was treated with hydrogen sulfide (H2S) emitted by 0.6 mm sodium hydrosulfide (NaHS) and stored at 15 °C for 16 days. The effects of H2S on cell wall degradation and other physiological characteristics were investigated. In comparison to control fruits, H2S‐treated bananas retained a higher level of fruit firmness, but lower hue values. Ethylene metabolism analysis suggested that H2S inhibited the production of ethylene and the accumulation of 1‐aminocyclopropane‐1‐carboxylic acid (ACC) and decreased the activities of ACC synthase (ACS) and ACC oxidase (ACO). Cell wall polysaccharides determination assays suggested that H2S treatment increased the proportion of HCl‐soluble pectin (HSP), NaOH‐soluble pectin (NSP), cellulose and hemicellulose but decreased water‐soluble pectin (WSP) in fruits. H2S treatment also inhibited the activities of polysaccharide degrading enzymes such as polygalacturonase (PG), pectin methylesterase (PME), pectin lyase (PL), cellulase (CL) and β‐galactosidase (β‐Gal). Transmission electron microscopy analysis suggested that H2S protected cell walls from structural breakdown. These results indicated that H2S is effective in delaying banana softening by regulating cell wall polysaccharide metabolism. [ABSTRACT FROM AUTHOR]