Effects of Nitric Oxide on the Quality and Pectin Metabolism of Yali Pears During Cold Storage

The effect of fumigation with 10, 20, and 30 mu L L-1 nitric oxide (NO) was investigated to study the effects of NO on the quality of Yali pears during cold storage. The ethylene production, composition of cell walls, and cell-wall-modifying enzyme activities were measured on fruits which were fumigated with NO (20 mu L L-1). The results showed that NO not only reduced the peak value of ethylene production rate, the soluble sugar, soluble solid content, maintained higher firmness, starch, and NO content, but also retarded the degradation of covalent soluble pectin, accumulation of ionic soluble pectin and water soluble pectin. Moreover, NO fumigation decreased the activities of polygalacturonase (PG) and beta-galactosidase (beta-Gal) and delayed the peak of PG activity of fruits. Therefore, it indicated that NO fumigation could delay the softening and ripening of Yali pears.