Low temperature
could suppress the activities of PME (Fig. 3C) and endo-PG
(Fig. 3B), but promoted the activity of exo-PG (Fig. 3A), in turn
maintained higher firmness (Fig. 1B) than that at 10 C and probably
avoided visible wooliness or internal breakdown symptom to
occur in flesh. MeJA-treated fruits had lower PME (Fig. 3C) with
correspondingly higher absorbance of ester (1735 cm1) and carboxyl
group (1400–1450 cm1) as compared to the control fruits
without MeJA treatment (Fig. 4B), which indicated MeJA treatment
inhibited the de-ester of pectin. In addition, MeJA-treated fruits
kept a stable level of calcium content in cell wall (Fig. 5D), and
had higher firmness than the control fruits stored at 5 C (Fig. 1B).