Changes in P-Galactosidase Activity in Peel and Pulp of Banana (Musa sp.) Fruits during Ripening and Softening

摘要

P-Galactosidase is thought to be involved in fruit softening through cleaving P (I→4) galactan bonds in cell wall hemicellulose. To find out whether p-Gal plays important roles in banana fruit softening, the enzyme activities in peel and pulp, fruit firmness, respiration rate and ethylene release rate were assayed during banana softening. The results showed that p-Gal activities in banana pulp and peel increased slightly at the beginning of storage and reached their maxima when the fruit firmness decreased drastically, P-Gal activity increased about 3~7 fold in both pulp and peel during ripening and pGal activities were higher in pulp than in peel. Treatment of banana fruits with ethylene absorbent postponed the time of reaching of its maxima of respiration and ethylene. enhanced the firmness of pup and decreased P-Gal activity in the peel and pulp. These results suggest that P-Gal induced the decrease of fruit firmness and played an important role in banana fruit softening, and its activity is regulated by ethylene.