Britannica Sources used in this answer

How do cell wall-degrading enzymes soften ripe fruit?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

Cutaway illustration of a plant cell showing labeled internal structures including the nucleus, nucleolus, chloroplast, mitochondrion, vacuole, endoplasmic reticulum, ribosomes, Golgi apparatus, cell wall, and other key organelles. — Cell wall Cutaway drawing of a plant cell, showing the cell wall and internal organelles.

Cell wall-degrading enzymes soften ripening fruit by breaking down the structural components of the plant cell wall.

A primary mechanism for this softening involves the degradation of pectin, a group of water-soluble carbohydrates that act as a cementing agent between adjacent cells. In immature fruit, pectin helps maintain firmness and shape; however, as the fruit ripens and eventually becomes overripe, these enzymes break down the pectin into simple, water-soluble sugars. This degradation process reduces the structural integrity of the cell walls, causing the fruit to lose its firmness and shape.123

While cell walls contain various enzymes—some of which cross-link structural molecules like lignin or extensin—it is specifically the activity of cell wall-degrading enzymes that facilitates the softening process during fruit maturation.23