Effect of freezing-induced pectin degradation on the texture stability of strawberry

Freezing causes a soft fruit texture. As an important component of cell wall, pectin content and structural changes can affect fruit texture greatly. The hardness and shear force showed that the increased freezing rate partly inhibited the decrease in hardness after freezing, while the lower freezing rate increased the shear force after freezing. The changes of the activities of the pectin degradation enzymes lead to a transition from covalently bound pectin to water-soluble pectin. The pectin was characterized by atomic force microscopy and Fourier transform infrared Spectroscopy, which showed that the structure of the pectin is destroyed, its fingerprint area was changed. Pectin of each group gathered in different degrees. The degradation of pectin weakens the support of cell wall, reduces the ability to combine water, and increases its discharged water content. Pectin degradation is an important reason for the softening of strawberry after the freezing.