Changes in fruit texture and cell structure of different pumpkin varieties (lines) during storage

Abstract

After harvest, the pumpkin fruit has strong respiration and metabolic activities, which easily induce quality deterioration, shortening the storage period and shelf life, which affects the farmers' income. To understand the quality change mechanisms of pumpkins and extend the storage period, the fruit cell wall components, related enzyme activities, and fruit texture of Baimi No. 2, Baimi No. 3, Baimi No. 5, Baimi No. 10 and 2020-X1 pumpkin varieties (lines) were monitored during storage at 18 ± 2 °C after harvest.The pumpkin fruit texture was analyzed via the texture profile analysis (TPA) method, and the cell structure changes in peel and pulp cells were monitored using paraffin sections. The results revealed that the hardness, brittleness, viscosity, and elasticity of the five pumpkin fruits were decreased, while the adhesiveness, cohesion, recovery, and chewiness were first increased before decreasing with the prolongation of storage time. In addition, the protopectin, cellulose, and hemicellulose contents were decreased, while the soluble pectin content was increased. In addition, the polygalacturonase activity was increased, and the β-galactosidase, Cx cellulase, and pectinesterase activities were decreased. The cell wall components and enzymatic activities in Baimi No. 10 had minor changes, implying it is storage resistant. In addition, its peel and pulp cells were small and tightly arranged, with minor cellular changes. The peel cells were nearly square, and the pulp cells nearly round, rendering this variety more storable. Baimi No. 5 pulp cells were large and loosely arranged, with large intercellular spaces, rendering this variety short-lived.