Effect of Ultrasound Combined with Calcium Impregnation Treatment on Structural Properties of Strawberry Pectin

In this paper,the effect of ultrasound combined with calcium impregnation (U+Ca) treatment on the pectin content of strawberry was studied. The structural characteristics of pectin were also characterized by fourier transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM). The results showed that U+Ca treatment inhibited the reduction of water soluble pectin (WSP) and sodium carbonate-soluble pectin(SSP) contents in strawberry. The results of pectin structure showed that the esterification degree of pectin in U+Ca group was lower,which promoted the cross-linking of pectin and Ca²⁺. According to AFM results,the frequency of WSP and SSP molecules of U+Ca group in the range of larger chain width (≥ 200 nm) was significantly higher than that of CK,U and Ca groups. It was concluded that ultrasound combined with calcium impregnation treatment inhibited the degradation of pectin in strawberry. The present study will provide a theoretical basis for the establishment of ultrasound combined with calcium impregnation solution preservation methods for fruits and vegetables.