Effects of pectin and glucose on the texture properties and microstructures of freeze-dried restructured fruits: Pectin-glucose sponge as a model

Abstract

This study prepared a series of freeze-dried sponges with different pectin-glucose concentrations at two shelf temperatures (−20 °C and 60 °C) to simulate the specific roles of pectin and glucose in the microstructure and textural properties of freeze-dried restructured fruit products. Pectin polysaccharide is mainly responsible for the construction of scaffolds after freeze-drying. When the content of pectin is more than 1.5% pectin, the occurrence of structural collapse could be significantly inhibited. The small molecule glucose is mainly responsible for the mechanical strength of the sponges. When the glucose increases from 4% to 12%, the mechanical strength of the sponge systems rises from 400 to 1400 g. Sponges with higher pectin content (>3.0%) could prevent the structural shrinkage of systems with greater sugar content (12%) or higher shelf temperature (60 °C), suggesting a possibility to achieve shrink-free lyophilization at high shelf temperature by adding the content of pectin.