Impact of biopolymers added to a grapefruit puree and freeze-drying shelf temperature on process time reduction and product quality

摘要

Freeze-drying provides high quality foods, despite the long time involved in the operation. Shortening the process time by increasing the heat supplied for sublimation to occur could affect the product quality. In this study, the impact of adding gum Arabic and bamboo fiber to a grapefruit puree and of raising the shelf temperature to 40 degrees C during freeze-drying has been considered. The increase in temperature allows a 57.5% time reduction and promotes a porosity increase without any impact on the cakes color and vitamin C content. The addition of biopolymers does not affect the drying kinetics and allows a crunchier and firmer cake to be obtained, despite the color changes and the fact that vitamin C becomes less available. In conclusion, raising the shelf temperature to 40 degrees C significantly reduces the freeze drying time without noticeably impairing the product, and the addition of biopolymers improves the product characteristics without adversely impacting upon drying times. (C) 2020 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.