Abstract: In order to optimize the explosion puffing drying process of kiwifruit by CO2-low temperature high pressure permeation, the one-factor-at-a-time and quadratic regression orthogonal rotary combination design methods were jointly adopted to study the influence of puffing pressure difference, puffing temperature and pumping time on the degree of expansion, hardness and brittleness of kiwifruit chips. The response surface methodology was further used to optimize the ranges of the three process parameters and the advantages of using CO2 as a puffing medium were evaluated by comparison with N2. The results showed that all the examined factors had significant effects on the puffing degree, hardness and brittleness of the product (P < 0.05), with a significant interaction between each other; the optimal process parameters were determined as follows: puffing pressure difference 1.03–1.1 MPa, puffing temperature 80–82.46 ℃, and pumping time 90–91.61 min. Compared with hot-air dried kiwifruit chips, kiwi chips prepared by CO2-low temperature high pressure permeation drying had a looser structure, better taste, and higher VC retention rate.

Key words: kiwifruit, CO2-low temperature high pressure permeation, response surface methodology, process optimization