Influence of Low‐temperature Blanching Combined with High‐pressure Shift Freezing on the Texture of Frozen Carrots

Abstract

ABSTRACT: Freezing causes texture loss of tissue‐based systems such as fruits and vegetables. To evaluate the potentials of high‐pressure freezing for minimizing freezing damage, the effects of high‐pressure shift freezing and regular freezing conditions on the texture of carrot cylinders were investigated. To improve the strength of the plant material by a pectin‐based network, carrot cylinders were submitted to different pretreatment conditions before freezing. The reduced freezing time of high‐pressure shift freezing compared with conventional freezing results in a limited positive effect on the hardness of non‐pretreated carrots. A pronounced hardness improvement was obtained when calcium soaking followed by thermal (30 min at 60°C) or high‐pressure (15 min at 60°C and 300 MPa) pretreatment was combined with high‐pressure shift freezing. During subsequent frozen storage at ‐18°C, the increased hardness values of pretreated, high‐pressure frozen carrots could not be maintained.