Freeze Texturing of Food Materials by Ice-nucleation with the BacteriumErwinia ananas

Abstract

We propose a new process for freeze texturing using Erwinia ananas cells as heterogeneous ice nuclei. The bacterial cells, when added to isotropic aqueous dispersions or hydrogels of proteins and polysaccharides, converted the bulk water into directional ice crystals at a subzero temperature of not lower than – 5°C, with formation of anisotropically textured products. Raw egg white, bovine blood, soybean curd, milk curd, aqueous dispersions or slurries of soybean protein isolate, hydrogel of agar, corn starch paste, and hydrogels of glucomannan and calcium-bridged glucomannan were used as materials to be textured. These were each mixed with a small mass of the bacterial cells and slowly cooled to – 5°C in an air bath. The frozen materials were vacuum-dried before setting the resulting textures by steaming for 2 min at 1 atm if necessary, forming flake-like textures. Slicing the textured products at right angles to the lamellas of the flakes gave fibrous products.