thermal gradients. Large numbers of small intra- and extracellular ice crystals appear at the surface of the product, but fewer large extracellular ice crystals form at the center, disrupting the cell walls (Fig. 3). A similar tendency has been observed in meat tis- sue (Otero and others 1997; Martino and others 1998; Sanz and others 1999), although plant and animal cells differed in their resistance to freezing damage. In plants, the parenchyma tissue is composed of semirigid, polyhedral cells containing cellulose cell walls bounded by pectinaceous middle lamella and often containing an extensive network of air spaces. In contrast, mus- cle cells are flexible, elongated fibers with minimal air spaces and separated by a glycoprotein-rich extracellular matrix. The texture damage often observed in freeze-thawed plant tissues is