Novel methods for rapid freezing and thawing of foods - a review

This paper reviews new developments in methods of freezing (high-pressure freezing, dehydrofreezing and applications of antifreeze protein and ice nucleation protein) and thawing (high-pressure and microwave thawing, ohmic thawing and acoustic thawing) for foods. With a good understanding of the solid-liquid phase diagram of water, the effects of pressure on food freezing-thawing cycles are highlighted. High-pressure freezing promotes uniform and rapid ice nucleation and growth through the whole sample. Dehydrofreezing has been successfully used in freezing of vegetables and fruits with the advantage of less damage to plant texture because of partial water removal before freezing. Recently, studies have been carried out for the biotechnological use of antifreeze and ice nucleation proteins because of their uniqueness in directly improving freezing processes. Thawing under pressure can be achieved at lower temperature than that at atmospheric pressures. Finally microwave, ohmic and acoustic thawing are described. It is hoped that this paper will attract more research in novel freezing and thawing processes and methods. (C) 2002 Elsevier Science Ltd. All rights reserved.