Biopolymers used as cryoprotectants in food freezing . Chapter 9

ZARITZKY NOEMI.

Biopolymer Engineering in Food Processing . Ed.Telis Vania R., CRC Press.Taylor and Francis Group

CRC Press Taylor and Francis Group

Año: 2012; p. 327 - 384

Biopolymer Engineering in Food ProcessingSeries: Contemporary Food Engineering.Published:May 29, 2012 by CRC Press - 416 Pages.Editor(s):Vania Regina Nicoletti Telis.The Book provides a range of information from biopolymer production and costs to applications.Examines pressure loss and heat transfer during flow of biopolymer suspensionsPresents details on the use of biolpoymers as drying aids in spray-drying and freeze-drying of fruit juices and as cryoprotectants in food freezingDiscusses the mechanical and mass transfer properties of films and coating produced from biopolymers, composites, and nanocompositesExplores the application of biopolymers in separation processes for the recovery of biocompoundsSummaryDue to their unique properties and ability to interact with other food components, biopolymers have traditionally played a major role in food processing. Biopolymer Engineering in Food Processing explores processing technology associated with biopolymer applications and discusses both operational and economic aspects.Following an overview of biopolymer applications and their functionality in different processes, the text examines: Production routes, availability, costs, and physicochemical properties of commercial biopolymers.Rheology of biopolymer suspensions, how concentration and shear may affect their flow behavior, and their response to pressure losses and heat transfer during flow. Effects of food processing and storage conditions on the viscoelastic and textural properties of food gels.Mechanical and mass transfer properties of films and coating produced from biopolymers, composites, and nanocomposites.The use of biopolymer coatings to reduce oil uptake during deep-fat frying of foods and in modified atmosphere storage of foods.The book also explores the application of biopolymers in separation processes for recovery of biocompounds. It discusses biopolymer behavior during thermoplastic extrusion and the response of certain cereals and snacks to extrusion operating parameters. Finally, it reviews engineering aspects of biopolymers used as drying aids in spray-drying and freeze-drying of fruit juices and pulps and discusses biopolymers used as cryoprotectants in food freezing.Abstract of the chapter : Living cells, biological materials (plant and animal tissues) and food derived from them contain a large proportion of water. Water is a very important component in foods affecting quality attributes and shelf-life stability.Freezing involves lowering the temperature of a system below its initial freezing point, converting water to ice by elimination of the latent heat associated to the change of phase. During freezing water is removed from the food matrix by forming ice crystals. Consequently the concentration of the dissolved substances in the unfrozen regions increases, lowering the water activity (aw) of the product.Freezing is considered a very efficient method for long-term food preservation not only because the effect of low temperatures on chemical reactions and microbial growth, but also due to the decrease of water activity (Fennema et al. 1973; Zaritzky 2000, 2006). Freezing inhibits the growth of deteriorative and pathogenic microorganisms, and retards biochemical and enzymatic reactions that would otherwise occur in unfrozen food. Although the physico-chemical reactions slow down at lowtemperatures, they continue during frozen storage conditions. In the present chapter the basic principles of freezing and the effect of hydrocolloids as cryoprotectants in frozen food systems are discussed