STRUCTURAL-PROPERTIES OF PECTIN-GELATIN GELS - PART II - EFFECT OF SUCROSE GLUCOSE SYRUP/

Small deformation dynamic oscillation and bright field microscopy were used to examine the structural properties of single and mixed high me thoxy pectin and gelatin systems in the presence of sucrose/glucose sy rup blends. Go-solute concentrated (greater than or equal to 78%) syst ems of the polysaccharide form rubbery structures which are readily tr ansformed into glassy consistencies according to the time-temperature superposition principle. Increasing amounts of co-solute in the gelati n samples induce changes in viscoelasticity from that of conventional hydrogels to mechanical traces that cover much of the plateau region a nd the beginning of the glass transition area. Furthermore, manipulati on of the protein/sugar ratio can result in strong crystalline matrice s, or viscoelastic solutions where the co-solute forms the continuous phase and the gelatin inclusions can undertake a conformational transi tion. The properties of the single components were used to rationalise the phase behaviour of their mixtures. Upon triggering the gelation o f pectin, mixtures call be made where either gelatin or both component s form a continuous phase. Results are discussed in the light of evide nce obtained from the ethylene glycol work in Part I. (C) 1998 Publish ed by Elsevier Science Ltd. All rights reserved.