Rheological properties of acid milk gels as affected by the nature of the fat globule surface material and heat treatment of milk

The effects of different fat globule surface materials on the rheological properties of acid milk gels, formed by acidification with glucono-delta-lactone at 30 degrees C, were investigated. Acid gels were prepared from recombined milks (similar to 3.4% fat) containing fat globules stabilized with low-heat, medium-heat or high-heat skim milk powder (SMP), sodium caseinate, whey protein concentrate (WPC), heated WPC or Tween 60. Unheated reconstituted skim milk (URSM) or milk heated at 80 degrees C for 30 min (HRSM) was used in the preparation of recombined milks. In URSM or HRSM systems, gels containing fat globules stabilized by non-interacting materials ('structure breaker') (Tween and unheated WPC) had low storage moduli (G') compared with interacting materials ('structure promoter') (SMP, sodium caseinate and heated WPC). HRSM systems had higher G' values than URSM. Gels containing fat globules stabilized by sodium caseinate or heated WPC had the higher G' values than those containing SMP-stabilized fat globules in both URSM and HRSM systems. (C) 1999 Elsevier Science Ltd. All rights reserved.