RHEOLOGICAL PROPERTIES OF ACID MILK GELS .1. EFFECT OF COMPOSITION, PROCESS AND ACIDIFICATION CONDITIONS ON PRODUCTS FROM RECOMBINED MILKS

The effects of nine factors [solids content, fat content, fat type, order of heating, severity of heat treatment, homogenization temperature, homogenization pressure, acidification temperature and concentration of glucono-delta-lactone (GDL)] on the theological properties of acid milk gels have been studied. The gelation time (time at which G' and G'' began to increase) was reduced by low level of solids, high heat treatment, high incubation temperature and high concentration of acidulant. The use of the higher level of fat, milk fat instead of olive oil, high heat treatment and high incubation temperature increased the gelation pH (the pH of the sample at gelation time). The rheological properties (elastic modulus, viscous modulus and phase angle) were only influenced by level of solids, heat treatment, incubation temperature and concentration of GDL. High heat treatment and high level of solids increased both elastic and viscous moduli, but only heat treatment influenced phase angle. Homogenization conditions (temperature, pressure and order of processing) had no significant effects on gel initiation or viscoelastic properties.