‘‘rule’’ that changes in enthalpy and entropy are roughly independent of
temperature.
Anyway, the hydrophobic effect exists by virtue of the extensive
hydrogen bonding in water. It is therefore of importance that various
solutes, unless present in quite small concentrations, significantly affect
water structure and thereby the hydrophobic effect and its consequences. It
concerns alcohols, sugars, well soluble organic molecules like urea, and most
salts. These phenomena are poorly understood.
The Hofmeister Series. The specific effects of salts are often
arranged in the lyotropic or Hofmeister series, or rather two series, one for
anions and one for cations. For some ions of importance in food science
FIGURE 3.4 Assumed relation between the free energy of formation of
hydrophobic bondsðDGÞand temperature. Also the entropicðTDSÞand enthalpic
ðDHÞcontributions toDGare given. The relations greatly depend on the chemical
constitution of the apolar groups involved.