Phospholipid/fatty acid-induced secondary structural change in beta-lactoglobulin during heat-induced gelation.
Effects of phosphatidylcholine (PC) and the predominant fatty acids (FAs) in milk, butyrate, oleate, and palmitate, on secondary structural changes in beta-lactoglobulin (beta-LG) during heat-induced gelation were analyzed on the basis of circular dichroism (CD) spectra. Small-strain oscillatory measurements were carried out to characterize viscoelastic properties of the heat-induced gels. In the absence of added salt, PC and FAs induced helix formation of beta-LG on heating to 80 degrees C and increased the storage moduli (G') of heat-induced gels. In the presence of 500 mM NaCl, PC did not change the CD spectrum of beta-LG but decreased G'. In contrast, butyrate substantially unfolded beta-LG in 500 mM NaCl on heating, forming very elastic gels with increased G' values. Palmitate and oleate induced beta-LG gel formation at 25 degrees C without heating; heating to 80 degrees C almost completely unfolded beta-LG in 500 mM NaCl.
Ikeda
S
S
Departments of Food Science and Biochemistry, North Carolina State University, Raleigh, North Carolina 27695, USA.
Foegeding
E A
EA
Hardin
C C
CC
D005227:Fatty Acids / Q000737:chemistry*; D005782:Gels; D006358:Hot Temperature; D006801:Humans; D007782:Lactoglobulins / Q000737:chemistry*; D010713:Phosphatidylcholines / Q000737:chemistry*; D017433:Protein Structure, Secondary
D005227:Fatty Acids; D005782:Gels; D007782:Lactoglobulins; D010713:Phosphatidylcholines