Structural changes of malt proteins during boiling.
Changes in the physicochemical properties and structure of proteins derived from two malt varieties (Baudin and Guangmai) during wort boiling were investigated by differential scanning calorimetry, SDS-PAGE, two-dimensional electrophoresis, gel filtration chromatography and circular dichroism spectroscopy. The results showed that both protein content and amino acid composition changed only slightly during boiling, and that boiling might cause a gradual unfolding of protein structures, as indicated by the decrease in surface hydrophobicity and free sulfhydryl content and enthalpy value, as well as reduced alpha-helix contents and markedly increased random coil contents. It was also found that major component of both worts was a boiling-resistant protein with a molecular mass of 40 kDa, and that according to the two-dimensional electrophoresis and SE-HPLC analyses, a small amount of soluble aggregates might be formed via hydrophobic interactions. It was thus concluded that changes of protein structure caused by boiling that might influence beer quality are largely independent of malt variety.
Jin
Bei
B
Department of Food Science and Technology, South China University of Technology, Guangzhou, PR China.
Li
Lin
L
Liu
Guo-Qin
GQ
Li
Bing
B
Zhu
Yu-Kui
YK
Liao
Liao-Ning
LN
D000596:Amino Acids / Q000032:analysis; D001515:Beer; D002523:Edible Grain / Q000737:chemistry*; D006358:Hot Temperature; D011489:Protein Denaturation; D017510:Protein Folding; D055503:Protein Multimerization; D017433:Protein Structure, Secondary; D011506:Proteins / Q000737:chemistry*; D013816:Thermodynamics
D000596:Amino Acids; D011506:Proteins