Conference PaperPDF Available

INTERACTION OF GREEN TEA FLAVANOIDS WITH MILK PROTEINS AND THE EFFECT OF HEAT TREATMENT

Authors:

Abstract

In this study, the interaction of green tea flavanoids with milk proteins was studied. Reverse-phase high-performance liquid chromatography (RP-HPLC) analysis revealed that the free flavonoids decreased in the presence of milk proteins and a binding ratio (%) was calculated based on this decrease. The effect of heat treatment on the flavonoid-protein binding was also examined. Green tea extract (GTE) was added into the milk protein system before and after heat treatment. Three different heat treatment norms were selected (80, 85, 90 o C x 10 min). Analyses were carried out in both sodium caseinate and skimmed milk samples to observe the possible effect of milk serum proteins on the interaction. The binding ratio between flavonoids and proteins was found to be higher in the samples where GTE was added before heat treatment than in the samples where GTE was added after heat treatment in both the skimmed milk and sodium caseinate systems. The results of the protein surface hydrophobicity (PSH) index and protein partition also demonstrated that heat treatment must be applied after the addition of GTE to improve the amount of GTE binding to milk proteins.
INTERACTION OF GREEN TEA FLAVANOIDS WITH
MILK PROTEINS AND THE EFFECT OF HEAT
TREATMENT
Ass. Prof. Zerrin Yuksel Onur1, Elif Avcı, Prof. Yasar Kemal Erdem2
1Canakkale Onsekiz Mart University, Turkey, Canakkale
2Hacettepe University, Turkey, Ankara
Main author email address: zyuksel@comu.edu.tr
In this study, the interaction of green tea flavanoids with milk proteins was studied. Reverse-phase high-
performance liquid chromatography (RP-HPLC) analysis revealed that the free flavonoids decreased in the
presence of milk proteins and a binding ratio (%) was calculated based on this decrease. The effect of heat
treatment on the flavonoid-protein binding was also examined. Green tea extract (GTE) was added into the milk
protein system before and after heat treatment. Three different heat treatment norms were selected (80, 85, 90oC
x 10 min). Analyses were carried out in both sodium caseinate and skimmed milk samples to observe the
possible effect of milk serum proteins on the interaction. The binding ratio between flavonoids and proteins was
found to be higher in the samples where GTE was added before heat treatment than in the samples where GTE
was added after heat treatment in both the skimmed milk and sodium caseinate systems. The results of the
protein surface hydrophobicity (PSH) index and protein partition also demonstrated that heat treatment must be
applied after the addition of GTE to improve the amount of GTE binding to milk proteins.
Keywords: Green tea flavanoids, Milk proteins, Interaction, Heat treatment, Hydrophobicity
... ANS À , as a hydrophobic fluorescence probe, could selectively bind to exposed hydrophobic protein regions and mirror the surface hydrophobicity and conformational change in proteins. Yuksel et al. (2015) reported that phenolics from tea interact with the hydrophobic regions of milk proteins and prevent the binding of ANS À to these regions, resulting in the decrease in FIA. Therefore, it could be speculated that as POH/WPH ratio increased from 1:600 to 1:120, POHs constantly occupied the exposed peptide hydrophobic sites that ANS À could bind to, so that FIA linearly decreased. ...
ResearchGate has not been able to resolve any references for this publication.