The Interaction of Protein and Polyphenol Species in Ready to Drink Black Tea Liquor Production

Abstract

Haze and tea cream generation is a serious problem in the production of ready‐to‐drink (RTD) black tea liquors. Such precipitates consist primarily of proteins and polyphenols. Tea protein and tea polyphenol have been separated successfully in this study. The interactions of (1) tea protein and mixed TF; and (2) tea protein and total tea polyphenol were studied by ITC. A series of techniques, including gel filtration chromatography, sodium dodecyl sulfate polyacrylamide gel electrophoresis, CBB assay and fourier transform infrared spectroscopy (FTIR), have been used to determine the quantity and properties of proteins isolated from black tea powder. The molecular mass of the tea protein was detected to be approximately 11 kD at pH 5.0. The purity of this protein isolate was 51.4 wt % and a possible β‐sheet secondary structure was indicated from FTIR spectra. The total phenols in the tea polyphenol sample separated by Zn 2+ precipitation under alkali conditions (pH 7.5) was increased to approximately 65 wt % of the sample tested. The binding mechanism of tea protein and TF was somewhat different from that of tea protein and total tea polyphenol, although both interactions were successfully fitted using a sequential sites binding model. PRACTICAL APPLICATIONS In black tea liquor production, polyphenols tend to interact with proteins, caffeine and metal cations to form colloidal suspensions of haze and “tea cream”, which are detrimental to product appearance and taste. This is a key concern in the production of ready‐to‐drink (RTD; iced tea) beverages, which are typically made from reconstituted spray dried tea powders and stored at low temperatures (potentially leading to precipitation). Tea cream and haze are traditionally removed by dissolution through pH adjustment. The size of haze and tea cream aggregates means that membrane technology can offer an alternative nonchemical separation option. To facilitate the removal of haze and tea cream in commercial RTD tea production, it is important to increase the level of understanding of polyphenol or tea protein interactions that occur in black tea liquor. Such interactions are the focus of this paper.

From Green Remediation to Polymer Hybrid Fabrication with Improved Optical Band Gaps

“…Thus, the IR spectrum indicates that the key functional groups in tea components arecarboxylic acid, polyphenols and amino acid. There is conclusive evidence that colloidal suspensions are the outcomes of the interaction of polyphenols with proteins, caffeine and metal cations [26]. Comparing Figure 1 and Figure 2, it is obvious that the peaks in the (1700−400) cm −1 region almost change in Figure 2.…”

Fabrication of Interconnected Plasmonic Spherical Silver Nanoparticles with Enhanced Localized Surface Plasmon Resonance (LSPR) Peaks Using Quince Leaf Extract Solution

“…Hence, it can be noted in the infrared spectra that the major functional groups in the quince leaf extract solution were carboxylic acid, polyphenols, and amino acid. It has been deduced that colloidal suspensions were a result of the interaction of polyphenols with the cations of silver metals [43]. Hence, the idea of the recent study was basically to exhibit that silver colloidal nanoparticles related to metallic silver particles can be productively identified from the FTIR analysis.…”

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“…Protein interactions with other proteins Protein interactions with small ligands (including co‐factors and drugs) Protein/peptide interactions with metals and ions …”