The influence of different water types and brewing durations on the colloidal properties of green tea infusion

Abstract

Summary Green tea infusions were prepared with three different water types: distilled water, commercial mineral water and CaCl2 added distilled water (at 20 mg L−1). The impact of different water type on the colloidal particle parameters, namely size, polydispersity index (PDI) and zeta potential, was examined within 24 h. Our results indicate that distilled water green tea infusion (DWT) brewed at 80 °C for 5 min contained the smallest particles (242.17 ± 11.78 nm) as examined by dynamic light scattering (DLS). Moreover, DWT showed smaller size increase during the 24 h storage than that of mineral water tea and CaCl2 added water tea infusion. The morphology characteristics of green tea infusion particles were visualised by transmission electron microscope (TEM) which revealed that green tea infusion particles had heteromorphic shapes. Our results suggest that mineral composition of water impacts the colloidal size and stability of green tea infusion. Additionally, DLS and TEM could be useful tools to provide colloidal information which is important to understand quality characteristics of green tea infusion during processing and storage.

Quality characteristics of green Tea's infusion as influenced by brands and types of brewing water

“…Among all the samples, T-MIN showed the lowest a∗ values (−7.50), indicating that it had the darkest shade of green colour. This could be due to higher concentration of chlorophyll extracted in the sample [ 27 – 29 ].…”

Synergistic Mechanisms of Constituents in Herbal Extracts during Intestinal Absorption: Focus on Natural Occurring Nanoparticles

“…Ktze.] infusion [103]. The average size of nanoparticles formed in a water extract of P. thomsonii Benth (Fenge) [104] or Rabdosia rubescens (Hemsl.)…”

Spontaneously Assembled Nano-aggregates in Clear Green Tea Infusions from Camellia ptilophylla and Camellia sinensis

“…34 On the other hand, Ca 2+ could compensate negative charges of tea nano-aggregates, resulting in the decrease of the electrostatic repulsion among colloidal particles and the flocculation of nano-aggregates. 35,36 Additionally, Ca 2+ would precipitate with oxalic acid, quinic acid, and tartaric acid in green tea infusions. 37 Thus, we proposed that the formation of tea cream particles involved the sedimentation of nano-aggregates resulting from the adsorption of methylxanthines from the supernatants onto the nano-aggregates via their associations with catechins as well as the flocculation among nano-aggregates due to the decrease of electrostatic repulsions induced by Ca 2+ .…”

“…On the one hand, carbohydrates would increase the solubility of polyphenol–protein complexes, and pectin molecules would compete with proteins to bind with polyphenols, resulting in inhibition on the precipitation of polyphenol–protein complexes. , Hayashi et al confirmed that pectin would associate with various catechin monomers, whereas gallate-type was a preferable structure for pectin . On the other hand, Ca 2+ could compensate negative charges of tea nano-aggregates, resulting in the decrease of the electrostatic repulsion among colloidal particles and the flocculation of nano-aggregates. , Additionally, Ca 2+ would precipitate with oxalic acid, quinic acid, and tartaric acid in green tea infusions . Thus, we proposed that the formation of tea cream particles involved the sedimentation of nano-aggregates resulting from the adsorption of methylxanthines from the supernatants onto the nano-aggregates via their associations with catechins as well as the flocculation among nano-aggregates due to the decrease of electrostatic repulsions induced by Ca 2+ .…”