Citric acid‐enhanced dissolution of polyphenols during soaking of different teas

Abstract

This study examined the dissolution kinetics and antioxidant activity of tea polyphenols during the soaking of white, yellow, green, oolong, black, and dark teas. All these teas were, respectively, soaked with either freshly boiled distilled water (DW) or 10 mmol/L citric acid–water solution. The residue obtained from one extraction was used for the next extraction and this process was performed consecutively 10 times, soaking for 30 s each time. UHPLC‐QqQ‐MS measurement identified epigallocatechin gallate as the major polyphenol in white, yellow, green, oolong, and black tea infusions. As soaking times increased, the polyphenol concentrations rose initially and then dropped. Antioxidant activity was noted to decrease as soaking times increased in all tea infusions except for the DW‐soaked oolong and dark teas. These findings suggested that citric acid could increase the polyphenol content in tea infusions. Specifically, the cumulative contents of epigallocatechin gallate was noted to increase 2.1–5.1 times. Practical applications After water, tea is one of the most consumed beverages in the world. Drinking tea has been linked to the reduced risk of various diseases, including cancer, cardiovascular system disease, obesity, and neurodegenerative diseases, largely due to its rich polyphenol content. Moreover, the addition of citrus to a tea infusion provides an interesting and feasible method for increasing the dissolution of tea polyphenols, a finding that offers extensive potential for applications in the development of compound tea drinks.

The GC-TOF/MS-based Metabolomic analysis reveals altered metabolic profiles in nitrogen-deficient leaves and roots of tea plants (Camellia sinensis)

“…Likely, the oxidation of N-ethylglycine generated the glyoxylate, ethylamine and hydrogen peroxide. The production of hydrogen peroxide strengthens the reactive oxygen species scavenging in plants [ 59 ].…”

Exogenous citric acid enhances drought tolerance in tobacco (Nicotiana tabacum)

“…2017; Li et al . 2019). Under salt stress, a foliar spray with citric acid resulted in higher proline content and total phenolic compounds (TPC) in G. barbadense (El‐Beltagi et al .…”

“…Upon drought stress, plants accumulate osmolytes and secondary metabolites in leaves in order to alleviate cell damage. Previous studies revealed that exogenous citric acid pretreatment promotes the synthesis of proline and other metabolites, including phenolic compounds, flavonoids and soluble sugars, in response to environmental stress (Kaur et al 2017;Li et al 2019). Under salt stress, a foliar spray with citric acid resulted in higher proline content and total phenolic compounds (TPC) in G. barbadense (El-Beltagi et al 2017), and also increased non-enzymatic antioxidants (TPC and proline accumulation) in H. sabdariffa and Melissa officinalis to maintain redox balance (Ahmed et al 2017;Abdellatif & Ibrahim, 2018).…”

The effect of storage time on tea Polyphenols, catechin compounds, total flavones and the biological activity of Ya’an Tibetan tea ( Camellia sinensis )

“…PCA analysis is an unsupervised statistical model that performs data reconstruction and dimensional reduction methods by means of principal components (PCs; Li et al, 2019). To investigate the difference in the profiles of catechins in Ya'an Tibetan tea, PCA was adopted to analyze the catechin contents of each tea extract.…”