Extraction of Green Tea Phenolics Using Water Bubbled with Gases

Abstract

Water was bubbled with gases including nitrogen (N2), oxygen (O2), hydrogen (H2), carbon dioxide (CO2), and air for 10 min and phenolics from green tea leaves were extracted using the prepared gas‐bubbled water. To retain the gases in water, the extraction conditions were maintained in an air‐tight container at room temperature under magnetic stirring. Radical scavenging ability, total phenolic content, and phenolic profiles of the extracts were analyzed, and gas‐bubbled water was examined to explain the differences in phenolic contents. Overall, green tea infusion prepared from H2‐bubbled water contained significantly high levels of total phenolic compounds and antioxidant activity compared to other gas‐bubbled waters including N2, O2, CO2, and air (P < 0.05).Control samples and those bubbled with CO2 showed the lowest antioxidant activities in green tea infusion. However, green tea extracts with O2 bubbling showed the lowest catechin content. Green tea leaves treated with hydrogen gas‐bubbled water had much greater damage to their surface morphological properties compared to the other groups, which may explain the higher yield of phenolic compounds. Overall, hydrogen gas‐bubbled water showed better extraction yield of phenolics from green tea leaves than other gas‐bubbled water. Practical Application Green tea or green tea infusion has diverse health beneficial functionality due to the presence of phenolic compounds. In this study, different gases including nitrogen, oxygen, hydrogen, and carbon dioxide were treated in water and these gas‐bubbled water were used to extract phenolics from green tea leaves. Among them, hydrogen‐bubbled water extracted the highest phenolic contents from tea leaves and showed the highest in vitro antioxidant ability in green tea infusion compared to other gas‐bubbled water. This new knowledge could help to produce green teas with higher antioxidant activity in beverage industry.

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 ].…”

Online Scavenging of Trace Analytes in Complex Matrices for Fast Analysis by Carbon Dioxide Bubbling Extraction Coupled with Gas Chromatography–Mass Spectrometry

“…Inspired by the naturally occurring selective enrichment of organic matter in bursting greenhouse gas microbubbles, numerous bubbling extraction systems have been developed to remove organic pollutants and natural products by using oxygen, hydrogen, ambient air, nitrogen, and other gases bubbling through liquid samples. − Fizzy extraction was recently developed to monitor the released medium-polarity volatile and semivolatile compounds dissolved in liquid matrices with CO 2 carrier gas. − An effervescent tablet-induced extraction can facilitate the extraction of volatiles dissolved in liquid matrices . Preconcentration of organic solutes in urine was achieved based on the collection of induced bursting bubble aerosols .…”

Phenolic Compounds in Tea: Phytochemical, Biological, and Therapeutic Applications

“…Green tea health benefits are linked to polyphenolic compounds, which have piqued the interest of the food industry and researchers [31]. Green tea can be used in the formulation of some products to boost antioxidant activity for nutritional or technological purposes.…”

“…The distinct fragmentation pattern of each phenolic compound enables identification in mass analyzers or provisional identification for compounds lacking a standard, even for complex and high molecular weight compounds (Figures 1, 3 and 4 depicts the phenolic structures present in different teas) [31,44]. Given the aforementioned characteristics, liquid chromatography separation followed by spectrophotometry and/or mass spectrometry analysis can provide valuable information for the investigation of the phenolic profile in tea extracts.…”