Optimum conditions for the water extraction of L‐theanine from green tea

Abstract

Theanine is a unique non-protein amino acid found in tea (Camellia sinensis). It contributes to the favourable umami taste of tea and is linked to various beneficial effects in humans. There is an increasing interest in theanine as an important component of tea, as an ingredient for novel functional foods and as a dietary supplement. Therefore, optimal conditions for extracting theanine from tea are required for the accurate quantification of theanine in tea and as an efficient first step for its purification. This study examined the effects of four different extraction conditions on the yield of theanine from green tea using water and applied response surface methodology to further optimise the extraction conditions. The results showed that temperature, extraction time, ratio of water-to-tea and tea particle sizes had significant impacts on the extraction yield of theanine. The optimal conditions for extracting theanine from green tea using water were found to be extraction at 80 °C for 30 min with a water-to-tea ratio of 20:1 mL/g and a tea particle size of 0.5-1 mm.

Optimum Conditions for Microwave Assisted Extraction for Recovery of Phenolic Compounds and Antioxidant Capacity from Macadamia (Macadamia tetraphylla) Skin Waste Using Water

“…The JMP software was also used to develop the model equation, to graph 3D plots and 2D contour plots of the responses, as well as predicting the optimum conditions of the independent variables. To express the amount of phenolic compounds and the level of antioxidant properties as a function of the independent variables, a second-order polynomial equation must be employed [17]:…”

“…Water was chosen as the extraction solvent as it is a safe and inexpensive solvent, and it is easily accessible when compared to other organic solvents [17]. The microwave extraction was conducted using a household microwave equipped with inverter technology (1200 W, Frequency 2450 MHz, Sharp Carousel, Abeno-ku, Osaka, Japan) at the pre-determined conditions that were designed by the Response Surface Methodology program for time (minutes), power (%, W), and sample-to-solvent ratio (g/100 mL).…”

Enzymatic Improvement in the Polyphenol Extractability and Antioxidant Activity of Green Tea Extracts

“…3) Green tea is a rich source of catechins, which account for up to 30% of leaf dry weight. 4) As catechins can donate hydrogens from the hydroxyl groups in their structure, they have excellent antioxidant activities, as evidenced by the fact that their free-radical scavenging ability is more powerful than that of vitamin C, vitamin E, or -carotene. 5) Catechins have been found to have antioxidant, antimutagenic, and anticarcinogenic properties, and they can also prevent cardiovascular disease.…”

Phenolic Compounds, Antioxidant and Anti-Cancer Properties of the Australian Maroon Bush Scaevola spinescens (Goodeniaceae)

“…To express the content of TPC as a function of the independent variables, the following second-order polynomial equation was used [6] (EQ1): …”