Processing Technologies for the Extraction of Value-Added Bioactive Compounds from Tea

Abstract

Tea ( Camellia sinensis) is the most widely consumed beverage in the world, with an excellent source of bioactive compounds such as catechins, caffeine, and epigallocatechin. There is an increasing trend to extract these bioactive compounds to deliver them as value-added products. Generally, the extraction of polyphenols and other functional compounds from different parts of tea is carried out using different solvents (e.g., water, water–ethanol, ethanol, methanol, acetone, ethyl acetate, and acetonitrile). The extraction efficiency of functional compounds from tea depends on the type and polarity of the solvent as well as the applied process. Several conventional techniques, such as boiling, heating, Soxhlet, and cold extraction, are used to extract bioactive ingredients. However, these procedures are unsuitable for achieving high yields and biological activities due to the long extraction times of cold brewing and the high temperatures in other heating methods. Many efforts have been carried out in food and pharmaceutical industries to replace conventional extraction techniques with innovative technologies (e.g., microwave (MAE), ultrasonic (UAE), pressurized liquid (PLE), pulsed electric field (PEF), and supercritical fluid (SFE)), which are fast, safe, energy-saving, and can present eco-friendly characteristics. These innovative extraction techniques have proven to improve the recovery rate of phenolic-based antioxidant compounds from tea and increase their extraction efficiency. In this review, the application of novel processing technologies for the extraction of value-added compounds from tea leaves is reviewed. The advantages and drawbacks of using these technologies are also highlighted.

Characterization of Bioactive Metabolites and Antioxidant Activities in Solid and Liquid Fractions of Fresh Duckweed (Wolffia globosa) Subjected to Different Cell Wall Rupture Methods

“…The inactivation of oxidative enzymes by thermal pretreatment might lower the degradation of TPC in BWR samples. A reduced percentage of bioactive compounds was recorded by Raghunath et al during boiling. While in wolffia filtrate samples, the BWF had the significantly higher ( p < 0.05) TPC of 773.29 ± 4.72 mg GAE g –1 , followed by 395.83 ± 4.58 and 312.54 ± 2.59 mg GAE g –1 in the TWF and CWF samples, respectively.…”

Advances in the novel and green-assisted techniques for extraction of bioactive compounds from millets: A comprehensive review

“…Various solvents like methanol, water, toluene, dichloromethane, ethyl acetate, and acetonitrile can be used in ASE for food. The selection of the extraction solvent should consider properties such as boiling point, polarity, specific density, and toxicity [ 186 ]. The process of extracting analytes from solid samples involves three key steps: desorption of analytes from solid particles, diffusion of analytes through the solvent within the particle pores, and transfer of analytes to the flowing fluid ( Fig.…”

“… -MAE at 50 °C, 1200 W, and 20 min extracted 3485 μg/g of anthocyanins. [ 135 ] ASE Rice Pressure: 100–200 atm Temperature: 100–200 °C Static time: 5–10 min Flushing: 50–100 % Purge time: 60–120 s Sample: 2.5–5.0 g Solvent: 80–100 % ethyl acetate in methanol -All the phenolics were extracted for 10 min with 2.5 g samples in 60 % ethyl acetate in methanol at 190 °C, 200 atm, and 100 % flush volume [ 186 ] ASE, UAE, and CSE Rice berry bran (RBB) ASE: Pressure: 100–200 atm Temperature: 60–80 °C Static time: 10–15 min Sample: diatomaceous earth in a 1:1 ratio UAE and CSE: Temperature: 60–80 °C Sample to ethanol: 1:20 w/v Time: 15–45 min -ASE offered TPC and TAC of 19.70 GAE/g and 885.4 μg/g, respectively. -ASE reduced solvent requirement by 90 %, extraction time by 3 times, and increased extraction of TPC by 3 times and TAC by 4 times compared to UAE and CSE.…”

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“…Ultrasonic Assisted Extraction showed better efficiency in the extraction of tea polyphenols, amino acids and caffeine as compared to conventional extraction strategies. UAE effectively increased the extraction efficiency of catechin and decreased the extraction time and solvent consumption 24 .…”