Application of Membrane Separation and Membrane Concentration Technology in Tibetan Tea Extracts

Tibetan tea, also known as Ya’an Tibetan dark tea from Sichuan, is a traditional post-fermented dark tea with a long history on the Ancient Tea Horse Road. Rich in theabrownins, tea polysaccharides, polyphenols and flavonoids, its extracts are widely developed for instant tea, functional food and beverage raw materials. Traditional thermal concentration and alcohol precipitation processes easily damage heat-sensitive active substances, degrade flavour and introduce solvent residues. Membrane separation and membrane concentration have become a preferred green industrial solution for Tibetan tea extract processing.

A typical multi-stage membrane workflow combines microfiltration (MF), ultrafiltration (UF) and nanofiltration (NF). First, ceramic microfiltration removes suspended fibre residues, colloids and microorganisms from crude tea liquor to reduce turbidity and eliminate sediment during storage. Next, ultrafiltration with selected MWCO cut-offs fractionates macromolecular impurities and target active components. This step separates high-molecular-weight theabrownins and tea polysaccharides from small-molecule amino acids and caffeine, enabling graded purification of functional fractions. Nanofiltration then performs low-temperature membrane concentration to remove water while retaining most bioactive compounds. The whole process runs near ambient temperature without heating or chemical flocculants.

Compared with evaporation concentration, membrane concentration protects the natural aroma, colour and antioxidant activity of Tibetan tea extracts. The loss rate of theabrownins and tea polysaccharides drops significantly, and the final concentrated liquid features stable taste and high clarity. It also cuts energy consumption greatly and simplifies downstream spray-drying for instant tea powder production.

However, membrane fouling remains the main challenge. Tea colloids and polyphenol complexes tend to adsorb onto membrane surfaces, lowering flux. Regular CIP cleaning with acid and alkali can recover membrane performance and extend module service life. Proper selection of membrane material, cross-flow velocity and operating pressure is critical for stable long-run production.

With rising global demand for clean-label plant extracts, membrane technology unlocks higher commercial value for Tibetan tea. It supports standardized, scalable production and helps retain the unique functional characteristics of this historic dark tea, providing reliable technical support for its deep processing and export market development.