Nanofiltration Membrane Technology for Desalination, Decolorization and Concentration of Plant Extracts

In industrial production of botanical functional ingredients, raw plant materials are processed through crushing, multi-stage leaching and coarse filtration to obtain crude extracting solution. In addition to high-value active components including saponins, flavonoids, polyphenols and glycosides, the crude extract contains a large amount of interfering substances introduced during extraction and raw material growth. Long-term accumulation of inorganic salts, soluble pigments, small-molecule organic acids and miscellaneous sugars will cause the finished plant extracts to have dark luster, high ash content, impure taste and easy moisture absorption. These quality defects seriously reduce the added value of plant products and limit their application in high-end cosmetics, health food and pharmaceutical fields.

Traditional plant extract purification and concentration processes have prominent technical bottlenecks. Resin adsorption can partially remove pigments and impurities, but it has limited desalination capacity, requires frequent regeneration, produces a large amount of waste liquid, and increases enterprise operating costs. Conventional vacuum thermal concentration relies on high-temperature evaporation to remove water, which easily causes oxidation and degradation of heat-sensitive plant active ingredients, resulting in reduced activity and darkened color of finished products. In addition, traditional processes require multiple independent procedures for impurity removal, decolorization and concentration, with cumbersome steps, long production cycles and low material utilization rates, failing to meet the requirements of modern large-scale and standardized production.

Nanofiltration membrane separation technology makes up for all the deficiencies of traditional plant refining processes. As a precision separation technology between ultrafiltration and reverse osmosis, nanofiltration has unique graded interception characteristics. It can stably retain medium and macromolecular plant active ingredients, while freely penetrating and removing small-molecule inorganic salts, pigment molecules and heterologous impurities. Different from ultrafiltration which only removes macromolecular colloids, nanofiltration realizes deep desalination and fine decolorization, fundamentally solving the problem of high ash content and dark color of plant extracts.

The entire refining and concentration process is carried out at room temperature and low pressure without high-temperature heating, organic solvent addition and chemical treatment. The mild physical separation environment completely protects the structural stability and biological activity of natural plant active substances, avoiding ingredient loss and efficacy attenuation caused by traditional processes. Adopting advanced cross-flow circulating operation mode, the material liquid continuously scours the membrane surface during operation, effectively inhibiting the adhesion and deposition of plant colloids and pigments, slowing down membrane fouling and ensuring long-term stable filtration flux and continuous production capacity.

In formal plant deep-processing production lines, nanofiltration equipment is matched with ultrafiltration clarification process to form a complete refining system. After ultrafiltration removes macromolecular impurities such as pectin and protein, the clear plant extract enters the nanofiltration system for deep desalination, decolorization and low-temperature concentration. This two-stage membrane combination process realizes graded purification step by step, greatly improving the comprehensive quality of extracts. The concentrated material liquid significantly reduces the water content, lowers the load of subsequent spray drying and crystallization processes, and saves a lot of energy consumption for enterprises.

The fully automatic PLC intelligent control system can flexibly adjust operating pressure, circulation flow and concentration multiple according to different plant raw material characteristics and product quality standards, realizing customized precise processing. Equipped with professional food-grade CIP online cleaning system, the membrane equipment can quickly remove adsorbed organic dirt after production, restore membrane flux, and ensure consistent and stable refining effect of each batch of products. The permeate water produced during the process can be recycled for raw material leaching and workshop cleaning, realizing resource recycling and green low-carbon production.

After nanofiltration refining, the plant extract features light color, high transparency, low salt content, stable properties and high active ingredient purity. It effectively solves common industry problems such as product precipitation, color reversion and unstable efficacy during storage. Modular skid-mounted nanofiltration equipment covers a small area, is easy to install and transform, and can be perfectly integrated into new or existing production lines. With outstanding advantages of high efficiency, energy saving and environmental protection, nanofiltration membrane technology has become the core upgrading solution for modern botanical extract processing enterprises, helping enterprises produce high-purity and high-stability natural plant active ingredients.