(401x) Integrated Membrane and Drying Techniques for the Recovery of Antioxidants from Lavender Spent Plant Material

The increasing industrial reliance on synthetic and semi-synthetic compounds in the food, cosmetic, and pharmaceutical sectors over recent decades has raised significant concerns regarding their potential adverse health and environmental effects. As a result, there has been a marked shift toward natural alternatives, including bio-based foods, packaging materials, and cosmetic formulations enriched with compounds of natural origin, particularly those exhibiting antioxidant properties. This transition underscores both the functional potential of plant-derived substances and the critical need for sustainable strategies for their extraction and utilization.

Bulgaria, as one of the world’s leading producers of essential oils, possesses well-established traditions in the cultivation and processing of aromatic and medicinal plants. However, the extraction of essential oils yields only a small portion of the total plant biomass, with the remaining residual material often discarded. The uncontrolled disposal of these fractions poses environmental risks such as soil and water contamination, while simultaneously resulting in the loss of valuable bioactive compounds.

Membrane technologies offer an effective alternative for processing these waste materials by enabling selective separation at the molecular level. Unlike conventional thermal separation methods (e.g., distillation and evaporation), membrane filtration operates at low temperatures, thereby preserving thermolabile substances and reducing energy consumption. Their integration into circular economy models—such as through the reuse of permeate as an extraction solvent—adds an additional layer of sustainability to membrane-based processes.

Although the valorization of agro-industrial residues has attracted considerable attention, systematic investigations into membrane-based processing of extracts derived from essential oil-bearing plants are still relatively scarce.

The current study focuses on lavender (Lavandula angustifolia), evaluating the effectiveness of membrane filtration for the recovery of key antioxidant constituents from spent plant material. The investigation includes the assessment of membrane selectivity toward rosmarinic acid, caffeic acid, and luteolin; determination of antioxidant activity; measurement of permeate flux; and analysis of factors influencing filtration resistance, such as osmotic pressure and concentration polarization.

A secondary objective is to evaluate the performance of spray drying applied to an extract derived from lavender spent plant material and its corresponding membrane-concentrated fraction with respect to their antioxidant activity. Spray drying was initially applied to the crude extract at elevated temperature, resulting in a noticeable decline in antioxidant activity—highlighting the thermal sensitivity of the bioactive compounds. Subsequent drying of the membrane-concentrated fraction under optimized, milder conditions led to markedly better preservation of antioxidant properties.

The combination of membrane filtration and spray drying provides an effective method for processing lavender by-products while preserving the antioxidant properties of the extracted compounds.

Acknowledgments: The study was conducted as part of the project BG-RRP-2.004-0002 BiOrgaMCT funded by the National Recovery and Resilience Plan.