Miguel García / 9 February 2026

Plant by-products with the highest potential for developing functional ingredients

Sustainable production models are increasingly spotlighting an undervalued resource: plant-based by-products.

Fruit peels, seeds, leaves, stems and oilseed press cakes generated during juicing, pressing or sorting still retain a significant fraction of bioactive compounds, natural pigments, residual aromas and high-value lipids. Far from being waste, these by-products are a strategic feedstock for developing functional ingredients.

Examples of high-impact sensory and functional by-products

Several agri-food by-products offer strong valorisation potential:

Citrus peels

Rich in essential oils, flavonoids and carotenoids, citrus peel by-products can be used to obtain aromatic extracts or antioxidant fractions.

Almond, walnut or hazelnut press cakes

These by-products contain valuable lipid and phenolic fractions, making them an excellent base for developing protein ingredients, functional oils or natural antioxidants.

Rosemary, thyme or sage residues

These aromatic plant by-products are used to obtain antioxidant and antimicrobial extracts of interest for natural preservation or cleaner formulation strategies.

Which valuable compounds are concentrated in plant by-products?

Compound Where it is concentrated Functional value
Polyphenols Fruit peels, seeds and oilseed press cakes High antioxidant potential
Carotenoids Outer layers of fruits and vegetables (carrot, citrus, pumpkin) Intense, stable colours
Essential oils Citrus peels and aromatic plant residues Rich in limonene, linalool or thymol
Phenolic compounds Fruit peels, winery residues, olive sector residues, nut press cakes… Bioactive fraction with industrial interest
Natural pigments Peels, leaves and stems Anthocyanins or chlorophylls
Aromatic and volatile fractions Leaves and stems of rosemary, thyme, sage and other aromatic species Antioxidant and antimicrobial activity

Benefits of valorising plant by-products

Valorising plant by-products delivers benefits on three levels:
  • Waste reduction, lowering environmental impact and the costs associated with by-product management.
  • Raw material savings, by using resources already present within the processing plant.
  • New revenue streams, turning low-value side streams into ingredients with rising demand in areas such as healthy foods, beverages, plant-based, nutraceuticals or spices.

How to replace solvents when obtaining bioactive and aromatic fractions

Many conventional processes rely on organic solvents to recover aromatic or bioactive fractions. While effective, they generate residues, require removal steps and may affect sensitive compounds. Moving towards cleaner processes means prioritising technologies based on natural fluids, such as supercritical CO₂. Because it operates without solvents, helps preserve volatile compounds and delivers purer fractions, supercritical CO₂ is a key tool for developing more sustainable, stable and technically consistent ingredients from plant by-products. The result is a cleaner, more stable extract aligned with market expectations for naturalness.

What is supercritical CO₂ used for in the valorisation of plant by-products?

Supercritical CO₂ supports a wide range of technical applications:
  • Obtaining essential oils and aromatic extracts from citrus peels, aromatic herbs, spices or nuts.
  • Producing antioxidant extracts and natural pigments with high sensory stability.
  • Defatting protein-rich ingredients, reducing lipid content in products such as cocoa, seeds or cereals.
  • Removing unwanted compounds such as caffeine in coffee and tea, residual odours, pesticide traces or oxidation products.
  • Reducing microbial load in heat-sensitive ingredients while preserving functional activity.
Avances biotecnológicos para transformar residuos vegetales en compuestos contra la inflamación colon
 

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