1. Coffee waste is an unconventional feedstock. What specific properties make it suitable for conversion into bio-based plastics and active skincare ingredients?
Despite being discarded daily, spent coffee grounds are nutrient-dense—packed with lipids, polysaccharides, proteins, polyphenols, and minerals. In bio-based plastics, their lignocellulosic content acts as a structural backbone, enhancing the strength of the final material. Meanwhile, in skincare, naturally occurring antioxidants like chlorogenic acids and tocopherols, alongside caffeine, deliver benefits from anti-inflammatory action to sebum regulation and skin protection. Their fine particle size and oil-binding properties make them a natural fit for refining both emulsion textures and exfoliant formulations.
2. You’ve integrated up to 15% coffee-derived organic fibre into plastic compounds. Could you elaborate on the mechanical or structural role this fibre plays within the polymer matrix?
When blended into polymers like PP or PE, coffee fibre works as a natural reinforcement, enhancing rigidity and dimensional stability. Its impact is particularly strong when surface-treated, which allows better bonding with the polymer matrix and leads to noticeable gains in Young’s modulus and tensile strength. At the same time, it helps reduce shrinkage and improves printability, making it a well-rounded additive. However, going beyond 15% fibre content tends to cause embrittlement, so this threshold ensures optimal performance without compromising processability.
3. What were the key technical hurdles in stabilising coffee waste for use in skincare formulations, particularly with regard to microbiome compatibility?
Turning coffee waste into a cosmetic-grade ingredient meant overcoming several hurdles. Its high organic content made it prone to microbial growth, which we controlled through careful dehydration, ethanol pre-treatment, and vacuum storage. To ensure microbiome compatibility, we avoided aggressive preservatives and instead relied on a fermentation-inspired approach, using natural agents like potassium sorbate and glyceryl caprylate. Another challenge was standardising levels of caffeine and acids to prevent skin irritation. With coffee's composition varying widely by origin, we implemented compositional fingerprinting, including polyphenol profiling, to ensure consistent quality from batch to batch.
4. How does your upcycling process differ when producing exfoliants versus active ingredients or plastic fillers, in terms of extraction and refinement?
Each product category requires a distinct treatment. For exfoliants, the approach is intentionally minimal—sieving, drying, and particle size control are enough to create a safe and effective abrasive. Active skincare ingredients, on the other hand, demand a more refined method: we use solvent-assisted extraction (with ethanol, glycerol, or CO₂ subcritical) followed by filtration, deodorisation, and microbial stabilisation to preserve the efficacy of bioactive compounds. For plastic fillers, we avoid solvents altogether. Instead, we rely on thermal drying, milling, and alkali treatment to enhance adhesion to polymer matrices, since any residual oils could disrupt plastic processing.
5. Given that espresso-extracted grounds retain 98% of their nutrients, what methods do you use to preserve and activate these compounds during processing?
Even after espresso extraction, coffee grounds are nutrient-rich—retaining most of their valuable compounds. To keep these actives intact, we apply low-temperature dehydration (below 45°C), which prevents thermal degradation, and use solvent extraction under reduced pressure to guard against oxidation. In skincare, we often go a step further with microencapsulation, stabilising delicate components like polyphenols for longer shelf life. A combination of gentle maceration and precise filtration also helps isolate lipids, acids, and antioxidants, which we then channel into high-performance serums and emulsions.
6. Biobased plastics often face trade-offs in durability and thermal performance. How does the inclusion of coffee fibre affect these parameters in your materials?
Adding coffee fibre to bio-based plastics enhances rigidity, but comes with a slight drop in impact resistance. The key to improving thermal performance lies in the treatment of the fibre itself: untreated, it degrades at 200°C; treated with alkali or silane coupling agents, it can withstand extrusion temperatures. Parameters like HDT and Vicat softening point remain suitable for non-load-bearing and packaging applications. Ultimately, performance depends on fibre dispersion and coupling, both of which are optimised to maintain durability, processability, and biodegradability.
7. In terms of end-of-life, how do your bio-based plastics perform? Are they biodegradable, recyclable, or designed for circular re-entry?
We offer two types of materials, tailored to different end-of-life scenarios. Our recyclable bio-composites are engineered to integrate into existing mechanical recycling systems, making them ideal for industrial applications like packaging. On the other hand, our biodegradable blends—particularly those made with PLA or PHA—are suited for compostable or soil-degradable environments. To close the loop, we're also piloting a closed-loop recovery system, allowing us to reprocess scrap and post-consumer items into new, filler-rich regranulates.
8. Your collaboration with Plastika Kritis and Papoutsanis indicates industrial scalability. What adaptations were needed to move from lab-scale to mass production?
Scaling up meant solving for consistency and compliance. We first had to fine-tune particle size and drying processes to match industrial compounding needs. For plastic production, we modified screw designs and compounding parameters—from torque to L/D ratios—to accommodate fibre-filled formulations. In cosmetics, we aligned with standards like ISO 16128 and ISO 22716 to ensure safe and compliant ingredient production. We also secured high-volume feedstock partnerships with chain cafés and office spaces, building a reliable supply chain to support large-scale manufacturing.
9. Has your experience with cosmetic-grade extraction informed the development of your bioplastics—perhaps in terms of filtration, purification, or residual value?
Absolutely—the crossover between cosmetics and materials has been invaluable. Our multi-stage filtration and solvent residue recovery protocols, originally developed for skincare, now ensure our plastic fillers are clean, dry, and free of residual oils. We also repurpose extract residues—known internally as “cake”—into valuable fibre fillers. Cosmetic analytical tools like GC-MS and UV-Vis polyphenol quantification further allow us to grade batches precisely, deciding whether they’re suited for cosmetic or material-grade applications.
10. What other agro-industrial residues do you see potential in, and how might your process be adapted to accommodate them?
Our roadmap includes a diverse range of residues. Brewer’s spent grain (BSG), for example, is high in lignocellulose and protein, making it ideal for bioplastics or even nutraceuticals. Wine pomace, rich in polyphenols, can be transformed into antioxidant extracts or compostable packaging. Meanwhile, citrus peel waste, brimming with terpenes and essential oils, holds promise for skincare and fragrance applications. Each feedstock comes with its quirks, so we adapt by tweaking solvent polarity, pH, and drying protocols to suit their unique chemical profiles.
