Brazilian researchers at the University of São Paulo (USP) have unlocked a groundbreaking application for an unexpected source: the leftover hop residue from beer production. This innovation transforms what was once industrial waste into a potent natural booster for sunscreens, enhancing their sun protection factor (SPF) while promoting sustainability in the cosmetics sector. Conducted at USP's Faculty of Pharmaceutical Sciences in Ribeirão Preto, the study demonstrates how repurposing hop waste—rich in antioxidants like polyphenols—could lead to more effective, eco-friendly photoprotectors.

The project's proof-of-concept reveals that extracts from used hops outperform even fresh hop material in bolstering UV defense. By incorporating these extracts into standard sunscreen formulations, the team achieved remarkable SPF elevations, all while addressing the environmental burden of beer manufacturing byproducts. This development not only highlights Brazil's prowess in pharmaceutical research but also aligns with global pushes for circular economy practices in higher education-driven innovation.

The Challenge of Beer Industry Waste in Brazil

Brazil stands as one of the world's top beer producers, churning out around 15 to 16 billion liters annually. This booming industry, dominated by giants like Ambev, generates substantial organic waste, primarily spent grain (bagaço de malte) estimated at up to 3 million tons per year, with hop residues adding to the tally especially from modern techniques like dry-hopping in craft beers. Hops (Humulus lupulus L.), added during boiling or maturation for bitterness, aroma, and stability, leave behind pellets processed into nutrient-dense biomass typically discarded or used minimally for animal feed or biogas.

At USP, scientists saw untapped potential in this residue. Rather than letting it burden landfills or wastewater systems, they extracted bioactive compounds—polyphenols, α-acids, and prenylated flavonoids like xanthohumol-like structures—capable of combating oxidative stress from ultraviolet (UV) radiation. Xanthohumol, a key prenylated chalcone in hops, is renowned for its antioxidant prowess, neutralizing free radicals that damage skin cells and degrade chemical UV filters in sunscreens.

Meet the USP Research Team Pioneering This Innovation

Led by Associate Professor André Rolim Baby from the Department of Pharmacy at FCF-USP Ribeirão Preto, the multidisciplinary effort involved master's student Ana Gabriela Urbanin Batista de Lima, Daniel Pecoraro Demarque, and collaborators Claudinéia Aparecida Sales de Oliveira Pinto, Thalita Marcílio Cândido, Fabiana Vieira Lima Solino Pessoa, and Maria Valéria Robles Velasco. Supported by FAPESP grants (projects 24/01920-0 and 22/08191-9), their work exemplifies how Brazilian public universities drive applied research addressing real-world industrial challenges.

"When comparing residue hop and unprocessed hop, the reused substance proved more active, likely due to the removal of volatile compounds during brewing," notes Demarque. Baby emphasizes the synergy: "We tested various cosmetic ingredients like purified water and emollients to optimize performance." This team effort underscores USP's role in fostering sustainable solutions through rigorous, lab-based experimentation.

Step-by-Step: How the Researchers Developed the Sunscreen Booster

The process began with sourcing hop samples: pure T90 pellets and brewing residue post-dry-hopping. Extraction used ethanol maceration (18 hours) followed by percolation until exhaustion, with pure extract rotary-evaporated and residue lyophilized.

• Phytochemical Profiling: High-performance liquid chromatography-mass spectrometry (HPLC-MS/MS) on C18 column identified α-acids (humulone m/z 385.1974, cohumulone 371.1821) in both, plus xanthohumol-like (393.1300) and humulinones (401.1925) uniquely in residue.
• Antioxidant Assay: DPPH radical scavenging showed pure extract at 36.4% inhibition (quercetin control 83.7%), residue lower at 0%, indicating different mechanisms for photoprotection.
• Formulation: Oil-in-water emulsions with ethylhexyl methoxycinnamate (UVB filter) and avobenzone (UVA), plus 10% hop extracts in solvents like water or isopropyl myristate.
• In Vitro Testing: Diffuse reflectance spectrophotometry (Labsphere UV-2000S, 290-400 nm) calculated SPF via Mansur equation; critical wavelength for broad-spectrum; UVAPF via persistent pigment darkening.

Statistical validation (ANOVA, Tukey p≤0.05) confirmed formulation stability and uniformity.

Impressive Results: Dramatic SPF Boost from Hop Residue

The standout finding: sunscreens with 10% reused hop extract in water skyrocketed SPF to 178 ± 21.5, tripling the control's 53.68 ± 9.63. Pure hop water reached 117.48 ± 13.28, while emollient-based versions ranged 40-78. Critical wavelengths held at 380-382 nm, ensuring UVA/UVB balance, though UVAPF didn't exceed control.

This superior performance stems from concentrated polyphenols in residue, post-volatile loss, synergizing with chemical filters against photodegradation. As Baby explains, "Water as solvent yielded optimal results, proving simple formulations suffice for enhanced efficacy." These metrics position the adjuvant as viable for commercial sunscreens.

Photo by Leo on Unsplash

The Science: Why Hop Waste Excels as a UV Protector

Hops' magic lies in secondary metabolites. Polyphenols scavenge reactive oxygen species (ROS) from UV exposure, preventing DNA damage, inflammation, and filter breakdown. Xanthohumol, absent in pure extracts here but structurally similar detected, inhibits UV-induced enzymes like matrix metalloproteinases.

Brewing concentrates these via hydrolysis and isomerization, enhancing bioavailability. Unlike synthetic antioxidants (e.g., BHT), natural ones like these reduce irritation risks, appealing for sensitive skin. Global studies affirm xanthohumol's photoprotective role, but USP's residue focus innovates by valorizing waste.

Sustainability Wins: Cutting Waste in Brazil's Booming Beer Sector

Brazil's craft beer surge amplifies hop use, with dry-hopping yielding residue pellets laden with valuables. Repurposing diverts organics from landfills, curbing methane emissions—spent grain alone ~1-3M tons/year. Economically, lower raw material costs could democratize high-SPF sunscreens, vital in sunny Brazil where skin cancer rates climb (INCA estimates 30k melanoma cases/year).

This aligns with UN Sustainable Development Goals, showcasing higher ed's role in circular bioeconomy. Partnerships with breweries could scale extraction, creating jobs in green chemistry.

Beyond Sunscreen: Broader Cosmetic and Industrial Applications

Hop residue's antioxidants suit anti-aging creams, serums, and hair protectors. Similar repurposing: spent grain in protein bars, biogas. In Brazil, Unicamp explores malt bagasse nutrition; global firms like ReGrained turn it into foods.

USP's adjuvant could hybridize natural-chemical filters, reducing synthetics' environmental footprint (e.g., oxybenzone ocean harm). Scalability hinges on standardization, but proof-of-concept paves commercialization.

Challenges Ahead and Next Steps for USP Team

In vitro success demands in vivo trials for skin penetration, irritation (OECD guidelines), long-term stability, and regulatory nods (ANVISA). Variability in hop strains/processing needs addressing. Baby notes: "Clinical safety/efficacy evaluations are essential." FAPESP funding eyes prototypes; industry collaborations loom.

Brazil's research ecosystem—bolstered by CNPq/CAPES—must tackle funding gaps for translation.

USP's Legacy in Pharmaceutical Innovation

FCF-USP Ribeirão Preto excels in cosmeceuticals, with Baby's lab pioneering natural adjuvants. This fits Brazil's pharma R&D surge, USP ranking top Latin America (QS 2026). It inspires students, fostering biotech talent amid 1.2M higher ed enrollments.

Explore research positions advancing such breakthroughs.

Photo by Ian Talmacs on Unsplash

Global Context and Future Outlook

Similar innovations: coffee waste antioxidants, algae UV filters. Hop xanthohumol patents grow (anti-cancer, metabolic). By 2030, sustainable cosmetics market hits $22B; Brazil, with 200+ universities, leads via public-private ties.

USP's work signals higher ed's pivot to waste-to-wealth, promising greener sunscreens protecting Brazil's 215M against UV menace. Ongoing trials could commercialize by 2028, revolutionizing industry.