Comprehensive non-targeted chemical fingerprinting of coffee silverskin extracts with MRMS

Importance of topic

Coffee silverskin represents a largely unused residue from the global coffee roasting industry. Despite annual generation of over 200 000 tons it holds high levels of polyphenols lipids and other bioactives. Valorizing this by-product can reduce waste and support pharmaceutical cosmetic and food sectors.

Objectives and study overview

This work aimed to achieve non target chemical fingerprinting of coffee silverskin extracts. Ultrahigh resolution magnetic resonance mass spectrometry MRMS was applied to identify hundreds of compounds across polar and non polar solvent extracts. The study explored solvent influence on extract composition and potential bioactive reservoirs.

Methodology and instrumentation

• Sample preparation continuous soxhlet extraction with nine solvents from non polar hexane chloroform dichloromethane to polar acetone acetonitrile methanol ethanol water
• Extract dilution in methanol for negative ion electrospray ESI or methanol toluene mix for positive ion photoionization APPI
• MRMS analysis on Solarix 12T XR with ParaCell ICR cell dynamic harmonization direct infusion via Apollo II sources flow rates 2 to 6.7 microliter per minute
• Mass range m/z 92 to 2000 resolving power approx 530000 at m/z 300 200 scans co added magnitude mode external calibration with NaTFA clusters internal recalibration with custom list
• Data processing using DataAnalysis 5.0 and MetaboScape 5.0 with CompoundCrawler database for formula assignment and structural annotation

Main results and discussion

• ESI negative mode detected up to 4600 spectral features including organic acids chlorogenic acid derivatives carbohydrates fatty acids
• APPI positive mode yielded around 2200 features including nitrogen heterocycles alkaloids terpenoids sterols and phenolic acids
• Caffeine was the most abundant analyte across solvents with other alkaloids like trigonelline theophylline liberine 6 methoxyquinoline
• Diterpenoids such as cafestol kahweol and dehydro forms were observed confirming presence of pharmacologically relevant compounds
• PCA of ESI data separated polar and non polar extracts and highlighted water extract unique profile driven by nitrogen containing compounds

Benefits and practical applications

• Comprehensive non target MRMS profiling enables rapid access to complex mixtures reducing need for extensive fractionation
• Identification of high value bioactives supports valorization of coffee silverskin in nutraceutical cosmetic and agrochemical products
• Solvent selection guides targeted recovery of specific compound classes

Future trends and applications

• Integration of MRMS with cheminformatics and molecular networking for deeper annotation
• Scale up of extraction and purification workflows for industrial deployment
• Exploration of silverskin derived nanomaterials and bio composites
• Assessment of bioavailability and functional testing of isolated compounds

Conclusion

Ultrahigh resolution MRMS offers a rapid non target approach for detailed chemical fingerprinting of coffee silverskin extracts. The study demonstrated broad chemical diversity and solvent dependent profiles. Findings support valorization of this abundant by-product as a feedstock for high value compounds in multiple industries.

Reference

1. Grosso G Godos J Galvano F Giovannucci EL 2017 Coffee Caffeine and Health Outcomes An Umbrella Review Annu Rev Nutr 37 131–56
2. International Coffee Organization ico org
3. Narita Y Inouye K 2014 Degradation Kinetics of Chlorogenic Acid Food Res Int 61 16-22
4. Toschi TG Cardenia V Bogana G Mandrioli M Rodriguez-Estrada MT 2014 Coffee Silverskin Characterization Possible Uses and Safety Aspects J Agric Food Chem 62 10836−10844
5. Bessada SMF Alves RC Oliveira MBPP 2018 Coffee Silverskin A Review on Potential Cosmetic Applications Cosmetics 5 5
6. Tores de la Cruz S Iriondo-DeHond A Herrera T Lopez-Tofiño Y Galvez-Robleño C Prodanov M Valezquez-Escobar F Abalo R Dolores Del Castillo M 2019 Assessment of Bioactivity of Coffee Silverskin Melanoidins Foods 8 68
7. Barbero-López A Monzó-Beltrán J Virjamo V Akkanen J Haapala A 2020 Revalorization of Coffee Silverskin for Antifungal Chemicals in Wood Preservation Int Biodeterior Biodegradation in press