Low-grade green coffee with Bacillus amyloliquefaciens NY124 protease: extraction, purification, and functional synergy of chlorogenic acid and trigonelline

What if the coffee beans you discard could become a treasure trove of health-boosting compounds? A new study turns low-grade green coffee into potent antioxidants and anti-obesity agents.

Defective coffee beans—often tossed aside—hide valuable bioactive compounds like chlorogenic acid (CGA) and trigonelline. But their high caffeine content has limited their use. Now, scientists have found a cost-effective way to extract and purify these ingredients using a bacterial enzyme and simple column chromatography.

Steam pretreatment boosted CGA levels to 35 g per kilogram of dry weight. Among six bacterial strains, Bacillus amyloliquefaciens NY124 stood out for its extraction prowess. Its enzyme, a 42 kDa protease, was purified and confirmed by SDS-PAGE and zymography. Using response surface methodology, the team doubled CGA production with optimal conditions: 1.88 U/mL of the protease, 7.87% green coffee, and 6.85 hours.

To remove caffeine, Diaion HP-20 resins stripped away 89% of it, while silica column chromatography yielded caffeine-free CGA and trigonelline, each over 95% pure. The decaffeinated mix, called Decaf, showed stronger functional activity than either compound alone—a clear synergy. Decaf exhibited tenfold higher antioxidant activity than the control and inhibited α-glucosidase by 52.97%, five times better than control.

In cellular tests, Decaf reduced lipid accumulation by 37% and boosted lipolysis, with free glycerol release up 89% compared to untreated adipocytes. This suggests a promising anti-obesity effect, turning waste beans into a functional food ingredient with real health potential.

Key Points

• Steam boosts CGA to 35 g/kg dry weight.
• NY124 protease doubles CGA production, removes 89% caffeine.
• Decaf shows synergy: 10x antioxidant, 37% less lipid.