Turning Agricultural Waste into Value-Added Products: A Review of Passion Fruit (Passiflora edulis) Peel

What if the secret to healthier snacks is hiding in a pile of soybean husks? A new study turns this agricultural waste into a functional food ingredient with antioxidant power.

Soybean husks are often discarded, yet they are packed with fiber and antioxidants. Researchers set out to unlock their potential using green extraction methods: ultrasound and pressurized liquid. The raw husks contained 67.98% fiber and 10.56% protein, making them a promising starting material.

Pressurized liquid extraction (PLE) proved to be the star. At 140°C with 50% ethanol, it yielded nearly 20% extract, rich in phenolic compounds and antioxidants. Isoflavones like daidzin and genistin were identified as key players.

To test real-world benefits, the team added the extract and husks to scones. The result? Scones with the extract had significantly higher phenolic content and antioxidant activity—about 36 µmol Trolox per gram—compared to controls. Plus, adding husks increased dietary fiber enough to legally label the scones as a "source of fiber."

This study shows that valorizing soybean husk through green extraction can boost the nutritional quality of everyday baked goods, turning waste into wellness.

Key Points

• Soybean husk: 67.98% fiber, 10.56% protein.
• PLE at 140°C, 50% EtOH yields 19.97% extract.
• Scones with extract show higher antioxidants (~36 µmol Trolox/g).