Comparison of microwave, ultrasound, and ultrasound-microwave assisted extraction on bioactive compounds, antioxidant activities and antimicrobial properties of hemp seed (Cannabis sativa L.) and wheat bran extracts

What if the secret to sustainable health products is hidden in agricultural waste? Hemp seeds and wheat bran are packed with bioactive compounds, yet they're often discarded—until now.

Agricultural by-products like wheat bran and hemp seeds are treasure troves of bioactive compounds, but they've been largely overlooked. This study set out to find the greenest way to unlock their potential, comparing four extraction methods: maceration, ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE), and a combined ultrasound-microwave approach (UMAE). Using water and 50% ethanol as solvents, the researchers measured polyphenol and flavonoid content, antioxidant activity, and antimicrobial effects against three bacteria: Staphylococcus epidermidis, Bacillus subtilis, and Pseudomonas stutzeri.

Results showed that 50% ethanol consistently boosted extraction efficiency. For wheat bran, all techniques yielded similar polyphenol and flavonoid levels, but MAE, UAE, and UMAE enhanced antioxidant activity compared to maceration. In contrast, hemp seed extracts from MAE and UMAE had the highest polyphenol and flavonoid content, alongside superior antioxidant activities. Notably, wheat bran extracts—especially from MAE—showed strong antibacterial activity at 6 mg/mL.

Optimizing the solid-to-liquid ratio was also crucial, reducing solvent use while improving efficiency. These findings highlight innovative green extraction technologies as a path toward sustainable recovery of bioactive compounds, with applications in functional foods, natural antimicrobials, and bioactive edible coatings.

Key Points

• 50% ethanol boosts extraction efficiency across all methods.
• MAE and UMAE yield highest bioactive content in hemp seeds.
• Wheat bran MAE extracts show strong antibacterial activity at 6 mg/mL.