Green energy-assisted versus conventional solvent extraction for the recovery of phenolic antioxidants from marine macroalgae: A meta-analysis

Abstract

Background: Marine macroalgae are a renewable source of phenolic antioxidants. Energy-assisted extraction may replace prolonged solvent-intensive maceration, but its effect on recovery had not been quantitatively pooled.

Methods: PubMed and Europe PMC were searched. Of 493 de-duplicated records, 35 full texts were assessed. Eligible reports compared energy-assisted and conventional extraction using paired arms from one homogenised macroalgal biomass. Hedges' g was pooled using random-effects models with cluster-robust inference; the ratio of means was a secondary measure. Risk of bias used laboratory analogues of five Cochrane domains.

Results: Thirteen studies yielded 35 comparisons across 22 species and 93 estimates; ultrasound contributed 56 estimates, brown seaweeds 73, red seaweeds 20, and green seaweeds none. Energy-assisted extraction increased phenolic antioxidant recovery (cluster-robust Hedges' g = 8.62, 95% CI 2.98 to 14.26, p = 0.0063; ratio of means 1.385, 95% CI 1.149 to 1.671, a 38.5% gain) in a median 10 versus 960 minutes. The advantage persisted in 12 duration-matched comparisons. Heterogeneity was high (I² = 87.8%); the prediction interval -2.26 to 16.16 included zero. No moderator survived robust testing. Supercritical carbon dioxide recovered 51.8% less than conventional extraction.

Conclusion: Energy-assisted extraction recovered about 39% more phenolic antioxidant activity about 21 times faster. Direction was robust, but magnitude and certainty remained uncertain; a green label did not guarantee superior recovery.