title: Effect of particle size on antioxidant activity and catechin content of green tea powders.
abstract: This work evaluated the effect of grinding and sieving process of green tea leaves on particle size distribution and antioxidant activity. Granulometric classes ranging from 20 μm to 500 μm were studied. Hydroalcoholic extracts of green tea powders (GTPs) were analysed for total phenolic, total flavonoid, and catechin contents. The fraction of 100-180 μm ground at 6000 rpm showed the maximum catechin content with 33.5 mg/g dry matter (DM) and, the best antioxidant activity with IC50 values of 0.28 μg/mL and 0.13 μg/mL using DPPH and ABTS radical scavenging assays, respectively. However, antioxidant properties and catechin content decreased for particle of sizes less than 50 μm. Catechin content was higher for those ground at 6000 rpm as compared to at 18,000 rpm. The best grinding conditions and particle size were 6000 rpm and 100-180 μm.
authors.affiliation: Unité de Recherche - Animal et Fonctionnalités des Produits Animaux, Université de Lorraine, 1 Boulevard Arago, F-57078, Cedex 03 Metz, France.
authors.forename: Ali
authors.initials: A
authors.lastname: Zaiter
authors.affiliation: Unité de Recherche - Animal et Fonctionnalités des Produits Animaux, Université de Lorraine, 1 Boulevard Arago, F-57078, Cedex 03 Metz, France.
authors.forename: Loïc
authors.initials: L
authors.lastname: Becker
authors.affiliation: LIBio (Laboratoire d'Ingénierie des Biomolécules), Université de Lorraine, 2 avenue de la Forêt de Haye, F-54505 Vandœuvre-lès-Nancy, France.
authors.forename: Marie-Céleste
authors.initials: MC
authors.lastname: Karam
authors.affiliation: Unité de Recherche - Animal et Fonctionnalités des Produits Animaux, Université de Lorraine, 1 Boulevard Arago, F-57078, Cedex 03 Metz, France.
authors.forename: Amadou
authors.initials: A
authors.lastname: Dicko
keywords: Antioxidant activity; Catechins; Fine grinding; Green tea powders; LC-MS