title: Influence of drying method on steviol glycosides and antioxidants in Stevia rebaudiana leaves.
abstract: The application of different drying conditions (hot air drying at 100 °C and 180 °C, freeze drying and shade drying) on steviol glycosides (stevioside, dulcoside A, rebaudioside A and rebaudioside C) and antioxidants in Stevia leaves was evaluated. Stevioside, the major glycoside found in fresh leaves (81.2mg/g), suffered an important reduction in all cases, although shade drying was the least aggressive treatment. Considering the antioxidant parameters (total phenols, flavonoids and total antioxidants), the most suitable drying method was hot air at 180 °C, since it substantially increased all of them (76.8 mg gallic acid, 45.1mg catechin and 126 mg Trolox, all equivalent/g Stevia, respectively), with respect to those present in fresh leaves (44.4, 2.5 and 52.9 mg equivalent/g). Therefore, the ideal method for drying Stevia leaves depends on their final use (sweetener or antioxidant), although, hot air at 180 °C is the most recommendable if only one treatment has to be chosen.
authors.affiliation: Institute of Food Engineering for Development, Food Technology Department, Universitat Politècnica de València, P.O. Box 46022, Valencia, Spain.
authors.forename: Angela
authors.initials: A
authors.lastname: Periche
authors.affiliation: Institute of Food Engineering for Development, Food Technology Department, Universitat Politècnica de València, P.O. Box 46022, Valencia, Spain.
authors.forename: María Luisa
authors.initials: ML
authors.lastname: Castelló
authors.affiliation: Institute of Food Engineering for Development, Food Technology Department, Universitat Politècnica de València, P.O. Box 46022, Valencia, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Heredia
authors.affiliation: Institute of Food Engineering for Development, Food Technology Department, Universitat Politècnica de València, P.O. Box 46022, Valencia, Spain. Electronic address: iescrich@tal.upv.es.
authors.forename: Isabel
authors.initials: I
authors.lastname: Escriche
mesh_terms: D000975:Antioxidants / Q000032:analysis*; D045786:Diterpenes, Kaurane / Q000032:analysis*; D005511:Food Handling / Q000379:methods*; D006027:Glycosides / Q000032:analysis*; D006358:Hot Temperature; D010936:Plant Extracts / Q000032:analysis*; D018515:Plant Leaves / Q000737:chemistry; D036625:Stevia / Q000737:chemistry*; D013549:Sweetening Agents / Q000032:analysis
chemical_list: D000975:Antioxidants; D045786:Diterpenes, Kaurane; D006027:Glycosides; D010936:Plant Extracts; D013549:Sweetening Agents; C012042:steviol
keywords: Antioxidants; Freeze drying; Hot air drying; Shade drying; Steviol glycosides; Total flavonoids; Total phenols