title: Influence of domestic processing and storage on flavonol contents in berries.
abstract: Effects of domestic processing and storage on the flavonols quercetin, myricetin, and kaempferol in five berries were studied using an optimized RP-HPLC method with UV and diode array detection after an acid hydrolysis of the corresponding glycosides. In fresh berries, the total content of flavonols was highest in lingonberry (169 mg/kg) and black currant (157 mg/kg), intermediate in bilberry (41 mg/kg) and strawberry (17 mg/kg), and lowest in red raspberry (9.5 mg/kg). Cooking strawberries with sugar to make jam resulted in minor losses (quercetin 15%, kaempferol 18%). During cooking of bilberries with water and sugar to make soup, 40% of quercetin was lost. Traditional preservation of crushed lingonberries in their own juice caused a considerable (40%) loss of quercetin. Only 15% of quercetin and 30% of myricetin present in unprocessed berries were retained in juices made by common domestic methods (steam-extracted black currant juice, unpasteurized lingonberry juice). Cold-pressing was superior to steam-extraction in extracting flavonols from black currants. During 9 months of storage at 20 C, quercetin content decreased markedly (40%) in bilberries and lingonberries, but not in black currants or red raspberries. Myricetin and kaempferol were more susceptible than quercetin to losses during storage.
authors.affiliation: Department of Clinical Nutrition, Department of Physiology, University of Kuopio, PO box 1627, FIN-70211 Kuopio, Finland.
authors.forename: S H
authors.initials: SH
authors.lastname: Häkkinen
authors.forename: S O
authors.initials: SO
authors.lastname: Kärenlampi
authors.forename: H M
authors.initials: HM
authors.lastname: Mykkänen
authors.forename: A R
authors.initials: AR
authors.lastname: Törrönen
mesh_terms: D005419:Flavonoids / Q000032:analysis*; D005511:Food Handling / Q000379:methods*; D005519:Food Preservation / Q000379:methods; D005638:Fruit / Q000737:chemistry*
chemical_list: D005419:Flavonoids