title: Reddish coloration of Chinese quince (Pseudocydonia sinensis) procyanidins during heat treatment and effect on antioxidant and antiinfluenza viral activities.
abstract: To investigate the effects of processing Chinese quince fruit on the denaturation of phenolics and their food functions, fruit phenolic extracts were heated together with organic acid for up to 12 h. Chinese quince phenolic (mostly procyanidins) solution subjected to heat treatment changed from almost colorless, pale yellow, to a reddish color. Before heat treatment, the absorption spectra of polymeric procyanidins were observed only around 280 nm; after heat treatment, absorption occurred between 400 and 600 nm, which is related to the reddish color appearance. Thioacidolysis of denatured reddish phenolics showed that (-)-epicatechin subunits decreased during heat treatment and, in contrast, cyanidin increased. In addition, novel substances that could not be degraded by thioacidolysis were formed. Meanwhile, antioxidant activities, assessed by linoleic acid peroxidation, 1,1-diphenyl-2-picrylhydrazyl (DPPH), Folin-Ciocalteu, and FRAP methods, increased during heat treatment. The antiinfluenza viral activity of denatured reddish phenolics was inferior to that of intact fruit phenolics; however, they retained moderate activity. These results indicate that red coloration of fruit products of Chinese quince was mainly due to the spectral (i.e. structural) changes of procyanidins accompanied with formation of cyanidin. Increasing the length of heat treatment increased the antioxidant capacity of phenolics, and the resultant reddish phenolics retained moderate antiinfluenza viral activity.
authors.affiliation: Department of Sciences of Functional Foods, Graduate School of Agriculture, Shinshu University, 8304 Minamiminowa 399-4598, Japan. hamauzu@gipmc.shinshu-u.ac.jp
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Hamauzu
authors.forename: Chihiro
authors.initials: C
authors.lastname: Kume
authors.forename: Hisako
authors.initials: H
authors.lastname: Yasui
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Fujita
mesh_terms: D000975:Antioxidants / Q000494:pharmacology*; D000998:Antiviral Agents / Q000494:pharmacology*; D003116:Color; D005638:Fruit / Q000737:chemistry; D006358:Hot Temperature; D009975:Orthomyxoviridae / Q000187:drug effects*; D010860:Pigments, Biological / Q000737:chemistry; D044945:Proanthocyanidins / Q000737:chemistry* / Q000494:pharmacology; D027824:Rosaceae / Q000737:chemistry*; D013053:Spectrophotometry
chemical_list: D000975:Antioxidants; D000998:Antiviral Agents; D010860:Pigments, Biological; D044945:Proanthocyanidins