title: The influence of protein-flavonoid interactions on protein digestibility in vitro and the antioxidant quality of breads enriched with onion skin.
abstract: Different types of breads enriched with onion skin were studied. The objectives were twofold: to show and examine protein-phenolic interactions and to discuss results concerning phenolic content, antioxidant activity and protein digestibility in the light of in vitro bioaccessibility. Phenolic contents and antiradical abilities were linked with the level of onion skin supplement however, the amounts determined were significantly lower than expected. Fortification influenced protein digestibility (a reduction from 78.4% for control breads to 55% for breads with a 4% supplement). Electrophoretic and chromatographic studies showed the presence of indigestible protein-flavonoid complexes - with molecular weights about 25 kDa and 14.5 kDa; however, the reduction of free amino group levels and the increase in chromatogram areas suggest that flavonoids also bind to other bread proteins. The interaction of phenolics with proteins affects antioxidant efficacy and protein digestibility; thus, they have multiple effects on food quality and pro-health properties.
authors.affiliation: Department of Biochemistry and Food Chemistry, University of Life Sciences, Skromna Str. 8, 20-704 Lublin, Poland. michal.swieca@up.lublin.pl
authors.forename: Michał
authors.initials: M
authors.lastname: Swieca
authors.forename: Urszula
authors.initials: U
authors.lastname: Gawlik-Dziki
authors.forename: Dariusz
authors.initials: D
authors.lastname: Dziki
authors.forename: Barbara
authors.initials: B
authors.lastname: Baraniak
authors.forename: Jarosław
authors.initials: J
authors.lastname: Czyż
mesh_terms: D000975:Antioxidants / Q000737:chemistry* / Q000378:metabolism; D001939:Bread / Q000032:analysis*; D004063:Digestion; D005419:Flavonoids / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D008954:Models, Biological; D019697:Onions / Q000737:chemistry / Q000378:metabolism*; D010936:Plant Extracts / Q000737:chemistry* / Q000378:metabolism; D010940:Plant Proteins / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding
chemical_list: D000975:Antioxidants; D005419:Flavonoids; D010936:Plant Extracts; D010940:Plant Proteins