title: Improvement in the in vivo digestibility of rice protein by alkali extraction is due to structural changes in prolamin/protein body-I particle.
abstract: Rice prolamin, constituting type-I protein body (PB-I), is indigestible and causes deterioration of rice protein nutritional quality. In this study, the in vivo digestibility of rice protein isolates was investigated by tracing their intraluminal transit in the gastrointestinal (GI) tract of rats by western blotting and by observing the structures excreted in the feces by electron microscopy. Two types of rice protein isolates, produced by alkali extraction (AE-RP) and by starch degradation (SD-RP), were compared. The protein patterns in the isolates were similar, but their digestion in the GI-tract showed striking differences. In the AE-RP group, 13-kDa prolamin (13P) quickly disappeared in the lower GI tract and was not excreted in the feces. By contrast, in the SD-RP group, 13P accumulated massively and nearly intact PB-Is were excreted. These results indicate that the in vivo digestibility of prolamin can be improved by alkali extraction through structural changes to it.
authors.affiliation: Department of Applied Biological Chemistry, Graduate School of Science and Technology, Niigata University, Ikarashi, Niigata, Japan.
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Kubota
authors.forename: Yuhi
authors.initials: Y
authors.lastname: Saito
authors.forename: Takehiro
authors.initials: T
authors.lastname: Masumura
authors.forename: Takehisa
authors.initials: T
authors.lastname: Kumagai
authors.forename: Reiko
authors.initials: R
authors.lastname: Watanabe
authors.forename: Shinobu
authors.initials: S
authors.lastname: Fujimura
authors.forename: Motoni
authors.initials: M
authors.lastname: Kadowaki
mesh_terms: D000468:Alkalies / Q000737:chemistry; D000818:Animals; D003296:Cooking; D004063:Digestion; D005243:Feces / Q000737:chemistry; D005766:Gastrointestinal Contents / Q000737:chemistry; D008297:Male; D009753:Nutritive Value; D012275:Oryza / Q000737:chemistry* / Q000378:metabolism; D055315:Prolamins / Q000737:chemistry* / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar
chemical_list: D000468:Alkalies; D055315:Prolamins