title: Gastric emptying rate and chyme characteristics for cooked brown and white rice meals in vivo.
abstract: BACKGROUND
  Rice structure is important to rice grain and starch breakdown during digestion. The objective of this study was to determine the gastric emptying and rice composition during gastric digestion of cooked brown and white medium-grain (Calrose variety) rice using the growing pig as a model for the adult human.
  
  
  RESULTS
  Brown and white rice did not show significantly different gastric emptying rates of dry matter or starch, but brown rice had slower protein emptying (P < 0.05). Moisture content was greater and pH was lower in the distal stomach compared to the proximal stomach (P < 0.0001), and varied with time (P < 0.0001). The mechanism of physical breakdown for brown and white rice varied. Brown rice exhibited an accumulation of bran layer fragments in the distal stomach, quantified by lower starch and higher protein content.
  
  
  CONCLUSIONS
  The quantity of gastric secretions observed after a brown or white rice meal may be related to the meal buffering capacity, and are accumulated in the distal stomach. The delayed rate of protein emptying in brown rice compared to white rice was most likely due to the accumulation of bran layers in the stomach.
authors.affiliation: Department of Biological and Agricultural Engineering, University of California Davis, Davis, CA 95616-5294, USA.
authors.forename: Gail M
authors.initials: GM
authors.lastname: Bornhorst
authors.forename: Lucy Q
authors.initials: LQ
authors.lastname: Chang
authors.forename: Shane M
authors.initials: SM
authors.lastname: Rutherfurd
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Moughan
authors.forename: R Paul
authors.initials: RP
authors.lastname: Singh
mesh_terms: D000818:Animals; D003433:Crosses, Genetic; D004043:Dietary Fiber / Q000032:analysis* / Q000378:metabolism; D004044:Dietary Proteins / Q000032:analysis / Q000378:metabolism; D004063:Digestion; D005511:Food Handling; D005746:Gastric Emptying; D005750:Gastric Juice / Q000737:chemistry / Q000378:metabolism; D005753:Gastric Mucosa / Q000378:metabolism; D005766:Gastrointestinal Contents / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008297:Male; D009520:New Zealand; D012275:Oryza / Q000737:chemistry* / Q000378:metabolism; D019518:Postprandial Period; D011897:Random Allocation; D055314:Seed Storage Proteins / Q000032:analysis / Q000378:metabolism; D012639:Seeds / Q000737:chemistry* / Q000378:metabolism; D013213:Starch / Q000032:analysis / Q000378:metabolism; D034421:Sus scrofa
chemical_list: D004043:Dietary Fiber; D004044:Dietary Proteins; D055314:Seed Storage Proteins; D013213:Starch
keywords: gastric emptying; gastric secretion; in vivo; pH; rice