Submitted to: American Chemical Society National Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 5/15/2007
Publication Date: 8/19/2007
Citation: Prior, R.L., Howard, L., Gu, L., Rooney, L., Hager, A. 2007. Procyanidins: Effects of source and extrusion conditions on structure, degradation and absorption/metabolism [abstract]. American Chemical Society 234th National Meeting and Exposition, August 19-23, 2007, Boston, Massachusetts. Abstract AGFD 209. 2007 CDROM.
Interpretive Summary: Procyanidins (PCAs), often referred to as tannins, exist as large molecules containing multiple subunits from 1 to over 100. PCAs have beneficial health effects; however, bioavailability (the amount and form that food compounds are absorbed into the blood) of PCAs is low; the smaller compounds with 1 to 3 subunits are the major forms of PCAs that have been shown to be absorbed. In these studies, extrusion (a form of food processing) was used as a means of degrading the large polymeric forms of procyanidins into smaller forms that might be more readily absorbed. PCAs from sorghum bran (SB), blueberry (BB) pomace, grape (G) pomace, or grape seeds were studied. Extrusion of BB and G pomace produced greater degradation of PCA than with SB or grape seed PCA. Absorption of the treated PCAs from SB was studied in a weanling pig model. Extrusion improved the bioavailability of PCAs in SB by more than 2-fold, due in part to depolymerization of polymers and/or release of bound PCAs in the bran.
Technical Abstract: Procyanidins (PCAs) are beneficial for health; however, bioavailability of PCAs is low; monomers thru 3-mer are the major forms of PCAs absorbed. Sorghum bran (SB), blueberry (BB) pomace, grape (G) pomace, or grape seeds were mixed in varying proportions (10 to 40%) with decorticated white sorghum (DWS) prior to extrusion. Extrusion of 20, 30 or 40% Hi-tannin SB with DWS increased 1- thru 3-mer and decreased 5-mer and higher. Destruction of total PCAs was greater with BB or G pomace at the higher ratios of pomace to DWS compared to lower ratios. Degradation of total PCA was not as great at higher ratios of either SB or grape seed to DWS compared to BB or G pomace. Six weanling pigs (8.9 kg) received a single dose by gavage of non-extruded SB, extruded SB, or white sorghum (50% grain + 50% SB) in a randomized crossover design. Serum levels of catechin, 3’-O-methylcatechin, and the total catechins were higher and urinary excretion of total catechins was higher (>2X) in pigs fed extruded vs non-extruded SB. Extrusion improved the bioavailability of PCAs in SB due in part to depolymerization of polymers and/or release of bound PCAs in the bran. Extrusion of BB and G pomace produced greater degradation of PCA than with SB or grape seed PCA.