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ARS Home » Southeast Area » Little Rock, Arkansas » Arkansas Children's Nutrition Center » Research » Publications at this Location » Publication #164301

Title: PROCESSING OF SORGHUM (SORGHUM BICOLOR) AND SORGHUM PRODUCTS ALTERS PROCYANIDIN OLIGOMER AND POLYMER DISTRIBUTION AND CONTENT

Author
item AWIKA, J
item DYKES, L
item GU, L
item ROONEY, L
item PRIOR, R

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/25/2003
Publication Date: 7/26/2003
Citation: Awika, J.M., Dykes, L., Gu, L., Rooney, L.W., Prior, R.L. 2003. Processing of sorghum (sorghum bicolor) and sorghum products alters procyanidin oligomer and polymer distribution and content. Journal of Agricultural and Food Chemistry. 51(18):5516-5521.

Interpretive Summary: Procyanidins are large complex compounds that are found in many foods, including sorghum. Methods of complete analysis of these compounds have not been available until work recently completed by Drs. Gu and Prior at the USDA ARS-funded Arkansas Children's Nutrition Center. In this study, sorghum procyanidins were characterized and quantified from two brown sorghum varieties and their processed products. The size distribution of the different procyanidins was also determined. Sorghum procyanidins were composed mostly of the large molecules. Significant differences were observed in levels as well as distribution of the different procyanidins between the sorghums. Processing of the sorghum brans into cookies and bread significantly reduced the levels of procyanidins. Cookies had a higher retention of procyanidins than bread. Extrusion which is a processing method for cereal grains which uses high temperature and pressure which was shown to breakdown some of the large procyanidin compounds into smaller units. Processing changes not only the content of procyanidins in sorghum products but also the relative ratio of the different sizes of procyanidins. Processing effects are important as we attempt to understand the effects of procyanidins on human health.

Technical Abstract: Sorghum procyanidins were characterized and quantified from two brown sorghum varieties and their processed products by normal phase HPLC with fluorescence detection. The DP of the procyanidins was determined by thiolysis. Quantification was done by using purified oligomeric and polymeric cocoa procyanidins as external standards. Sorghum procyanidins were composed mostly of high MW (DP > 10) polymers. Significant differences were observed in levels as well as distribution of the different MW procyanidins between the sorghums. Processing of the sorghum brans into cookies and bread significantly reduced the levels of procyanidins; this effect was more pronounced in the higher MW polymers. Cookies had a higher retention of procyanidins (42-84%) than bread (13-69%). Extrusion of sorghum grain resulted in an increase in the levels of procyanidin oligomers with DP 4 and decrease in polymers with DP 6. This suggests a possible breakdown of the high MW polymers to the lower MW constituents during extrusion. Processing changes not only the content of procyanidins in sorghum products but also the relative ratio of the different molecular weights. Keywords: Sorghum; procyanidins; HPLC; extrusion; baking.