Awika Joseph M, Dykes Linda, Gu Liwei, Rooney Lloyd W, Prior Ronald L
Cereal Quality Lab, Texas A&M University, College Station, Texas 77843-2474, USA.
J Agric Food Chem. 2003 Aug 27;51(18):5516-21. doi: 10.1021/jf0343128.
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.
采用正相高效液相色谱-荧光检测法对两个棕色高粱品种及其加工产品中的原花青素进行了表征和定量分析。通过硫解反应测定原花青素的聚合度（DP）。以纯化的低聚和聚合可可原花青素为外标进行定量分析。高粱原花青素主要由高分子量（DP>10）聚合物组成。在不同高粱品种之间，不同分子量原花青素的含量和分布存在显著差异。将高粱麸加工成饼干和面包会显著降低原花青素的含量；这种影响在高分子量聚合物中更为明显。饼干中原花青素的保留率（42-84%）高于面包（13-69%）。高粱籽粒挤压后，DP≤4的原花青素低聚物含量增加，而DP≥6的聚合物含量减少。这表明在挤压过程中，高分子量聚合物可能分解为低分子量成分。加工不仅改变了高粱产品中原花青素的含量，还改变了不同分子量的相对比例。
