Patent ID: 8383413

Claim:
A method for determining a total weight of a mixture of n-polymers (n≧2) of flavan-3-ol (oligomeric proanthocyanidin or OPC) contained in a predetermined weight of a sample, said method comprising measuring a weight of anthocyanidin produced by hydrolysis of OPC in the sample, separately measuring an amount of anthocyanidin produced by hydrolysis of a known weight of a standard substance, wherein the standard substance is an OPC standard substance or a n-polymer (n≧2) of flavan-3-ol, and determining the total weight of OPC in the sample and/or a weight ratio of OPC (a %) in the sample by a calibration curve or the following equation based on a fact that an amount of anthocyanidin produced by hydrolysis of OPC is in proportion to the total amount of OPC, regardless of an amount ratio of n-polymers contained in OPC and different in a magnitude of a polymerization degree n, and a complete hydrolysis reaction of a n-polymer (n≧2) of flavan-3-ol generates n/2 molecules of anthocyanidin: Total weight of OPC=(measured value of sample/measured value of standard)×weight of standard substance (Equation 1) Weight ratio of OPC ( a %) in sample=(total weight of OPC/weight of sample)×100 (Equation 2), wherein the mixture of n-polymers (n≧2) of flavan-3-ol of the sample is different from that of the standard substance.