Pearled barley kernels are usually cooked with rice in Japan. Their discoloration during and after cooking is one of the problems to promote barley consumption as a staple food. When cooked barley kernels were incubated, their a* values increased with time, which was influenced by water content of kernels. To evaluate a browning of cooked barley kernels, pearled barley kernels (10 varieties and 6 lines) were heated in mineral water at 105°C for 1 hour and further incubated at 70°C for 24 hours in a test tube. The a* value of the flour was measured after lyophilized and pulverized, and the increase in a* value during incubation after cooking (
Δa*) was used as an indicator of the browning. The contents of flavanols in barley kernels decreased during incubation after cooking, as the
Δa* increased. Prodelphinidin B3 decreased faster than procyanidin B3 and (+)-catechin. Varieties with high flavanol content in pearled kernels showed high flavanol content in cooked kernels (
r=0.986) and large flavanol loss during incubation after cooking (
r=0.921), when flavanol contents were determined by
p-dimethylaminocinnamaldehyde (DMACA) method. The browning of cooked kernels was significantly correlated with the flavanol content in pearled kernels (
r=0.716) as well as the flavanol loss during incubation after cooking (
r=0.838). The browning of cooked kernels was slightly observed in proanthocyanidin-free lines. These results indicate that flavanols are the major factor to cause the browning of cooked barley kernels.
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