2006 Volume 17 Issue 3 Pages 247-254
Six kinds of heated mushrooms after being damaged by slow freezing were analyzed for their 5'-GMP and RNA contents. 5'-GMP is a major umami component in mushrooms and is a degraded product from RNA. In some of the mushrooms,the RNA contents in the frozen mushrooms indicated significantly lower contents than those in raw mushrooms, while the others showed a tendency to decrease. Along with this tendency, the 5'-GMP contents in the frozen mushrooms significantly increased when compared with the contents in the raw mushrooms. Based on the electron microscope observations of the mushrooms tissues, it is thought that when slowly frozen mushrooms were heated, a lot of dripping occurred and the enzyme (RNase) action became active.
A sensory evaluation was carried out for the Japanese pilafs which is rice cooked with frozen mushrooms or raw mushrooms. In pilafs using L.edodes, there was a significant difference in its taste. The pilaf using frozen mushrooms was more preferable than that using the raw mushrooms. In H.marmoreus, the taste, flavor, texture and total evaluation were significantly difference. The pilaf using frozen mushrooms got high evaluations. For T.matsutake, there was a significant difference only in the flavor.
Concerning G.frondosa, a sensory evaluation was carried out using two kinds of Japanese pilafs.
One was treated with salt and the other using soy souse. In the G.frondosa rice treated with salt, there were significantly differences in the color, texture and total evaluation. The pilaf using raw mushrooms was more preferable. On the other hand, for that treated with soy souse, there was no defference in the flavor. When these mushrooms were used as an ingredient of miso soup, the frozen mushrooms were more preferable than the raw mushrooms regarding the color, the taste, the taste of the mushrooms and the total evaluation.
Based on these results, we concluded that it is useful and advantageous when cooking to use mushrooms after freezing without blanching, because their sturdy tissues when defrosting and the increase in the umami taste by heating.
