Abstract
We developed an efficient method to increase the amount of vitamin D_2 in Lentinula edodes and the equipment to produce vitamin D_2-enriched shiitake mushrooms. The relationship between the photoisomerization of the ergosterol to previtamin D_2 was very close, separated by 295nm. This study used a lamp with a 310nm dominant wavelength. This lamp formed 1.5 to 3.5 times as much vitamin D_2 in L. edodes as a germicidal lamp of a 254 nm dominant wavelength. Using the lamp with the 310 nm dominant wavelength, one fruit-body of the shiitake mushroom included a one-day requirement of vitamin D_2 (100 IU), which formed the condition of an irradiation intensity of 100μW/cm^2 from 15 to 30 seconds. Based on this knowledge, the equipment can be adjusted from 0 to 150μW/cm^2 on ultraviolet irradiation intensity and is able to control the irradiation time by changing the conveyer belt speed from 1.7 to 16.5cm/sec. If we use this equipment, it is possible that the vitamin D_2 contents are able to be changed for any type of mushroom or for the purpose of its use.
