Effect of humidity on the quality characteristics of the 3 rd day of 5 th instar silkworm powder

Freeze-dried 3rd day of 5th instar silkworm powder (FDSP) has been produced and consumed as functional food ingredient in Korea. Generally, FDSP is distributed in the dehumidification state. In this study, the effect of humid condition (30%, 50%, 70%, and 90% RH) on the quality characteristics of FDSP was examined. The color of FDSP, greenish yellow, becomes dark with the change of redness and yellowness. When FDSP is exposed for 4 h at 90% RH, the lightness was changed from 56 to 51, redness from -0.8 to 3.7, and yellowness from 26.5 to 21.6. The proximate composition of FDSP was not significantly changed except 90% RH condition. At that condition, moisture content (5.7%) was increased to 26.8% and crude fat (11.3%) decreased to 1.9% (3 wk 90% RH). Mineral content change during storage can be classified to 3 types; sulfur rapidly decreased, potassium mostly stable with some decreased with humidity, and sodium increased with high humid condition. Vitamins were not significantly affected. However, DNJ was abruptly decreased to 0.03 g/100g in humid condition.