PROBLEM TO BE SOLVED: To provide a method for producing inexpensively freeze-drying natto (fermented soybeans) which holds flavor, nutrient components and furthermore shape of a grain of natto original.SOLUTION: In the production method of freeze-drying natto, natto is produced by continuously carrying out: a steaming process S11 to carry out steaming of the soybean a bacillus natto inoculation process S12 for inoculating bacillus natto into steamed soybeans a filling process S13 to level the soybean into which bacillus natto is inoculated to the predetermined height and fill up a container with this soybean a fermentation step S14 to ferment the soybean with which the container is filled up and an aging process S15 to ripen the fermented soybean, and a vacuum freeze dry process S20 is performed. In the fermentation process S14, natto becomes with little yarn by carrying out ferment at 36-43°C of atmospheric temperatures for 12-14 hours. The freeze-drying natto in which adhesion of grains by yarn is weakened and the grains are easily ravelled one by one is obtained, since the soybean filled up into the container in the filling process S13 is not be moved out of the container till completion of the vacuum freeze dry process S20.COPYRIGHT: (C)2012,JPO&INPIT【課題】納豆本来の風味や栄養成分、さらに粒の形状を保持された凍結乾燥納豆を、低コストで製造する方法を提供する。【解決手段】本発明にかかる凍結乾燥納豆の製造方法は、大豆を蒸煮する蒸煮工程S11と、蒸煮された大豆に納豆菌を接種する納豆菌接種工程S12と、容器に納豆菌を接種された大豆を所定の高さに均して充填する充填工程S13と、容器に充填された大豆を発酵させる発酵工程S14と、発酵させた大豆を熟成させる熟成工程S15と、を連続して行って納豆を製造し、真空凍結乾燥工程S20を行う。発酵工程S14は、雰囲気温度36~43℃で12~14時間発酵させることにより、糸の少ない納豆となり、充填工程S13で容器に充填された大豆は、真空凍結乾燥工程S20の完了まで当該容器内から移動させないため、糸による粒同士の密着を弱くして容易に一粒ずつほぐせる凍結乾燥納豆が得られる。【選択図】図1
