PB0557 - Fermentation of Sweet Corn Produced A Very High Concentration of Vitamin K₂

Background: Corn is one of the world's major cereal crops, with a production volume comparable to that of wheat and rice.

Aims: In this study, we report on a fermentation test using Bacillus subtilis that showed high production of vitamin K₂, which is used as a preventive drug for osteoporosis, as well as thrombolytic activity.

Methods: Whole kernel corn from Meidi-ya (Tokyo, Japan) was used as the corn, and two types of Bacillus subtilis, M and N, cultured in the laboratory, were used. Fibrin platelet method, resolution against synthetic amide substrate, and vitamin K₂ analysis (HPLC) were performed as previously reported.

Results: Fermentation of sweet corn was performed with M bacteria at 37ºC for 48 hours. The results showed a very high concentration of vitamin K₂ (1,890µg/100g: dry weight).
The thrombolytic activity of the ferment was quite resistant to heat at 100-150ºC for 30 min, but the substrate I/substrate II was about 2.0 in resolution against the synthetic amide substrate, indicating that it was nattokinase.
N bacteria were also used for comparison under various conditions. The morphology was better puree, pH increased, and fermentation at 45ºC for 4-8 days showed a maximum vitamin K₂ value of 406.0µg/g (dry weight).

Conclusion(s): The main feature of sweet corn fermented product is that it has less odor or stickiness compared to ordinary stringy natto. In addition, the thrombolytic activity of this ferment was extremely stable under heat.
The vitamin K₂ content of natto (wet weight) in 600µg/100g, the maximum value of vitamin K₂ was 40,600µg/100g (dry weight) of the corn fermented product is calculated to be several tens of times higher than that. This is equivalent to approximately 0.37g of our fermented product, based on the daily requirement of 150µg for adults, and is considered to be a very good functional food.