Fermentations involving highly alkaline fermentations are generally safe.
Alkaline fermentations involving bacilli fermenting protein rich beans and seeds are
of considerable importance in widely separated parts of the world. Africa has a
number of very important foods/ condiments that are not only used to flavor soups and
stews but also serve as low-cost sources of protein in the diet (Odunfa, 1989). Among
these are Nigerian dawadawa, Ivory cost soumbara and West African iru made by
fermentation of soaked, cooked locust bean Parkia biglobosa seeds with bacteria
belonging to genus Bacillus, typically Bacillus subtilis. Nigerian ogiri made by
fermentation of melon seed (Citrullus vulgaris); Nigerian ugba made by fermentation
of the oil bean (Pentacletha macrophylla); Sierra Leone ogiri-saro made by
fermentation of sesame seed (Sesamum indicum); Nigerian ogiri-igbo made by
fermentation of castor bean (Ricinus communis) seeds and Nigerian ogir-nwan made
by fermentation of the fluted pumpkin bean (Telfaria occidentale) seeds. Soybeans
can be substituted for locust beans.
This group also includes Japanese natto, Thai Thua-Nao and Indian kenima
all based upon soybean.
The essential microorganisms are Bacillus subtilis and related bacilli. The
organisms are very proteolytic and the proteins are hydrolyzed to peptides and amino 12
acids. Ammonia is releases and the pH rapidly reaches as high as 8.0 or higher. The
combination of high pH and free ammonia along with very rapid growth of the
essential microorganisms at relatively high temperatures above 40°C make it very
difficult for other microorganisms that might spoil the product to grow. Thus, the
products are quite stable and well-preserved especially when dried. They are safe
foods even though they may be manufactured in an unhygienic environment.