190 Modern Food Microbiology
with A. oryzae or A. soyae and allowing them to stand for 3 days. This results in the production of large
amounts of fermentable sugars, peptides, and amino acids. The second stage, the moromi, consists of
adding the fungal-covered product to around 18% NaCl and incubating at room temperatures for at
least a year. The liquid obtained at this time is soy sauce. During the incubation of the moromi, lactic
acid bacteria, L. delbrueckii subsp. delbruckeii in particular, and yeasts such as Zygosaccharomyces
rouxii carry out an anaerobic fermentation of the koji hydrolysate. Pure cultures of A. oryzae for the
koji and L. delbrueckii subsp. delbrueckii and Z. rouxii for the moromi stages have been shown to
produce good quality soy sauce.
93
Tempeh is a fermented soybean product. Although there are many variations in its production, the
general principle of the Indonesian method for tempeh consists of soaking soybeans overnight in order
to remove the seed coats or hulls. Once seed coats are removed, the beans are cooked in boiling water
for about 30 minutes and spread on a bamboo tray to cool and surface dry. Small pieces of tempeh
from a previous fermentation are incorporated as starter, followed by wrapping with banana leaves.
The wrapped packages are kept at room temperature for 1 or 2 days during which mold growth occurs
and binds the beans together as a cake—the tempeh. An excellent product can be made by storing in
perforated plastic bags and tubes with fermentations completed in 24 hours at 31
◦ C.
27 The desirable
organism in the fermentation is Rhizopus oligosporus, especially for wheat tempeh. Good soybean
tempeh can be made with R. oryzae or R. arrhizus. During the fermentation, the pH of soybeans rises
from around 5.0 to values as high as 7.5.
Miso, a fermented soybean product common in Japan, is prepared by mixing or grinding steamed
or cooked soybeans with koji and salt and allowing fermentation to take place usually over a 4- to
12-month period. White or sweet miso may be fermented for only a week, whereas the higher-quality
dark brown product (mame) may ferment for 2 years. In Israel, Ilany-Feigenbaum et al.
38 prepared
miso-type products by using defatted soybean flakes instead of whole soybeans and fermenting for
around 3 months. The koji for these products was made by growing A. oryzae on corn, wheat, barley,
millet or oats, potatoes, sugar beets, or bananas, and the investigators found that the miso-type products
compared favorably to Japanese-prepared miso. Because of the possibility that A. oryzae may produce
toxic substances, koji was prepared by fermenting rice with Rhizopus oligosporus at 25
◦ C for 90 days;
the product was found to be an acceptable alternative to A. oryzae as a koji fungus.
76
Ogi is a staple cereal of the Yorubas of Nigeria, and it is often the first food given to babies
at weaning. It is produced generally by soaking corn grains in warm water for 2–3 days followed
by wet-milling and sieving through a screen mesh. The sieved material is allowed to sediment and
ferment and is marketed as wet cakes wrapped in leaves. Various food dishes are made from the
fermented cakes or the ogi.
10 During the steeping of corn, Corynebacterium spp. become prominent
and appear to be responsible for the diastatic action necessary for the growth of yeasts and lactic
acid bacteria.
4 Along with the corynebacteria, S. cerevisiae and L. plantarum have been found to
be prominent in the traditional ogi fermentation, as are Cephalosporium, Fusarium, Aspergillus, and
Penicillium. Most of the acid produced is lactic, which depresses the pH of desirable products to
around 3.8. The corynebacteria develop early, and their activities cease after the first day; those of
the lactobacilli and yeasts continue beyond the first day of fermentation. A newer process for making
ogi has been developed, tested, and found to produce a product of better quality than the traditional
process.
9 By this newer method, corn is dry-milled into whole corn and dehulled corn flour. Upon the
addition of water, the mixture is cooked, cooled, and then inoculated with a mixed culture (starter) of
L. plantarum, L. lactis, and Z. rouxii. The inoculated preparation is incubated at 32
◦ C for 28 hours,
during which time the pH of the corn drops from 6.1 to 3.8. This process eliminates the need for
starch-hydrolyzing bacteria. In addition to the shorter fermentation time, there is also less chance for
faulty fermentations.
with A. oryzae or A. soyae and allowing them to stand for 3 days. This results in the production of large
amounts of fermentable sugars, peptides, and amino acids. The second stage, the moromi, consists of
adding the fungal-covered product to around 18% NaCl and incubating at room temperatures for at
least a year. The liquid obtained at this time is soy sauce. During the incubation of the moromi, lactic
acid bacteria, L. delbrueckii subsp. delbruckeii in particular, and yeasts such as Zygosaccharomyces
rouxii carry out an anaerobic fermentation of the koji hydrolysate. Pure cultures of A. oryzae for the
koji and L. delbrueckii subsp. delbrueckii and Z. rouxii for the moromi stages have been shown to
produce good quality soy sauce.
93
Tempeh is a fermented soybean product. Although there are many variations in its production, the
general principle of the Indonesian method for tempeh consists of soaking soybeans overnight in order
to remove the seed coats or hulls. Once seed coats are removed, the beans are cooked in boiling water
for about 30 minutes and spread on a bamboo tray to cool and surface dry. Small pieces of tempeh
from a previous fermentation are incorporated as starter, followed by wrapping with banana leaves.
The wrapped packages are kept at room temperature for 1 or 2 days during which mold growth occurs
and binds the beans together as a cake—the tempeh. An excellent product can be made by storing in
perforated plastic bags and tubes with fermentations completed in 24 hours at 31
◦ C.
27 The desirable
organism in the fermentation is Rhizopus oligosporus, especially for wheat tempeh. Good soybean
tempeh can be made with R. oryzae or R. arrhizus. During the fermentation, the pH of soybeans rises
from around 5.0 to values as high as 7.5.
Miso, a fermented soybean product common in Japan, is prepared by mixing or grinding steamed
or cooked soybeans with koji and salt and allowing fermentation to take place usually over a 4- to
12-month period. White or sweet miso may be fermented for only a week, whereas the higher-quality
dark brown product (mame) may ferment for 2 years. In Israel, Ilany-Feigenbaum et al.
38 prepared
miso-type products by using defatted soybean flakes instead of whole soybeans and fermenting for
around 3 months. The koji for these products was made by growing A. oryzae on corn, wheat, barley,
millet or oats, potatoes, sugar beets, or bananas, and the investigators found that the miso-type products
compared favorably to Japanese-prepared miso. Because of the possibility that A. oryzae may produce
toxic substances, koji was prepared by fermenting rice with Rhizopus oligosporus at 25
◦ C for 90 days;
the product was found to be an acceptable alternative to A. oryzae as a koji fungus.
76
Ogi is a staple cereal of the Yorubas of Nigeria, and it is often the first food given to babies
at weaning. It is produced generally by soaking corn grains in warm water for 2–3 days followed
by wet-milling and sieving through a screen mesh. The sieved material is allowed to sediment and
ferment and is marketed as wet cakes wrapped in leaves. Various food dishes are made from the
fermented cakes or the ogi.
10 During the steeping of corn, Corynebacterium spp. become prominent
and appear to be responsible for the diastatic action necessary for the growth of yeasts and lactic
acid bacteria.
4 Along with the corynebacteria, S. cerevisiae and L. plantarum have been found to
be prominent in the traditional ogi fermentation, as are Cephalosporium, Fusarium, Aspergillus, and
Penicillium. Most of the acid produced is lactic, which depresses the pH of desirable products to
around 3.8. The corynebacteria develop early, and their activities cease after the first day; those of
the lactobacilli and yeasts continue beyond the first day of fermentation. A newer process for making
ogi has been developed, tested, and found to produce a product of better quality than the traditional
process.
9 By this newer method, corn is dry-milled into whole corn and dehulled corn flour. Upon the
addition of water, the mixture is cooked, cooled, and then inoculated with a mixed culture (starter) of
L. plantarum, L. lactis, and Z. rouxii. The inoculated preparation is incubated at 32
◦ C for 28 hours,
during which time the pH of the corn drops from 6.1 to 3.8. This process eliminates the need for
starch-hydrolyzing bacteria. In addition to the shorter fermentation time, there is also less chance for
faulty fermentations.