History of Natto and Its Relatives (1405-2012 - SoyInfo Center

sun-dried, and sifted to remove small pieces, which are
discarded. In a separate process, gingerroot is cut thinly,
soaked in boiling water, sun dried, and soaked in moromi
(shoyu mash) for about 10 days to make pickled gingerroot.
Sansho seeds are also added to some types.
The microbiology and chemistry of Hamanatto
fermentation: The molds found in fresh hamanatto koji and
commercial hamanatto, in addition to Aspergillus oryzae,
include Rhizopus species and A. niger. Hamanatto such as
that made at Daifukuji using a low incubation temperature
(20-25ºC) and a long time contains a large proportion of
Rhizopus on the surface of the soybeans. Moreover the
amylase and protease enzymes in these molds are weaker
and less active than those from the koji used for commercial
shoyu or miso. For this reason the soybeans are not broken
down, but rather remain in their whole form. If the koji
is made mechanically, the enzyme strength and quality
increases. The incubation proceeds more quickly in summer
since the temperature is higher; the koji is ready in 3 days.
In general during the koji production, amylase, protease,
and pepsidase activity reach a maximum at 50 hours, but
in order to dry it, it must be left longer which causes the
activity to decrease. In addition to molds, lactic acid bacteria
and fi lm yeasts, which are related to Pediococcus, are found
in all hamanatto; they are mixed in during contact with the
straw mats. If air circulation during koji production is poor,
lactic acid bacteria proliferate more than usual. Unlike most
lactic acid bacteria, they ferment soybean sugars creating
undesirable effects, but do not ferment lactose. After the kojibrine
mixture is in the vats, fi lm yeasts proliferate among
the various fl avors; at 45 days they are most abundant, then
later decrease. Especially on the surface of vats with poor
air circulation, they are found as a white mold. These yeasts
produce hamanatto’s unique aroma.
Hamanatto’s special characteristics: Because the
fermentation time is long, the color turns a dark brown.
The form of the beans is well preserved. The composition
of nutrients is shown in fi gure 2. Compared with regular
natto, hamanatto has less moisture and more salt. Free amino
acids are shown in fi gure 3. Those abundant are glutamic
acid, leucine, and proline, while cystine, tryptophan and
methionine are the most scarce. Compared with soybean
miso, arginine, cystine, and histidine are also relatively
scarce. Since soybean miso undergoes an even longer
fermentation than hamanatto the difference is the amino
acids freed from the soybeans, which is particularly
enhanced by protease enzymes from the koji molds.
Hamanatto fl avor is rich and full-bodied, somewhat like that
of soybean miso, but with a special aroma, more tartness,
and a unique fl avor component that Japanese call egumi.
The latter, related to oil rancidifi cation, imparts what some
describe as a subtle harsh or unpleasant stimulation to the
tongue or throat. Kiuchi et al, in 1976, in an analysis of
hamanatto lipids, found that this egumi originates from
© Copyright Soyinfo Center 2012
HISTORY OF NATTO AND ITS RELATIVES 230
linoleic acid. Hamanatto fats, unlike those of regular natto,
are more than 70 percent of free fatty acids. The majority
of fats in both natto and soybeans are triglycerides, with
other fat components being relatively low. The lipase in
hamanatto koji breaks down a large percentage of the fats but
the composition of the resulting fatty acids is not different
from those found in soybeans; in both cases, linoleic acid
comprises more than 50 percent of the total.
Hamanatto’s volatile acids and aromatic compounds are
shown in fi gures 5 and 6. The aroma of Yamaya’s hamanatto
was superior to that of Daifukuji or Hamana. This aroma was
very poor just after the koji was made but during the ripening
of various fl avors, isobutyl aldehyde, isobutyl alcohol, and
various amines decrease together with a decrease in the poor
aroma. However if the air circulation is bad while making
koji or during the vat fermentation, alien microorganisms
proliferate, leaving an undesirable aroma.
672. Ito, Hiroshi. 1976. Hamanattô [Hamanatto (Continued–
Document Part III. Continued)]. Nippon Jozo Kyokai Zasshi
(J. of the Society of Brewing, Japan) 71(3):173-76. March.
[Jap; eng+]
• Summary: Continued. Serving Hamanatto: Hamanatto
is used both as a seasoning and as a protein source. Like
Daitokuji-natto it is sprinkled as a seasoning over hot rice
in a small bowl, then doused with hot green tea to make the
popular Ochazuke. It may also be served as an hors d’oeuvre
with sake, used in place of tea cakes with whisked green tea
as Chauke, or served as a rice seasoning in box lunches like
shoyu-simmered kombu. Since ancient times it has been used
in Zen Temple Cookery as a source of subtle fl avor, diced
and mixed with grated daikon, sprinkled with vinegar, or
used in the Chinese tofu dish Mabo-dofu. Its abundance of
glutamic acid and nucleic acids enrich the fl avor of any food
with which it is served.
Conclusion: Hamanatto, a progenitor of today’s miso
and shoyu, has been made by traditional methods since
ancient times. Long lasting, it embodies the fermentation
and nutritional wisdom of our forebears. Thus its scientifi c
study reveals new and valuable information. In its traditional
processing there are points that should be improved, yet
today it is a long lasting food with its own distinctive
characteristics.
Acknowledgements: I would like to thank the Yamaya
and Hamana companies for supplying documents and
samples, and allowing me to quote selected portions;
Professor Kayo Kon of Shizuoka Women’s University; and
my colleagues at the National Food Research Institute, Kan
Kikuchi, Teruo Ota, and Shinkuni Sasachi.
Figures show: (1) Hamanatto production methods:
Flow charts of the Yamaya-Horinji method (Horinji is in
parentheses), and of the Daifukuji method.
Tables show: (1) Distribution of microorganisms in
Hamanatto made by Yamaya, Horinji, and Daifukuji. For