World Journal
of Microbiology
& Biotechnology
10, 479480
Short Communication
Natural fermentation of soybean (G/y&e max) with added salt for ‘soy-daddawa’ production B.O. Omafuvbe Microbial growth, pH and titratable acidity decreased with increasing NaCl concentration during the fermentation soybeans. NaCl at 1% (w/w) in the fermenting mash improved the organoleptic quality of ‘soy-daddawa’. Key words: Natural
food, organoleptic
quality, salt, soy-daddawa.
Soybean (Glycine max) is fermented to produce ‘soy-daddawa’, an important soup condiment widely used in the middle belt areas of Nigeria (Popoola & Akueshi 1985). The bacteria associated with soybean daddawa have been identified (Ogbadu & Okagbue 1988). As NaCl plays an important role in the fermentation of sauerkraut, cheese and oriental foods (Steinkraus 1983) we have examined the effects of NaCl on microbial load, pH and titratable acidity during the fermentation of soybean and on the organoleptic qualities of ‘soy-daddawa’.
Materials
of
The bacteria involved were predominantly lar to B. pumilus and B. subtilis.
Bacillus spp. simi-
and Methods
Soybeans, 25 to 30 g, were incubated at 35°C for up to 72 h using the traditional method of Popoola & Akueshi (1985) with NaCl added up to 5% (w/w). Samples (2 g) were taken aseptically from duplicate fermenting mashes, serially diluted in 0.1% peptone, plated on Tryptone/soya agar and incubated at 35°C for 48 h. Colonies were counted and isolates identified by standard methods; pH and titratable acidity (expressed as mg lactic acid/g sample) were determined as previously described (Ikenebomeh 1989). A modification of the organoleptic quality score rating method of Ikenebomeh (1989) was used in assessing the ‘soy-duddawa’ by a panel of blindfolded regular consumers. A score range of +, ++ and +++ (fair, good and very good, respectively) was used.
Results
and Discussion
I
0
7994 Rapid Communications
of Microbiology,
Obafemi Awolowo
Univer-
J
72
48 Fermentation time (h)
During the fermentation of soybean, the maximum microbial population was found in samples with 1% NaCl (Figure 1). The author is with the Department sity, He-lfe, Nigeria.
1
24
Figure 1. Bacterial (O), 1% (A), (w/w)
counts
in fermenting
2% (0).
3% (O),
soybean
substrate
4% (A)
or
with 0% 5%
(m)
NaCI.
of Oxford Ltd World Journal
ofMicrobiology
6 Biotechnology, Vol 10, 1994
479
B.O. Omafuvbe Table 1. The effect of NaCl concentration ties of soybean fermented for 72 h.
on the organoleptic
NaCl concentration (“70 w/w)
quality
Organoleptic
*+ -
Fairly
daddawa’;
o=
48
24
Fermentation Figure (0),
2. Changes 1% (A), 2%
time (h)
in pH in fermenting
(O),
72
soybean
substrate
3% (O), 4% (A) or 5% (m) (w/w)
with 0% NaCI.
well fermented, +t
daddawa’; daddawa’
I
score’
” +tt ” ” + +
0 1 2 3 4 5
6.5
quali-
-
fairly hard texture,
well fermented,
++t - very well fermented, better than +I.
soft
aroma
texture, soft texture,
not of typical
aroma aroma
typical
‘soy-
of ‘soy-
of typical
‘soy-
The pH of samples increased as fermentation progressed (Figure 2) and was maximal in samples without NaCl. The maximum titratable acidity was again with 1% NaCl (Figure 3). The simultaneous increase in titratable acid and pH with fermentation time is not unusual, since a similar trend occurs in tempeh fermentation (Wagenkuecht et al. 1961). The organoleptic score showed that the quality of ‘soyduddawa was also optimal with 1% NaCl (w/w) in the fermenting mash (Table 1). This study shows that the incorporation of 1% NaCl (w/w) provides a favourable condition for soybean fermentation for ‘soy-dudduwu’ production.
Acknowledgements Soybean seeds for this research were from the International Institute for Tropical Agriculture, Ibadan, Nigeria. Drs D.O. Kolawole and B.O. Oyedapo are thanked for their useful suggestions.
References Ikenebomeh, M.J. 1989 The influence of salt and temperature on the natural fermentation of African locust bean. International journal of Food Microbiology 8,133-139. Ogbadu, L. & Okagbue, R.N. 1988 Bacterial fermentation of soybean for daddawa production. Journal of Applied Bucteriology
65,353-356.
Popoola, T.O.S. & Akueshi, C.O. 1985 Microorganisms associated with the fermentation of soybean for the production of daddawa (a condiment). Nigerian Food ]ournal 2, 194-196.
a
1 24
40
Fermentation Figure substrata
(w/w)
480
3.
I 72
time (h)
Changes in titratable acidity in fermenting soybean with 0% (0), 1% (A), 2% (O), 3% (O), 4% (A) or 5% (I)
NaCI.
World @mml
of Microbiology
b Biotechnology, Vol lo,1994
Steinkraus, K.H. 1983 Miscellaneous Oriental Fermented Foods, Microbiology Series, Vol. 9. New York: Marcel Dekker. Wagenkuecht, A.C., Mattick, L.R., Lewin, L.M. Hand, D.B. & Steinlcraus, K.H. 1961 Changes in soybean lipids during tempeh fermentation. Journal of Food Science 26,373-376. (Received in revised form 12 January 1994; accepted 20 January 2994)
of Microbiology
& Biotechnology
10, 479480
Short Communication
Natural fermentation of soybean (G/y&e max) with added salt for ‘soy-daddawa’ production B.O. Omafuvbe Microbial growth, pH and titratable acidity decreased with increasing NaCl concentration during the fermentation soybeans. NaCl at 1% (w/w) in the fermenting mash improved the organoleptic quality of ‘soy-daddawa’. Key words: Natural
food, organoleptic
quality, salt, soy-daddawa.
Soybean (Glycine max) is fermented to produce ‘soy-daddawa’, an important soup condiment widely used in the middle belt areas of Nigeria (Popoola & Akueshi 1985). The bacteria associated with soybean daddawa have been identified (Ogbadu & Okagbue 1988). As NaCl plays an important role in the fermentation of sauerkraut, cheese and oriental foods (Steinkraus 1983) we have examined the effects of NaCl on microbial load, pH and titratable acidity during the fermentation of soybean and on the organoleptic qualities of ‘soy-daddawa’.
Materials
of
The bacteria involved were predominantly lar to B. pumilus and B. subtilis.
Bacillus spp. simi-
and Methods
Soybeans, 25 to 30 g, were incubated at 35°C for up to 72 h using the traditional method of Popoola & Akueshi (1985) with NaCl added up to 5% (w/w). Samples (2 g) were taken aseptically from duplicate fermenting mashes, serially diluted in 0.1% peptone, plated on Tryptone/soya agar and incubated at 35°C for 48 h. Colonies were counted and isolates identified by standard methods; pH and titratable acidity (expressed as mg lactic acid/g sample) were determined as previously described (Ikenebomeh 1989). A modification of the organoleptic quality score rating method of Ikenebomeh (1989) was used in assessing the ‘soy-duddawa’ by a panel of blindfolded regular consumers. A score range of +, ++ and +++ (fair, good and very good, respectively) was used.
Results
and Discussion
I
0
7994 Rapid Communications
of Microbiology,
Obafemi Awolowo
Univer-
J
72
48 Fermentation time (h)
During the fermentation of soybean, the maximum microbial population was found in samples with 1% NaCl (Figure 1). The author is with the Department sity, He-lfe, Nigeria.
1
24
Figure 1. Bacterial (O), 1% (A), (w/w)
counts
in fermenting
2% (0).
3% (O),
soybean
substrate
4% (A)
or
with 0% 5%
(m)
NaCI.
of Oxford Ltd World Journal
ofMicrobiology
6 Biotechnology, Vol 10, 1994
479
B.O. Omafuvbe Table 1. The effect of NaCl concentration ties of soybean fermented for 72 h.
on the organoleptic
NaCl concentration (“70 w/w)
quality
Organoleptic
*+ -
Fairly
daddawa’;
o=
48
24
Fermentation Figure (0),
2. Changes 1% (A), 2%
time (h)
in pH in fermenting
(O),
72
soybean
substrate
3% (O), 4% (A) or 5% (m) (w/w)
with 0% NaCI.
well fermented, +t
daddawa’; daddawa’
I
score’
” +tt ” ” + +
0 1 2 3 4 5
6.5
quali-
-
fairly hard texture,
well fermented,
++t - very well fermented, better than +I.
soft
aroma
texture, soft texture,
not of typical
aroma aroma
typical
‘soy-
of ‘soy-
of typical
‘soy-
The pH of samples increased as fermentation progressed (Figure 2) and was maximal in samples without NaCl. The maximum titratable acidity was again with 1% NaCl (Figure 3). The simultaneous increase in titratable acid and pH with fermentation time is not unusual, since a similar trend occurs in tempeh fermentation (Wagenkuecht et al. 1961). The organoleptic score showed that the quality of ‘soyduddawa was also optimal with 1% NaCl (w/w) in the fermenting mash (Table 1). This study shows that the incorporation of 1% NaCl (w/w) provides a favourable condition for soybean fermentation for ‘soy-dudduwu’ production.
Acknowledgements Soybean seeds for this research were from the International Institute for Tropical Agriculture, Ibadan, Nigeria. Drs D.O. Kolawole and B.O. Oyedapo are thanked for their useful suggestions.
References Ikenebomeh, M.J. 1989 The influence of salt and temperature on the natural fermentation of African locust bean. International journal of Food Microbiology 8,133-139. Ogbadu, L. & Okagbue, R.N. 1988 Bacterial fermentation of soybean for daddawa production. Journal of Applied Bucteriology
65,353-356.
Popoola, T.O.S. & Akueshi, C.O. 1985 Microorganisms associated with the fermentation of soybean for the production of daddawa (a condiment). Nigerian Food ]ournal 2, 194-196.
a
1 24
40
Fermentation Figure substrata
(w/w)
480
3.
I 72
time (h)
Changes in titratable acidity in fermenting soybean with 0% (0), 1% (A), 2% (O), 3% (O), 4% (A) or 5% (I)
NaCI.
World @mml
of Microbiology
b Biotechnology, Vol lo,1994
Steinkraus, K.H. 1983 Miscellaneous Oriental Fermented Foods, Microbiology Series, Vol. 9. New York: Marcel Dekker. Wagenkuecht, A.C., Mattick, L.R., Lewin, L.M. Hand, D.B. & Steinlcraus, K.H. 1961 Changes in soybean lipids during tempeh fermentation. Journal of Food Science 26,373-376. (Received in revised form 12 January 1994; accepted 20 January 2994)
