56
1995). It has been shown that Rhizopus sp. can survive under low oxygen concentration (0.2%), but not under absolute anaerobic conditions (Lin and Wang 1991).
It has also been seen that tempe-forming Rhizopus sp. were capable of utilizing
raffinose as the sole carbon source for obtaining energy (Rehms and Barz 1995).
Mitchell et al. (1990) described the growth of Rhizopus oligosporus sp. on a starchy
model substrate as a multiple-stage process. The mycelium of the fungus penetrates
up to 25% of the width of cotyledon by puncturing several layers of soya bean (Ko
and Hesseltine 1979). An improved technique reported that tempe developed maximum strength after 30 h incubating at 30 °C, and later on the mycelium degenerated
gradually (Ariffin et al. 1994). Mixed inoculation of R. oryzae, Citrobacter freundii,
R. oligosporus and Brevibacterium epidermidis can result in the production of
tempe nutritionally rich in niacin, tocopherol, pyridoxine, riboflavin, biotin, vitamin
K and ergosterol (Wiesel et al. 1997).
4.4.5.2 Manufacturing Process
Predominantly, tempe is still a home-made or cottage-industry product manufactured in the areas of Indonesia and Malaysia. It is practically not known in Japan. It
has recently been introduced to the USA and to Europe, specifically for the population of Indonesian origin and for the expanding Indonesian restaurant trade. It is
made in modern, sanitary plants, using stainless steel equipment and sometimes,
pure cultures of mould. The schematic representation of tempe production is shown
in Fig. 4.5.
In small-scale industries in Indonesia, the dehulling of soya beans is carried out
in a wet process. The major advantage of this process is that the beans suffer very
less mechanical damage. This method is convenient only if sufficient water and
cheap labour are available. The major disadvantage associated with dry dehulling in
large-scale industries is the loss of soya beans. The split beans are then soaked in
fresh water at 30 °C for 3–20 h in order to increase the moisture content of beans to
enable microbial activity during fermentation. The soaking water is then discarded
and the beans are cooked in fresh water. The cooking is carried out at approximately
100 °C for about 20–30 minutes. The cooking time varies depending upon the
equipment being used. The hot water is then drained and the beans are exposed in
air and spread out on trays to cool down. The beans are then inoculated with the
sporangiospores R. oryzae, R. oligosporus and sometimes Mucor species. These are
then mixed homogenously spread out in layered beds of 3–5 cm in thickness.
Incubation of 2–3 days at 25–30 °C is sufficient enough for the spores to grow,
thereby allowing the growth of mycelium to bind the beans together into sliceable
cakes (Nout and Aidoo 2010).
R. Kumari et al.
1995). It has been shown that Rhizopus sp. can survive under low oxygen concentration (0.2%), but not under absolute anaerobic conditions (Lin and Wang 1991).
It has also been seen that tempe-forming Rhizopus sp. were capable of utilizing
raffinose as the sole carbon source for obtaining energy (Rehms and Barz 1995).
Mitchell et al. (1990) described the growth of Rhizopus oligosporus sp. on a starchy
model substrate as a multiple-stage process. The mycelium of the fungus penetrates
up to 25% of the width of cotyledon by puncturing several layers of soya bean (Ko
and Hesseltine 1979). An improved technique reported that tempe developed maximum strength after 30 h incubating at 30 °C, and later on the mycelium degenerated
gradually (Ariffin et al. 1994). Mixed inoculation of R. oryzae, Citrobacter freundii,
R. oligosporus and Brevibacterium epidermidis can result in the production of
tempe nutritionally rich in niacin, tocopherol, pyridoxine, riboflavin, biotin, vitamin
K and ergosterol (Wiesel et al. 1997).
4.4.5.2 Manufacturing Process
Predominantly, tempe is still a home-made or cottage-industry product manufactured in the areas of Indonesia and Malaysia. It is practically not known in Japan. It
has recently been introduced to the USA and to Europe, specifically for the population of Indonesian origin and for the expanding Indonesian restaurant trade. It is
made in modern, sanitary plants, using stainless steel equipment and sometimes,
pure cultures of mould. The schematic representation of tempe production is shown
in Fig. 4.5.
In small-scale industries in Indonesia, the dehulling of soya beans is carried out
in a wet process. The major advantage of this process is that the beans suffer very
less mechanical damage. This method is convenient only if sufficient water and
cheap labour are available. The major disadvantage associated with dry dehulling in
large-scale industries is the loss of soya beans. The split beans are then soaked in
fresh water at 30 °C for 3–20 h in order to increase the moisture content of beans to
enable microbial activity during fermentation. The soaking water is then discarded
and the beans are cooked in fresh water. The cooking is carried out at approximately
100 °C for about 20–30 minutes. The cooking time varies depending upon the
equipment being used. The hot water is then drained and the beans are exposed in
air and spread out on trays to cool down. The beans are then inoculated with the
sporangiospores R. oryzae, R. oligosporus and sometimes Mucor species. These are
then mixed homogenously spread out in layered beds of 3–5 cm in thickness.
Incubation of 2–3 days at 25–30 °C is sufficient enough for the spores to grow,
thereby allowing the growth of mycelium to bind the beans together into sliceable
cakes (Nout and Aidoo 2010).
R. Kumari et al.