Asians, particularly the Indonesians, have introduced meat-like textures into vegetable substrates. A prime example is Indonesian tempeh in which soybeans are soaked, dehulled, briefly cooked, cooled, inoculated with the mould Rhizopus oligosporus, wrapped in wilted banana or other large leaves, and fermented from 36 to 48 hours. During this time the white mould-mycelium knits the soybean cotyledons into a tight cake that can be sliced thin and deep-fat fried or cut into chunks and used in soups (20 - 22). Tempeh is a major meat substitute in Indonesia, and it is produced daily by small factories in the villages.
Containing nearly 47 per cent protein, it is very nutritious and, in fact, kept thousands of Westerners alive in Japanese prisoner-of-war camps during World War I I. The mould not only introduces texture, but it also solubilizes the proteins and lipids, making them more digestible. It releases a peppery flavour that adds to the nutty flavour of the soybean substrate. The mould doubles the riboflavin content, increases the niacin level by almost seven times, decreases pantothenate slightly, and, unfortunately, decreases thiamine content, but surprisingly vitamin B12 is found in nutritionally significant amounts (23).
One of the problems of vegetarian diets is that vegetable foods generally do not contain significant vitamin B12. It was found that a bacterium sometimes present in the mould is responsible for the vitamin B12 in tempeh (24). If the fermentation is carried out with pure mould, the tempeh does not contain B12. If the bacterium is present, the tempeh will contain as much as 150 mg B12 per g. Thus, this single food provides both protein and vitamin B12 for vegetarians.
There are at least five vegetarian communes in the United States today (for example, The Farm, Summertown, Tennessee) where tempeh has been adopted as the major protein source, replacing meat in the diet. In California, Nebraska, and Canada (Toronto), there are at least six small factories producing tempeh commercially. The acceptance of this Indonesian food technology in the United States and Canada suggests that the technology could also be extended to developing countries, thus improving the diversity and nutritive value of the diets of the poor.
It has already been demonstrated that the tempeh process can be used to introduce texture into other substrates made, not only from soybeans, but from wheat and other cereals as well (25). A bacterium has also been used to raise the content of vitamin B12 in Indian idli, which is made by fermenting a batter of ground soaked rice and black gram dahl with Leuconostoc mesenteroides (26).
There is a similarity between the Miller, Rank, Hovis, MacDougall meat analogue process discussed above and tempeh production In both cases, the texture is derived from mould mycelium, but the former process is sophisticated and relatively costly, while the latter is low-cost technology.
B12 from plant fermentation
or beef extract (0.05%), added as protein sources to the inoculated kimchi, further increased the vitamin activity to 197 and 203 ng/100g, respectively, at 1 wk. The fresh, unfermented kimchi contained 16.8 mg of ascorbic acid per 100g and the vitamin decreased at a constant rate during the first 5 wk of fermentation.
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