Biotechnology Homework Help: Fermented Foods
A variety of foods are produced by fermentation, mainly in Asia and Africa, but some of the processes are now used worldwide. Initially, it was noted that natural growth of certain microbes on grains, mostly cereals, improved their flavour, texture and nutritional value. According to homework help web site this prompted detailed studies on the various conditions required for obtaining quality products. Later, the micro-organisms were isolated and their strains were improved. Most fermented foods are produced by solid substrate fermentation and several of them are processed on an industrial scale. These processes are called koji in Japan; some of the koji processes have been adopted in the west as well e.g. Tempeh.
Problems in solid substrate fermentation
The koji or solid substrate fermentation processes present the following difficulties: (i) they are difficult to scale up, (ii) it is difficult to monitor and control the various factors, e.g. pH, temperature, nutrient distribution etc. during the process, (iii) gas exchange, i.e. O2 supply and removal of CO2 presents problems and (iv) heat transfer and removal are not as easy and efficient as with liquid fermenters.
However, according to studydaddy.com/homeworks-answers the fermentation systems are low cost and simple devices and their power requirement is very low.
Advantages of fermented foods
The fermented foods offer the following advantages: (i) improved flavour, (ii) elimination of undesirable flavours, (iii) improvements in the texture of food, (iv) enhanced nutritional value (higher levels of proteins, minerals, vitamins and even antibiotics), (v) increased digestibility an reduced (vi) cooking time. Some of the fermented foods are used as valuable supplements in preparation of certain dishes. For example, tempeh is a protein-rich, good flavoured fermented food; it is used as a meat supplement in Europe and USA.
A general procedure for the production of fermented foods may be as follows: (i) seeds are soaked in water (and may be dehulled in some cases), (ii) the seeds are either cooked by boiling, e.g. tempeh, miso etc. or ground into a paste, e.g. idli, sofu etc. (iii) the substrate is then inoculated with the appropriate microbial strain and incubated at the specified temperature, and (iv) after the desired period of fermentation, the fermented food is either prepared and used, stored or processed further to obtain usable food products.
The soybean seeds used for tempeh preparation are soaked in water 12-18 hr. and dehulled (seed coat is removed). The dehulled seeds are then boiled in water for 30-60 min. cooled and dried to the desired moisture level by natural evaporation of moisture; excess water is drained off after boiling.
According to chemistry homework help experts the boiled and dried seeds are inoculated with spore suspension of Rhizopus oligosporus and incubated at 30˚C for 2-3 days. Usually, the seeds are wrapped in banana leaves as small packets and incubated in shallow pans. At the end of incubation, the seeds become completely covered with fungal mycelium. The fermented seeds are now pressed into cakes, tempeh cakes, which may be stored or used. Thin strips of tempeh are deep-fried and eaten, while larger chunks are added to soups or meat preparations.
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