Tempe is usually eaten in Indonesia. The micro fungus Rhizopus oligosporus is traditionally used there to ferment mainly soya beans to tempe. It is the metabolism of the fungus which in a beneficial way, inter alia through the synthesis of enzymes, increases the content and accessibility of proteins, minerals and vitamins. In her thesis, Charlotte Eklund-Jonsson has developed and adapted tempe fermentation to barley and oats, two Swedish cereals known for their good health giving properties. The aim was to produce a vegetarian food that preserves the rich mineral content of whole grain and their high fibre content, which benefits health and promotes absorption of the nutrients in the gut.
Hardy cereals
Cooperative partner Svalöf Weibull helped select varieties of barley and oats which contain a lot of minerals and soluble dietary fibres. The barley also contains a large proportion of the starch amylose which can contribute to a low glycaemic response (low GI). Both barley and oats are unusually hardy cereals. Barley tolerates both cold and drought and can grow on both alkaline soils and soils with a high salt content. Oats tolerate cold and wet conditions better than either rye or wheat. The choice of domestic cereals also benefits the environment since they need not be transported over long distances.
Important minerals
A vegetarian diet has been shown to have favourable health effects, such as a low systolic blood pressure, reduced risk of cardiovascular diseases, and higher contents of antioxidants in the blood. At the same time, vegetarians run a certain risk of having an inadequate intake of minerals, mainly iron. One of the reasons is that plants contain substances that prevent effective uptake. With the fermentation, Charlotte Eklund Jonsson wanted to break down the phytate present in cereal grains which prevents the uptake of minerals. Tempe fermentation has also been found to increase the folate content – the Vitamin B that is necessary for foetal development and can protect against a number of diseases. One of the challenges was to keep the cereal grains whole, which is needed for the low GI value.
Test subjects were asked to eat tempe, and a corresponding meal had to pass through a computerised gastrointestinal model in which the fractions during digestion could be investigated. The results showed in both cases that tempe fermentation of barley produced an increase in accessible iron and good accessibility of folate. Tempe from both barley and oats also has a low glycaemic index and low release of insulin.
Tempe from barley and oats has been developed in cooperation with Swedish Farmers' Food, and Charlotte Eklund-Jonsson is hoping that whole-grain tempe will be launched by Swedish Farmers.