| The Slow Route To Health: Lactic Acid Bacteria
The harmful effects of industrial bread on our health...
Industrial bread is made far too fast. If you leave dough long enough it ferments producing lactic acid - this is otherwise known as sourdough fermentation.
In Germany, Poland and Russia especially, the cultivation of lactic and acetic acids in traditional sourdough fermentation was valued for the flavour and digestibility of the local (mainly rye) breads. Industrial bread making does not allow sufficient time for the lactic acids to develop in the dough.
What is outlined here is the importance of lactic acid in our diet and the problems that may come about if we do not get enough.
Nutritional enhancement and bioavailability
More and more research is demonstrating the remarkable power of lactic acid bacteria, not just to control potentially harmful substances but also to enhance beneficial ones. For instance, sourdough rye bread has larger quantities of the antioxidant pronyl-L-lysine than breads made with an ordinary yeast fermentation. Sourdough fermentation has also been shown to more than double levels of folate, as well as enhancing levels of several other micronutrients and antioxidants. Baking bread using the long sourdough process may make minerals, especially magnesium, iron and zinc, more available to the body. |
Counteracting anti-nutrients
Lactic acid bacteria play a part in neutralising substances in wheat flour that can limit nutrient availability to human consumers. The bran layers on the outside of the wheat grain contain important sources of minerals such as potassium, magnesium, iron and zinc, but the bran also contains considerable amounts of phytic acid, which inhibits the absorption of these valuable minerals and trace elements.
Mineral deficiencies are widely reported in developing countries and even in France a survey revealed that 72% of men and 77% of women had magnesium intakes below the dietary guidelines. Wholemeal bread is one of the best sources of magnesium (it has three times as much as white bread) but much of it remains in accessible unless the phytic acid (phytate) is neutralised. A recent French study demonstrated that the action of the lactic acid bacteria in sourdough fermentation improves the nutritional quality of wheat bread by reducing the amount of phytate. Simple fermentation with yeast produced less than half the quantity of soluble (available) magnesium at the end of a four hour period compared with the sourdough.
All this raises serious questions about the bioavailabilty of important nutrients in fast systems used by industrial bakers. The industrial bakers are showing renewed interest in wholegrain cereals for their “healthy eating” ranges. It looks as though their ultra-fast doughs will be unable to deliver all the expected (and aggressively advertised) nutritional goodies.
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Glycaemic response
The production of acids by lactic acid bacteria can lower the body’s glycaemic response (the speed at which food raises blood glucose levels) to sourdough bread. This is potentially of greater significance than any glycaemic effect attributable to the difference in fibre content between wholemeal and white breads. In view of the enormous public health implications of obesity and diabetes, a natural way of reducing the glycaemic index of bread should be of great interest to responsible bakers.
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