As promised, I’ll feed you a little soaking grains research as I can unravel it. I have so many more journal articles to read, but I think I can at least define phytase and explain its definite and potential roles in phytate reduction.
What is phytase?
Phytase is an enzyme. An enzyme is a protein in a living thing that causes action. Scientists call them catalysts; I’d just call them doers. They make life happen. Enzymes are not always in an active state, but can be dormant and need certain conditions to be activated.
Imagine a vehicle sitting in your driveway. Unless you have the key, it’s just a large object blocking your path. Once you have the key, however, it becomes a mode of transportation and quite useful. Phytase is the key to starting the engine within the grain. Making the phytates move out of the way is not possible without the “key” of phytase. (Am I the Charlie Epps of nutrition? Maybe I’ll have a TV show someday.)
How does phytase work?
The action we want phytase to complete, if you remember our discussion of phytates and phytic acid, is to separate the phytates and phytic acid from one another, thus releasing phosphorus and other minerals trapped in that bond. When activated, phytase attaches to the phytate to help release the phosphorus (phytic acid).
Because it’s an enzyme, phytase must be alive in order to have the opportunity to be activated. Heat would damage or destroy the enzyme, so do realize that we’re only talking about raw foods here. Anything that has been cooked, baked, steamed (rolled oats???) will not have active enzymes.
Where is phytase found?
Phytase is in plants, including grains, as well as in the form of microbial phytase in yeast and sourdough leaven.
Various plants have differing amounts of the enzyme phytase. For example, wheat, rye, and barley have considerable amounts of phytase, whereas corn, oats, sorghum, and millet have little or no phytase activity. Baker’s yeast also contains phytase.
There is even some evidence of phytase in the digestive system, so some researchers think phytates are broken down to a certain extent by normal digestion. However, very few studies have been done on human digestion seeking phytase specifically.
Here is a key quote from one of them: “Studies in humans showed that 37–66% of dietary phytate is degraded during digestion in the stomach and small intestine when the diet is rich in plant food phytases.”(3) Note: remember that only raw plants, grains, etc count. The American diet includes much cooked food, therefore as a whole we are very low in phytases.
How is phytase activated?
There’s the rub. I have more to learn on this subject, but it’s key to understanding our issue of soaking grains. If phytates are going to be broken away from phytic acid, at least in non-intact grains that can no longer germinate (think flour), you’re going to need phytase. How to get it to leave its dormant state and work on the tough bonds is up for discussion to a certain extent, and I will come back to this topic again later.
One fact I know so far: phytase is activated through germination. That’s why we’re sprouting things this week here at KS. I like to focus on where the research findings are clear and well-documented, similar to last week’s challenge to start some sourdough because that is the most effective way to reduce the phytates in bread.
For cracked grains and milled flour, there are various perspectives on possibility, pH, temperature, and method for activating phytase. More to come!
Phytase in freshly ground grain
Enzymes degrade over time, and once the hull of a grain is broken, they’re more open to the processes that will break them down. Once a whole grain is milled into flour, the phytase content immediately begins to decrease. Therefore, to have the best chance of dissolving phytates and releasing minerals, one would want the highest phytase levels possible. Freshly ground flour is the optimal choice.
Some have asked if soaking or souring freshly ground flour defeats the purpose: if it’s sitting around soaking for so long, won’t the nutrients begin to fade anyway? Although I don’t have strong evidence for this, my common sense tells me that when you use freshly ground flour, the high levels of phytase are then activated by the souring (or perhaps, soaking). Once activated, they aren’t going to degrade. They’re already doing their job. That’s my hunch!
3 Phytate in foods and significance for humans: Food sources, intake, processing, bioavailability, protective role and analysis by Ulrich Schlemmer, Wenche Frølich, Rafel M. Prieto, and Felix Grases. Mol. Nutr. Food Res. 2009, 53, S330 –S375
4 Phytase activity and degradation of phytic acid during rye bread making by Merete Møller Nielsen, Marianne Linde Damstrup, Agnete Dal Thomsen, Søren Kjærsg˚ rd Rasmussen, Åse Hansen.