Alright, here goes a cooking science post …scary! I’ve been reading a lot on some bio-chemistry topics recently and I feel like I can barely see above the surface of the ocean I’m swimming in. I’m hoping for some interest in conversation online to clear up a few questions I have. Before I can ask them though, I’ll have to write a few posts about what I currently understand.
Today’s topics are phytic acid and phytase, what they are, where they’re found, and how are bodies react to it. (And you’re probably wondering about the snowflake robber… so just keep reading.)
This is what we call the phosphorus inside a phytate bond. Unless already hydrolyzed though, phytic acid cannot supply phosphorus to the human body since the human digestive tract is unable to absorb it while it’s still bound with phytates. These bound up molecules are structured like a snowflake, with several “arms” sticking out all around.
In the human body, these “arms” coming out from the phytic acid molecules will grab other minerals they come in contact with and bind with them (particularly calcium, iron, zinc, potassium, and maganese). This means that for humans to consume bound phytic acid we will not only miss out on some added phosphorus, but other minerals our body would otherwise benefit from are now being stolen by this phytic acid snowflake robber. Since mineral deficiencies lead to a wide variety of health problems, too much phytic acid can make a person very sick. Diminishing phytic acid in food could allow bodies to absorb up to 20% more zinc, and 60% more magnesium than they would when consuming food with natural phytic acid levels.
Phytase (The good guy who melts the snowflake robber)
This is an essential enzyme for good digestive tract and bone health. The enzyme is found in plants and catalyzes the hydrolysis of phytic acid into a usable form of phosphorous for the plants.
Human bodies will typically not produce phytase, but by adding lactobacilli into our gut microflora there will be some production of this important enzyme—making it easier for humans to digest food with phytic acid.
This enzyme is killed if frozen, left at about 176 degrees for ten minutes, or if left soaking at 131-149 degrees, for this reason the naturally present phytic acid in plant-food can only be used to human advantage if food is kept under these temperatures while preparing. Phytase also dies off as it’s stored, so for this reason it’s best to grind flour (using a grain mill) fresh right before it’s needed.
The amounts of phytase within plants vary, but its levels are high in some grains including wheat, rye, barley and buckwheat and particularly low in corn, millet, brown rice and oats. With proper preparation nearly all the phytic acid can be neutralized from food. 8 hours of wheat or rye fermentation using a wild yeast starter is sufficient to neutralize all the phytic acid within grains rich in phytase, and a food like rice, which hardly has any phytase in it but is very high in phytic acid, can have 96% of the phytic acid eliminated be soaked for 24 hours using the accelerated soaking technique.
Reducing Phytic Acid
Phytic acid can be reduced dramatically in seeds, grain, beans, and nuts through particular food preparation strategies that break the phytic acid apart from the phytates. These strategies include sprouting, soaking (in non-acidic liquid, or acidic liquid), fermenting and cooking (cooking is less effective than sprouting or fermenting); sometimes two or three processes are necessary to reduce the phytic acid as much as possible. Roasting will greatly reduce phytic acid as well, but will kill the phytase enzyme within the food.
Soy products, sesame seeds, Brazilian nuts, bran and almonds are exceptionally high in phytic acid levels.
How does this information affect us?
You may be under the strong impression all whole grain products are good, and all white flour is bad. Knowing about phytic acid, understanding the molecular makeup of food, and how good and bad qualities are either maximized or diminished helps us really understand what makes a product nutritious, or not. 100% whole grain bread for instance, while we think of it being oh-so-healthy (unless you’re gluten intolerant), can actually be low in nutrition and even detrimental to our bodies in some cases:
- If the phytic acid is left bound our bodies will be starved of essential minerals.
- Consuming bread prepared without a pre-breakdown of the grain’s complex carbohydrates our digestive tract would be unable to stand up to its tough task. It would work so hard, gaining little headway which would leave us feeling worn-out.
- Unless flour is milled fresh, many nutrients and enzymes will die before the flour is used. This is one reason it’s so much better to grind flour fresh in your home than to buy it in the store already packaged.