Phytic acid or phytate and soaking or sprouting

© CC-by 2.0, Kristina Fürst, Stiftung Gesundheit und Ernährung Schweiz

Pulses are soaked in water before cooking. Why? And what about nuts and whole grains? What exactly is the purpose of soaking and are there alternatives to soaking, such as sprouting?

Conclusion

Soaking nuts and seeds only makes sense if you eat them more often and in larger quantities. Pulses, on the other hand, should always be soaked for two reasons: to reduce phytic acid and to dissolve polysaccharides that cause flatulence.

1. What is phytic acid?

Phytic acid is a secondary plant substance and is found primarily in the outer layers of whole grains, nuts and seeds, as well as in legumes. It protects the energy reserves of the plant, which it needs for growth. Phytic acid also plays the role of warding off predators such as insects and other herbivorous animals.

Phytic acid has complex-forming properties and binds the minerals ingested by humans with food in the stomach and intestines, especially iron, zinc, calcium and magnesium . These are then in an insoluble form and are no longer readily available to the body. Unfortunately, this is often overemphasized, because just the long chewing and the gastric juices help the phytase to work. The term phytase refers to a group of enzymes that break down phytic acid. Phytic acid also has positive effects.

Function of phytic acid in the plant

Phytic acid is an inositol ring with 6 phosphate groups (IP6). This acid is a completely natural substance that plants use to store phosphorus.

© Public Domain, Harbinary, Wikipedia

When the seed has enough warmth and water available, life awakens within it. As soon as the germination process begins, the grain produces the enzyme phytase. The phytase breaks down the phytic acid into sugar and phosphate, thereby inactivating it and releasing the phosphate stored in it. This is now available to the baby plant as an important nutrient for growth and development. The phosphate-containing phytic acid thus has a similar energy storage function to ATP ( adenosine triphosphate ) in the human organism.

2. Effects on the human body

Phytic acid is useful for the germ, but not so for us:

• Phytic acid binds minerals and trace elements. These complexes are then not available to the body or are less available. This particularly affects minerals that are present in divalent or trivalent form, such as calcium, zinc, iron, magnesium and manganese .
  Iron and zinc appear to form a stronger complex than calcium and magnesium. Only with very high consumption of foods containing phytin can this lead to a mineral deficiency in the body in the medium to long term. ^1,2
• If phytic acid forms complexes with food proteins, these are insoluble or less digestible.
• Phytic acid can have an inhibitory effect on various enzymes, in particular it can inhibit the digestive enzymes pepsin and trypsin.

But phytic acid also has positive properties for us:

• Phytic acid appears to have an antioxidant and anti-carcinogenic effect. It is suspected that the chelation with iron causes the positive effect. This bond prevents iron oxidation, which reduces the risk of colon cancer. But phytic acid also appears to have positive effects on prostate, breast and pancreatic cancer. ^3,4
• Other health-promoting effects of phytic acid are also being increasingly discussed: a blood sugar-lowering effect by delaying the digestion of starch and an immune-boosting effect.

Phytin and its degradation products are also found in the human organism. The body produces them itself and uses them in particular as neurotransmitters, hormones and growth factors such as acetylcholine (ACh) or a hormone with an antidiuretic effect that promotes the reabsorption of water in the collecting ducts between the kidneys and bladder.

3. Occurrence of phytic acid in foods

Phytic acid is found in the outer layers of grains and nuts. In legumes, it is located in the endosperm.
Seeds and pseudocereals also contain phytic acid.

Corn, soy, wheat, barley and rye bran contain particularly high levels of phytic acid - or the anion phytate. Peanuts also contain a lot of phytic acid. In terms of phytic acid, pulses are somewhere between cereals and quinoa.

Since neither white flour nor polished rice contain outer layers, they are relatively low in phytic acid. White rice still contains around 240 mg. However, white flour products and white rice not only lack a large part of the original phytic acid, but also - in addition to a number of other useful secondary plant substances and fiber - most of the minerals that are also found in the outer layers.

It should be noted that the amount of phytic acid in a particular food also depends on the type of plant, the climatic conditions in which the plant is grown, the quality of the soil and, in particular, the use of phosphate-containing fertilizers. One should also be very careful with the figures given, as the values vary depending on the method used.

A distinction must also be made as to whether only the actual phytic acid with its 6 phosphate groups or also its derivatives with fewer phosphate groups are included.

Phytic acid: content of some foods (g/100g), Wikipedia

4. How to reduce phytic acid

The activation of the enzyme phytase occurs during soaking, the germination process, the production of sourdough and lactic acid fermentation as well as during digestion. Even prolonged chewing can break down some of the phytic acid. See below.

In addition, removing the aleurone layer from grains by hulling and grinding can significantly reduce the phytic acid content (but also the mineral content!).

4.1 Degradation of phytic acid during soaking and germination by the grain’s own phytase

Soaking and germination in combination with heat, water and light activates metabolic processes in the seed, which cause an enzymatic conversion or degradation of various substances. The nutrients are available to us humans after germination. The activated phytase in the grain breaks down the phytic acid enzymatically. The soaking water should not be reused, as it may still contain dissolved phytic acid.

When phytic acid is broken down, phytic acid derivatives are formed that have a different number of phosphate groups bound to them. Phytic acid itself has 6 phosphate groups. The inositol ring does not lose all of the phosphate groups at once, but rather they fall away one by one.

The aim is therefore to achieve the highest possible phytase activity. The industry therefore often adds phytases isolated from bacteria or fungi to accelerate the degradation process.

At home, you can take advantage of the different phytase activities of plants by combining foods that have little phytase activity with “phytase-active” foods.

Rye, wheat and buckwheat have relatively high phytase activities. Chickpeas, corn, rice, oats and soybeans have low phytase activity. ⁸ So if you can tolerate gluten, just add some rye or wheat. If you can't tolerate gluten, use buckwheat as an "accelerator".

In a study under laboratory conditions, husked rice (30%) and chickpeas (60%) were used, while buckwheat (10%) served as a phytase accelerator. After 200 minutes, the phytic acid was completely broken down when soaking with buckwheat, whereas without buckwheat, the amount of phytic acid after 200 minutes was as high as after 120 minutes with buckwheat. ⁸
The addition of phytase-active foods can therefore reduce the degradation time of phytic acid.

Heat destroys the enzyme phytase, the enzyme that breaks down phytic acid. ⁹ The industry practically always treats oats and oat flakes with heat, which is called "dried" but is not indicated on the product! It is very difficult to buy raw oats - or even oat flakes. It would therefore be better to buy naked oats or organic sprouted oats and turn them into oat flakes yourself using a mill/flaker. If you are deficient in the nutrients calcium, zinc, iron, magnesium and/or manganese, you can soak them in water overnight. Pour away the soaking water the next morning and process the oat flakes further.

EE: With Erb-Müesli, I have decades of daily experience with a short soaking time for a combination of seeds and even daily flaked sprouted oats. This is only the processing time before you start eating. There may be advantages to letting the muesli stand for a while before you eat it. But I never needed that. See my "condition" at 80 or 83 .

During soaking, the difficult-to-digest carbohydrates (such as the polysaccharide raffinose and stachyose and verbascose, which belong to the raffinose family) dissolve at least partially.

The small intestine can only break down and absorb raffinose to a small extent. Raffinose consists of fructose, glucose and galactose. It is normally not a problem for humans to digest fructose and glucose. However, we lack the enzymes needed to digest galactose. This means that larger amounts reach the large intestine. The anaerobic microorganisms of the intestinal flora present there utilize the galactose and produce, among other things, gases that lead to flatulence.

Since some of the raffinose dissolves in the spring water, the soaking water should no longer be used.

© Public Domain, Yikrazuul, Wikipedia

4.2 Degradation of phytic acid during fermentation

Microorganisms that also have the enzyme phytase are involved in fermentation or lactic acid fermentation. This breaks down the phytic acid during fermentation. Optimal conditions for enzyme activity are a pH value of 4.5 and temperatures between 45° and 55°C. This pH value is achieved when preparing dough with sourdough. ⁹

Under optimal conditions, fermentation can reduce phytic acid content by up to 90%. ⁹ Dishes made from fermented grains, but also seeds, nuts and legumes can be found in many traditional cultures - in combination with methods such as soaking (and then fermenting) or sprouting (and roasting). These are natural methods aimed at increasing both the digestibility and the health value of these foods. ¹⁰ Examples of such dishes are Kishk (from Arabia), Banku (from Ghana), Mawe (from Africa) and Injera (from Ethiopia).

4.3 Degradation of phytic acid during digestion

The body can also break down phytic acid in the gastrointestinal tract, but this seems to be directly dependent on the presence of activated phytases in the food itself: If they are present in the food (e.g. through fermentation or in raw food), the body can break down phytates by a total of 37-66%. The phytase inactivated by heating or other processing steps reduces the breakdown of phytates in the gastrointestinal tract to 0-28%. ^11,13

5. This is how much phytic acid can be reduced

Legumes

Soaking beans for 24 hours and then cooking them for a longer period of time can reduce phytic acid by 50%. A study with peas and lentils even found 80%. However, legumes contain less phytase than most grains and there are also studies that report a reduction of less than 10% in phytic acid when soaking legumes. The soaking times for legumes vary and range between 6 and 24 hours.

Nuts

There is not yet enough adequate information about soaking and sprouting nuts to say with certainty how much phytic acid can be removed by this process.

Many indigenous peoples in America soaked their nuts in water and then dried or roasted them.

Eating large amounts of nuts - such as using almond flour instead of regular flour when baking or eating peanut butter every day - can result in high doses of phytic acid.

However, it is known that citric acid can significantly improve the absorption of minerals despite phytic acid. A glass of orange juice or a splash of lemon juice with a nut-rich meal can help to significantly improve iron absorption. See Erb-Müesli .

When is it beneficial to soak nuts?

• If you want to process and eat large quantities of nuts, e.g. for a raw food cake, for nut bars or nut sauces.
• If you make your own almond milk, it doesn't take much extra effort to soak nuts for a quick snack.
• If you eat large amounts of nuts and have an iron deficiency, for example.

When is it not beneficial to soak nuts?

• If you eat only a few (4-10 pieces / day) and have enough iron in your blood.
• If the nuts are already roasted.

An exception is the coconut, which is not a nut either, but a stone fruit. It contains no or very small amounts of phytic acid. For centuries, the coconut has been considered a traditional raw food that people in the countries of origin have always enjoyed without "processing". However, it has a very poor ratio of omega-6 to omega-3 fatty acids and contains too many saturated fatty acids (see coconut oil ).

Grain

One study examined the reduction of phytic acid in quinoa and found that soaking before cooking reduced the phytic acid content by about 50%. Fermenting before cooking reduced the phytic acid by about 60%. Cooking, on the other hand, only reduced it by 20%. ¹²

With brown rice, which has a high proportion of phytic acid, the effect of soaking is less. The same applies to oats, because they are dried.

However, untreated (unheated) rice and oats show a better reduction in phytic acid through soaking. This is caused by the higher proportion of the enzyme phytase, which is originally contained in these types of grain. ^12,13 In addition, the process can be accelerated by using orange and/or lemon juice to improve the nutritional value of seeds or grains for a very short time. Mandal and Biswas showed in 1970 that the opposite is true for mung beans (pH 7.5 is the most favorable value at 57°C, according to Paula Brünig 2009).

6. Guidelines for soaking nuts, seeds, pulses and grains

Basically, a distinction is made between germinated seeds (1), seedlings (2), sprouts (3) and sprout greens (4). In germinated seeds, which typically germinate for 24 hours, the seed has released its actual life force (e.g. citric acid, malic acid, etc.) and broken through the testa (seed coat): the seedling is perhaps one millimeter in size, a real "vital product" or superfood. This seedling sprouts (grows) in a moist environment (warm, sometimes dark) to form sprouts (3) and then produces leaves (4). It is still the ingredients of the seed that allow growth. If this supply is exhausted, the seedling begins to die (starve) without any further substances (if the seed is very small) and the decomposers (bacteria/fungi) can attack it. Larger seeds produce larger seedlings, sprouts. When planted or in a nutrient solution, the sprout greens develop, and ultimately the plant.

How long the soaking takes varies from legume to legume and from grain to grain. It is often easiest to soak overnight in twice the amount of water. You can also let the seeds drown - and the decomposers will appear: So if in doubt, use the shorter time if you want them to germinate; the longer time if you want to eat them straight away.

Some guidelines for soaking times as well as germination times are given in the table below. The soaking times apply to both germination and eating or cooking - in the next column.

The cooking time varies greatly and is between 30 minutes and 180 minutes (red and yellow lentils only 15 minutes). Grains and pulses should only be boiled briefly and then cooked over a low heat. If the pulse or grain has a soft bite, it is cooked sufficiently.

6.1 From germination to sprouting greens

© CC0, Stux, Pixabay

Sprouts and seedlings are small, healthy sources of nutrients that you can easily grow yourself if you follow a few tips. See the instructions. The small seeds contain everything the plant needs for later growth, including numerous vitamins and minerals.

Sprouts are digested food. They are pre-digested, so to speak. This means that even sprouted grains can easily be eaten raw. During the sprouting process, numerous complex nutrients and enzymes are formed, which make the sprout much more valuable than the bare seeds. However, after 24 to 48 hours, the transformation into a plant begins and numerous "nutrients" are converted back into "normal" ones.

A seedling is the young plant that develops fresh from the germ. It includes both the roots that develop later and the above-ground parts. Strictly speaking, however, sprouts are only the above-ground parts, i.e. only stems and leaves.

In the table below, germination time refers to the time it takes for a seed to grow to the point where it can be harvested as a sprout.

Basically, all types of grain can be germinated, as can grains such as sunflower seeds or pseudo-grains such as quinoa and canihua. Pulses and nuts can also be germinated.

7. Instructions for sprouting

You don't need much to grow sprouts. A propagator, organic seeds and a little patience are all you need. In the simplest case, all you need is a clean screw-top jar with a lid and a few holes drilled into it. If you want to enjoy seedlings and sprouts more often, we recommend a sprouting jar or a multi-tier propagator.

1. Prepare glasses

The jars and tools should be boiled and clean, as the young plants are very susceptible to mold.

2. Rinse seeds

The seeds used should also be clean. To do this, rinse the seeds thoroughly with water over a sieve.

3. Soak seeds

The seeds must be soaked in water for several hours before they can germinate. The seeds can use the water they absorb to start the germination process. The soaking time varies between 4 and 12 hours (see table below), but rice takes longer.

4. Growth of sprouts

After soaking, rinse the seeds for the first time by pouring away the soaking water and filling and draining it again with fresh water. During the germination period, the jars should be placed in a bright but not sunny place. Others should germinate in the dark (dark germinator). To prevent waterlogging, place the jars with the opening (sieve lid or water-permeable fabric) facing downwards. Do this in such a way that the water can drain away. Rinse the seedlings two to three times a day with fresh water and allow them to drain well.

Some types of seeds develop roots covered with white fluff after one to three days. This should not be confused with mold.

5. Harvest

After the recommended germination time, rinse the sprouts one last time and then enjoy them raw, fresh and crisp. They can be used to enhance fresh dishes and salads in a variety of ways.

Various websites recommend blanching mung bean sprouts - usually just copied from others... There is no reason to do so.

Grain sprouts tend to have a mild and sweet taste, while radishes, cress and lentils have a sharp, spicy taste. Beans and sunflower seeds have a nutty taste.

Please note (this information is indicated in the table below by three stars: ***)

Never eat pulses raw: They contain the toxic protein phasin. The protein denatures after 20 minutes of cooking and is then non-toxic. Peas and sugar snap peas are an exception, which can be eaten raw. However, after the specified soaking time plus germination time, pulses are also edible raw and are particularly healthy.
Mucilage-forming sprouting seeds: basil, buckwheat, chia, cress, linseed, arugula (rocket), mustard.
Dark germinators: broad beans, adzuki beans, amaranth, anise, cauliflower, broccoli, peas, chickpeas, beetroot. Usually larger seeds that can fight their way to the light on their own. Legumes in particular can be easily germinated covered with a paper tissue or cotton wool, for example to show children the process.
Particularly suitable for raw consumption after germination: ²³ amaranth, fenugreek, brown millet, spelt, fennel, cress, linseed (linseed), beetroot, arugula (rocket), mustard, sunflower, wheat.
Particularly popular: cress (kindergarten etc.), alfalfa, broccoli, radishes, mung beans (simple).
Seeds: Sprouts from oil-containing seeds such as linseed (linseed), sesame, chia, and sunflower seeds are more susceptible to spoilage. The seeds must be in particularly good condition. It is better to just let them germinate.

Alfalfa: Fresh and salad-like (particularly healthy ²² ). Light germinates.

Fenugreek : Spicy, bitter if left to germinate for a long time.

Pea shoots: Dark germinators - and like runner beans (beware of lectins), they have cotyledons that remain in the soil (hypogeic germination), while in epigeic germination the cotyledon dies later (steamykitchen com), but carries out the first photosynthesis until the next leaves appear. Sugar snap peas can be eaten directly with their tender pods.

Kidney beans: Dark germinator. Variety of common bean. Red kidney beans (Phaseolus vulgaris) are easily confused with the adzuki bean (Vigna angularis) or the runner bean (Phaseolus coccineus).

Flaxseed: Tends to produce mucus, rinse more often.

Lentils (4-5 mm are sugar lentils; medium lentils (5-6 mm), plate lentils (6-7 mm), giant lentils are larger): dark germinators. Seeds only germinate when they are raw and not spoiled or peeled! Because you can also see red and yellow lentils on websites, we have included them in the list, but they no longer germinate because they are peeled, just like peeled lentils. Yellow lentils are made by peeling brown or green lentils. Unpeeled red lentils have a darker shell color (depending on the country of origin), which is why they are often referred to in stores as brown, purple or black lentils. See the ingredient Lentils, raw .

Lupins: Dark germinators. They are a special case because traditional varieties are placed in salt water for 14 days.

Mung beans: Dark germinators. They are particularly easy to handle - they need darkness if they are to taste good! They need a lot more water to soak, as they can absorb up to 7 times more water than their dry weight. Room temperature from 18 to 22 degrees (or more) and you should water them 3 times a day when germinating. They are edible raw after 3 days of germination ( Wikipedia ). After the fourth day they are discolored and have a bitter taste and are no longer as tender. This bean is more digestible than the European garden bean (e.g. it does not contain phasin) and does not cause flatulence (it does not contain any indigestible triple sugars). Suitable for beginners. See mung bean sprouts .

Wheat and rye: Sweet, only tasty when young.

Unfortunately, you often see other numbers on websites, for example a germination time of 6 to 7 days for quinoa - completely unrealistic. Not only do the sprouts break off easily when washed - they also cannot develop further without soil due to the low nutrient content and are more likely to spoil. Once again: When soaking, it is important to note that the longer times in brackets are only suitable if you eat after soaking without further germination, because the sprout can drown and harmful microorganisms develop during germination.

If you want to enjoy the prime of the development of "nutrients" such as citric acid, malic acid, etc. - the actual superfood - you only need to soak them for a few minutes (if at all) and then let them germinate for 24 hours, no more - except for rice. If you want to learn more about the subject, you should read this Wikipedia article in English.

Generally, at the beginning of germination, the main nutrients that are produced or multiply are vitamin B₁, vitamin B₂, vitamin B₆, vitamin K (up to ten times as much), folic acid, and vitamin C. The amino acid content (proteins, especially lysine ) increases, as does the content of the omega-3 fatty acid ALA (alpha-linolenic acid) . Enzyme activity and fiber also increase. Phytic acid, flatulent substances, tannins, protease inhibitors, starch content, and calorie content (water) are (desired) broken down. At least the green parts of alkaloid-containing seeds from the nightshade family ( aubergines, potatoes, peppers, tomatoes ), lupins, and soy (biothemen de) must not be eaten. Solanine can only be reduced by heat, in contrast to phytine.

A completely different issue is germinating kitchen waste, vegetable scraps, etc. Beetroot, celery, onions and garlic are particularly suitable for this. Simply place them in a plate with a little water and a sprouted onion or garlic will produce excellent tasting shoots that can grow up to 15 cm long. Of course, ginger and turmeric can also be propagated in a pot. But celery also grows back, as do carrots, romaine lettuce, kohlrabi, leeks, etc. You can eat the greens or allow them to develop into a plant in a pot.

8. Mineral absorption

How many minerals the body ultimately absorbs – even if the phytic acid is removed – is still difficult to predict and there are still too few meaningful studies.

The combination of foods also plays a major role. In one study, the phytates from cereal porridge for children were industrially removed and iron absorption was then examined. If the porridge was mixed with milk, as recommended on the packaging, no improvement in iron absorption was observed. If the porridge was mixed with water, a significantly better iron absorption was noted. ⁹

Studies on the consumption of whole grains have shown that although complex formation removes minerals from the body, the high mineral content in whole grain products also compensates for these losses.

Literature - Sources: