Soaking has been a method used for centuries by indigenous populations all over the world. Our ancestors may not have known the biochemical reasons for why this was the best practice, but they continued to soak their nuts, seeds, beans and grains to avoid deficiencies and to improve digestion of these foods.
A step carried out before cooking beans and grains,
The initial step prior to sprouting nuts, seeds, beans and grains, and
A practice that is encouraged for those consuming nuts and seeds in its raw form
Benefits of Soaking:
Reduces phytic acids
Reduces tannins and polyphenols
Promotes production of beneficial enzymes (serves to further reduce phytic acids and polyphenols)
Improves the body's ability to absorb minerals such as iron, zinc and calcium
Makes proteins more available for absorption
Reduces anti-nutritional enzyme inhibitors
Removes gas-causing compounds
Decreases cooking time and improves food texture
Reducing Phytic Acid
Phytic acid (also known as phytate) is a compound commonly found in cereals and grains that binds to certain proteins and minerals such as iron, zinc and calcium, thus minimizing their availability for absorption in the small intestine. Processes that remove or degrade phytates have been shown to improve the absorption proteins and some minerals (see this, this, this, this, or this publication for more information).
Soaking decreases phytate content of foods in two ways:
It increases the activity of enzymes, called phytases, in the seed that breakdown the phytic acid molecule (see this publication for more information).
Some phytate molecules leach into the water that is drained and discarded (as pointed out in this, this, this, this, and this publication). The amount of phytic acid decreases as soaking time increases.
Reducing Tannins and Polyphenols
Polyphenols are found in a variety of fruits, vegetables, grains, beans and nuts, in addition to some beverages. Tannins are a subclass of polyphenols.
Dietitian's Intermission: You may have heard of this compound in your coffee, tea, red wine, and dark chocolate. Polyphenols and tannins are what give these foods their bitter and astringent characteristic traits.
Polyphenols have been recognized as the most abundant source of antioxidants in our diet. However, they bind to positively charged mineral and proteins, making them unavailable for absorption by the human body (see this, this, or this publication for more information). Reducing levels of tannins and polyphenols through soaking enhances the body's ability to absorb minerals such as iron, zinc and calcium, as well as proteins in foods including chickpeas, mung beans, lentils and peas.
Similar to phytates, soaking serves to reduce polyphenol and tannin concentrations in two ways:
Soaking activates the enzyme polyphenol oxidase, resulting in breakdown and loss of polyphenols (see this, this, or this publication for more information).
Losses may result simply from leaching into the soaking medium, as these compounds are water-soluble and are mostly located on the seed coat (per this and this publication).Significant reductions are observed in the levels of phenolics and tannins during the first 2–4 h of soaking in water.
Reducing Enzyme Inhibitors
Leguminous crops contain several anti-nutritional factors that bind beneficial enzymes, thus decreasing their activity. Removal of these factors (which includes trypsin and chymotrypsin inhibitors, proteolytic enzyme inhibitors, oligosaccharides and lectins) improves the availability of nutrients present in these foods. Several studies have recognized the importance of soaking in order to discard these compounds in the soaking water.
Reducing Flatulence (a.k.a. Gas, Bloating, Farting)
Eating large quantities of beans is known to cause flatulence (gas) in humans; a result of oligosaccharide compounds. Animals with one stomach, such as humans, cannot break down these oligosaccharides due to the lack of an enzyme in the small intestine. As a result, naturally occurring bacteria in the large intestine use these undigested oligosaccharides, producing gases as a result that then cause abdominal rumbling, diarrhea and discomfort in some people. Soaking beans prior to cooking has long been shown to reduce the degree of flatulence experienced.
Dietitian's Recommendation: When soaking beans, discarding and re-filling the soaking water several times during the soaking period helps to remove more of these gas-forming compounds than one single soak.
Improving Texture and Cooking Time
In addition to the removal of flatulence-causing compounds, soaking of beans before cooking is also a common practice to soften texture and quicken the cooking process. Soaking the seeds for several hours increases the water in the seeds which accelerates chemical reactions, such as starch gelatinization, during cooking.
The health benefits of consuming nuts, seeds, beans and grains are many. By simply soaking these foods before preparing or eating them, the anti-nutritional properties can be significantly reduced. A vast array of literature has demonstrated the varied benefits of soaking, including increased nutrient availability and overall digestibility, as well as quicker cooking times. Soaking between 2 - 8 hours is recommended, but even a few minutes is better than nothing at all. When soaking un-cooked beans and lentils, discarding the soaking water and re-filling with fresh water one or two times during the soaking period helps to decrease the gas and bloating that may result from eating these foods.
Want To Learn More?
Read this other nutrition article called BONE HEALTH » introduction & osteoporosis
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❤ Written by: Sadia