Why soak and sprout
Anti-nutrients are a plant’s chemical defense against invaders to ensure its survival and reproduction. They function as the immune system of the plant, offering protection against bacterial, fungal and viral infestations, insects and foraging animals. Anti-nutrients occur in particularly significant amounts in seeds – grains, beans, nuts and seeds. The most studied anti-nutrients include phytate, lectin, enzyme inhibitors, tannins, and non-starch oligosacchairdes. When ingested by humans, anti-nutrients found in plant foods limit or inhibit nutrient absorption, stimulate immune response and cause general negative effects on nutrition.
Soaking, sprouting, fermentation and cooking applied to plant produce has been proven to reduce the anti-nutrients found in seeds and maximize nutrient bioavailability for the human body. Such are ancient practices that date back 12,000 years. Whether our ancestors understood the scientific theories behind such practices or not, they definitely understood the benefit of slow-processing for improved health and vitality!
Understanding the different anti-nutrients
Phytic Acid Binds Minerals
Phytate is the principal storage form of phosphorous in grain, legume and nut seeds where it rapidly accumulates in the developing seed during ripening. The majority of phytate is concentrated in the bran for grain seeds, whereas it is uniformly distributed throughout the cotyledons for legume seeds. Tubers, leafy vegetables and fruits contains less amount of phytates, and animal foods contain none.
Phytic acid has a high affinity for divalent mineral ions calcium, magnesium, zinc and iron. The function of phytic acid during germination is to release the chelated minerals and supply the nutritional needs for seedling germination and growth upon hydrolysis by the enzyme phytase. Unfortunately monogastric animals including humans do not produce sufficient amount of phytase. Instead, phytic acid binds minerals thereby reducing their availability in the human body. Mineral deficiencies occur in populations that subsist on unleavened whole grain bread, usually in undeveloped countries, attributed to the presence of phytate.
Phytate is considered to be fairly heat-stable. Soaking followed by sprouting or fermentation and then cooking is most effective method to reduce phytate concentration.
Enzyme (Trypsin) Inhibitors Block Digestive Enzymes
Protease inhibitors including trypsin inhibitors are present in considerable amounts legume seeds, particularly soybeans, where they may serve as inhibitors of proteases in tissues during synthesis and storage of protein prior to dormancy, where there is a need for protein accumulation. Ingesting poorly prepared or partially cooked legumes with residual protease activity inhibits intestinal protein digestion. Rats fed raw soybean meal exhibited depressed growth and pancreas hypertrophy through negative feedback regulation, further depleting protein availability.
Enzyme inhibitors may be denatured by cooking at high temperatures.
Lectins Bind Sugars On Intestinal Epithelial Cells
Lectins are sugar-binding glycoproteins found particularly in the bran-rich outer coating of grains – wheat, rye, barley, oats and spelt – bean skins, nightshades and some nuts. One of the best known examples of lectin toxicity is incomplete cooking of red kidney beans, which causes diarrhea, malabsorption, and growth reduction in rats. Lectin toxicity is mediated in part by altering gut permeability and activating immune responses. Their interaction with surface glycans on intestinal epithelial cells is said to damage villi and cause increased intestinal permeability (leaky gut). A leaky gut permits passage of bacteria and their endotoxins into the systemic circulation which cause immunological stimulation. Autoimmune diseases associated with leaky gut are rheumatoid arthritis, Celiac disease, type I diabetes, and multiple sclerosis.
Lectins are fairly resistant to cooking and to digestion by stomach acids. They may be reduced by soaking, sprouting, slow-cooking, or fermenting.
Tannins Bind Proteins
Tannins are a group of polyphenols that produce sensations of astringency characteristic of wine. Its name pays homage to “tanning” process in the leather making, where extracts of plants are used to cure leather into hides. This process exploits a key property of tannin: to crosslink proteins. Tannins are widespread in the skins of fruits, beans, cocoa and certain grains such as sorghum and millet. Ingested tannins may bind dietary protein which reduces the amount of bioavailable protein for metabolism, or bind proteins of the microflora and reduce the efficiency of fiber fermentation, or bind and reduce the efficiency of proteolytic enzymes. The salivary proteins proline-rich proteins (PRPs) and histidine-rich proteins (HRPs) are believed to bind efficiently to tannins to mitigate this effect by producing the unpalatable astringent taste and act as a defense.
Raffinose Oligosacchairdes Ferment and Cause Flatulence
Raffinose-family oligosaccharides (raffinose, stachyose and verbascose) are found predominantly in the cotyledons of beans. These sugars are non-digestible by humans due to the lack of alpha-galactosidase in the intestinal tract. Instead, they are metabolised by colonic bacteria leading to flatulence and stomach upset.
Like phytate, raffinose may be reduced by soaking followed by sprouting or fermentation and then cooking. Mobilization of raffinose sugars by the bean during germination results in sprouts with improved nutritional value compared to the raw seed. In addition, raising the pH by adding baking soda during cooking helps alkaline hydrolysis of pectin in the bean skin and aid the release of anti-nutrients.
methods to minimizing anti-nutrients
Soaking, sprouting, fermenting, and heat application are the four major ways to reduce levels of anti-nutrients. However, each anti-nutrient may be more sensitive to a specific method as detailed below. In general the longer you allow the seed to continue on its program of activation or fermentation, the greater the reduction of anti-nutrients. Below is a chart depicting a general process with specific conditions highlighted as necessary.
Soak first in the optimum condition for the type of seed
Moisture activates the phytase enzyme that breaks down phytic acid. Grain phytases work best in weakly acidic pH between 5 and 5.5 whereas legume phytases require a more alkaline pH of 8.0. The temperature optimum falls between 45°C and 65°C. Many studies on different types of grains and legumes have confirmed the positive effect of soaking in reducing phytate levels by up to one-third within 24 hours.
Allow the seed to sprout
Sprouting or germination is the next level of seed activation. Sprouting occurs within two to three days of soaking, and over the time course activated enzymes bring about a maximal decline of anti-nutrients. In addition, sprouting changes the nutritional profile of the seed. Sprouting typically lowers carbohydrate content, while increasing essential fatty acids, protein quality, dietary fiber and vitamins, in particular vitamin C. Overall sprouting increases the nutritive value beyond soaking.
Let it ferment!
Almost anything can be fermented, whether soaked, sprouted or cooked, thanks to the ever-present lactobacillus bacteria that convert sugars to lactic acid. More tips and techniques over at the fermentation page!
Leverage on high phytase complementary grains
Certain grains have higher intrinsic phytase activity and we can use these grains to complement low phytase grains during soaking. Whole raw buckwheat, wheat, barley and particularly rye have high phytase activity, whereas corn, rice, oats, maize, millet and sorghum do not contain much phytase activity. The latter grains will benefit from the addition of the aforementioned high phytase grains to the soaking batter.
Soaking, Sprouting and Harvesting Times
|Soak Time (hours)||Sprout Time (days)||Harvest Length|
|Nuts. Initiate soak in warm, non-chlorinated brine - 4 cups nuts + 8 cups water + 1 tablespoon sea salt, 42°C|
|Almond||12-14||Does not sprout||-|
|Brazil Nut||4-6||Does not sprout||-|
|Cashew||4-6||Does not sprout||-|
|Hazelnut||10-12||Does not sprout||-|
|Macadamia||4-6||Does not sprout||-|
|Pecan||8-10||Does not sprout||-|
|Pistachio||10-12||Does not sprout||-|
|Pine Nut||1-2||Does not sprout||-|
|Walnut||8-10||Does not sprout||-|
|Seeds. Initiate soak in warm, non-chlorinated brine - 4 cups nuts + 8 cups water + 1 tablespoon sea salt, 42°C|
|Sesame||6-8||2-3||When root is length of seed|
|Sunflower||6-8||1-2||When root is length of seed|
|Grains. Initiate soak in warm, acidic non-chlorinated water - 1 cup grains + 2 cups water + 1 tablespoon acid, 42°C|
|Barley||8-10||3-4||When root is length of seed|
|Oats||10-12||3-4||When root is length of seed|
|Rice||12-14||3-4||When root is length of seed|
|Rye||8-10||3-4||When root is length of seed|
|Spelt||8-10||3-4||When root is length of seed|
|Sorghum||8-10||3-4||When root is length of seed|
|Amaranth||4-6||1-2||50 mm - 1 cm|
|Buckwheat||4-6||2-3||50 mm - 1 cm|
|Quinoa||4-6||2-3||50 mm - 1 cm|
|Wild Rice||10-12||3-4||"Blooms" rather than sprouts|
|Legumes. Initiate soak in warm, non-chlorinated water - 1 cup legumes + 3 cups water, 42°C|
|Pea||10-12||2-3||When root is length of seed|
|Peanut||10-12||2-3||When root is length of seed|
|Other beans in general||12-14||3-5||2-5 cm|
References and Recommended Links
Bellamy I and MacLean D. Radiant Healing: The Many Paths to Personal Harmony and Planetary Wholeness. Google Books. Available Online.
Beck JL and Reed, JD. Tannins: Anti-quality effects on forage protein and fiber digestion. Idaho Forest, Wildlife and Range Experiment Station 2001;73:18-22. Available online.
Bohn L, Meyer AS, Rasmussen SK. Phytate: impact on environment and human nutrition. A challenge for molecular breeding. J Zhejiang Univ Sci B. 2008;9:165–191.
Gibson RS, Bailey KB, Gibbs M, Ferguson EL. A review of phytate, iron, zinc, and calcium concentrations in plant-based complementary foods used in low-income countries and implications for bioavailability. Food Nutr Bull. 2010;31:S134–46.
Nagel R. Living with phytic acid. Weston A. Price Foundation 2010.
Soaking grains: The food science behind it. Phytic Acid.Org