Sprouting

See also Microgreen for similar immature vegetables; for blood vessel sprouting, see Capillary sprouts
Mixed bean sprouts
Soybean sprouts on a plate

Sprouting is the practice of germinating seeds to be eaten raw or cooked. Sprouts can be germinated at home or produced industrially. They are a prominent ingredient of the raw food diet and common in Eastern Asian cuisine.

Sprouting, like cooking, reduces anti-nutritional compounds in raw legumes. Raw lentils, for example, contain lectins, antinutrional proteins which can be reduced by sprouting or cooking. Sprouting is also applied on a large scale to barley as a part of the malting process. A downside to consuming raw sprouts is that the process of germinating seeds can also be conducive to harmful bacterial growth.

Seeds suitable for sprouting

All viable seeds can be sprouted, but some sprouts should not be eaten raw. The most common food sprouts include:

alfalfa, clover, fenugreek, lentil, pea, chickpea, mung bean and soybean (bean sprouts).
oat, wheat, maize (corn), rice, barley, and rye
quinoa, amaranth and buckwheat
sesame, sunflower, almond, hazelnut, hemp, linseed, peanut.
broccoli, cabbage, watercress, mustard, mizuna, radish, and daikon (kaiware sprouts), rocket (arugula), tatsoi, turnip.
carrot, celery, fennel, parsley.
onion, leek, green onion (me-negi in Japanese cuisine)
spinach, lettuce, milk thistle, lemon grass

Although whole oats can be sprouted, oat groats sold in food stores, which are dehulled and require steaming or roasting to prevent rancidity, will not sprout. Whole oats may have an indigestible hull which makes them difficult or even unfit for human consumption.

In the case of rice, the husk of the paddy is removed before sprouting. Brown rice is widely used for germination (GBR - Germinated Brown Rice) in Japan and other countries.

All the sprouts of the solanaceae (tomato, potato, paprika, aubergine or eggplant) and rhubarb cannot be eaten as sprouts, either cooked or raw, as they can be poisonous.[1] Some sprouts can be cooked to remove the toxin, while others cannot.[2]

With all seeds, care should be taken that they are intended for sprouting or human consumption rather than sowing. Seeds intended for sowing may be treated with chemical dressings. Several countries, such as New Zealand, also require that some varieties of imported edible seed be heat-treated, thus making them impossible to sprout. Quinoa in its natural state is very easy to sprout but when polished, or pre-cleaned of its saponin coating (becoming whiter), loses its power to germinate.

The germination process

Sprouting mung beans in a glass sprouter jar with a plastic sieve-lid

The germination process takes a few days and can be done at home manually, as a semi-automated process, or industrially on a large scale for commercial use.

Typically the seeds are first rinsed to remove soil and dirt and the mucilaginous substances produced by some seeds when they come in contact with water. Then they are soaked for 20 minutes to 12 hours, depending on the type and size of seed. The soaking increases the water content in the seeds and brings them out of quiescence. After draining and then rinsing seeds at regular intervals they germinate, or sprout.

For home sprouting, the seeds are soaked (big seeds) or moistened (small), then left at room temperature (13 to 21 °C or 55 to 70 °F) in a sprouting vessel. Many different types of vessels can be used. One type is a simple glass jar with a piece of cloth or nylon window screen secured over its rim. "Tiered" clear plastic sprouters are commercially available, allowing a number of "crops" to be grown simultaneously. By staggering sowings, a constant supply of young sprouts can be ensured. Any vessel used for sprouting must allow water to drain from it, because sprouts that sit in water will rot quickly. The seeds swell, may stick to the sides of the jar, and begin germinating within a day or two.

Another sprouting technique is to use a pulse drip method. The photo below on the right shows crimson clover sprouts grown on 1/8" urethane foam mats. It's a one-way watering system with micro sprinklers providing intermittent pulses of fresh water to reduce the risk of bacterial cross-contamination with Salmonella and E. coli during the sprouting process.

Crimson clover sprouts grown on 1/8" urethane foam mats with a pulse drip technique. Four micro-sprinklers cycle pulsing continuously over a 7-day period, each putting out about 1/2 gallon per hour. The four micro-sprinklers were each fitted with an LPD[3] to keep the lines fully charged between pulses.

Sprouts are rinsed two to four times a day, depending on the climate and the type of seed, to provide them with moisture and prevent them from souring. Each seed has its own ideal sprouting time. After three to five days the sprouts will have grown to 5 to 8 centimetres (2–3 in) in length and will be suitable for consumption. If left longer they will begin to develop leaves, and are then known as baby greens. A popular baby green is sunflower after 7–10 days. Refrigeration can be used as needed to slow or halt the growth process of any sprout.

Common causes for sprouts to become inedible:

Mung beans can be sprouted either in light or dark conditions. Those sprouted in the dark will be crisper in texture and whiter, as in the case of commercially available Chinese Bean Sprouts, but these have less nutritional content than those grown in partial sunlight. Growing in full sunlight is not recommended, because it can cause the beans to overheat or dry out. Subjecting the sprouts to pressure, for example, by placing a weight on top of them in their sprouting container, will result in larger, crunchier sprouts similar to those sold in grocery stores.

A very effective way to sprout beans like lentils or azuki is in colanders. Soak the beans in water for about 8 hours then place in the colander. Wash twice a day. The sprouted beans can be eaten raw or cooked.

Sprouting is also applied on a large scale to barley as a part of the malting process. Malted barley is an important ingredient in beer and is used in huge quantities. Most malted barley is distributed among wide retail sellers in North American regions.

Many varieties of nuts, such as almonds and peanuts, can also be started in their growth cycle by soaking and sprouting, although because the sprouts are generally still very small when eaten, they are usually called "soaks".

Nutritional information

Sprouts used for a verrine.
Fresh mung bean sprouts in a bowl

Sprouts are said to be rich in digestible energy, bioavailable vitamins, minerals, amino acids, proteins, and phytochemicals, as these are necessary for a germinating plant to grow.[4][5][6][7] These nutrients are essential for human health. The nutritional changes upon germination and sprouting are summarised below.

Chavan and Kadam (1989)[8] concluded that

Increases in Protein Quality Chavan and Kadam (1989) stated that "Very complex qualitative changes are reported to occur during soaking and sprouting of seeds. The conversion of storage proteins of cereal grains into albumins and globulins during sprouting may improve the quality of cereal proteins. Many studies have shown an increase in the content of the amino acid Lysine with sprouting."

"An increase in proteolytic activity during sprouting is desirable for nutritional improvement of cereals because it leads to hydrolysis of prolamins and the liberated amino acids such as glutamic and proline are converted to limiting amino acids such as lysine."

Increases in Crude Fibre content Cuddeford (1989),[9] based on data obtained by Peer and Leeson (1985)[10] stated that "In sprouted barley, crude fibre, a major constituent of cell walls, increases both in percentage and real terms, with the synthesis of structural carbohydrates, such as cellulose and hemicellulose”. Chung et al. (1989)[11] found that the fibre content increased from 3.75% in unsprouted barley seed to 6% in 5-day sprouts."

Crude Protein and Crude Fibre changes in Barley Sprouted over a 7-day period

Crude Protein (% of DM) Crude Fibre (% of DM)
Original seed 12.7% 5.4%
Day 1 12.7% 5.6%
Day 2 13.0% 5.9%
Day 3 13.6% 5.8%
Day 4 13.4% 7.4%
Day 5 13.9% 9.7%
Day 6 14.0% 10.8%
Day 7 15.5% 14.1%

Source: Cuddeford (1989), based on data obtained by Peer and Leeson (1985).

Increase of protein is not due to new protein being manufactured by the germination process but by the washing out of starch and conversion to fiber—increasing the relative proportion of protein.

Increases in Essential Fatty Acids

An increase in lipase activity has been reported in barley by MacLeod and White (1962),[12] as cited by Chavan and Kadam (1989). Increased lipolytic activity during germination and sprouting causes hydrolysis of triacylglycerols to glycerol and constituent fatty acids.

Increases in Vitamin content According to Chavan and Kadam (1989), most reports agree that sprouting treatment of cereal grains generally improves their vitamin value, especially the B-group vitamins. Certain vitamins such as α-tocopherol (Vitamin-E) and β-carotene (Vitamin-A precursor) are produced during the growth process (Cuddeford, 1989).[9]

According to Shipard (2005),[13] "Sprouts provide a good supply of Vitamins A, E & C plus B complex. Like enzymes, vitamins serve as bioactive catalysts to assist in the digestion and metabolism of feeds and the release of energy. They are also essential for the healing and repair of cells. However, vitamins are very perishable, and in general, the fresher the feeds eaten, the higher the vitamin content. The vitamin content of some seeds can increase by up to 20 times their original value within several days of sprouting. Mung Bean sprouts have B vitamin increases, compared to the dry seeds, of - B1 up 285%, B2 up 515%, B3 up 256%. Even soaking seeds overnight in water yields greatly increased amounts of B vitamins, as well as Vitamin C. Compared with mature plants, sprouts can yield vitamin contents 30 times higher."

Chelation of Minerals Shipard (2005)[13] claims that - “When seeds are sprouted, minerals chelate or merge with protein, in a way that increases their function.”

It is important to note that while these changes may sound impressive, the comparisons are between dormant non-sprouted seed to sprouted seed rather than comparisons of sprouts to mature vegetables. Compared to dry seeds there are very large increases in nutrients whereas compared with mature vegetables the increase is less. However, a sprout, just starting out in life, is likely to need and thus have more nutrients (percentage wise) than a mature vegetable.

Following table lists selected nutrients in kidney beans to show the effect of sprouting. Nutrients are calculated for 100 gms of non-water components to take the water out of equation since after sprouting beans absorb lot of water.

GABA Sprouting also have shown that can improve the levels of GABA,[14] a compound involved in the regulation of blood pressure,[15] and promoted the liberation of bioactive peptides in diverse legumes.

Nutrients in grams per 100 grams of non-water components of kidney beans
Nutrient DRI[16] Raw Beans[17] Sprouted Beans[18] Ratio
Protein (g) 50 26.72 45.15 1.7
Vitamin C (mg) 90 5.1 416 81.56
Thiamin (mg) 1.2 0.6 3.98 6.63
Riboflavin (mg) 1.3 .248 2.78 11.2
Niacin (mg) 16 2.33 31.40 13.47
Vitamin B-6 (mg) 1.3 0.45 0.91 2.02
Folate (µg) 400 446 634.25 1.422
Vitamin E(mg) 15 .25 0 0
Vitamin K (µg) 120 21.527 0 0

Health concerns

Bacterial infection

FDA health warning on a sprouts package

Commercially grown sprouts have been associated with multiple outbreaks of harmful bacteria, including salmonella and toxic forms of Escherichia coli.[19] Such infections may be a result of contaminated seeds or of unhygienic production with high microbial counts.[20][21] Sprout seeds can become contaminated in the fields where they are grown, and sanitizing steps may be unable to kill bacteria hidden in damaged seeds.[19] A single surviving bacterium in a kilogram of seed can be enough to contaminate a whole batch of sprouts, according to the FDA.[19]

To minimize the impact of the incidents and maintain public health, both the U.S. Food and Drug Administration (FDA) and Health Canada issued industry guidance on the safe manufacturing of edible sprouts and public education on their safe consumption.[22][23] There are also publications for hobby farmers on safely growing and consuming sprouts at home.[24][25] The recommendations include development and implementation of good agricultural practices and good manufacturing practices in the production and handling of seeds and sprouts, seed disinfection treatments, and microbial testing before the product enters the food supply.

In June 2011, contaminated fenugreek sprouts (grown from seed from Egypt) in Germany was identified as the source of the 2011 E. coli O104:H4 outbreak which the German officials had blamed wrongly, first on cucumbers from Spain and then on mung bean sprouts.[19] In addition to Germany, where 3,785 cases and 45 deaths had been reported by the end of the outbreak,[26][27] a handful of cases were reported in several countries including Switzerland,[27] Poland,[27] the Netherlands,[27] Sweden,[27] Denmark,[27] the UK,[27][28] Canada[27] and the USA.[29] Virtually all affected people had been in Germany shortly before becoming ill.

Antinutritional factors

Some legumes, including sprouts, can contain toxins or antinutritional factors, which can be reduced by soaking, sprouting and cooking (e.g., stir frying). Joy Larkcom advises that to be on the safe side “one shouldn’t eat large quantities of raw legume sprouts on a regular basis, no more than about 550g (20oz) daily”.[30]

Phytic acid, an antinutritional factor, occurs primarily in the seed coats and germ tissue of plant seeds. It forms insoluble or nearly insoluble compounds with many metal ions, including those of calcium, iron, magnesium and zinc, reducing their dietary availability. Diets high in phytic acid content and poor in these minerals produce mineral deficiency in experimental animals (Gontzea and Sutzescu, 1968,[31] as cited in Chavan and Kadam, 1989).[8] The latter authors state that the sprouting of cereals has been reported to decrease levels of phytic acid. Similarly, Shipard (2005)[32] states that enzymes of germination and sprouting can help eliminate detrimental substances such as phytic acid. However, the amount of phytic acid reduction from soaking is only marginal, and not enough to counteract its antinutrient effects [33]

Standards and regulations

EU regulation

In order to prevent incidents like the 2011 EHEC epidemic, the European Commission has issued three new, tightened regulations on March 11, 2013.

The origin of the seeds has to be traceable always at all stages of processing, production and distribution. Therefore, a full description of the seeds or sprouts needs to be kept on record.(see also Article 18 of Regulation (EC) No 178/2002)

This regulation amends Regulation (EC) No 2073/2005 in respect of microbiological criteria for sprouts and the sampling rules for poultry carcases and fresh poultry meat.

Imported sprouts or seeds intended for the production of sprouts need a certificate according to the model declared in the Annex of this regulation. The certificate serves as proof that the production process complies with the general hygiene provisions in Part A of Annex I to Regulation (EC) No 852/2004 and the traceability requirements of Implementing Regulation (EU) No 208/2013.

See also

Wikimedia Commons has media related to Sprouted grains.

References

Notes

  1. ↑ Donald G. Barceloux MD. "Potatoes, Tomatoes, and Solanine Toxicity (Solanum tuberosum L., Solanum lycopersicum L.)". Retrieved 7 August 2011. Paid subscription required to access article.
  2. ↑ "The Vegetarian Society - Information Sheet - pulses". Vegetarian Society. Retrieved 2009-11-16.
  3. ↑ "Super LPD".
  4. ↑ "Plant-based nutrition". Spring 2002. Retrieved 2007-11-14.
  5. ↑ Dikshit, Madhurima; Ghadle, Mangala (2003). "Effect of sprouting on nutrients, antinutrients and in vitro digestibility of the MACS-13 soybean variety". Plant Foods for Human Nutrition. 58 (3): 1–11. doi:10.1023/B:QUAL.0000040357.70606.4c.
  6. ↑ Rumiyati; Jayasena, Vijay; James, Anthony P. (13 August 2013). "Total Phenolic and Phytosterol Compounds and the Radical Scavenging Activity of Germinated Australian Sweet Lupin Flour". Plant Foods for Human Nutrition. 68 (4): 352–357. doi:10.1007/s11130-013-0377-6. PMID 23943234.
  7. ↑ Świeca, Michał; Gawlik-Dziki, Urszula; Kowalczyk, Dariusz; Złotek, Urszula (June 2012). "Impact of germination time and type of illumination on the antioxidant compounds and antioxidant capacity of Lens culinaris sprouts". Scientia Horticulturae. 140: 87–95. doi:10.1016/j.scienta.2012.04.005.
  8. 1 2 Chavan, J. K.; Kadam, S. S.; Beuchat, Larry R. (January 1989). "Nutritional improvement of cereals by sprouting". Critical Reviews in Food Science and Nutrition. 28 (5): 401–437. doi:10.1080/10408398909527508. PMID 2692609.
  9. 1 2 Cuddeford, D. (1 September 1989). "Hydroponic grass". In Practice. 11 (5): 211–214. doi:10.1136/inpract.11.5.211.
  10. ↑ Peer, DJ; Leeson (Dec 1985). "S". Animal Feed Science and Technology. 13 (3-4): 191–202. doi:10.1016/0377-8401(85)90022-7.
  11. ↑ Chung, CT; Niemela, SL; Miller, RH (April 1989). "One-step preparation of competent Escherichia coli: transformation and storage of bacterial cells in the same solution.". Proceedings of the National Academy of Sciences of the United States of America. 86 (7): 2172–5. PMID 2648393.
  12. ↑ MacLeod, Anna M.; White, H. B. (12 November 1962). "LIPID METABOLISM IN GERMINATING BARLEY. II. BARLEY LIPASE". Journal of the Institute of Brewing. 68 (6): 487–495. doi:10.1002/j.2050-0416.1962.tb01894.x.
  13. 1 2 Shipard, Isabell (2005). How can I grow and use sprouts as living food?. [Nambour, Qld.?]: David Stewart. ISBN 9780975825204.
  14. ↑ Martínez-Villaluenga, Cristina; Kuo, Yu-Haey; Lambein, Fernand; Frías, Juana; Vidal-Valverde, Concepción (18 March 2006). "Kinetics of free protein amino acids, free non-protein amino acids and trigonelline in soybean (Glycine max L.) and lupin (Lupinus angustifolius L.) sprouts". European Food Research and Technology. 224 (2): 177–186. doi:10.1007/s00217-006-0300-6.
  15. ↑ Diana, Marina; Quílez, Joan; Rafecas, Magdalena (September 2014). "Gamma-aminobutyric acid as a bioactive compound in foods: a review". Journal of Functional Foods. 10: 407–420. doi:10.1016/j.jff.2014.07.004.
  16. ↑ Dietary Reference Intake
  17. ↑ http://ndb.nal.usda.gov/ndb/foods/show/2874?manu=&fgcd=
  18. ↑ http://ndb.nal.usda.gov/ndb/foods/show/4741?manu=&fgcd=
  19. 1 2 3 4 Neuman, William (10 June 2011). "The Poster Plant of Health Food Can Pack Disease Risks". New York Times. Retrieved 11 June 2011.
  20. ↑ Breuer, Thomas; et al. "A Multistate Outbreak of Escherichia coli O157:H7 Infections Linked to Alfalfa Sprouts Grown from Contaminated Seeds". Retrieved 19 November 2007.
  21. ↑ Gabriel, Alonzo A.; Berja, M; Estrada, A; Lopez, M; Nery, J; Villaflor, E; et al. (2007). "Microbiology of retail mung bean sprouts vended in public markets of National Capital Region, Philippines". Food Control. 18 (10): 1307–1313. doi:10.1016/j.foodcont.2006.09.004.
  22. ↑ Food and Drug Administration (May 17, 2005). "Transcript of Proceedings of Public Meeting on Sprout Safety". Retrieved 19 November 2007.
  23. ↑ Health Canada. "Sprouted Beans and Seeds". Retrieved 19 November 2007.
  24. ↑ Harrison, H. C. "Growing Edible Sprouts at Home" (PDF). Retrieved 5 September 2016.
  25. ↑ Suslow, Trevor V.; Linda J. Harris. "Growing Seed Sprouts at Home" (PDF). Retrieved 23 November 2007.
  26. ↑ Shiga toxin-producing E. coli (STEC): Update on outbreak in the EU, 27 July 2011
  27. 1 2 3 4 5 6 7 8 "Outbreak of Shiga toxin-producing E. coli in Germany (22 June 2011, 11:00)". ECDC. 22 June 2011. Retrieved 22 June 2011.
  28. ↑ "E. coli cucumber scare: Russia announces import ban". BBC News Online. 30 May 2011. Archived from the original on 30 May 2011. Retrieved 30 May 2011.
  29. ↑ "E. Two in U.S. infected in German E. coli outbreak". MSNBC Online. 31 May 2011. Retrieved 2 June 2011.
  30. ↑ Douglass, Joy Larkcom ; illustrated by Elizabeth (1995). Salads for small gardens (2nd ed.). [London]: Hamlyn. ISBN 0-600-58509-3.
  31. ↑ Natural Antinutritive Substances in Foodstuffs and Forages (1 ed.). S. Karger; 1 edition (August 28, 1968). p. 184. ISBN 978-3805508568.
  32. ↑ Shipard, Isabell (2005). How can I grow and use sprouts as living food?. [Nambour, Qld.?]: David Stewart. ISBN 0975825208.
  33. ↑ Egli, I.; Davidsson, L.; Juillerat, M.A.; Barclay, D.; Hurrell, R.F. (November 2002). "The Influence of Soaking and Germination on the Phytase Activity and Phytic Acid Content of Grains and Seeds Potentially Useful for Complementary Feedin". Journal of Food Science. 67 (9): 3484–3488. doi:10.1111/j.1365-2621.2002.tb09609.x.
  34. ↑ Commission Implementing Regulation (EU) No 208/2013 European Commission, Retrieved 04-20-2013
  35. ↑ Commission Regulation (EU) No 209/2013 European Commission, Retrieved 04-20-2013
  36. ↑ Commission Regulation (EU) No 211/2013 European Commission, Retrieved 04-20-2013

Bibliography

*  Pioneers in Hemp Sprouts and other Activated Living Hemp Foods(c2016)
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