Pulses – Storehouse of Energy and Nutrition

Pulses have been a part of staple foods for many civilizations around the world for over 10,000 years, in fact, pulses are believed to be one of the first crops cultivated by human civilisation. Pulses are the best food to introduce after six months of age of the child. For vegetarians, pulses are boon, an inexpensive alternative to meat. India is the foremost in the production of pulses all over the world!

Legumes or Pulses?

Pulse or legume is the plants whose seeds are enclosed in a pod. Commonly,  terms “legumes” and “pulses” are used interchangeably. However, all pulses are considered legumes but not all legumes are not pulses. Food and Agriculture Organization defines “pulse” exclusively for crops harvested solely for the dry seed of leguminous plants. So, legumes used for oil extraction (soybean, peanut) and those harvested green for food (green beans, peas and sprouts) are excluded from the category of pulses.

Common Edible Legumes

Common edible legumes include dry beans, broad beans, dry peas, chickpeas, lentils, soybeans, lupins, mung beans, lotus, sprouts, alfalfa, green beans and peas and peanuts. On the basis of size and shape, spatial pulses may be grouped as small seed pulses (black gram, green gram, lentil, and pigeon pea) and bold seed pulses (chickpea, cowpea, fab bean, field pea, and kidney bean).

Besides their food value, pulses also play an important role in cropping systems. They do not require nitrogen fertilizers because of their nitrogen-fixing properties, thus increasing soil fertility. Water requirement of legumes is low because of their deep root system.

Nutritional value of pulses

Pulses are a storehouse of essential macronutrient and micronutrients. Consumption of pulses decreases the risk of cancer, obesity, diabetes and heart diseases. Nutrients in pulses is divided into two categories; Macronutrients and Micronutrients.

Macronutrients in Pulses

1. Carbohydrates (55%–65% of the total weight). The energy content of most pulses is between 300 and 540 Kcal / 100g. Majority of carbohydrate exist in the form of starch. The high dietary fibre content of pulses helps in reducing the transit time in the mammalian gut and relieve gastrointestinal conditions such as constipation and diverticular disease.

Pulses have low glycaemic indices, making them valuable foods for diabetics. Pulses reduce postprandial glucose and insulin concentrations.

2. Protein

Protein is a building block for the human body. Pulses have a high protein content, about twice that in cereal and several times that in root tuber. Per 100 gram Pulses can provide you up to 22 g of protein.

Both pulses and cereals compliment nutritional profile of each other. Pulse proteins are rich in lysine, deficient in sulphur containing amino acids where cereal proteins are rich in sulphur containing amino acids and deficient in lysine.

3. Fat
Pulses are low in calories and fat (1%–4%).

Micronutrients in Pulses

Pulses provide minerals, water-soluble and lipid-soluble vitamins, and healthy lipids such as polyunsaturated fatty acids.

Vitamins

The vitamins present in appreciable quantities in pulses are thiamin, riboflavin, pyridoxine and folic acid; vitamin E (antioxidant) and K are also found in pulses.

Non-nutritive bioactive compounds
Apart from the compounds that are actively important for nutrition, pulses contain some bioactive compounds which do not provide nutrition and evolve in order to prevent consumption from predators during adverse conditions.

Earlier these compounds were considered as anti-nutrients because of their activity to reduce protein digestibility and mineral bioavailability, recently these compounds have been shown to have health protective effects.

These properties are referred to as anti-nutritional compounds (ANCs) and categorized as

Protein ANCs

Protein ANCs have a range of potentially harmful components and includes lectins, agglutinins, trypsin inhibitors, chymotrypsin inhibitors, and antifungal peptides.

Non-protein ANCs.

Non-protein ANCs are relatively harmless and include alkaloids, phytic acid, saponins and other phenolic compounds.

Enzyme inhibitors (trypsin, chymotrypsin and α- amylase inhibitors)

a.Trypsin inhibitors

They are capable of binding to trypsin, which is a proteolytic enzyme secreted by the pancreas and interfering with the digestion of proteins.

b. Chymotrypsin

Chymotrypsin is an enzyme similar to trypsin. Chymotrypsin inhibitor is considered to have a similar mode of action as a trypsin inhibitor.

b. Amylase inhibitors

Amylase is responsible for the digestion of starch. The digestibility of starch is reduced due to the inhibition of pancreatic and salivary α-amylase activity may lead to pancreatic hypertrophy.

Phytates and Oxalates

Phytic acid, or phytate when in salt form, accounts for 60-90% of the total phosphorus in legume seeds. Phytic acid and oxalates reduce the bioavailability of minerals, protein, starch and essential minerals (e.g. calcium, zinc, iron and magnesium) by the formation of insoluble compounds with them.

Phytic acid may also act as antioxidant, anti-cancer and in lowering blood sugar.

Oxalic acid [(COOH)2] and its salts, known as oxalates, can influence mineral availability and formation of
kidney stones.

Lectins

Lectins or haemagglutinins are found in most plant foods. Lectins are able to agglutinate red blood cells of all blood type and bind to intestinal mucosa cells, hindering the biosynthesis and secretion of proteins. Lectins may act also act in preventing certain cancers and boosting immunity.

Phytosterols

In pulses, phytosterols are present in small quantities, and the most common phytosterols are β-sitosterol, campesterol, and stigmasterol. has been reported to lower serum cholesterol.

Phenolic compounds 

Phenolic compounds chelate metals, inhibit lipid peroxidation and scavenge free radicals. Bitterness and astringency in foods and beverages can result from phenolic compounds. The main polyphenols in pulses include flavonoids, phenolic acids and tannins.

Raffinose family oligosaccharides:

Raffinose family oligosaccharides are broken down by the enzyme α-galactosidase, an enzyme, lacking in the human digestive tract. These substances undergo fermented by bacteria into gases leading to the flatulence associated with pulse consumption. On contrary, they reduce the risk of intestinal cancer; increase stool weight and frequency.

Phytoestrogen

Phyto-oestrogens are naturally occurring plant chemicals having an action similar to estrogen hormone. They can be useful in the prevention of a range of hormone-dependent conditions, including cancer prevention, menopausal symptoms, coronary heart disease and osteoporosis.

Saponins 

Saponins are responsible for a frothy appearance on the surface of pulses. Saponins found in pulses have plasma cholesterol-lowering effect in humans, this reduces the risk of chronic diseases. Soybean and chickpea constitute major sources of saponins in the human diet. Saponins have cytotoxic effects against cancer cell lines. Processing leads to the loss of saponins from foods.

Pigments

Three main pigments can be found in pulses, blue-red pigments (anthocyanins) which are found in black beans, kidney beans and black soybeans at relatively high levels; yellow pigments (carotenoids) which are present in high amounts in yellow peas, lentils and chickpeas; and green pigments (chlorophylls) present in green peas. These pigments play significant roles in human health.

How to Decrease ANCs?

Fortunately, traditional processing methods reduce the content of the non-nutritive component of pulses.

• Dehulling
• Milling
• Soaking
• Cooking
• Pressure cooking
• Roasting
• Germination
• Fermentation

What are the variousBenefits of Pulses?

Health Benefits of Pulses

• With a low glycemic index, low fat and high fibre content, pulses are suitable for people with diabetes.
• High dietary fibre content reduces LDL cholesterol, a recognized risk factor in coronary heart disease
• Pulses are high in fibre and protein, low in the glycemic index and low in fat, this promotes weight loss and maintenance. Overweight is a risk factor for Hypertension, Diabetes and Cardiovascular disease.
• Good sources of vitamins, such as folate, which reduces the risk of neural tube defects (NTDs) like spina bifida in newborn babies.
• High iron content prevents iron deficiency anaemia in women and children. It would be more beneficial to consume pulses with vitamin C to improve iron absorption.
•  Pulses are gluten-free, can be consumed in gluten sensitive people. Gluten is present in wheat, barley, and rye.
• Pulses are rich in bioactive
  compounds such as phytochemicals and antioxidants that may contain anti-cancer properties.
•  Pulses promote bone health.
• Phytoestrogens may also prevent cognitive decline and reduce menopausal symptoms.
• Extracts of amylase inhibitors can also be used as starch blockers to treat obesity and in diabetes therapy for calorie control, since they affect carbohydrate breakdown, leading to reduced glucose absorption.
• Polyphenols in pulses are considered potent antioxidants and reduce the risk of oxidative stress, inflammation, cardiovascular disease, cancer and osteoporosis. Ferulic is the main phenolic acid in pulses.

Daily intake of pulses

According to the Indian Council of Medical Research (ICMR), 40 grams of pulses is the recommended daily intake for a balanced diet of an average sedentary man.

Lactating women add two extra portions of pulses to their diets, and that they consider giving pulses to their infants as a complementary food.