Nutrient Content Of Pulses And Toxic Substances In Pulse

PULSES

Pulses are the edible fruits or seeds of pod-bearing leguminous plants. The term pulse in India is used for edible legumes and dhal is used for decuticled split legumes.

Bengal gram, red gram, black gram, green gram, lentil, horse gram, peas and kesari dhal are some of the major pulse crops in India. Soyabean is also grown.

NUTRIENT CONTENT OF PULSES

Pulses  give  340  calories  per  100  gm which is almost

similar to cereal calorie. They are a rich source of protein containing about 18 - 25 percent protein. Soyabean is an exception containing about 35 to 40 percent protein.

All pulses contain sufficient amount lysine which is deficient in cereals and therefore they can supplement cereal protein. A mixture of cereals and pulses is superior to that of either one. Hence a combination of cereals and pulses is ideal for human consumption.

Pulses contain 55 - 60 percent of carbohydrate including starch soluble sugar and fibre.

They contain 1.5 percent lipids. Pulses also contain calcium, magnesium, zinc, iron, potassium and phosphorus.

They are a poor source of carotene and vitamin C but fairly rich in niacin. Germination increases the vitamin C content of pulses. The thiamine content of pulses is equal to or exceeds that of cereals. Being rich in B - Vitamins, they contribute significantly to B - Vitamin intake.

TOXIC SUBSTANCES IN PULSES

Some toxic substances are naturally present in some pulses. These include trypsin inhibitors and haemagglutinins. Trypsin  inhibitor, as the name indicates, interferes with digestion of proteins by inhibiting the action of the enzyme trypsin. Haemagglutinins combine with haeme and thus destroy haemoglobin. Fortunately, both of these toxic substances are destroyed by heat, which is used in the normal cooking process.

Broad beans contain some toxic substances. When these beans are consumed raw a disease called favism occurs. This disease is characterized by haemolytic anemia. Since human beings usually do not consume broad beans raw, they are not likely to suffer from favism.

Kesari dhal also contains a toxic substance. This dhal is grown in Madya Pradesh(M.P) It was observed that during the drought conditions, only this dhal is grown and used as a staple food. When this dhal is consumed over a long time paralysis of lower limbs occurs in males. This is known as lathyrism.

It is reported that when the intake of kesari dhal is restricted to 30 per cent of the total calorie intake, no adverse effects are observed. Therefore it is important to ensure that the intake of this dhal must be restricted to a maximum of 30 percent of the total calorie intake.

GERMINATION - NUTRIENT ENHANCEMENT

Germination is a process that involves the soaking of pulses overnight. The water is then drained and the seeds are tied in a loosely woven cotton bag and hung.

Water is sprinkled twice or thrice a day and sprouts usually appear within 6 - 8 hours.

Advantages of germination :

1.     Vitamin C is synthesised during germination. The increase in vitamin C is around 7 - 20 mg per 100 gm of pulses.

2.     Riboflavin, niacin, choline and biotin are increased.

3.     Starch is converted into sugars.

4.     It reduces the anti-nutritional and toxic factor in pulses.

5.     Increased variety in the diet as sprouted pulses can be added to salads.

6.     Dormant enzymes get activated and digestibility and availability of nutrients is improved.

7.     Minerals like calcium, zinc and iron are released from bound form.

8.     Sprouted pulses can be eaten raw, since germination improves taste and texture.

FACTORS AFFECTING PULSE COOKERY

1.     Soaking in water hastens the cooking of dried pulses.

2.     Soaking in boiling water reduces cooking time as the enzyme phytase present in the legume is inactivated.

3.     Hard water prolongs the cooking time of dried pulses. This may be due to the reaction of calcium and magnesium ions in hard water with the pectic constituents of dried beans.

4.     Addition of cooking soda (Sodium bicarbonate) will hasten cooking. However this causes loss of thiamine. Excess soda also makes cooked legumes dark and mushy.

5.     Addition of acidic component such as tomato juice tamarind juice prolong the time required to make pulses tender.

6.     Cooking time is considerably reduced when pulses are cooked by the use of steam under pressure.