December 20, 2017 belezza 1Comment

Pulses


Pulses

INTRODUCTION

  • Edible fruits or seeds of pod-bearing plants : family leguminosae
  • Keywords
    • Legumes : Alternate name for pulses
    • Gram : Dry legume seeds with husk
    • Dhal : Split decorticated grains
    • Over 13,000 plants belong to family leguminosae

Nutritive value and composition

  • Energy :
    • 340 cal/100g
    • 100 cal/30g (per serving)
  • Protein
    • Deficient in Sulphur containing amino acids e.g. methionine
    • Pulses are rich in lysine. Cereals lack in lysine.
    • (FAO) Soybean contains adequate tryptophan.
    • contain mainly globulins, a few albumins.
    • high protein content-20-40%
  • Carbohydrate :
    • 55-60% carbohydrates
    • Include-starch, fibre
  • LIPIDS-
    • 5% lipid by dry weight.
    • Most of the pulses contain, high amount of PUFA – Linoleic acid, linolenic acid
    • Undesirable changes due to oxidative rancidity during storage
      • Loss of protein solubility
      • Off-flavor development
      • Loss of nutritive quality
    • Minerals-
      • Important sources of Ca, Mg, Zn, Fe, K, and P
      • Around 80% of Phosphorus – in form of phytate
      • Phytin complexes with proteins & minerals & render them biologically unavailable
    • Vitamins-
      • Excellent source of Thiamine, folic acid & pantothenic acid.
      • Fairly rich in Niacin.
      • Contain small amount of Vitamin A-carotene.
      • Germinated legumes contain some Vitamin C.

Digestibility of Pulses

  • Chick pea protein has high digestibility
    • Lentils such as Rajmah – low digestibility due to albumin-which is not easily digestible
  • Factors that reduce digestibility of pulse proteins-
    • Pulse proteins have high molecular weight & compact molecules
    • Some proteins complex with carbohydrate & influence digestibility
    • Some proteins complex with phytin

Processing of pulses

  • Important to improve nutritive value
  • Various processing methods:
    • Milling
    • Soaking
    • Germination
    • Fermentation
    • Cooking

Decortication or Milling

  • Dry pulse seeds have a fibrous seed coat (husk) which is indigestible & may have a bitter taste.
  • Dhals-dehusked & split pulses.
  • Yield of dhal during milling-around 82 %

Advantages-

  1. Protein digestibility improves.
  2. Removal of husk reduces fibre content.
  3. Improves appearance, texture, cooking quality & palatability.
  4. Keeping quality is improved.

Disadvantage-

During  dehusking germ gets removed causing loss of some thiamine content.

Soaking

  • Whole pulses are soaked in cold water-overnight
  • Or in warm water -60-700C for 4-5 hours.

Advantages-

  1. Makes the pulse tender
  2. Hastens the process of cooking

Germination

  • Advantages:
  1. Improves nutritive value of pulses.
  2. Dormant enzymes are activated.
    • Starch, proteins -> simple substances
    • Provide more essential amino acids
  • Phytic acid amount is reduced. Availability of proteins & minerals increases.
  • Riboflavin, niacin, choline & biotin content increases
  • Vitamin C is synthesized during germination.
  • Decreases cooking time
  • Improves taste & texture, add variety to diet.
  • Fermentation
    • Increases digestability, palatability & nutritive value
    • Toxic substances can be eliminated by fermentation
    • Availability of EAA increases

E.g. idly making.

  • Lathyrism-
    • Nervous disease
    • Cause-excessive consumption of pulse kesari dhal for long period.
    • Group affected- young men 15-45years old
    • Lathyrism develops only when the consumption of this dhal is in high amounts (300 g/day) for six months& the diet does not contain adequate quantity of cereals.
    • Contain 28%protein.
    • 1st stage –Difficulty in walking
    • Final stage-Bending of knees & extreme stiffness of lower limbs, patient has to crawl.
    • Toxin can be reduced by parboiling. Special hot & cold water treatment for prolong time.
  • Favism-
    • Disease-Hemolytic anemia
    • Occurrence-when individual deficient in G-6PD (Glucose-6 Phosphate Dehydrogenase) consumes broad beans or by inhaling the pollen grains.
    • Deficiency of G-6PD affects the metabolism of glutathione in red blood cells. Red blood cell is more prone to injury & destruction.
    • In severe cases of favism-death may occur within 24-48 hours of onset of attack. Children are more vulnerable. If the victim survives acute stage, recovery takes four weeks.

Other Harmful Substances

  • Goitrogens
  • Tannins
  • Trypsin inhibitors

 

  • Goitrogens-
    • Thiocyanates, isothiocyanates present in soybean, lentil, groundnut etc. are called goitrogens.
    • They interfere with Iodine uptake by thyroid gland.
    • Excessive intake of these foods with marginal intake of Iodine from food & water may lead to Goiter.
    • Trypsin Inhibitors-
    • A protein found in many pulses, suppresses the release of amino acids
    • stimulates th
    • e production of extra trypsin by the pancreas & brings about its loss of activity.

 

  • Tannins-
    • are condensed polyphenolic compounds.
    • Tannins bind with Iron & interfere with iron absorption .
    • They also bind proteins & reduce their availability.
    • Removal of seed coat reduces tannins.
    • Black & red seed coat – More tannin content
    • White coat beans- less tannin content

 

  • Hemagglutinins-
    • They are also proteins which combine with products of digestion & thus impair the efficiency of absorption of nutrients.

PULSE COOKERY

  • Role of pulses in cookery:
    • Give bulk to the diet
    • Give satiety-due to high protein & fibre
    • Rich in protein & B-vitamins
    • Give variety to diets :
      • Used in salads-e.g. sprouts
      • Used in sweets & deserts-e .g. Laddu, Mysore Pak
      • chivada, chutney making
      • In snacks-bhajji, pharsan, potato vada.
      • Fermented pulses in-idly, dosa.
    • Soybean-useful pulse & an oilseed
      • 1st produced in China
      • Now U.S.A. is the no. 1 producer
      • Is used to produce textured vegetable protein-TVP-also known as nutrinuggets , to replace the meat.
      • So many products are available,-Soya curd-also known as Tofu
        • Soybean milk, Soy sauce
        • Infant formula-for lactose intolerant babies

Medicinal Uses

  • Bengal gram-long time consumption decreases serum cholesterol by increasing fecal excretion of bile acids.
  • Provide high fibre-decreases rise in blood sugar, so good for diabetics.
  • Guar gum-a gel derived from cluster bean.
    • decreases plasma cholesterol.
    • decreases cholesterol absorption of liver.
    • Increases insulin sensitivity.
    • Acts as soluble fibre.
    • Able to form a viscous gel in small intestine.

Conclusion

  • Pulses in human nutrition-
    • Protein malnutrition is common in underdeveloped & developing countries.
    • Pulse protein is a cheaper source of protein.
    • By a suitable combination of pulses, rice and oil seeds a formula can be prepared with a high quality protein, an amino acid profile as close as to that of good animal proteins.

 

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