Antinutritional factors: Uncooked legume seeds contain antinutritional factors tha can be toxic if large amounts are consumed. Trypsin inhibitors and haemagglutinins disappear at 90 m, however, polyphenolic compounds although decreasing with time are still found in the cooked material.
Protein quality: Protein quality of pulses is improved more by moist heat than by dry heat treatment, as available lysine is decreased in roasted pulses as compared to boiled and pressure cooked ones. Heat treatment causes loss of methionine, the most important amino acid of legume.
Minerals: Cooking has a little effect on calcium, magnesium and total iron content of pulses.
Vitamins: Loss of thiamine may occur due to heat applied.
Colour: Sodium metabisulphite is found to be effective in maintaining colour of lentils, other seeds acquire a darker colour during processing.
Factors effecting cooking quality
Inherent character: Some varieties are hard – to – cook inherently. Cooking time of whole seed is usually the highest in chick peafollowed by pigeon pea and black gram and green gram.
Environmental factors: Variation in cooking quality of pulses within and between varities could be due to location, soil fertility, soil moisture and other environmental factors.
Storage condition: Cooking quality is influenced by time, temperature and relatively humidity during storage. Cooking time for the same hardness increases with storage time. Moisture content during storage above 10 percent may couse deterioration in the cooking quality.
Seed maturity: High temperature at the time of maturing affects the cooking time. Cooking time increases with the increase in seed maturity. The very hard mature seeds take long time to cook.
Dehulling: This reduces the cooking time by 70 percent and increases digestability.
Soaking: Whole grams are soaked in water to improve the cooking quality. Whole grams like Bengal gram cannot be cooked to the desirable consistency without this pretreatment.
Salts: Hard – to – cook condition can be eliminated by soaking seeds in salt solution consisting of 1 percent NaC1 and 0.75percent NaHCO3 instead of only water. Separation of cotyledon cells occur in salt solution soaked seeds. Carbonate or bicarbonate not only act as an alkaline agent and buffer but also acts as a protein dissociating, solubilising or tenderising agent. Salts such as trisodium phosphate, sodium bicarbonate and ammonium carbonate in small quantities improves cooking quality without appreciably raising the salt and altering the taste. These chemicals could be added to cooking water or impregnate or coated on the surface of the dal as a final step in milling.
Precooking: The cooking time for precooked lentil seeds is less compared to untreated ones. Precooking is done by cooking, treating with enzymes and dehydrating in controlled conditions.
Phytin content: High available phosphorous in the soil contributes to high phytin content in the seed and consequently to good cooking.
Calcium and magnesium: Large amounts of insoluble calcium and magnesium pectates are formed in the middle lamella of the cell walls when the seed is high in calcium and magnesium or when the cooking water is high in these elements.
Cellulose: The thickness of the palisade layer and the content of lignin and alpha cellulose in the seed coats are probably important factors in the cooking quality of pulses. Hard shell seeds in legumes resist water absorption and thereby delay the cooking process. Middle – lamella of the cell wall and cell separation affects the cooking time. Compared to other pulses, lentils require shorter time to cook due to their soft seed coat content.
Sodium bicarbonate softens the cellulose and hastens cooking.
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