Processing of Cereals, Pulses, and Oilseeds
Scope of the domain
This domain tests the structure and processing of cereals, pulses and oilseeds, including milling, parboiling, malting, extrusion, dal milling, anti-nutritional factors and oil extraction.
Core rules and concepts
- A cereal grain has bran, germ and endosperm. Bran is rich in fibre and minerals; germ contains oil and vitamins; endosperm is mainly starch.
- Milling separates bran and germ from endosperm. Excessive polishing removes micronutrients and raises starch loss.
- Parboiling involves soaking, steaming and drying before milling. It gelatinises starch, reduces broken grains and drives some bran vitamins into the endosperm.
- Malting is controlled germination followed by drying; it develops enzymes for brewing and improves digestibility.
- Extrusion uses heat, pressure and shear to cook and shape cereals or protein blends.
- Pulses contain anti-nutritional factors such as trypsin inhibitors, phytic acid and lectins. Soaking, cooking, germination and fermentation reduce them.
- Oilseeds are processed by mechanical pressing (ghani or expeller) or solvent extraction, followed by refining: degumming, neutralisation, bleaching and deodorisation. Hydrogenation creates trans fats.
Worked example
A processor wants to reduce trypsin inhibitor in soybean meal and improve digestibility. Reasoning: simple soaking is insufficient. Adequate moist heat denatures the inhibitor; boiling, roasting, extrusion or controlled heat treatment is needed. Overheating would damage lysine and reduce protein quality, so the process must be controlled. The correct answer is adequate heat treatment, not solvent extraction alone.
Traps that cost marks
- Confusing bran with germ; the germ is the oil-rich embryo.
- Assuming refining only removes impurities; it also removes some vitamins, pigments and flavour compounds.
- Treating parboiling as simple boiling; it is soaking, steaming and drying before milling.
- Forgetting that anti-nutritional factors are reduced by heat, soaking, germination or fermentation, not by milling alone.