Fruits, Vegetables and Cereal Processing
Cereals
Punjab wheat and paddy dominate this domain. Roller milling of wheat uses repeated grinding and sieving; extraction rate is flour obtained per 100 kg wheat, and higher extraction retains more bran and ash. Rice milling: paddy → cleaning → shelling → separation → polishing → grading. Parboiling (soaking, steaming, drying) gelatinises starch, reduces broken grains and retains B vitamins, though it darkens the grain. Bran and broken rice are valuable by-products.
Fruits and vegetables
Post-harvest spoilage is driven by respiration, transpiration and ethylene. Pre-cooling, cool storage, waxing, controlled atmosphere and MAP slow these processes. Processing routes: canning, juices, squash, jam, jelly, candy, chips, dehydration, freezing and pickles. Jam quality depends on the sugar–acid–pectin gel: TSS about 68–70 °Brix, pH 3.0–3.4, pectin 0.5–1.0%. FPO and FSSAI prescribe minimum fruit content for each product.
Worked example
Jam from 1 kg guava pulp at 10 °Brix, target 68 °Brix with sugar of 100 °Brix: sugar = (68 − 10)/(100 − 68) × 1 kg = 58/32 ≈ 1.81 kg. Add about 0.7% pectin and citric acid to bring pH to 3.2, boil to the sheet or thread end point, then hot-fill. Reasoning: too little acid gives a soft set, too much causes syneresis, and excess sugar crystallises.
Traps
Judging jam by eye instead of a refractometer; forgetting to blanch vegetables before drying or frying, leading to enzyme browning and off-flavour; storing ethylene producers such as mango with leafy vegetables; over-polishing rice and then claiming it is more nutritious; ignoring peel, pomace and bran as by-products that improve the economics.