Kshirod R Bhattacharya

‘Intan’ variety of paddy (Oryza sativa) was tested for puffing. It was parboiled under a wide range of paddy moisture content, steaming pressure and time, as also temperature and time of sand heating. The resulting milled rices were studied for their diverse properties including puffing. Indices of starch changes in the samples were calculated as: (1) gelatinisation index from the solubility of amylose in 0.2 N KOH; (2) amylopectin retrogradation from the post-production drop in room-temperature hydration power of the parboiled paddy during air-drying, (3) thermal breakdown of starch from the drop in gel permeation chromatographic fraction I of starch; lipid-amylose complexation indirectly from (4) drop in rate of water uptake during cooking and (5) cooked-rice firmness. It was found that the puffing expansion was very highly correlated with the combined above 5 indices of starch changes, as much as 90% of the variation in puffing being explainable on that basis. Puffing was promoted by gelatinisation as well as lipid-amylose complexation, but was retarded by amylopectin retrogradation and probably starch breakdown.

BACKGROUND: Basmati comprises a small group of premium aromatic rice from India (and Pakistan), prized in international trade. These varieties have not so far been fully characterized physicochemically. To address this gap, all available recognized as well as unrecognized varieties/lines of basmati and its derivatives (crosses) were exhaustively studied for their physical, chemical and cooking properties over eight years.RESULTS: It was found that all five basmati land races (‘traditional’ varieties) had similar properties. They had substantial σ₁ distal end (DE) shape of brown and milled rice; good aroma; intermediate amylose (∼230 g kg⁻¹), alkali score and viscogram breakdown (BD_r); and they yielded a high elongation ratio (>1.9) and good ‘rings’ after cooking. The 23 Indian crossbred (basmati derivative) varieties/lines (plus 13 supermarket samples of Pakistani basmati) studied were different. Each of them differed in at least two or three and sometimes several of the above properties from the land races.CONCLUSION: These results provided a framework of what constituted basmati properties and a benchmark to decide how close a cross was. Additionally, the varying combinations of the observed values of the ten or more key indices enabled any of the above varieties/lines to be identified by simple physicochemical techniques. Copyright © 2008 Society of Chemical Industry