Protein and starch characteristics of milled rice from different cultivars affected by transplantation date.

The effects of transplantation date on milled rice (physicochemical, amino acids composition and protein profiling) of different cultivars and their starch characteristics (granules size distribution, pasting and thermal) were investigated. Head rice yield increased (2.0-4.1 %) and chalky grains (5-10 %) decreased with delaying the paddy transplantation of different cultivars by 20 days. Delayed transplantation of paddy significantly increased asparagine, glutamine, threonine, cysteine, methionine, tryptophan, lysine and proline content in milled rice. Early transplantation of paddy showed higher accumulation of glutelin and prolamines than that in milled rice from delayed transplantation. The change in amino acid composition of milled rice with delay in transplantation was related to variation in accumulation of glutelin and prolamines. Starch from delayed transplanted paddy showed higher peak viscosity and lower breakdown viscosity than those from early transplanted paddy. These differences were due to higher accumulation of amylose in starch from delayed transplanted paddy than that from early transplanted paddy due to exposure of former to lower night air temperature during starch synthesis.