Effect of different doses of nitrogen on protein profiling, pasting and quality attributes of rice from different cultivars

Abstract

Effect of different level (60, 120 and 180 kg N/ha) of nitrogen (N) application on protein profiling, pasting and cooking quality characteristics of milled rice from different paddy cultivars was evaluated. N dose showed positive correlation with protein content and negative correlation with L*, whiteness and amylose content. N application significantly affected the protein profile, textural and pasting properties of different cultivars. All the cultivars expect PR120 and PAU201, showed an increase in the amount of accumulation of 60 kDa polypeptide with increase in N application. Accumulation of prolamines (16 and 14 kDa) and polypeptides of 38 and 35 kDa increased in all the cultivars. Size exclusion chromatography revealed decrease in low molecular weight subunits and increase in medium molecular weight subunits in all the cultivars upon N application. However, high molecular weight subunits increased in IET21214 and decreased in PR120 and PAU20 upon N application. N application resulted in increase in glutelins and decrease in peak and breakdown viscosity. PAU201 and PR120 showed lower AAC due to low accumulation of 60 kDa granule-bound starch synthase (GBSS), in response to N application. Gumminess and hardness of cooked rice increased with the increase in N dose and the increase was significant at 60 kg N/ha.

Effects of Nitrogen Rates on the Physicochemical Properties of Waxy Maize Starch

“…Excessive N topdressing at the early stage reduced pasting viscosities . The reduction in the PV, TV, and FV of rice and buckwheat under high N rates might be attributed to changes in amylose and amylopectin ratio, amylopectin chain length, starch granule size, and crystal structure. However, starch granule size and amylopectin chain length distribution did not affect PV and BD in this study.…”

Effect of agronomic management on rice grain quality Part I: A review of Australian practices

“…It is interesting to note that protein content in the 150N treatment in Perez et al. (1996) study was ~1% higher than the control which is a large enough increase to elicit a change in cooked rice texture (Kaur et al., 2016).…”

“…Although increases in N rate generally improve grain strength during milling, extensive N rates increase grain protein content to such an extent it reduces milled grain appearance and cooking and eating quality (Champagne et al., 2007). Increasing N rate has been shown to decrease grain brightness and increase yellowness, reducing milled grain appearance (Kaur et al., 2016). Some prior reports (Ata‐Ul‐Karim et al., 2017; Gunaratne et al., 2011; Perez et al., 1996) suggest amylose content decreases as protein content increases while others have observed no significant interaction between protein content and amylose content (Champagne et al., 2007).…”

“…During the wet season, Kaur et al. (2016) found a greater accumulation of amylose in delayed sown rice which they attributed to lower night air temperatures during starch synthesis.…”

“…(2017) reported the effect of temperature stress on individual protein fractions differed between cultivars. The effect of N application on amylose content also varies between cultivars (Kaur et al., 2016). Changes to both protein and amylose content will affect the pasting and thermal properties of rice, as previously discussed.…”