Submitted to: Cereal Chemistry
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/2/2011
Publication Date: 6/20/2012
Publication URL: http://handle.nal.usda.gov/10113/58031
Citation: Lanning, S.B., Siebenmorgen, T.J., Ambardekar, A.A., Counce, P.A., Bryant, R.J. 2012. Effects of nighttime air temperature during kernel development on rice physicochemical and functional properties. Cereal Chemistry. 89(3):168-175. Interpretive Summary: High nighttime temperature (NTAT) during the grain-filling stage can affect the processing and cooking quality of rice. The objectives of this study were to provide a comprehensive and systematic design that accounted for the natural variation in environmental temperature occurring across years and locations. Therefore, six cultivars were grown at multiple field locations in Arkansas over four years (2007 to 2010). Temperature was recorded throughout the experiment at each location and during the grain filling stage. The effect of NTAT on apparent amylose, RVA profile, protein and lipid content, and gelatinization temperature were determined. The study showed that rice physicochemical and functional properties were strongly correlated with NTAT. NTAT decreased apparent amylose content, crude protein content and setback viscosity while increasing total lipid content, peak viscosity and gelatinization temperature. Since commercially grown rice is blended from a variety of cultivars, growing locations, and harvest dates, the impact of variation in processing and cooking quality due to NTAT may be difficult to predict. Minimizing the variation in grain quality may best be achieved through a multi-systems approach that includes breeding programs, production practices, and processing options.
Technical Abstract: Elevated nighttime air temperatures (NTATs) occurring during critical grain-filling stages affected rice physicochemical properties, which impacted functional quality. Six cultivars were grown at multiple field locations from northern to southern Arkansas during 2007 to 2010. Nighttime temperatures were recorded throughout production at each of the locations, and 95th percentiles of NTATs were calculated for each cultivar’s reproductive (R) stages. Amylose content and crude protein content decreased linearly, while total lipid content increased linearly, with increasing NTATs occurring during the grain-filling stages (R6-R8). Effects of NTAT on proximate composition influenced functional properties. Peak viscosities increased linearly as NTAT increased, while setback viscosities decreased. Setback viscosities were linearly correlated to NTATs for medium-grain cultivars, but correlations were quadratic for the long-grain cultivars. Gelatinization temperatures increased linearly with increasing NTAT. The R-stages in which correlations were strongest varied by cultivar and by property, hypothesized to be due to differences in kernel development patterns among cultivars. These findings have significant implications for rice production scientists and processors, in that understanding the effects of NTAT on physicochemical and functional properties may help explain and reduce quality variation.