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Effects of Organic Fertility Management on Physicochemical Properties and Sensory Quality of Diverse Rice Cultivars

¹USDA/ARS Southern Regional Research Center, New Orleans, LA. Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by the USDA implies no approval of the product to the exclusion of others that may also be suitable. ²Corresponding author. Fax: 504-286-4430. E-mail: etchamp@srrc.ars.usda.gov ³USDA/ARS Rice Research Unit, Beaumont, TX.

The demand for organically grown rice has increased with consumer demand for organic foods. The objective of this research was to determine whether there are physicochemical differences in organically and conventionally grown rice that contribute to flavor and texture differences, as determined by descriptive sensory analysis, an objective tool. Five diverse cultivars (four nonwaxy and one waxy) were grown at Beaumont, TX, with 100 or 50% recommended nitrogen fertilizer using conventional management or with chicken litter using organic management. Mean protein content differed significantly (P < 0.05) with fertilizer input, whereas mean apparent amylose and mineral contents (with few exceptions) did not differ. The mean protein content of each cultivar grown with the 100% N rate typically used was significantly higher (P < 0.05) than that of the cultivar grown organically or at the 50% N rate. The mean protein contents of the cultivars grown organically and at the 50% N rate did not significantly differ (P > 0.05). Slickness, which correlates negatively with protein content, was significantly higher (P < 0.05) in four of the five organically grown rice cultivars than in the same cultivars grown conventionally using the 100% N rate. There was no significant difference (P > 0.05) between the slickness of the cultivars grown organically and conventionally using the 50% N rate. Roughness and hardness, which have a weak positive correlation with protein content, also differed significantly (P < 0.05) with fertilizer input in some of the cultivars. Observed differences in pasting and cooked textural properties of cultivars grown with different fertilizer types and input were the result of differences in protein content and not organic management, per se. In addition, no differences in flavor were observed due to management method. These results demonstrate that rice grown on land that is being transitioned into organic production is not expected to have significant differences in cooking or processing quality. The organic management method resulted in reduced protein content and a change in texture that may positively affect consumer acceptance of organically grown rice in markets that prefer rice that is more slick.