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

Authors: Champagne, Elaine; Bett Garber, Karen; Grimm, Casey; McClung, Anna

Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/22/2007
Publication Date: 6/24/2007
Citation: Champagne, E.T., Bett Garber, K.L., Mcclung, A.M., Grimm, C.C. 2007. Effects of organic fertility management on physicochemical properties and sensory quality of diverse rice cultivars. Cereal Chemistry. 84(4):320-327.

Interpretive Summary: The demand for organically-grown rice has increased with consumer demand for organic foods. Organic rice is perceived by the consumer to be safer, fresher, healthier, and taste better than conventionally-grown rice. Perception of differences in flavor and texture between cooked, organically- and conventionally-grown rice could be influenced by preference. This poses the question as to what extent there is a scientific basis for the claims that organic rice tastes better. Are there compositional differences in organically- and conventionally-grown rice that contribute to flavor and texture differences? The objective of this research was to determine if there are compositional differences in organically- and conventionally-grown rice that contribute to flavor and texture differences, as determined by a sensory panel. Protein contents of rice grown with 50% of the recommended nitrogen fertilizer rate and organically were the same and lower than those of rice grown with 100% of the recommended nitrogen fertilizer rate. Starch and mineral contents did not differ. Slickness of the cooked rice, which is influenced by protein content, was higher in the organically-grown rice and in that grown with 50% of the recommended nitrogen fertilizer level than in that grown with 100% of the recommended nitrogen fertilizer rate. Protein content, and not organic management, affected the texture of the rice. Flavor was not affected by management method. This research provides information needed by industry in the marketing of conventionally-grown and organically-grown rice.

Technical Abstract: The demand for organically-grown rice has increased with consumer demand for organic foods. The objective of this research was to determine if 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 (4 non-waxy and 1 waxy) were grown at Beaumont, Texas 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 level and type; whereas mean apparent amylose and mineral contents (with few exceptions) did not differ. The mean protein content of each cultivar grown with the typically-used 100% N rate 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 observed to be significantly higher (P < 0.05) in the organically-grown rice cultivars (with one exception) 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 are reported to have a weak, positive correlation with protein content, were the only other textural attributes that differed significantly (P < 0.05) with fertilizer type and input. Observed differences in pasting and cooked textural properties of cultivars grown with differing fertilizer type and input were concluded to have been a result of differences in protein content. Organic management, per se, did not influence the properties. Flavor did not differ with treatment.