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ARS Home » Southeast Area » New Orleans, Louisiana » Southern Regional Research Center » Food Processing and Sensory Quality Research » Research » Publications at this Location » Publication #231942
Title: Unraveling the impact of nitrogen nutrition on cooked rice flavor and texture.

Author
item Champagne, Elaine
item Bett Garber, Karen
item Thomson, Jessica
item FITZGERALD, MELISSA - INT. RICE RES. INSTIUTE

Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/19/2009
Publication Date: 5/1/2009
Citation: Champagne, E.T., Bett Garber, K.L., Thomson, J.L., Fitzgerald, M. 2009. Unraveling the impact of nitrogen nutrition on cooked rice flavor and texture. Cereal Chemistry. 86(3):274-280.

Interpretive Summary: Rice is an important provider of nourishment for the world’s population. Unlike most food crops, rice is generally eaten whole without seasoning, making the sensory properties of the rice grain itself important. Small variations in sensory properties can make rice highly desired by or unacceptable to consumers. Understanding the influences of amylose (form of starch) and protein contents on rice sensory properties is key to maintaining quality, and providing consumers with rice with desired flavor and textural attributes. This research focused on determining the effects of protein content on cooked rice texture and flavor. The sensory properties of cultivars grown in adjoining fields with differing rates of nitrogen fertilizer (to yield grains with a large spread in protein contents) were measured by a panel trained in descriptive analysis. Fertilizer level affected protein and amylose contents, and in turn, cooked rice texture. Protein contents were significantly higher, and amylose contents were significantly lower at the higher fertilizer level. As protein content increased, the intensities of initial starchy coating, slickness, and stickiness between grains decreased. Roughness, hardness, and moisture absorption increased with increase in protein content. Statistical models were developed and provide insight into how much of a change in protein content is likely required to observe textural changes in cooked rice. This data will enable the rice industry to have better control over the textural properties of the crop.

Technical Abstract: Understanding the influences of amylose and protein contents on rice sensory properties is key to maintaining quality, and providing consumers with rice with desired flavor and textural attributes. This research focused on delineating the effects of protein content on cooked rice texture and flavor. The sensory properties of cultivars grown in adjoining fields with differing rates of nitrogen fertilizer (to yield grains with a large spread in protein contents) were measured by a panel trained in descriptive analysis. Secondly, rice sensory properties were modeled using apparent amylose and protein data. Fertilizer level affected protein and amylose contents, and in turn, cooked rice texture. Protein contents were significantly higher (P < 0.0007) and apparent amylose contents were significantly lower (P < 0.0001) at the higher fertilizer level. Models revealed a negative correlation of protein content with initial starchy coating, slickness, and stickiness between grains – three attributes that are perceived when cooked rice is first introduced into the mouth. Models for roughness, hardness, and moisture absorption -- attributes representing three phases of evaluation in the mouth – showed a positive correlation with protein content. The models provide insight into how much of a change in protein content is likely required to observe textural changes in cooked rice.