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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 #221051
Title: Impact of pre-soaking on the flavor of cooked rice.

Author
item Champagne, Elaine
item Bett Garber, Karen
item Thomson, Jessica
item Shih, Frederick
item Lea, Jeanne
item Daigle, Kim

Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/21/2008
Publication Date: 9/1/2008
Citation: Champagne, E.T., Bett Garber, K.L., Thomson, J.L., Shih, F.F., Lea, J.M., Daigle, K.W. 2008. Impact of pre-soaking on the flavor of cooked rice. Cereal Chemistry. 85:706-710.

Interpretive Summary: Water soaking rice for 30 minutes or longer prior to cooking is traditionally practiced in Japan, Korea, and other Asian countries. When soaked, rice grains hydrate, develop cracks, and water is absorbed. Soaking facilitates uniform cooking and shortens cooking time. The present study was undertaken to determine the effects of pre-soaking on the release of volatile aroma compounds from the cooked rice. A trained descriptive sensory panel measured the intensities of the aroma compounds in cooked pre-soaked and unsoaked rice. Undesirable sewer/animal flavor significantly increased and sweet taste significantly decreased with pre-soaking for the 11 rice samples combined. The flavor of the basmati rice samples was affected the most by pre-soaking. Pre-soaking may have undesirable effects on cooked rice flavor.

Technical Abstract: Water soaking rice for 30 minutes or longer prior to cooking is traditionally practiced in Japan, Korea, and other Asian countries. When soaked, rice grains hydrate, develop cracks, and water is absorbed. Soaking facilitates uniform cooking and shortens cooking time. The cooked kernel is usually less firm. The present study was undertaken to determine the effects of pre-soaking on the flavor of cooked rice and whether flavor differences are associated with textural changes that could influence retention of the aroma compounds. Eleven samples of short, medium, and long grain milled rice representing scented and non-scented rice, and a wide range of amylose contents were presented to a descriptive sensory panel. In the rice samples combined, undesirable sewer/animal flavor significantly increased and sweet taste significantly decreased with pre-soaking for 30 min. For individual rice samples, significantly higher sewer/animal intensity was observed with pre-soaking for the 2 Basmati rice samples and one of the U.S. long grain rice samples. When pre-soaked, sweet taste was significantly lower in one of the Basmati and Jasmine rice samples, the U.S. medium grain rice, and one U.S. long grain rice. Water-like metallic was also found to be significantly higher in one of the pre-soaked Basmati samples. Pre-soaking also resulted in significant increases in combined negative flavor attributes, and significant decreases in combined positive flavor attributes for all rice samples combined. The effects of pre-soaking on texture, as measured by TPA hardness and chewiness, did not explain the observed increases in negative flavor attributes. An increase in free sulfur-containing free amino acids with pre-soaking could have resulted in an increase of their breakdown products and contributed to the increase in sewer/animal flavor. The decreases in sweet taste and combined positive flavor attributes were likely the result of masking caused by the increases in sewer/animal and combined negative flavor attributes.