Oxidative gelation measurement and influence on soft wheat batter viscosity and end-use quality.

Authors: Bettge, Arthur; Morris, Craig

Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/12/2007
Publication Date: 6/1/2007
Citation: Bettge, A.D., Morris, C.F. 2007. Oxidative gelation measurement and influence on soft wheat batter viscosity and end-use quality. Cereal Chemistry 84:237-242.

Interpretive Summary: Batter viscosity plays a crucial role in the end-use quality of wheat-based products such as cakes, pancakes and batter coatings (i.e. tempura batters). Viscosity controls the ability of the product to flow, which affects the diameter of pancakes, the volume of cakes and the ability of batters to be pumped during commercial processing. Viscosity is important also in retention of gas bubbles from leavening agents (i.e. baking soda and baking powder). Viscosity limits the amount of settling that occurs in batters if they are left sitting over time. Better understanding factors contributing to viscosity will lead to wheat varieties better suited for end-uses such as pancakes and batter-based products. Generally, gluten proteins have been understood to contribute to batter viscosity, but there is a large amount of variation in viscosity that remains unexplained by protein alone. This research demonstrates that non-starch carbohydrates, arabinoxylans, play an important role in contributing to viscosity, having almost as much influence on viscosity as does gluten protein. Arabinoxylans are long chains of carbohydrates (arabinose and xylose) that can chemically cross-link among themselves, and with proteins, through a process called oxidative gelation that occurs under specific conditions that can exist naturally. To better understand and study oxidative gelation, a test was developed to measure the viscosity of batters that is due to the effect of proteins and arabinoxylans, both singly and together. Results indicate that viscosity due to oxidative gelation is important to end-use quality in flours used for cookies, cakes, pancakes and batter coatings.

Technical Abstract: Viscosity is an important end-use attribute for some soft wheat flour formulations. Specifically, in formulations with minimal gluten development, such as batters (cake, pancake and doughnut) and coatings (tempura), viscosity is important to leavening gas retention and flow characteristics. Current tests for predictors of viscosity leave considerable unexplained variation. The potential for water extractable arabinoxylans to form oxidative gels through ferulic acid dimerization may represent an important component of viscosity variation. A method was developed to identify variation in viscosity due to oxidative gelation. This method, comparing viscosity of flour slurries made with water, a peroxide-peroxidase system, and a system with xylanase, indicated that two, and likely three, types of oxidative gelation were contributing to viscosity. Predicted viscosity due to inter-arabinoxylan gelation through ferulic acid dimerization, di-tyrosine formation among proteins and ferulic acid-tyrosine bond formation varied among wheat varieties. Oxidative gel formation increased batter viscosity probably due to water sequestration; this effect was correlated with reduction in sugar snap cookie spread (diameter). Results indicate that oxidative gelation is an important contributor to batter viscosity and also contributes to the quality attributes of dough systems.