Effect of Tempering Condition on Milling Performance and Flour Functionality

Authors: KWEON, MEERA; MARTIN, RONALD; SOUZA, EDWARD

Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/11/2008
Publication Date: 1/15/2009
Citation: Kweon, M., Martin, R.J., Souza, E.J. 2009. Effect of Tempering Condition on Milling Performance and Flour Functionality. Cereal Chemistry. 86(1):12-17.

Interpretive Summary: Four screening factors (initial wheat moisture, tempered wheat moisture, tempering temperature, and tempering time) were used for exploring the effect of tempering condition on milling characteristic and flour functionality for three SRW cultivars. The most critical factor to all responses was tempered wheat moisture, and the milling performance and flour functionality were different in the cultivars. Flour yield for the wheat tempered at high moisture (15%) was lower than that for the wheat tempered at low moisture (12%), but flour quality of the former was better with decreased flour ash and PPO activity. Lactic acid SRC values were higher for the milled flour tempered at high moisture, suggested the better separation of mellowed endosperm from toughened bran, and higher gluten strength. Although each cultivar responded differently by tempering condition, and their optimum tempering conditions would be different, milling industries cannot temper differently depending on wheat cultivars because the idea is not practical. Using correct tempered wheat moisture for tempering would be reasonable and practical. In our study, only hard strong and soft weak cultivars have been used, and cultivar selection was not complete because the complete category of genetic x environment are hard weak, hard strong, soft weak and soft strong. For future study, the optimum tempering condition with complete cultivar selection could be explored.

Technical Abstract: Tempering conditions of wheat grain change the quality of the flour; yet most experimental milling systems use a standard tempering without optimization. The effect of tempering condition on milling performance and flour functionality for three SRW cultivars ('Roane', 'Cyrus', and 'Severn') was tested by measuring changes in flour yield, ash, polyphenol oxidase (PPO), and solvent retention capacity (SRC). Tempering was conducted with a full factorial design of initial wheat moisture, tempered wheat moisture, tempering temperature, and tempering time at two levels. Tempered wheat moisture had the largest effect on milling performance and flour functionality. Roane and Cyrus were similar in most responses to treatments except for SE and water SRC, while Severn differed from Roane and Cyrus in the effect of treatments on milling performance and flour functionality. Flour yield was lower on all samples tempered at high moisture (15%), flour quality had lower bran contamination, as measured by flour ash and PPO. Higher lactic acid SRC and lower sodium carbonate SRC for the samples tempered at high moisture suggested that correct tempering results in better endosperm separation from toughened bran, and obtains better flour.