Determinants of wheat noodle color

Authors: MORRIS, CRAIG

Submitted to: Journal of the Science of Food and Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/10/2018
Publication Date: 10/1/2018
Citation: Morris, C.F. 2018. Determinants of wheat noodle color. Journal of the Science of Food and Agriculture. 98(14):5171-5180. https://doi.org/10.1002/jsfa.9134.
DOI: https://doi.org/10.1002/jsfa.9134

Interpretive Summary: Noodles are a primary wheat food in much of the world, especially East Asia. Although styles vary widely based on consumer and cultural preferences, in their basic form they are comprised of flour, water and one or more salts. Processing and post-processing culinary presentation add additional variation and nuance. In this review, the factors influencing noodle color are enumerated. Although many divisions can be made, here, two basic noodle classifications are considered: white salted noodle and alkaline noodle. This division is made on the basis of pH and whether or not alkaline salts are included in the formulation. White salted noodles are empirically sub-divided into two styles, one with a softer bite popular in Japan and South Korea, here referred to as ‘udon’, and one with a firmer bite preferred in China and further south.

Technical Abstract: Noodles are a leading food in the world, and color is a key determinant of consumer acceptance. In this review the two prominent forms of wheat noodles are considered, white salted and alkaline. Many of the preparation and evaluation strategies are the same for both, with prominence placed on ‘brightness’ or a lack of discoloration (L* or 'L*), and the absence of ‘specks’. We recognize that all raw noodles darken over time. Increasing protein content of flours almost always translates into darker noodles. Greater discoloration is also associated with higher flour extraction rates, higher ash contents and higher starch damage. There is a very large range in noodle color variation, and much of this variation is due to genetics. Consequently much research has been devoted to methods of screening germplasm, either as whole seeds, meals, flours or noodle sheets. Polyphenol oxidase (PPO) is a primary culprit in noodle discoloration and has guided much of the research on noodle color. We are now able to select germplasm with very low levels of PPO through the use of efficacious phenotype screens and the use of molecular markers. Lastly, the success of much of this research has given us with the ability to select wheat breeding lines with nil PPO activity, and combine favorable alleles at multiple PPO loci. Yet, when we make noodles, we continue to observe discoloration. As our ability to minimize PPO activity increases, this ‘non-PPO’ discoloration has become more important. Perhaps the ‘holy grail’ is a noodle that never discolors, and has the ‘perfect’ level of a* (redness, zero?) and b* (yellowness/creaminess).