Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/7/2004
Publication Date: 4/15/2004
Citation: Vignaux, N., Doehlert, D.C., Hegstad, J., Elias, E.M., Mcmullen, M.S., Grant, L.A., Kianian, S.F. 2004. Grain quality characteristics and milling performance of full and partial waxy durum lines. Cereal Chemistry. Vol. 81(3):377-383. Interpretive Summary: One way to offer better benefits to durum wheat growers is to develop a crop with added value. Recently, durum wheat with a unique starch in its grains was developed. Instead of containing 25% of amylose and 75% of amylopectin, this wheat contains only amylopectin in its starch. This particular character is called waxy and is due to a mutation at two locations of the genome. When only one location has the mutated gene, the crop is called partial waxy durum. Both full and partial waxy wheat were tested along with normal wheat to evaluate the value of this new durum wheat. Quality characteristics of waxy durum such as field yield and protein content and strength were similar to the quality of current US cultivars. The main differences were seen in the milling for semolina. Semolina yield was lower and starch damage was higher for the waxy samples. However, this problem is expected to be limited using more adapted tempering and milling conditions. Partial waxy wheat performance was not different from the major durum wheat cultivars currently used in the US. Overall, waxy durum wheat was found suitable for application testing.
Technical Abstract: Mutation of the gene coding for the granule bound starch synthase (waxy protein) leads to reduced amylose content in cereal endosperm. Durum wheat has one waxy locus on each of its two genomes. Full waxy durum wheat is produced when both genomes carry the waxy null alleles. When only one locus is mutated, partial waxy durum wheat is obtained. Partial and full waxy near-isogenic lines of durum wheat (Triticum turgidum L. durum) developed by a breeding program were analyzed as to their quality characteristics. Amylose was largely eliminated in full waxy lines; however, no reduction in amylose content was detected in partial waxy lines. The waxy mutation did not affect grain yield, kernel size, or kernel hardness. Full waxy durum lines had higher kernel ash content, alpha amylase activity and altered color properties. Protein quality, as evaluated by sodium dodecyl sulphate (SDS) micro-sedimentation value, gluten index and wet gluten was slightly lower in the full waxy lines than in the other genotypes. However, comparisons with current cultivars indicated that protein quality of all derived lines remained in the range of strong gluten cultivars. Semolina yield was lowered by the waxy mutations due to lower friability that resulted in less precise separation of the endosperm from the bran. Waxy semolina was more sensitive to mechanical damage during milling, but modified tempering and milling conditions can possibly limit the damage. Overall, quality characteristics of waxy durum grain were satisfactory and suitable for application testing.