Cereal Chem. 71:494-501   |  VIEW ARTICLE


Effects of Frost Damage and Immaturity on the Quality of Durum Wheat.

J. E. Dexter, B. A. Marchylo, and V. J. Mellish. Copyright 1994 by the American Association of Cereal Chemists, Inc. 

Frost damage and immaturity were the predominant grading factors associated with the 1992 Canadian durum wheat crop. Canadian Grain Commission grain inspectors composited samples from the 1992 durum wheat harvest survey to yield a series of samples representative of the visual limits of frost damage and immaturity for each Canada Western Amber Durum (CWAD) wheat grade. The greater severity of frost damage and immaturity permitted in No. 4 CWAD and No. 5 CWAD compared to the higher quality milling grades was reflected by lower test weight and reduced kernel size. End-use quality assessment of the composites verified that the CWAD visual grade standards correctly classify Canadian durum wheat. There was a gradual decrease in milling performance and spaghetti quality from No. 1 CWAD to No. 3 CWAD. No. 4 CWAD, which is not intended for high quality pasta, exhibited significantly poorer quality, and No. 5 CWAD, which is a feed-wheat grade, was very poor. Severe frost damage and immaturity had a negative impact upon semolina milling performance due to the combined effects of low semolina yield, unacceptable speck counts, high semolina ash content, and dull semolina color. The poor refinement of semolina from severely frosted and immature durum wheat resulted in duller, browner spaghetti. However, frost damage and immaturity did not influence spaghetti cooking quality, even though a lower yield of wet gluten per unit protein and abnormal mixograph mixing properties indicated that gluten properties had been adversely affected. The proportion of gliadins to glutenins declined with increasing frost damage and immaturity, but no qualitative differences in gluten proteins were apparent.