| dc.description.abstract | Bleaching of durum wheat (Triticum turgidum L. ssp. durum [Desf.] Husn.) was evaluated by determining the effect of grain moisture content, temperature, and wet/dry cycles with bulk water and with high relative humidity on the hydration of durum wheat grain and their effect on some physical grain quality parameters. Low initial grain moisture, high temperature, and wet/dry cycles increased water gain. Scanning electron microscopy and light microscopy showed that the germ and ventral surface of grain were important for water absorption. A single exposure to moisture (bulk water or high relative humidity) seems to be enough to cause a decline in grain quality. The effect of the environment on pasta color was evaluated by quantifying the relative importance of environment and genotype effects on pasta color and related traits. The relationship between environmental growing conditions, pasta color and semolina quality traits was determined. The environment had the highest relative proportion of variance for pasta color and related traits. Stepwise multiple linear regression indicated that the number of days with RH ≥ 80% diminished pasta color which could be related to increased speck count in semolina, soluble brown pigment content and an increased in semolina redness. The number of days ≤ 13°C enhanced pasta yellowness and pasta color score. However, why the positive effect occurred was not clear. Milling and processing effects on pasta color were evaluated by determining the effect of milling and pasta processing on polyphenol oxidase (PPO) activity, peroxidase (POD) activity, soluble brown pigment content, and yellow pigment content. Milling caused a reduction in yellow pigment content, soluble brown pigment content, PPO activity and POD activity while pasta processing reduced yellow pigment content, and for some genotypes, increased soluble brown pigment content. Stepwise multiple linear regression indicated that yellow pigment content had a positive effect and protein content, semolina ash content, and speck count had a negative effect on pasta color. | en_US |
