No abstract

No abstract

In some wheat growing countries, considerable quantities of commercial wheat are rendered unusable in standard milling because of pre-harvest damage of the grain by protease-injecting insects. The possibility of mitigating the detrimental effects of bug damage by eliminating the mill streams of lower quality from straight run flour was investigated. The changes in the amount of damaged kernels by cleaning and washing prior to milling were also examined. Dry cleaning decreased the level of insect damage from 26.4% to 23.0%. A further improvement to 12.8% was obtained by removing the light-density bug-damaged kernels by washing. There were substantial differences among the mill streams of the commercial mill as evaluated by the standard and modified sedimentation tests and standard alveograph test. The best streams were those from the first, second, third and fourth reductions.

Cereal Chem. 84(3):290-293In this study, a practical spectrophotometric approach was used to determine the hydroperoxidation activity of durum wheat lipoxygenase (LOX). As stated in the related literature, the buffered linoleic acid solution used as the reaction medium is not optically clear enough at neutral and lower pH values due to its limited solubility. In our study, the optical clarity was obtained by the formation of sodium-salt of unreacted linoleic acid just before absorbance measurement. The durum wheat LOX was characterized in terms of pH and temperature optima as well as kinetic parameters. The maximum linoleic acid hydroperoxidation activ-ities were determined at pH 5.0 and 6.5 and at 40°C This result can be considered as evidence for the presence of at least two LOX isoforms with respective optima at pH 5.0 and 6.5 in the crude durum wheat extract. The Michaelis constant (K m ) and maximum hydroperoxidation activity rate (V max ) of durum wheat LOX for linoleic acid were estimated to be 0.131 ± 0.019 mM and 42.37 ± 3.32 units/mg of protein/min, respectively. The method seems to be useful for the determination of LOX activity in durum wheat and its milling fractions.

No abstract