Effect On Whole Wheat Flour Quality With Microwave Stabilization

Ruixing 8998 was used as research materials in this study. Wheat kernel was stabilized with different tempering moisture and microwave processing time. Then whole wheat flour was obtained by grinding full grain. The influences of microwave stabilization on the enzymes activities(lipase,lipoxygenase and ?-amylase), nutritional quality(total protein content and total starch content), processing quality(the gluten characteristics, farinograp H property, pasting properties), edible quality, microstructure and volatile substances of whole wheat flour were investigated. The results were showed as follows:(1)The influences of microwave treatment on enzyme activities and storage characteristics of whole wheat flour.Microwave sensitivities: lipoxygenases > lipase > ?-amylase. Microwave prolonged the the storage time of whole wheat flour. With the extension of microwave processing time, enzyme activities all declined. After tempering(20%) and microwave treatment(60s), lipoxygenases activities fell from 1.95 u to 0.17 u, lipase activities dropped to 0 u from15.7 u, and falling number rose from 280 s to 409 s. After 4 week-storage under 35 ?, fatty acid value of the sample with 60 s microwave treatment rose from 32 mg KOH/100 g to 66 mg KOH/100 g, while fatty acid value of the sample without microwaving rose from 47 mg KOH/100 g to 124 mg KOH/100 g.(2) The influence of microwave treatment on nutritional quality and processing quality.of whole wheat flourMicrowave had no effect on total protein content and total starch content. Microwave treatment affected the gluten content, sedimentation value, and farinograp H property obviously, and the gluten was damaged more than 30 s microwave treatment. With the extension of microwave processing time, among pasting properties index, through viscosity, peak viscosity, and final viscosity increased, while break down declined, and the shear resistance and thermal stability reduced. Pasting temperature and setback value were not affected by the treatment.(3) The effect of microwave treatment on edible quality of whole wheat flour.Wheat pretreated by microwave with time ranging from 0s to 20 s showed no effect onthe steaming bread quality, while pretreated by microwave more than 20 s showed obvious effects. With microwave treatment ranging from 0s to 40 s, the whole wheat short biscuit got good results in the sensory evaluation and texture characteristic, such as uniform texture, good color and taste. With the increasing of the microwave processing time, the quality of short biscuits tasted good from 0s to 40 s. When the microwave processing time was more than 50 s, the taste was also good, and hardness and toughness decreased significantly, fracturability increased, while the flavor declined.(4) Microwave treatment on the microstructure of the wheat kernel.When microwave treatment time was shorter than 20 s, the effect on wheat kernel can not be observed. When treating time was more than 30 s, the endosperm microstructure and germ cell ultrastructure suffered substantial deterioration. The starch granule in the endosperm was damanged, germ cell vacuolation degeneration, liposome ruptured and agminated, mitochondrial crista structure disappeared.(5) Microwave treatment on the volatile components of whole wheat flourAlong with the microwave treat time, the total contents of the high threshold of volatile substances such as the total contents of alkanes first decreased, then increased, and then decreased, the total contents of alcohol first decreased and then increased. The total contents of low threshold volatile components such as aldehydes had no obvious change, acids and esters decreased, so that the flavor of whole wheat flour declined.