Study On Factors Related To The Processing Of Traditional Corn Foods

This thesis reported the study on the processing of the corn traditional foods (including Chinese dumpling, noodles) using yellow corn as raw material, precooked corn flour, wheat gluten, Artemisia glue, and guar gum as assistant material. The effects of corn varieties characteristic such as test weight, protein content and starch pasting propriety on the quality of corn produced food. The different between dry milling and wet milling has been studied. The effects of different assistant material on the dough viscoelasticity has been measured by using Reology, RVA, Farinograph, SEM. Parameters for mixing dough like water level, temperature of adding water, mixing time and resting time has been investigated. The major results are presented below: It was showed that precooked corn flour higher than 15% raw material could make the viscoelasticity dough. The Chinese Dumpling could be prepared by adding 15% precooked corn flour, 5% wheat gluten, 0.5% Artemisia glue and 0.2% guar gum at the same time, and noodles could be prepared by adding 5% wheat gluten and 0.8% Artemisia glue. The comparison of processing quality among six corn varieties showed: tested varieties Zhongdan94o9, Nongdal 08, Nongda 80, Gaoyou298 have bright yellow color. Zhongyuandan32 has light yellow color and Nongda3I38 has gray yellow color. So it is necessary to control the color of corn in order to keep the consistence of corn processed products. The foods prepared by six varieties have significant difference. The high protein varieties demonstrated the better quality. The quality protein maize also showed better quality because its nutritive value is higher. The corn kernel is transformed into valuable foods and industrial products by two processes dry milling arid wet milling. Compared to the wet milling, the flavor corn food from dry milling is stronger, the color is deeper and the particle size can reach the same level. The best particle size for processing is 120 mesh by dry milling or 100 mesh by wet milling. The microstructure and function character of corn flour changed after extruding. Precooked corn flour was from extruding. The cold viscosity was increased from 300 cP to 850 cP by extruding. The water absorbed rate increased from 73 ml to 108.4 ml. So the adding of the precooked corn flour could increase the viscoelasticity of the dough and at the same time the maize fiavor also increased.The parameters of the dough mixing have been StUdied. The resultS showed tha theadding water for makjng Chinese dumpling was more than that for noodles. The level of waterfOr making dumpling was 60o/ofwtw), the leveI of water for making noodles was 55%.TemperatUre of adding water was room temPeratUr. The mixing time and resting time duringdumpling dough preparaion were l0 minutes each. The miking time fOr noodIe dough was l0minutes and the resting time was 0.The effects of the assistantS materiaIs on the dough viscoelasticity have been stUdied. Theorthogonal tests revealed that Artemisia gluc was in the first place in the effect on doughtoughness. And the precooked com flour was in the first place in the effect on the extensionIength. Wheat gluten was the first in the effect on the dumpling sensory judgInent value.