Study On The Changes Of Gluten Viscoelasticity And Control Measures Of Wheat During Storage

This study selected 3 kinds of post-harvest wheats(high- gluten Zhengmai 379,medium-gluten Aikang 58, medium-gluten Yangmai 16) as experimental materials,simulating the condition of the storage in the laboratory with two variables(the water content and the storage time) to measure the germination rate, protein content, wet gluten content, SRC value, the change of hardness, viscoelasticity and secondary structure of wheat gluten.The main conclusions of this study are as follows:1, Using the ratio value of water-soluble protein accounting for the total flour to determine wheat gluten, after verification, this method is reliable, fast and effective.There are three criterias, the GW value is less than 0.925% for low-gluten flour; when the GW value is in the range of 0.925%-1.054% for medium-gluten flour; when the GW value higher than 1.054% for high-gluten flour.2, After the moisture content of the wheat was changed, the hardness and viscoelasticity of the gluten protein were measured using TA.XTPlus.When the moisture content is 12%, the hardness of the gluten(Zhengmai 379, Aikang 58 and Yangmai 16)in the storage of 12 months was less than the hardness of 4 months,reducing 24.82%, 29%, 21.18%; elasticity reducing 6.2%, 20.7%, 19.5%, viscosity increasing by 3.98%, 20.95%, 59.26%; the water content is 15%, the hardness of the gluten(Zhengmai 379, Aikang 58 and Yangmai 16)in the storage of 12 months was less than the hardness of 4 months, reducing 27.12%, 29.79%, 27.42%; elasticity reducing 8.2%, 20.2%, 25.6%, viscosity increasing by 63.21%, 52.92%, 60.39%; the water content is 18%, the hardness of the gluten(Zhengmai 379, Aikang 58 and Yangmai 16)in the storage of 12 months was less than the hardness of 4 months,reducing 32.49 %, 36.90%, 29.51%; elasticity reducing 12.8%, 30.9%, 32.6%,viscosity increasing by 54.83%, 62.79%,24.98%,the hardness and elasticity of the gluten protein decreased and the viscosity increased during storage.The higher water content, the more obvious changes.3, After the moisture content of the wheat was changed, the secondary structure of the gluten protein were measured using Fourier transform infrared spectroscopy.When the moisture content is 12%, the content of α-helical of the gluten(Zhengmai379, Aikang 58 and Yangmai 16)in the storage of 12 months was less than the hardness of 4 months, reducing 0.28%, 10.11%, 13.52%;the content of β-turn increasing 36.58%, 77.73%, 11.97%; The α-helical / β-sheet increasing 118.07%,121.43%, 71.54%; When the moisture content is 15%, the content of α-helical of the gluten(Zhengmai 379, Aikang 58 and Yangmai 16)in the storage of 12 months was less than the hardness of 4 months, reducing 2.25%, 16.95%, 8.49%;the content ofβ-turn increasing 84.50%, 23.71%, 20.69%; The ratio of α-helical / β-sheet increasing 144.58%, 66.45%, 118.80%; When the moisture content is 18%, the content of α-helical of the gluten(Zhengmai 379, Aikang 58 and Yangmai 16)in the storage of 12 months was less than the hardness of 4 months, reducing 3.38%,12.49%, 8.79%;the content of β-turn increasing 55.35%, 5.63%, 24.08%; The ratio of α-helical / β-sheet increasing 82.17%, 13.64%, 146.47%;It shows that, the content of α-helical of the gluten protein decreased, the content of β-turn and the ratio ofα-helical / β-sheet increased during storage.4, After the moisture content of the wheat was changed, the quality of the gluten protein were changed. The results show that the germination rate of Zhengmai 379 after the storage of 4 months was 90.34%, germination rate decreased to 80.39%, 76.94%, 60.93% with the difference of the moisture content after 12months; the germination rate of Aikang 58 after the storage of 4 months was91.09%, germination rate decreased to 79.21%, 73.14%, 61.21% with the difference of the moisture content after 12 months; the germination rate of Yangmai 16 after the storage of 4 months was 89.8%, germination rate decreased to 76.42%, 72.16%,60.08% with the difference of the moisture content after 12 months; the content of wet gluten of Zhengmai 379 decreased by 4.73%, 6.76%, 13.52% with the difference of the moisture content from 4 month to 12 month; the content of wetgluten of Aikang 58 decreased by 7.39%, 8.08%, 13.61% with the difference of the moisture content from 4 month to 12 month; the content of wet gluten of Yangmai16 decreased by 6.15%, 6.42%, 9.17% with the difference of the moisture content from 4 month to 12 month; the SRC values of trace water of Zhengmai 379 after the storage of 4 months was 62.02%, the SRC values of trace water decreased to52.53%, 58.74%, 60.03% with the difference of the moisture content after 12months; the SRC values of trace water of Aikang 58 after the storage of 4 months was 61.62%, the SRC values of trace water decreased to 52.76%, 53.48%, 59.26%with the difference of the moisture content after 12 months; the SRC values of trace water of Yangmai 16 after the storage of 4 months was 65.80%, the SRC values of trace water decreased to 51.33%, 52.91%, 57.06% with the difference of the moisture content after 12 months; the SRC values of micro lactic acid of Zhengmai379 after the storage of 4 months was 64.25%, the SRC values of micro lactic acid decreased to 49.36%, 52.31%, 63.28% with the difference of the moisture content after 12 months; the SRC values of micro lactic acid of Aikang 58 after the storage of 4 months was 63.25%, the SRC values of micro lactic acid decreased to 47.88%,52.44%, 56.78% with the difference of the moisture content after 12 months; the SRC values of micro lactic acid of Yangmai 16 after the storage of 4 months was62.14%, the SRC values of micro lactic acid decreased to 49.11%, 56.62%, 65.27%with the difference of the moisture content after 12 months;The germination rate 、the content of wet gluten, the SRC value of trace water and lactic acid decreased,the total content of protein was basically unchanged.The higher water content, the more obvious changes.In summary, the quality of wheat was in the deterioration during storage of 4-12 months.The hardness and elasticitity of gluten protein decreased, viscosity increased. The most optimum moisture content was 12% for the storage of wheat.