Study On The Stability Of Wheat Flour In Controlled Atmosphere Storage

The study used the high-gluten wheat flour, medium-gluten strength wheat flour as theresearch object, simulated storage the materials in different temperature (15℃,25℃,35℃),under different controlled atmosphere conditions(filling nitrogen, deoxidization withdeoxidizer, vacuum pumping, control)respectively, the regular determination of all the qualityindexes during the eleven months storage period was done. The change law of the storagequality, amylase activity, starch pasting properties, dough rheological properties, cookingquality of the two kinds of wheat flours during the storage period was investigated, and theeffect of the related factors on the wheat flour quality during storage was discussed by meansof regression analysis, the results showed that:Along with the increase storing time, the fatty acid value and Δb~*of the high-glutenwheat flour and the medium-gluten wheat flour in different storage conditions increasedgradually, wet gluten content, gluten index, ΔL~*, the colony total of bacteria and mouldpresented the downward trend. The water content of the wheat flour, crude protein andcontent, dry gluten content did not change significantly during storage.With the storage of time prolonging, the falling number, peak viscosity, breakdown, finalviscosity, setback from trough of the high-gluten wheat flour and the medium-gluten wheatflour increased gradually. α-amylase activity decreased under high temperature but lowtemperature can keep the activity of α-amylase; the inhibitory effect of controlled atmospherestorage on wheat flour α-amylase activity and starch pasting properties change was betterthan the control treatment.The dough water absorption, dough development time of the high-gluten wheat flourand the medium-gluten wheat flour fall at different degree and stability time, farinographquality number and degree of softening increased after eleven months storage. The curve areaof dough tensile, the extension resistance and the extension proportion showed an increasingtendency, but the extensibility decreased. The result indicated that the dough quality of boththe wheat flour presented the downward trend.Along with the increase storing time, the score value of all indexes of quality by sensory evaluation declined gradually, the hardness of steamed bread increased gradually, butflexibility, springiness, cohesiveness and resilience in different degree. The results showedthat the edible quality of steamed bread began to decrease. Treated with controlledatmosphere compared with control have a significant effect, showed that the controlledatmosphere reduced the upgrade rate of the cooking quality indexes.Under different storage conditions, the change of storage quality of the high-glutenwheat flour is slower than the medium-gluten wheat flour, storage stability is better than themedium-gluten wheat flour.15℃was the best temperature for fresh keeping of wheat flour.Under the condition of25℃and35℃, compared with control treatment, the controlledatmosphere storage with filling nitrogen(98%), deoxidizer or vacuum could delay the changeof the storage quality changes of the high-gluten wheat flour and the medium-gluten wheatflour for about two months. Filling nitrogen(98%), deoxidizer is better than the vacuumtreatment. Low temperature (15℃) and the controlled atmosphere storage with fillingnitrogen(98%) or deoxidizer under the condition of25℃and35℃,could well maintain thestability of the quality of wheat flour and extend the storage period.