Preparation And Application Of Ice Structuring Protein In Chinese Frozen Doughs

Both the method of isolation of ice structuring protein from Ligustrum lucidum and the application of raw ice structuring protein in Chinese frozen dough were studied in this paper.A raw ice structuring protein from Ligustrum lucidum was achieved by using heat-treating after smashing. The raw protein, containing a molecular weight of 66 kDa, have the thermal hysteresis activity (THA) identified by DSC, and the THA value of the raw protein was approximately 0.269 when the raw protein concentration was 10 mg/ml.Both microscope and rheofermentometer experiments are applied to research the effect of ice structuring protein on the antifreezing property of compressed yeast, and the results showed that: Compare to control sample, both Trehalose and ice structuring protein effectively improved the antifreezing property of compressed yeast. Adding same amount, raw ice structuring protein is much better than trehalose for a long frozen storage.The thermo-mechanical indexes of dough, which detected using mixolab, showed that the raw ice structuring protein could increase the developing time of dough from 1.48min to 2.38min, the stability time of dough from 4.84min to 5min, the stability of steaming from 0.95 to 0.97, and decrease the speed of starch gelatinization from 0.573 to 0.232. The results of Dynamic Rheometer experiments showed that: adding raw ice structuring protein can increase storage modulus G'and loss modulus G''of frozen dough, indicated the network of frozen dough was improved by raw ice structuring protein. SEM pictures indicated that raw ice structuring protein could protect the microstructure of frozen dough effectively: For the control dough, the gluten was completed destroyed and the starch granules were seperated after 8 weeks frozen storage, while gluten network could also be seen in the dough added with raw ice structuring protein at 0.5% level. Appllying frozen dough technique on steamed bread and baozi for researching the effect of raw ice structuring protein on texture property of frozen dough: Between the frozen storage of 15 days, the springiness and cohesiveness of all steamed bread samples were decreased, but the sample adding raw ice structuring protein was better than the control sample in the same frozen storage. And raw ice structuring protein could improve the specific volume of frozen baozi made by frozen dough pre-fermentation effectively. After 4 weeks, the specific volume of control decreased from 3.00ml/g to 2.45ml/g, and the specific volume of adding raw ice structuring protein decreased from 3.08ml/g to 2.81ml/g, which is caused by ice structuring protein that could enhance the antifreezing property of compressed yeast and gluten to improve the gassing property of yeast and holding property of gluten.