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Rheology, Microstructure, and Baking Characteristics of Frozen Dough Containing Rhizopus chinensis Lipase and Transglutaminase

¹Graduate research assistant, professor, and visiting professor, respectively, The State Key Laboratory of Food Science and Technology, School of Food Science and Technology, International Exchange and Cooperation Program, Jiangnan University, Wuxi, Jiangsu 214122, China. ²Corresponding author. Tel.: +86 (510) 8591 9139. Fax: +86 (510) 8591 9139. E-mail: wnhuang@jiangnan.edu.cn ³Research scientist, Zhejiang Newland Foods Co., Hangzhou, Zhejiang 311107, China. ⁴Research chemist, U.S. Department of Agriculture (USDA), Center for Grain and Animal Health Research, Manhattan, KS. Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the USDA. USDA is an equal opportunity provider and employer.

The beneficial effects of a new recombinant lipase (Rhizopus chinensis lipase [RCL]) and transglutaminase (TG) were investigated on frozen dough systems and their breadmaking quality. Rheological properties and microstructure of doughs were measured using a dynamic rheometer, rheofermentometer F3, and scanning electron microscopy (SEM). Measurements of viscoelastic properties showed that both G′ and G″ of dough containing RCL and TG were greater than those of the control after 35 days of frozen storage. The SEM micrographs showed that dough containing RCL and TG had the most starch granules embedded in or attached to the gluten network, and the gluten seemed more powerful and resilient than for the control dough after 35 days of frozen storage. Results of the gas production and dough development tests indicated that RCL and TG improved the rheofermentative characteristics of frozen dough. RCL and TG could improve water-holding capacity and significantly increase the glycerol content of the control dough. Image analyses showed that bread crumbs containing RCL and TG had a more open network and uniform crumb structure, which resulted in higher specific volume. This combination also yielded a product with higher sensory scores for test breads.