Effects of egg yolk/egg white on the aggregation characteristics of second-grade wheat flour

Abstract

Objective: Egg yolk and egg white were added to wheat flour to provide data support for the processing and improvement of characteristic flour food. Methods: The present study aims to disclose the influence of egg yolk and white on the aggregation characteristics of gluten in wheat flour using a special gluten aggregation instrument, as well as second-grade wheat flour and eggs as materials. Moreover, the dough microstructure and starch particle size during the aggregation process were also analyzed. Results: The results showed that BEM dropped 9.5 BU （i.e., 19.39%） with 5 mL egg yolk added. However, the BEM increased by 4.08% to the peak with the addition of 3 mL egg white, indicating that egg white is helpful to the maintenance of BEM. The supplement of 2 mL egg yolk or 1 mL egg white resulted in the 18.56% decrease （to the min. value） or the 29.52% increase （to the max. value） of PMT, which suggested that yolk and white may exert the opposite effect on PMT. Interestingly, with the addition of yolk and white, the ratios of S3/total energy scaled up from 81% and 43% to 96% and 52%, respectively. Such a fact indicated that both yolk and white from egg significantly change the distribution of gluten aggregation energy. Conclusion: Taken together, yolk and white have varied roles in regulating gluten aggregation properties. To be noted, egg yolk inhibited the linking strength of the gluten network, giving rise to its breakage and a more even distribution; while egg white promoted such connection, and protected the starch particles. Our data will technically support the improvement of quality for flour-associated food.

Keywords

• the second-grade wheat flour
• egg yolk
• egg white
• peak maximum time (pmt)
• brabender equivalents maximum (bem)
• microstructure of dough