**Dan Xu \*, Jing Wang, Dan Ren and Xiyu Wu**

College of Food Science, Food Storage and Logistics Research Center, Southwest University, Chongqing 400700, China; darenwl@foxmail.com (J.W.); rendan0709@swu.edu.cn (D.R.); xiyu.w@163.com (X.W.)

**\*** Correspondence: xud@swu.edu.cn; Tel.: +86-23-6825-1298

Received: 8 August 2018; Accepted: 3 September 2018; Published: 7 September 2018

**Abstract:** To explore the influences of chitosan coating structure and structure changes during storage on egg preservation, eggs coated by chitosan solution for single time (CS1), two times (CS2), and three times (CS3) were prepared separately and stored with untreated eggs (CK1), eggs washed by water (CK2) and eggs treated by acetic acid solution (CK3) at 25 ◦C, 80% RH. The weight loss, Haugh unit, yolk index, albumen pH, eggshell morphologies and infrared (FTIR—Fourier Transform Infrared) spectra of all the samples were monitored. CS2 and CS3 presented the lowest weight loss, highest Haugh unit and yolk index, stabilized pH, and the highest thickness of chitosan coating layers (>2 μm) among all the groups, which extended egg shelf life for 20 days longer compared to CK1 and CK2. CS1 with very thin chitosan coating showed similar egg qualities with CK3, which are second only to CS2 and CS3. Furthermore, destructions were found on chitosan coatings during storage as revealed by the eggshell morphologies and FTIR spectra, which caused the quality deterioration of eggs. The results demonstrated that eggs with the thickest coating showed the best qualities during storage, while destructions on coating layers led to the quality drop of eggs.

**Keywords:** chitosan; coating; structural changes; egg preservation; shelf life
