Effect of molecular weight, type of chitosan, and chitosan solution pH on the shelf-life and quality of coated eggs.

Effects of the molecular weight and type of chitosans and pH of chitosan solution on antibacterial activity against Salmonella enterica Enteritidis and on internal quality of chitosan-coated eggs were evaluated during 4 wk of storage at 25 degrees C. Two types of chitosans were studied: alpha-chitosans with 4 different molecular weights (Mw = 282, 440, 746, and 1110 kDa) and beta-chitosan (Mw = 577 kDa). The alpha-chitosan with 282 kDa exhibited stronger bactericidal effects than did other alpha- and beta-chitosans. The weight loss, Haugh unit, and yolk index values suggested that coating of eggs with alpha-chitosan with 282 kDa increased the shelf-life of eggs by almost 3 wk at 25 degrees C compared with noncoated eggs. The pH (4.5, 5.0, and 5.5) of the alpha-chitosan (282 kDa) solution did not affect the internal quality of chitosan-coated eggs. Therefore, coating of eggs with 282 kDa alpha-chitosan without pH adjustment (initial pH of 4.5) may offer a protective barrier against contamination of S. Enteritidis while simultaneously preserving the internal quality of eggs.