Antibacterial activities of six acid-soluble [two degrees of deacetylation (DD) · three viscosities] and two water-soluble chitosans (two DD with similar viscosities) were examined against eight gram-negative (Pseudomonas fluorescens, Proteus vulgaris, Erwinia carotovora, Serratia marcescens, Escherichia coli, Vibrio parahaemolyticus, V. vulnificus, and Salmonella Typhimurium) and six gram-positive bacteria (Listeria monocytogenes, Staphylococcus aureus, Bacillus subtilis, B. cereus, Lactobacillus curvatus, and L. plantarum). Antibacterial activities of chitosans differed depending on the chitosan types and bacteria tested. Watersoluble chitosans inhibited bacterial growth by one to eight log cycles at 0.1% concentration; however, the effects were much lesser than those observed with 0.05% acid-soluble chitosans. Minimum inhibitory concentration (MIC) values (0.03% to above 0.1%) of acid-soluble chitosans were much lower than those (0.05% to above 0.8%) of water-soluble chitosans. Based on MIC values, the acid-soluble chitosan with 99% DD and lower viscosity (17.9 mPa s) was most effective in inhibiting bacteria growth among eight chitosans tested.

Effects of chitosan coating and storage positions (small-end down, small-end up or horizontal) on internal quality and shelf life of eggs were evaluated during 5 weeks of storage at 25°C. Compared with noncoated eggs, all chitosan-coated eggs, irrespective of storage positions, had significantly lesser weight loss, higher Haugh units and higher yolk index throughout the storage. Chitosan coating, irrespective of storage positions, extended the egg shelf life by at least 3 weeks at 25°C compared with noncoated eggs. Noncoated and chitosan-coated eggs placed small-end down tentatively showed better quality than eggs placed smallend up after 3 and 4 weeks of storage. After 5 weeks of storage, storage positions did not significantly affect quality of noncoated and chitosan-coated eggs. There were no notable differences in total amino acid content of the albumen and fatty acid composition of the yolk between noncoated and chitosan-coated eggs after 5 weeks of storage.

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Summary Squid (Todarodes pacifica) pen was an excellent source of β‐chitin with 25.5% yield. The optimal condition to prepare squid pen β‐chitin was established: deproteinisation with 3% NaOH for 30 min at 15 psi/121 °C and a solid/solvent ratio of 1:10 (w/v) and a subsequent demineralisation with 1 N HCl for 30 min at room temperature and a solid/solvent ratio of 1:10 (w/v). Squid pen β‐chitin contained 6.29% nitrogen, 0.25% ash, and negligible fat with degree of acetylation of 94.02%, residual amino acid of 0.499 g/100 g and bulk density of 0.28 g mL−1. Depending on its particle size, squid pen β‐chitin visually looked white (L* = 82.82, a* = −0.67, b* = 6.31; particle size of 0.15–0.18 mm) or light grey (L* = 62.88, a* = 0.33, b* = 10.66; particle size of 0.425–0.841 mm). Water, fat and dye‐binding capacity of squid pen β‐chitin was 694.67%, 194.03% and 79.81%, respectively.

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