Effects of acetylation conditions on properties of chitin nanofibers for extending the shelf life of Fresh food products

Chitin nanofibers (ChNFs) were successfully disintegrated from shrimp shell waste with the combined deacetylation reaction and mechanical disintegration. The deacetylation reaction time by NaOH varied between 0 and 480 min. With the introduction of the deacetylation treatment process, acetyl groups in chitin structures were converted to amino groups. With longer deacetylation reaction times, large quantities of amino groups in chitin molecules were observed. These amino groups were protonated to generate repulsive forces, resulting in the individualization of ChNFs using mechanical defibrillation. ChNFs deacetylated for 240 min showed spaghetti-like structures with widths of 9 nm and lengths of up to several μm; on the other hand, rod-like structured ChNFs with a mean width of 7 nm and lengths of 222 nm were obtained with the reaction time of 480 min. These ChNFs were coated on cucumbers, and these different morphologies of ChNFs affected the shelf life extension of cucumbers. These renewable ChNF coatings will help reduce food waste and the use of petroleum-based packaging.