Comparison of the physicochemical, rheological, and morphologic properties of chitosan from four insects

The present work aimed to compare the physicochemical, rheological, and morphologic properties of chitosan extracted from cicada slough, silkworm chrysalis, mealworm, grasshopper and shrimp shells. The physicochemical properties including solubility, fat binding capacity, water binding capacity, ash, viscosity average molecular weight and moisture content of them were determined. The characterization results showed that insect chitosan was quite different from shrimp shell chitosan including thermal stability, rheological characteristics and surface morphology. Crystallinity index values of chitosan from cicada slough, silkworm chrysalis, mealworm, grasshopper and shrimp shells were observed to be 64.8%, 32.9%, 51.9%, 50.1% and 49.1%, respectively. The crystallinity indices of shrimp shell, mealworm and grasshopper chitosan were very close to each other. Flow behavior revealed that chitosan from four insects exhibited the lower viscosity than shrimp shell chitosan. According to dynamic oscillatory analysis, insect chitosan revealed lower modulus values than shrimp shell chitosan. Each of them had a novel structure and different morphologic properties. These results will contribute to increasing potential application of insect chitosan in food and pharmaceutical industries.