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Chitosan nanoparticles (CSNs) have widely studied for many potential applications as a bioactive nanomaterial because of their excellent properties, such as quantum size effect, large surface area, high mobility, and high permeability. In this study, various CSNs prepared from squid pen chitosan with different molecular weight (Mw) and degree of deacetylation (DD). The lower Mw and higher DD of initial chitosan used, the smaller size of CSNs obtained. Small size CSNs (about 30 nm) are formed from the initial chitosan (Mw of 8 kDa, DD of 96%). In vitro tests, all as-prepared CSNs showed high antibacterial activity against Salmonella sp. and Staphylococcus aureus. In particular, the lowest CSNs concentration of 50 ppm, which was prepared from chitosan with a low Mw of 8 kDa and high DD of 96%, showed the highest activity. Besides, by using the similar initial chitosans, CSNs prepared from squid pens exhibit higher antibacterial activity than that one from shrimp shells. This study presents high potential applications of CSNs prepared from squid pen chitosan with small size and excellent antibacterial activity for various fields. [ABSTRACT FROM AUTHOR]

Summary: This study was performed to evaluate the efficacy and applicability of low molecular weight shrimp chitosan (LMWC) and its derivatives (chitosan nanoparticles, CN; chitosan hydrochloride salt, CHS) as a preservative against lipid oxidation and microbial growth in seasoned‐dried Pangasius hypophthalmus fillets during storage. All chitosans exhibited antioxidant activity in vitro (2,2‐diphenyl‐1‐picrylhydrazyl radical scavenging activity, total reducing power ability and lipid peroxidation inhibition activity). The lipid oxidation in dried pangasius fillets that were seasoned by immersing in a solution containing 1.5% chitosan was suppressed during the 8‐week storage; such effect was more effective than immersing in a solution containing 0.05% vitamin C. Likewise, LMWC and its derivatives were more effective in inhibiting microbial growth (lower total viable count and yeast/mould counts) than the control. These results clearly show that LMWC and its derivatives could be a potent antioxidant and antimicrobial preservative in seasoned‐dried pangasius fillets during 8‐week storage at 20 °C. [ABSTRACT FROM AUTHOR]

Abstract: The functional properties of three shrimp chitosan preparations with different degrees of deacetylation (75%, 87% and 96% DD) but with a constant molecular weight (about 810kDa) were investigated. Chitosan with 75% DD had a 1.5 times higher water absorption, probably due to its 20% lower level of crystallinity. Membranes cast from this chitosan also exhibited 1.5 times more water absorption and 2 times higher permeability. However, chitosan with 87% and 96% DD had 1.5–2 times higher absorption of fat and the orange II dye. This is attributed to the higher content of positively charged amine groups in the polymer. Cast into membrane, chitosan of higher degree of deacetylation showed a higher tensile strength and a higher elongation at break, probably due to the higher level of crystallinity. [Copyright &y& Elsevier]

In this study, pretreatment procedures have been investigated preceding the standard production of chitin and chitosan. These steps can be used in industrial processes to preserve raw shrimp shells as long as the amount of material is not enough for one production batch. After these treatments, shrimp shells are clean and are facile for further demineralization, deproteinization and deacetylation processes. The prepared chitin and chitosan show a high purity with very low ash (less than 0.3%) and protein residues (less than 0.5%), along with their high molecular weight and high crystallinity. This modified approach has potential for application in large-scale production due to its ease of operation and reduction of environmental concerns. Image 1 • The pretreatment procedure removes a disproportional high amount of waste. • After pretreatment, shrimp shells are clean and are facile for further processes. • The prepared chitin and chitosan show high purity, molecular weight and crystallinity. • This modified approach has potential for application in large-scale production. [ABSTRACT FROM AUTHOR]

Abstract In this study, low molecular weight chitosan salt (LMWC-HCl) highly soluble in water was prepared from low molecular weight chitosan (LMWC) in the solid state exposed to hydrogen chloride gas as a reagent. The effects of chitosan particle size, exposure conditions, reaction temperature and reaction time were investigated on the solubility and the molecular weight of obtained products. The formation of the chloride salt was observed after 3 h in a range of temperatures from 4 to 50 °C. The solubility of prepared LMWC-HCl was over 98% for all samples, much higher than that of the original LMWC. The average molecular weight of the LMWC-HCl was about 20–90 kDa with a quite narrow distribution and lower compared to the LMWC. LMWC-HCl and LMWC showed the same high antibacterial activity against Bacillus cereus and Vibrio parahaemolyticus. This facile and efficient process for solubilization of LMWC has potential for industrial application of chitosan. Highlights • Low molecular weight chitosan salts were prepared. • The low reaction temperature limited the degradation of chitosan. • The product showed high solubility and high antibacterial. [ABSTRACT FROM AUTHOR]

Squid pens were extracted by a NaOH solution at 80 °C for 10 h to remove protein and minerals. The as-prepared β-chitin had a high molecular weight (8.5 ± 0.1 × 10 3 kDa), a low protein content (0.63 ± 0.02 wt.%), and a negligible amount of minerals. This method avoids the conventional method for the removal of minerals from shrimp and crab shells by HCl. The purity of resulting products was measured by NMR and FTIR. Moreover, the morphology and crystallinity of β-chitin was characterized by SEM and XRD. The β-chitin with long chains and high purity is suitable for producing high quantity β-chitosan for various potential applications. [ABSTRACT FROM AUTHOR]