Chitosan Nanoparticle Penetration into Shrimp Muscle and its Effects on the Microbial Quality

Chitosan (CH) and chitosan-sodium tripolyphosphate (CH-TPP) solutions were produced with and without sonication and ultra-shearing. The CH and CH-TPP particles and solutions were evaluated for physicochemical properties, and fluorescently labeled particle penetration into shrimp muscle tissue through vacuum tumbling was observed. Two solutions were prepared: (1) a 0.5 % CH solution in 1 % acetic acid and (2) a CH-TPP solution, prepared by adding 0.167 % sodium tripolyphosphate to the CH solution, instantly forming CH-TPP nanoparticles through ionotropic gelation. Untreated shrimp meat and shrimp meat vacuum tumbled with CH, CH-TPP, acetic acid, sodium tripolyphosphate, and distilled water solutions were analyzed for aerobic plate counts for 24 days of refrigerated storage at 4 A degrees C. Processing with sonication and ultra-shearing reduced the particle sizes of CH and CH-TPP nanoparticles and the molecular weight of CH. It was observed that after processing, fluorescently labeled CH and CH-TPP nanoparticles could penetrate inside of and attach to shrimp muscle tissues through vacuum tumbling. At 24 days of refrigerated storage, shrimp vacuum tumbled with processed CH solution had the lowest aerobic plate counts of all treatments and it was the only treatment to have unchanged microbial quality throughout the entire storage time. Vacuum tumbling with sonicated and ultra-sheared CH solution enhanced particle penetration into shrimp and inhibited microbial growth during refrigerated storage.