Master of Science (MS)
School of Nutrition and Food Sciences
Chitosan (CH) is a biopolymer obtained from the deacetylation of chitin, a polysaccharide present in the exoskeleton of crustaceans and cell walls of fungi. Application of CH may be limited by its water-insolubility. It can be dissolved in acids and forms relatively high viscosity solutions. CH solutions have antioxidant and antimicrobial properties. CH penetration into shrimp may be facilitated by vacuum tumbling with low viscosity chitosan-sodium tripolyphosphate (CH-TPP) nanoparticle or water-soluble chitosan (WSC) solutions. It is expected that this would reduce lipid oxidation and microbial loads. In this study, CH-TPP and WSC solutions were developed and applied to shrimp, and the quality characteristics during frozen storage were evaluated. This research was conducted in two separate studies. In the first study, four treatment solutions were prepared: (1) a 1% acetic acid (AA) solution, (2) a CH in AA solution, (3) a sodium tripolyphosphate (TPP) in AA solution, and (4) a CH-TPP in AA solution. The solutions were sonicated and then sheared in an ultra-homogenizer to reduce particle size. In the second study, WSC was produced by enzymatic hydrolysis. Two treatment solutions were prepared: (1) a 0.1 M AA solution and (2) a WSC in distilled water (DW) solution. In both studies, fresh shrimp meat was separately vacuum tumbled with the solutions, cryogenically frozen, and evaluated for quality characteristics under frozen storage. Fresh shrimp meat tumbled with DW and fresh shrimp meat without tumbling (NT) were used as controls. Shrimp treated with CH, CH-TPP, and WSC had lower aerobic plate counts (APC) compared to other treatments after 120 days of storage at -20 °C. However, only the WSC treatment decreased yeast and mold counts (YMC) in the shrimp. CH, CH-TPP, and WSC treatments could aid in retention of color, texture, and moisture content of shrimp. Additionally, CH, CH-TPP, and WSC treatments produced the highest reduction in lipid oxidation compared to other treatments. This research indicated that CH, CH-TPP, and WSC solutions, combined with vacuum tumbling, can be effective at reducing APC and lipid oxidation in shrimp during frozen storage. As WSC can be dissolved in water, it may have greater application potential in seafood than CH or CH-TPP.
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Chouljenko, Alexander, "Evaluating the Effects of Vacuum Tumbling with Chitosan Nanoparticles and Water-Soluble Chitosan on the Shelf Life of Cryogenically Frozen Shrimp" (2015). LSU Master's Theses. 2814.