Application of Chitosan as a Natural Antimicrobial and Antioxidant Agent for Extension Shelf Life of Meat
Chitosan is the deacetylation derivative of chitin, which is the second most abundant polysaccharide found in nature after cellulose and commonly found in the shells and exoskeletons of crustacean, which are available in large quantities as waste products and by products of the shellfish industry. The present study described the effectiveness of different concentrations of chitosan solutions (0.25%, 0.5% , 1%) as a preservative on some quality characteristics of meat, as microbiological quality, lipid stability and organoleptic characteristic during 10 days of refrigerated storage. The microbiological quality and shelf life of meat treated with different concentrations of chitosan (0.25%, 0.5% and 1%).was investigated. The meat were evaluated for microbiological counts (total bacterial count, total psychotropic bacteria and total coliform bacteria) on 1, 7 and 10 days of storage. Microbial counts increased gradually (p≤ 0.05) in all samples during storage but the rate of increase was lower in 0.5% and 1% chitosan dipped samples with the mean value 7.12±0.16 , 6.79±0.29 respectively compared with control samples . There is a significantly decrease (p≤ 0.05) in the total psychotropic count with a long lag phase from the beginning of the storage period, the meat samples dipping in 0.5%,1% chitosan decreased significantly (p ≤ 0.05) up to 10 days of storage and reached 6.63±0.07 CFU/g and 5.60±0.06 CFU/g respectively. In addition, the rate of coliform proliferation was generally slower than that of the control samples, reached 4.75±0.09 and 4.61±0.13 CFU / g respectively there was a decrease bacterial contamination of meat samples dipping in 0.25% chitosan but this decrease was not significantly difference (p≤ 0.05) after 10 day of storage. There were significant differences (p≤0.05) among the samples preserved in chitosan 0.5%, 1% in TBARS value 0.44±0.02, 0.36±0.01 compared with those of the control sample 1.49±0.05 after 10 days of storage. The pH values of the control samples were found to increase (P ≤ 0.05) at the end of the storage period while samples which treatments with chitosan 0.5% ,1% inhibited the increase in pH during the storage period which caused the pH to reach a level of only 6.38±0.10, 5.98±0.03 compared with that measured for the control 6.92±0.04. The last part of present study was an attempt to know the effect of chitosan on organoleptic characteristic, all chitosan treated samples (0.5%, 1%) received good sensory attributes than the control samples, which after 7 days became unacceptable. Higher microbial counts and lipid oxidation in samples without chitosan treatment might be the reason for their early spoilage. While meat samples treated with chitosan had a better sensory appearance and showed highly improvement of organoleptic characteristics