ANTIMICROBIAL AND ANTIOXIDANT PROPERTIES OF CHITOSAN by PALLAVI CHHABRA (Under the direction of Dr. Yao-wen Huang) ABSTRACT The effect of chitosan as coatings for evaluating the antimicrobial and antioxidant effects

Inhibition and inactivation of Staphylococcus aureus, the pathogen involved inthe post-contamination of oysters, was studied using chitosan. Raw oysters were coatedwith 0, 0.5, 1.0, and 2.0% chitosan, dissolved in 0.5% hydrochloric acid with pH adjustedto 5.6 using 1N NaOH. Oysters without coating were used as the control. All samples were stored at 4 °C for 12-15 days. The outgrowth of the bacterium was observed with and without the pre-enrichment of samples (incubation at 35 °C for 24 hr). After pre-enrichment, the growth of S. aureus cells was inhibited by all treatments on day 15, dueto the drastic fall in the pH of the oyster homogenates. Thus, the effectiveness of chitosanagainst S. aureus was not very clear after pre-enrichment. Similarly, the growth inhibitionof S. aureus by chitosan was studied without pre-enrichment of samples. For this, thestorage time was reduced to 12 days. Cells were most sensitive to chitosan at 2.0%concentration, followed by 0.5% and 1.0%. Hence, 2.0% chitosan emerged as the besttreatment for the inhibition and inactivation of S. aureus in raw oysters. It was concludedthat chitosan may have potential for use as an antimicrobial agent.