Synergistic Antioxidant and Antibacterial Effects of the Combination of Chitosan from Shrimp Shells with Polyphenols from Cynara cardunculus var. scolymus (L.)

Abstract

Natural compounds are often endowed with biological properties of health, food and pharmalogical interest. Chitosan from crustacean shells and polyphenols from artichoke heart, Cynara cardunculus var. scolymus (C. scolymus), are examples of natural compounds that are preferable to chemical substances as food preservatives. The current study investigates the antioxidant and antibacterial properties of chitosan extracted from shrimp shells waste, both alone and combined with polyphenols of C. scolymus. Shrimp shells were washed, dried, ground, and the issued flour was demineralized and deproteinised to prepare chitin. Chitosan was obtained by deacetylation of chitin and then analyzed on the basis of its moisture, ash, protein, molecular weight and degree of deacetylation. The polyphenols of C. scolymus were extracted using water and methanol as solvents. Total phenolic and flavonoid contents of C. scolymus were determined using spectrophotometry. DPPH and β-carotene bleaching tests were used to assess the antioxidant activity of chitosan and C. scolymus extracts. The antibacterial activity of chitosan and C. scolymus extracts against five pathogenic strains and two beneficial strains was determined. Results have shown that chitosan extraction yield was about 5.80 ± 1.09 %, and it contains 4.43 ± 0.57, 1.32 ± 0.62 and 0.18 ± 0.04 % of moisture, ash and protein, respectively. Its molecular weight and its degree of deacetylation were about 859.48 ± 21.62 KDa and 75%, respectively. The combination of chitosan and C. scolymus extracts was more effective on DPPH radical scavenging capacity and β-carotene degradation prevention (P<0.05) than those of chitosan or C. scolymus extracts used separately. Furthermore, this combination significantly inhibits the growth of the five pathogenic bacteria. This suggests that chitosan, in association with C. scolymus polyphenols might be used to prevent food spoilage.