physicochemical and functional properties of crawfish chitosan as ...

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activities, and there were marked morphological alterations in treated microorganisms when examined by electron microscopy (Muzzarelli, 1990). Conversely, growth inhibition and inactivation of mould and yeasts seem to depend on chitosan concentration, pH, and temperature (Rout, 2001). According to Cuero (1999), the antimicrobial action of chitosan is influenced by intrinsic and extrinsic factors such as the type of chitosan (e.g., plain or derivative), degree of chitosan polymerization, host nutrient constituency, substrate chemical and/ or nutrient composition, and environmental conditions such as substrate water activity. In an extensive research by Tsai and Su (1999) on the antimicrobial activity of chitosan prepared from shrimp against E.coli, they found that higher temperature and acidic pH of foods increased the bactericidal effect of chitosan. They also explained the mechanism of chitosan antibacterial action involving a cross-linkage between polycations of chitosan and the anions on the bacterial surface that changes membrane permeability. Chitosan has been approved as a food additive in Korea and Japan since 1995 and 1983, respectively (Weiner, 1992; KFDA, 1995; No, 2002). Higher antibacterial activity of chitosan at lower pH suggests that addition of chitosan to acidic foods will enhance its effectiveness as a natural preservative (No et al., 2002). Chitosan coating have been shown to significantly delay fruit spoilage or decaying of fruits and vegetables such as tomatoes, strawberries, etc., at different temperatures. Chitosan coated fruits were not only firmer and higher in titratable acidity, but were slow to decay and exhibited less pigmentation than control samples at the end of storage (El Ghaouth et al., 1992). The low molecular weight chitosan has a greater inhibitory effect against phytopathogens than the high molecular weight chitosan (Hirano et al., 1989). 16
2.2.10 Formation of Film Chitosan has an ability to form film which makes it suitable for use as food preservation for control of psychotropic pathogen in fresh/ processed meat and fish products packaged under modified atmosphere (Smith et al., 1994). According to Charles et al. (1994), the most potential application of chitosan is as a coating agent in the area of fruit preservation. The biodegradability of chitosan is one of the most advantageous features for concern of the environmental damage occurring by improper disposal of petrochemical based plastics (Knorr, 1991). N, O-carboxymethyl chitosan can form a strong film that is selectively permeable to such gases as oxygen and carbon dioxide. Apples coated with this material remain fresh for up to six months. The chitosan coating has been shown to delay ripening of banana for up to 30 days where as chitosan film manifests a slightly yellow appearance, with the color darkening as thickness increased (Setha et al., 2000). 2.3 Production of Chitin and Chitosan Chitosan as mentioned before is extracted from crustacean shell waste such as crab, shrimp, lobster, and crawfish. The shells contain approximately 30-40% protein, 30-50% calcium carbonate, and 20-30% chitin on a dry basis (Johnson and Peniston, 1982). These portions vary with crustacean species and seasons (Green and Mattick, 1979). Isolation of chitosan from crawfish shell wastes involves four traditional steps (Figure 4): demineralization (DM), deproteinization (DP), decolorization (DC), and deacetylation (DA). However, the isolation of chitin specifically consists of only two steps: demineralization (DM) and deproteinization (DP), which involves the dissolution of calcium carbonate with 1.0 N HCl and the removal of proteins with 3% NaOH, respectively. 17
Page 1 and 2: PHYSICOCHEMICAL AND FUNCTIONAL PROP
Page 3 and 4: TABLE OF CONTENTS ACKNOWLEDGEMENTS
Page 5 and 6: LIST OF TABLES 1. Applications of C
Page 7 and 8: ABSTRACT Chitosan is made from chit
Page 9 and 10: CHAPTER 1 INTRODUCTION Chitosan is
Page 11 and 12: Crawfish shell as well as crustacea
Page 13 and 14: 5. Investigate the effect of deacet
Page 15 and 16: With regards to their chemical stru
Page 17 and 18: acetic acid. The second advantage i
Page 19 and 20: lower viscosity chitosan obtained f
Page 21 and 22: not deacetylated sufficiently to be
Page 23: 2.2.8 Emulsification Even though ch
Page 27 and 28: Fortunately, the sequence of demine
Page 29 and 30: of the demineralization process. El
Page 31 and 32: 2.4 Factors Affecting Production of
Page 33 and 34: (0.841-0.177 mm) had no effect on t
Page 35 and 36: methods are those of Hackman (1954)
Page 37 and 38: degree of deacetylation, and molecu
Page 39 and 40: 2.6.3 In Medical In the study condu
Page 41 and 42: 2) DM (Demineralization) Depending
Page 43 and 44: analyze. The encapsulated sample wa
Page 45 and 46: and centrifuged at 10,000 rpm for 1
Page 47 and 48: with 0.03% Oil-Red-O biological sta
Page 49 and 50: CHAPTER 4 RESULTS AND DISCUSSION Re
Page 51 and 52: The shell was almost impossible to
Page 53 and 54: ut the values were slightly higher
Page 55 and 56: %DD values. Thus, accurate determin
Page 57 and 58: degradation of the chitosan structu
Page 59 and 60: treatment for deproteinization. In
Page 61 and 62: chitosan samples, we arbitrarily de
Page 63 and 64: Amongst the five types of oil used,
Page 65 and 66: - 0.5% chitosan solution only. Even
Page 67 and 68: showed 271 ml/g. All modified chito
Page 69 and 70: At 0.1% concentration of chitosan,
Page 71 and 72: CHAPTER 5 SUMMARY AND CONCLUSIONS T
Page 73 and 74: REFERENCES Alimuniar and Zainuddin.
Page 75 and 76:
pigment concentration in oil extrac
Page 77 and 78:
Jeon, Y.J., Shahidi, F., and Kim, S
Page 79 and 80:
Utilization of Louisiana Crawfish P
Page 81 and 82:
Ogawa, S., Decker, E., McClememts D
Page 83 and 84:
Smith, J.P. Simpson, B.K. and Morri
Page 85 and 86:
APPENDIX A. DATA OF PHYSICOCHEMICAL
Page 87 and 88:
APPENDIX 5. Degree of Deacetylation
Page 89 and 90:
Bulk density (g/ml) APPENDIX 9. Bul
Page 91 and 92:
WBC (%) 1200.0 1000.0 800.0 600.0 4
Page 93 and 94:
APPENDIX 13. Emulsion Capacity Meas
Page 95 and 96:
APPENDIX 15. Emulsion Viscosity Mea
Page 97 and 98:
APPENDIX 18. DMPCA y = 33.471x + 9.
Page 99 and 100:
APPENDIX 21. Vanson 75 y = 21.926x
Page 101 and 102:
APPENDIX C. DATA OF DEGREE OF DEACE
Page 103 and 104:
APPENDIX 27. DPMCA(control) A1655 =
Page 105 and 106:
APPENDIX D. DATA OF AMOUNTS OF OIL
Page 107:
VITA The author was born in Taegu,
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