14 | Bashir et al. RESEARCH PAPER OPEN ACCESS Effects of shrimp chitosan on shelf life extension of orange Abdullah Al Bashir 1 , M Khorshed Alam 2 , M Mahbood Hossain Khan 1 , M Alam Morshed *1, 3 , Mirza Golam Sarwar 1 1 Department of Biotechnology and Genetic Engineering, Islamic University, Kushtia-7003, Bangladesh 2 Microbiology and Industrial Irradiation Division, Institute of Food & Radiation Biology, Bangladesh Atomic Energy Commission, Savar, Dhaka, Bangladesh 3 Department of Biochemistry and Cell Biology, Bangladesh Institute of Health Sciences (BIHS), Darus Salam, Dhaka-1216, Bangladesh Received: 11 May 2011 Revised: 24 May 2011 Accepted: 25 May 2011 Key words: Chitin, chitosan, degree of deacetylation (dd), orange, shelf-life. Abstract Chitin and chitosan are being used in the preservation of fruits as a natural preservative. This study was conducted to extend the shelf-life of orange using chitosan. Initial molecular weight of chitosan was 1.6 X 10 6 Da which was reduced to 2.7 X 10 4 Da through stepwise pretreatments using alkali, acid and H2O2. and at this level, the degree of deacetylation (DD) was 70%. Chemical treatments deproteinated and decalcified the chitin. Chitosan, the deacetylated form of chitin, was dissolved in lactic acid and then irradiated to deacetylate molecular weight for using in the preservation of orange. To conduct the experiment, seven different strains of bacteria were isolated from spoiled orange and it was found that chitosan was more effective to inhibit the growth of these bacteria. During preservation, non-irradiated orange coated with 500 ppm chitosan both in polythene bag and not in polythene bag showed shelf-life extension up to a certain time. On the other hand, the irradiated orange, coated with 500ppm solution of chitosan both in polythene bag and not in polythene bag showed an extended shelf-life up to 12 – 20 days, which were better than the non-irradiated orange. *Corresponding Author: M Morshedul Alam  morshedbt@gmail.com International Journal of Biosciences (IJB) ISSN: 2220-6655 (Print) 2222-5234 (Online) Vol. 1, No. 3, p. 14-19, 2011 http://www.innspub.net