67D-1 |
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T. WU and S. Zivanovic. Department of Food Science and Technology, University of Tennessee, Food Chemistry & Biophysics Labs, 2605 River Drive, Knoxville, TN 37996-4591 Agaricus bisporus is the most produced mushroom in the U.S. Waste accumulated during harvest consists of stalks, mushrooms of irregular shapes and dimensions, and compost remains. Nowadays this waste creates environmental problems due to its large volumes and volatile degradation products. However, it is rich in chitinous polymers, chitin and chitosan, which can be used in agriculture, food and pharmaceutical industries. The objectives of this research were to evaluate accumulation of chitinous compounds in mushroom stalks during storage at different temperatures and to compare physico-chemical characteristics of fungal and commercial (shrimp) products. The stalks were collected at harvest and stored at 4 and 25ºC for 15 and 5 days, respectively. Samples were taken periodically, freeze-dried, powdered, and stored in desiccator until analysis and extraction. Extraction was performed in two steps: proteins and alkali-soluble polysaccharides were removed with 1N NaOH and chitosan was extracted from alkali-insoluble solids with 2% acetic acid. Chitin remained in insoluble residue. The amount of chitinous compounds in stalks, and chitin and chitosan yields were analyzed as total glucosamine and degree of acetylation (DA) of chitin and chitosan were determined by HPLC-PDA and FTIR-ATR. The total glucosamine content in stalks increased from 7.1 %dw at day 0, to 11.0 %dw and 19.0 %dw after 15 days at 4ºC and 5 days at 25ºC, respectively. Most of the extracted chitinous material was obtained as chitin with the average yield of 11.5 %dw. The glucosamine content in alkali-insoluble residues was affected by storage time and temperature and reached 42.5% after 5 days at 25ºC. DA of fungal chitin ranged from 50% to 64% and was between the values for commercially available chitins and chitosans (85% and 15%, respectively). Our results indicate that mushroom waste can be efficiently utilized for production of fungal chitin and chitosan with unique physico-chemical characteristics.
Session 67D, Food Chemistry: Lipid and carbohydrate chemistry
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