Vol.:(0123456789) 1 3 Bioprocess and Biosystems Engineering https://doi.org/10.1007/s00449-020-02441-2 RESEARCH PAPER Key parameters optimization of chitosan production from Aspergillus terreus using apple waste extract as sole carbon source Alireza Habibi 1  · Salar Karami 2  · Kambiz Varmira 3  · Malihe Hadadi 1 Received: 25 January 2020 / Accepted: 7 September 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020 Abstract Chitosan is commonly obtained from shrimp and crab shell chitin by deacetylation; however, such supplies appear limitation. An alternative source of chitosan is cell wall in certain fungi. In this study, chitosan production through submerged fermenta- tion of Aspergillus terreus on apple waste extract as sole carbon source was investigated. Monod equation with a maximum specific growth rate of 0.083 h −1 and half-saturation constant of 6.67 w/v% was best described the kinetic of growth. Results of response surface methodology showed the highest chitosan to substrate yield of 49.32 mg g substrate −1 , chitosan to fungal biomass yield of 140.9 mg g cell −1 , and fungal biomass to substrate yield of 0.387 g cell g substrate −1 were simultaneously obtained at temperature 30.0 °C, initial pH 5.98, and ammonium nitrate concentration 5.0 g L −1 . The chitosan produced at the optimum condition was characterized by FTIR, TGA, and DSC analysis, and degree of deacetylation was 88.2%. Graphic abstract Keywords Fungal chitosan · Aspergillus terreus · Fruit residue · Process optimization Introduction Chitosan is a linear polysaccharide composed of randomly distributed β-(1–4)-linked D-glucosamine β-(1 → 4)-linked D-glucosamine (deacetylated unit) and N-acetyl-D-glu- cosamine (acetylated unit) [1]. Chitosan has widespread application in food [ 2, 3], paper [ 4], pharmaceutical industries [5–7], and as well as in agriculture [5–8] and * Alireza Habibi a.habibi@razi.ac.ir 1 Faculty of Petroleum and Chemical Engineering, Razi University, Kermanshah, Iran 2 Department of Chemical Engineering, Kermanshah Branch, Islamic Azad University, Kermanshah, Iran 3 Research Center of Oils and Fats, Kermanshah University of Medical Sciences, Kermanshah, Iran