Encapsulation of crocin using low-molecular-weight Penicillium expansum-derived chitosan and process optimization via Taguchi orthogonal array design.

The aim of this study was to produce fungal chitosan from a potential fungus using a cost-effective substrate (sugar beet molasses) and optimize the growth conditions using Taguchi L9 orthogonal array (OA). The obtained fungal chitinous chitosan (FC) was then used for the microencapsulation of crocin. Optimal conditions were found as 120 mL/L molasses, initial pH at 6 and 5 g/L magnesium sulphate. The dried biomass was weighed as 22.7 g/L, while 8.1 g/L alkali insoluble material (AIM), 5.3 g/L FC and 2.7 g/L native chitosan (NC) were obtained. Deacetylation degree (DD) of the obtained chitosan was calculated as 80.27 and 78.81% for NC and FC, respectively. Matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS) was employed for molecular weight detection of the chitosan samples. Molecular weights were found for FC and commercial chitosan (CC) as 145 and 219 kDa, respectively. The solubility of NC and FC in 1% acetic acid was found as 84 and 78% respectively. The fungus was isolated from jujube fruit which was identified as Penicillium expansum HNP11 (GenBank Accession Number: PQ057454). To deepen the research, antimicrobial activity was carried out. The zeta potential of crocin loaded alginate-chitosan microparticles was about - 49 mV and loading capacity was found as 46%. Cytotoxicity of FC was found lower than CC at low concentrations. Consequently, P. expansum has higher antimicrobial activity and minimal toxic structure and Taguchi orthogonal array contributes economic chitosan production.