Production of biocomposite materials from filamentous fungi grown on apple pomace

Abstract: Managing and reducing food waste has increasingly become a global problem in later years, including food waste in the form of fruit pulp from the juice and beverage production industries. Another current urgent issue is the need for a replacement of fossil fuel-based plastics with more sustainable biopolymers. Research has shown that it is possible for a cultivation of microorganisms to engage in the production of biocomposites, while grown on mediums containing fruit waste. In this study fungal biomass grown on apple pomace was observed, as well as the mechanical properties of the obtained biomass, with and without additions of apple pomace, in the form of films. For the cultivations the strain of filamentous fungi Rhizopus Delemar was used. Different types of pre-treatments to the apple pomace were performed such as enzymatic hydrolysis, heat treatment and storing it at room temperature, before filtering and using the apple pomace extract as a cultivation medium. For the enzymatic pre-treatment the enzymes experimented with were pectinase and hemicellulase. The greatest amount of soluble solid concentration in the extracted apple pomace liquid reached was 4.44%, and highest yield of the apple pomace attained was 0.67 g dry substrate/ g dry apple pomace. For the cultivation, the highest obtained concentration of the fungi was 3.91 g/L and the highest yield of the biomass was 0.10 g dry biomass/ g dry substrate. The different types of films produced were also partially treated with glycerol in order to determine whether this treatment was beneficial for the properties of the material. The films showed tensile strength ranging from 1.79 ± 0.06 to 10.37 ± 3.11 MPa, elongation between 0.65 ± 0.08 and 9.86 ± 0.42% and E-modulus at 0.12 ± 0.02 to 0.96 ± 0.07 GPa. Although growing fungi in apple pomace was achievable, the types of biocomposite materials made were discovered to be relatively brittle. However, certain traits similar to those of leather and paper were displayed.