Sterilization treatments on polysaccharides: Effects and side effects on pectin

Thermal and irradiation treatments represent techniques used for a wide range of materials intended for different applications in the food and medical industry aimed to decontamination and sterilization of different technologic processes. Traditional treatments with vapor combined with pressure, reactive gases, and radiation can be used for sterilization of medical implants and to prevent food deterioration. On the other side, these treatments can be employed to obtain a controlled distribution of molecular weight of polymers, as reported by literature. Pectin, as many polysaccharides, may be susceptible to side effects and modifications caused by the sterilization treatments. In this perspective, physico-chemical and biological properties of pectin powders and solutions were investigated after sterilization. Traditional methods, i.e., ethylene oxide, gamma irradiation and moist heat sterilization, were compared and their effects on pectin structure were evaluated. Results indicate that each sterilization procedure affected pectin powders and solutions, resulting in a decrease of viscosity, molecular weight and rheological properties with respect of non-sterilized samples. For sterilized powders properties were better retained than for sterilized solutions, being EtO the optimal method for pectin powders and gamma rays, especially at low doses, for pectin solutions, independently of their structure and initial degree of esterification. Moist heat sterilization was found to significantly depolymerize pectin chains in solution, with the production of cytotoxic residues.