Valorisation of ovine cheese whey through PHA production

The ovine dairy supply chain plays an important role in Mediterranean economic systems and is experiencing a much needed phase of development and innovation looking beyond traditional dairy products. The same attention to innovation has not yet been applied to the management of the effluents produced during milk processing. Cheese whey is the main biowaste produced by cheese production and, at present, few, partial and sometimes unprofitable options for its proper management are available. Environmentally-sound management of residues should be based preferably on valorisation through the recovery of high added value products and energy. In this framework, cheese whey fermentation and further conversion of the obtained organic acids to biopolymers like polyhydroxyalkanoates (PHA) appear to be extremely interesting. In the present study, PHA production from ovine cheese whey (oCW) through a 3-step process (fermentation, biomass selection and PHA accumulation process) was investigated. Different pH values were adopted during fermentation and no external nutrients were supplied at any step of the process. Results showed that the bioconversion of oCW into PHA is a promising valorisation approach. The operating pH values adopted during the fermentation step were found to affect polymer composition and storage yield, whilst the biomass selection step was positively affected by some oCW peculiar characteristics, such as the high protein content.