Produzione di micoproteine quali sostituti della carne: sviluppo di un protocollo per l'estrazione delle proteine dal micelio e loro quantificazione

Due to the raising awareness about sustainability and the need of feeding the rapidly growing world population, much effort is being paid on searching alternative food sources as well as on developing food processes and products with a low environmental impact, with the goal to answer both to the climate change threats and the challenge of pursuing new food systems. The food sector constitutes one of the largest contributors to both local and global environmental impact and resource use. According to recent reports, it is estimated that not less than 70% of the water footprint caused by human activities is associated with the agricultural activity. At the same time, approximately 18% of the total greenhouse gases derived as a side product of the agricultural sector (30%) has been ascribed to the production of meat. Reducing the consumption of meat by replacing it with the so-called “meat substitutes” or “meat analogues” is a way to pursue a sustainable and healthier diet. Protein-rich food made of filamentous fungal biomass, i.e. mycoprotein, have a high protein and fiber content and are low in fats and carbohydrates, display the same nutritional benefits of meat, and can be thus consumed as an alternative to it. Moreover, mycoprotein has been designated as GRAS (Generally Regarded As Safe) by the Food and Drug Administration (FDA) in the US since 2002. This thesis has been carried out at Mycorena (Sweden), a biotechnology company that produces fungi-based protein for human nutrition by fermentation. The workflow of this project involved two main goals: on one hand, the optimization of the fermentation process by modulation of the cultivation medium. The results of this activity could not be described in this thesis for confidentiality reasons (patent pending). On the other hand, a protocol for extraction of proteins from mycelium and their quantification was developed with the aim to have a fast, reliable and cheap method to assess protein content in biomass samples and, after a scale-up, to recover proteins for the formulation of high-protein drinks and beverages. After growing the biomass, the harvest was filtered, and the mycelium collected was used as starting material for protein extraction after being freeze-dried and grinded into a fine powder. Techniques tested for protein extraction included chemical and enzymatic treatments, heating, and freeze-thawing, used either individually or in combination. Protein quantification, performed by the bicinchoninic acid method, afforded a generally scarce protein recovery if compared with the benchmark value (50% w/w of the dry biomass) assessed by elemental analysis (nitrogen content). The combination of a chemical pre-treatment and a detergent-based cell lysis protocol resulted to be statistically reliable and suitable for the goal laid out.