Understanding the Digestion and Health Impact of Mycoprotein Based Products

Mycoprotein is a food ingredient comprising intact fungal cells, rich in protein and fibre. Clinical trials have shown that mycoprotein reduces blood lipids and increase insulin sensitivity, and the protein contained within the hyphal cells is highly bioavailable. However, the mechanisms underlying these effects are not clearly understood. This thesis aimed to investigate the simulated digestion of mycoprotein to understand its protein bioaccessibility and the impact on digestive enzymes and macronutrients involved in carbohydrate and lipid digestion. Furthermore, the release of -glucans and minor compounds (i.e., ergothioneine and phenolic acids) from the mycoprotein cell walls was investigated, as well as the colonic fermentation of mycoprotein following gastrointestinal in vitro digestion. The simulated digestion of mycoprotein showed that proteins were released from the fungal matrix and digestive enzymes such as -amylase, remained entrapped within hyphal cells by diffusing through the cell wall, which resulted in a reduced carbohydrate digestion (75% lower with 20 mg/mL of mycoprotein compared to the control; p-value < 0.001). Moreover, mycoprotein reduced lipid digestion by lowering enzymatic lipolysis (38% lower compared to the control; p-value < 0.001) and binding bile salts. Although the cell walls remained intact after gastrointestinal digestion, -glucans (56.52 ± 5.14%) were released from the cell walls (p-value < 0.01) if mycoprotein was previously cooked. Notwithstanding, the cell walls maintained their shape, and only colonic bacteria degraded its structure by fermenting its fibre and producing short-chain fatty acids. Minor compounds that could have played a role in promoting health benefits were not detected, except for ergothioneine, which deserves future research. The findings presented in this thesis describes the behaviour of mycoprotein during simulated gastrointestinal digestion and proposes biochemical mechanisms associated with physiological processes that can promote health effects. Understanding these mechanisms is essential to developing new products and strategies to improve human health